1896 lines
80 KiB
C
1896 lines
80 KiB
C
/**
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* Copyright (c) 2014-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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#include <assert.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "CSSLayout-internal.h"
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#ifdef _MSC_VER
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#include <float.h>
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#define isnan _isnan
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/* define fmaxf if < VC12 */
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#if _MSC_VER < 1800
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__forceinline const float fmaxf(const float a, const float b) {
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return (a > b) ? a : b;
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}
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#endif
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#endif
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#define POSITIVE_FLEX_IS_AUTO 0
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CSSNodeRef CSSNodeNew() {
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CSSNode* node = (CSSNode*)calloc(1, sizeof(*node));
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CSSNodeInit(node);
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return node;
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}
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void CSSNodeFree(CSSNodeRef node) {
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free(node);
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}
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void CSSNodeInit(CSSNodeRef node) {
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node->style.alignItems = CSSAlignStretch;
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node->style.alignContent = CSSAlignFlexStart;
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node->style.direction = CSSDirectionInherit;
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node->style.flexDirection = CSSFlexDirectionColumn;
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node->style.overflow = CSSOverflowVisible;
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// Some of the fields default to undefined and not 0
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node->style.dimensions[CSSDimensionWidth] = CSSUndefined;
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node->style.dimensions[CSSDimensionHeight] = CSSUndefined;
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node->style.minDimensions[CSSDimensionWidth] = CSSUndefined;
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node->style.minDimensions[CSSDimensionHeight] = CSSUndefined;
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node->style.maxDimensions[CSSDimensionWidth] = CSSUndefined;
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node->style.maxDimensions[CSSDimensionHeight] = CSSUndefined;
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node->style.position[CSSPositionLeft] = CSSUndefined;
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node->style.position[CSSPositionTop] = CSSUndefined;
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node->style.position[CSSPositionRight] = CSSUndefined;
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node->style.position[CSSPositionBottom] = CSSUndefined;
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node->style.margin[CSSPositionStart] = CSSUndefined;
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node->style.margin[CSSPositionEnd] = CSSUndefined;
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node->style.padding[CSSPositionStart] = CSSUndefined;
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node->style.padding[CSSPositionEnd] = CSSUndefined;
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node->style.border[CSSPositionStart] = CSSUndefined;
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node->style.border[CSSPositionEnd] = CSSUndefined;
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node->layout.dimensions[CSSDimensionWidth] = CSSUndefined;
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node->layout.dimensions[CSSDimensionHeight] = CSSUndefined;
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// Such that the comparison is always going to be false
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node->layout.lastParentDirection = (CSSDirection)-1;
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node->shouldUpdate = true;
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node->layout.nextCachedMeasurementsIndex = 0;
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node->layout.measuredDimensions[CSSDimensionWidth] = CSSUndefined;
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node->layout.measuredDimensions[CSSDimensionHeight] = CSSUndefined;
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node->layout.cached_layout.widthMeasureMode = (CSSMeasureMode)-1;
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node->layout.cached_layout.heightMeasureMode = (CSSMeasureMode)-1;
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}
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#define CSS_NODE_PROPERTY_IMPL(type, name, paramName, instanceName) \
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void CSSNodeSet##name(CSSNodeRef node, type paramName) { \
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node->instanceName = paramName;\
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} \
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\
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type CSSNodeGet##name(CSSNodeRef node) { \
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return node->instanceName;\
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} \
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#define CSS_NODE_STYLE_PROPERTY_IMPL(type, name, paramName, instanceName) \
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void CSSNodeStyleSet##name(CSSNodeRef node, type paramName) { \
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node->style.instanceName = paramName;\
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} \
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\
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type CSSNodeStyleGet##name(CSSNodeRef node) { \
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return node->style.instanceName;\
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} \
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#define CSS_NODE_LAYOUT_PROPERTY_IMPL(type, name, instanceName) \
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type CSSNodeLayoutGet##name(CSSNodeRef node) { \
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return node->layout.instanceName;\
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} \
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CSS_NODE_PROPERTY_IMPL(void*, Context, context, context);
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CSS_NODE_PROPERTY_IMPL(int, ChildCount, childCount, childCount);
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CSS_NODE_PROPERTY_IMPL(CSSMeasureFunc, MeasureFunc, measureFunc, measure);
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CSS_NODE_PROPERTY_IMPL(CSSChildFunc, ChildFunc, childFunc, getChild);
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CSS_NODE_PROPERTY_IMPL(CSSIsDirtyFunc, IsDirtyFunc, isDirtyFunc, isDirty);
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CSS_NODE_PROPERTY_IMPL(CSSPrintFunc, PrintFunc, printFunc, print);
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CSS_NODE_PROPERTY_IMPL(bool, IsTextnode, isTextNode, isTextNode);
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CSS_NODE_PROPERTY_IMPL(bool, ShouldUpdate, shouldUpdate, shouldUpdate);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSDirection, Direction, direction, direction);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSFlexDirection, FlexDirection, flexDirection, flexDirection);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSJustify, JustifyContent, justifyContent, justifyContent);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSAlign, AlignContent, alignContent, alignContent);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSAlign, AlignItems, alignItems, alignItems);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSAlign, AlignSelf, alignSelf, alignSelf);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSPositionType, PositionType, positionType, positionType);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSWrapType, FlexWrap, flexWrap, flexWrap);
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CSS_NODE_STYLE_PROPERTY_IMPL(CSSOverflow, Overflow, overflow, overflow);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, Flex, flex, flex);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PositionLeft, positionLeft, position[CSSPositionLeft]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PositionTop, positionTop, position[CSSPositionTop]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PositionRight, positionRight, position[CSSPositionRight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PositionBottom, positionBottom, position[CSSPositionBottom]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginLeft, marginLeft, margin[CSSPositionLeft]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginTop, marginTop, margin[CSSPositionTop]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginRight, marginRight, margin[CSSPositionRight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginBottom, marginBottom, margin[CSSPositionBottom]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginStart, marginStart, margin[CSSPositionStart]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MarginEnd, marginEnd, margin[CSSPositionEnd]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingLeft, paddingLeft, padding[CSSPositionLeft]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingTop, paddingTop, padding[CSSPositionTop]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingRight, paddingRight, padding[CSSPositionRight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingBottom, paddingBottom, padding[CSSPositionBottom]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingStart, paddingStart, padding[CSSPositionStart]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, PaddingEnd, paddingEnd, padding[CSSPositionEnd]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderLeft, borderLeft, border[CSSPositionLeft]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderTop, borderTop, border[CSSPositionTop]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderRight, borderRight, border[CSSPositionRight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderBottom, borderBottom, border[CSSPositionBottom]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderStart, borderStart, border[CSSPositionStart]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, BorderEnd, BorderEnd, border[CSSPositionEnd]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, Width, width, dimensions[CSSDimensionWidth]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, Height, height, dimensions[CSSDimensionHeight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MinWidth, minWidth, minDimensions[CSSDimensionWidth]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MinHeight, minHeight, minDimensions[CSSDimensionHeight]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MaxWidth, maxWidth, maxDimensions[CSSDimensionWidth]);
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CSS_NODE_STYLE_PROPERTY_IMPL(float, MaxHeight, maxHeight, maxDimensions[CSSDimensionHeight]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Left, position[CSSPositionLeft]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Top, position[CSSPositionTop]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Right, position[CSSPositionRight]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Bottom, position[CSSPositionBottom]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Width, dimensions[CSSDimensionWidth]);
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CSS_NODE_LAYOUT_PROPERTY_IMPL(float, Height, dimensions[CSSDimensionHeight]);
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int gCurrentGenerationCount = 0;
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bool layoutNodeInternal(CSSNode* node, float availableWidth, float availableHeight, CSSDirection parentDirection,
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CSSMeasureMode widthMeasureMode, CSSMeasureMode heightMeasureMode, bool performLayout, char* reason);
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bool isUndefined(float value) {
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return isnan(value);
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}
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static bool eq(float a, float b) {
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if (isUndefined(a)) {
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return isUndefined(b);
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}
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return fabs(a - b) < 0.0001;
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}
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static void indent(int n) {
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for (int i = 0; i < n; ++i) {
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printf(" ");
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}
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}
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static void print_number_0(const char* str, float number) {
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if (!eq(number, 0)) {
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printf("%s: %g, ", str, number);
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}
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}
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static void print_number_nan(const char* str, float number) {
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if (!isnan(number)) {
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printf("%s: %g, ", str, number);
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}
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}
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static bool four_equal(float four[4]) {
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return
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eq(four[0], four[1]) &&
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eq(four[0], four[2]) &&
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eq(four[0], four[3]);
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}
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static void print_css_node_rec(
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CSSNode* node,
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CSSPrintOptions options,
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int level
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) {
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indent(level);
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printf("{");
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if (node->print) {
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node->print(node->context);
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}
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if (options & CSSPrintOptionsLayout) {
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printf("layout: {");
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printf("width: %g, ", node->layout.dimensions[CSSDimensionWidth]);
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printf("height: %g, ", node->layout.dimensions[CSSDimensionHeight]);
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printf("top: %g, ", node->layout.position[CSSPositionTop]);
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printf("left: %g", node->layout.position[CSSPositionLeft]);
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printf("}, ");
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}
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if (options & CSSPrintOptionsStyle) {
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if (node->style.flexDirection == CSSFlexDirectionColumn) {
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printf("flexDirection: 'column', ");
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} else if (node->style.flexDirection == CSSFlexDirectionColumnReverse) {
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printf("flexDirection: 'column-reverse', ");
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} else if (node->style.flexDirection == CSSFlexDirectionRow) {
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printf("flexDirection: 'row', ");
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} else if (node->style.flexDirection == CSSFlexDirectionRowReverse) {
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printf("flexDirection: 'row-reverse', ");
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}
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if (node->style.justifyContent == CSSJustifyCenter) {
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printf("justifyContent: 'center', ");
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} else if (node->style.justifyContent == CSSJustifyFlexEnd) {
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printf("justifyContent: 'flex-end', ");
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} else if (node->style.justifyContent == CSSJustifySpaceAround) {
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printf("justifyContent: 'space-around', ");
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} else if (node->style.justifyContent == CSSJustifySpaceBetween) {
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printf("justifyContent: 'space-between', ");
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}
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if (node->style.alignItems == CSSAlignCenter) {
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printf("alignItems: 'center', ");
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} else if (node->style.alignItems == CSSAlignFlexEnd) {
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printf("alignItems: 'flex-end', ");
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} else if (node->style.alignItems == CSSAlignStretch) {
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printf("alignItems: 'stretch', ");
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}
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if (node->style.alignContent == CSSAlignCenter) {
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printf("alignContent: 'center', ");
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} else if (node->style.alignContent == CSSAlignFlexEnd) {
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printf("alignContent: 'flex-end', ");
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} else if (node->style.alignContent == CSSAlignStretch) {
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printf("alignContent: 'stretch', ");
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}
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if (node->style.alignSelf == CSSAlignFlexStart) {
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printf("alignSelf: 'flex-start', ");
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} else if (node->style.alignSelf == CSSAlignCenter) {
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printf("alignSelf: 'center', ");
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} else if (node->style.alignSelf == CSSAlignFlexEnd) {
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printf("alignSelf: 'flex-end', ");
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} else if (node->style.alignSelf == CSSAlignStretch) {
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printf("alignSelf: 'stretch', ");
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}
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print_number_nan("flex", node->style.flex);
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if (node->style.overflow == CSSOverflowHidden) {
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printf("overflow: 'hidden', ");
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} else if (node->style.overflow == CSSOverflowVisible) {
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printf("overflow: 'visible', ");
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}
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if (four_equal(node->style.margin)) {
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print_number_0("margin", node->style.margin[CSSPositionLeft]);
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} else {
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print_number_0("marginLeft", node->style.margin[CSSPositionLeft]);
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print_number_0("marginRight", node->style.margin[CSSPositionRight]);
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print_number_0("marginTop", node->style.margin[CSSPositionTop]);
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print_number_0("marginBottom", node->style.margin[CSSPositionBottom]);
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print_number_0("marginStart", node->style.margin[CSSPositionStart]);
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print_number_0("marginEnd", node->style.margin[CSSPositionEnd]);
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}
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if (four_equal(node->style.padding)) {
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print_number_0("padding", node->style.padding[CSSPositionLeft]);
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} else {
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print_number_0("paddingLeft", node->style.padding[CSSPositionLeft]);
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print_number_0("paddingRight", node->style.padding[CSSPositionRight]);
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print_number_0("paddingTop", node->style.padding[CSSPositionTop]);
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print_number_0("paddingBottom", node->style.padding[CSSPositionBottom]);
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print_number_0("paddingStart", node->style.padding[CSSPositionStart]);
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print_number_0("paddingEnd", node->style.padding[CSSPositionEnd]);
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}
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if (four_equal(node->style.border)) {
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print_number_0("borderWidth", node->style.border[CSSPositionLeft]);
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} else {
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print_number_0("borderLeftWidth", node->style.border[CSSPositionLeft]);
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print_number_0("borderRightWidth", node->style.border[CSSPositionRight]);
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print_number_0("borderTopWidth", node->style.border[CSSPositionTop]);
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print_number_0("borderBottomWidth", node->style.border[CSSPositionBottom]);
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print_number_0("borderStartWidth", node->style.border[CSSPositionStart]);
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print_number_0("borderEndWidth", node->style.border[CSSPositionEnd]);
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}
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print_number_nan("width", node->style.dimensions[CSSDimensionWidth]);
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print_number_nan("height", node->style.dimensions[CSSDimensionHeight]);
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print_number_nan("maxWidth", node->style.maxDimensions[CSSDimensionWidth]);
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print_number_nan("maxHeight", node->style.maxDimensions[CSSDimensionHeight]);
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print_number_nan("minWidth", node->style.minDimensions[CSSDimensionWidth]);
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print_number_nan("minHeight", node->style.minDimensions[CSSDimensionHeight]);
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if (node->style.positionType == CSSPositionTypeAbsolute) {
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printf("position: 'absolute', ");
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}
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print_number_nan("left", node->style.position[CSSPositionLeft]);
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print_number_nan("right", node->style.position[CSSPositionRight]);
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print_number_nan("top", node->style.position[CSSPositionTop]);
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print_number_nan("bottom", node->style.position[CSSPositionBottom]);
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}
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if (options & CSSPrintOptionsChildren && node->childCount > 0) {
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printf("children: [\n");
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for (int i = 0; i < node->childCount; ++i) {
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print_css_node_rec(node->getChild(node->context, i), options, level + 1);
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}
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indent(level);
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printf("]},\n");
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} else {
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printf("},\n");
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}
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}
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void CSSNodePrint(CSSNode* node, CSSPrintOptions options) {
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print_css_node_rec(node, options, 0);
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}
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static CSSPosition leading[4] = {
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/* CSSFlexDirectionColumn = */ CSSPositionTop,
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/* CSSFlexDirectionColumnReverse = */ CSSPositionBottom,
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/* CSSFlexDirectionRow = */ CSSPositionLeft,
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/* CSSFlexDirectionRowReverse = */ CSSPositionRight
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};
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static CSSPosition trailing[4] = {
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/* CSSFlexDirectionColumn = */ CSSPositionBottom,
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/* CSSFlexDirectionColumnReverse = */ CSSPositionTop,
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/* CSSFlexDirectionRow = */ CSSPositionRight,
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/* CSSFlexDirectionRowReverse = */ CSSPositionLeft
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};
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static CSSPosition pos[4] = {
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/* CSSFlexDirectionColumn = */ CSSPositionTop,
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/* CSSFlexDirectionColumnReverse = */ CSSPositionBottom,
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/* CSSFlexDirectionRow = */ CSSPositionLeft,
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/* CSSFlexDirectionRowReverse = */ CSSPositionRight
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};
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static CSSDimension dim[4] = {
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/* CSSFlexDirectionColumn = */ CSSDimensionHeight,
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/* CSSFlexDirectionColumnReverse = */ CSSDimensionHeight,
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/* CSSFlexDirectionRow = */ CSSDimensionWidth,
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/* CSSFlexDirectionRowReverse = */ CSSDimensionWidth
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};
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static bool isRowDirection(CSSFlexDirection flexDirection) {
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return flexDirection == CSSFlexDirectionRow ||
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flexDirection == CSSFlexDirectionRowReverse;
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}
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static bool isColumnDirection(CSSFlexDirection flexDirection) {
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return flexDirection == CSSFlexDirectionColumn ||
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flexDirection == CSSFlexDirectionColumnReverse;
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}
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static bool isFlexBasisAuto(CSSNode* node) {
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#if POSITIVE_FLEX_IS_AUTO
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// All flex values are auto.
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(void) node;
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return true;
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#else
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// A flex value > 0 implies a basis of zero.
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return node->style.flex <= 0;
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#endif
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}
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static float getFlexGrowFactor(CSSNode* node) {
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// Flex grow is implied by positive values for flex.
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if (node->style.flex > 0) {
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return node->style.flex;
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}
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return 0;
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}
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static float getFlexShrinkFactor(CSSNode* node) {
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#if POSITIVE_FLEX_IS_AUTO
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// A flex shrink factor of 1 is implied by non-zero values for flex.
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if (node->style.flex != 0) {
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return 1;
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}
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#else
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// A flex shrink factor of 1 is implied by negative values for flex.
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if (node->style.flex < 0) {
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return 1;
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}
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#endif
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return 0;
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}
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static float getLeadingMargin(CSSNode* node, CSSFlexDirection axis) {
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if (isRowDirection(axis) && !isUndefined(node->style.margin[CSSPositionStart])) {
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return node->style.margin[CSSPositionStart];
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}
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return node->style.margin[leading[axis]];
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}
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static float getTrailingMargin(CSSNode* node, CSSFlexDirection axis) {
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if (isRowDirection(axis) && !isUndefined(node->style.margin[CSSPositionEnd])) {
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return node->style.margin[CSSPositionEnd];
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}
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return node->style.margin[trailing[axis]];
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}
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static float getLeadingPadding(CSSNode* node, CSSFlexDirection axis) {
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if (isRowDirection(axis) &&
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!isUndefined(node->style.padding[CSSPositionStart]) &&
|
|
node->style.padding[CSSPositionStart] >= 0) {
|
|
return node->style.padding[CSSPositionStart];
|
|
}
|
|
|
|
if (node->style.padding[leading[axis]] >= 0) {
|
|
return node->style.padding[leading[axis]];
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static float getTrailingPadding(CSSNode* node, CSSFlexDirection axis) {
|
|
if (isRowDirection(axis) &&
|
|
!isUndefined(node->style.padding[CSSPositionEnd]) &&
|
|
node->style.padding[CSSPositionEnd] >= 0) {
|
|
return node->style.padding[CSSPositionEnd];
|
|
}
|
|
|
|
if (node->style.padding[trailing[axis]] >= 0) {
|
|
return node->style.padding[trailing[axis]];
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static float getLeadingBorder(CSSNode* node, CSSFlexDirection axis) {
|
|
if (isRowDirection(axis) &&
|
|
!isUndefined(node->style.border[CSSPositionStart]) &&
|
|
node->style.border[CSSPositionStart] >= 0) {
|
|
return node->style.border[CSSPositionStart];
|
|
}
|
|
|
|
if (node->style.border[leading[axis]] >= 0) {
|
|
return node->style.border[leading[axis]];
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static float getTrailingBorder(CSSNode* node, CSSFlexDirection axis) {
|
|
if (isRowDirection(axis) &&
|
|
!isUndefined(node->style.border[CSSPositionEnd]) &&
|
|
node->style.border[CSSPositionEnd] >= 0) {
|
|
return node->style.border[CSSPositionEnd];
|
|
}
|
|
|
|
if (node->style.border[trailing[axis]] >= 0) {
|
|
return node->style.border[trailing[axis]];
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static float getLeadingPaddingAndBorder(CSSNode* node, CSSFlexDirection axis) {
|
|
return getLeadingPadding(node, axis) + getLeadingBorder(node, axis);
|
|
}
|
|
|
|
static float getTrailingPaddingAndBorder(CSSNode* node, CSSFlexDirection axis) {
|
|
return getTrailingPadding(node, axis) + getTrailingBorder(node, axis);
|
|
}
|
|
|
|
static float getMarginAxis(CSSNode* node, CSSFlexDirection axis) {
|
|
return getLeadingMargin(node, axis) + getTrailingMargin(node, axis);
|
|
}
|
|
|
|
static float getPaddingAndBorderAxis(CSSNode* node, CSSFlexDirection axis) {
|
|
return getLeadingPaddingAndBorder(node, axis) + getTrailingPaddingAndBorder(node, axis);
|
|
}
|
|
|
|
static CSSAlign getAlignItem(CSSNode* node, CSSNode* child) {
|
|
if (child->style.alignSelf != CSSAlignAuto) {
|
|
return child->style.alignSelf;
|
|
}
|
|
return node->style.alignItems;
|
|
}
|
|
|
|
static CSSDirection resolveDirection(CSSNode* node, CSSDirection parentDirection) {
|
|
CSSDirection direction = node->style.direction;
|
|
|
|
if (direction == CSSDirectionInherit) {
|
|
direction = parentDirection > CSSDirectionInherit ? parentDirection : CSSDirectionLTR;
|
|
}
|
|
|
|
return direction;
|
|
}
|
|
|
|
static CSSFlexDirection getFlexDirection(CSSNode* node) {
|
|
return node->style.flexDirection;
|
|
}
|
|
|
|
static CSSFlexDirection resolveAxis(CSSFlexDirection flexDirection, CSSDirection direction) {
|
|
if (direction == CSSDirectionRTL) {
|
|
if (flexDirection == CSSFlexDirectionRow) {
|
|
return CSSFlexDirectionRowReverse;
|
|
} else if (flexDirection == CSSFlexDirectionRowReverse) {
|
|
return CSSFlexDirectionRow;
|
|
}
|
|
}
|
|
|
|
return flexDirection;
|
|
}
|
|
|
|
static CSSFlexDirection getCrossFlexDirection(CSSFlexDirection flexDirection, CSSDirection direction) {
|
|
if (isColumnDirection(flexDirection)) {
|
|
return resolveAxis(CSSFlexDirectionRow, direction);
|
|
} else {
|
|
return CSSFlexDirectionColumn;
|
|
}
|
|
}
|
|
|
|
static float getFlex(CSSNode* node) {
|
|
return node->style.flex;
|
|
}
|
|
|
|
static bool isFlex(CSSNode* node) {
|
|
return (
|
|
node->style.positionType == CSSPositionTypeRelative &&
|
|
getFlex(node) != 0
|
|
);
|
|
}
|
|
|
|
static bool isFlexWrap(CSSNode* node) {
|
|
return node->style.flexWrap == CSSWrapTypeWrap;
|
|
}
|
|
|
|
static float getDimWithMargin(CSSNode* node, CSSFlexDirection axis) {
|
|
return node->layout.measuredDimensions[dim[axis]] +
|
|
getLeadingMargin(node, axis) +
|
|
getTrailingMargin(node, axis);
|
|
}
|
|
|
|
static bool isStyleDimDefined(CSSNode* node, CSSFlexDirection axis) {
|
|
float value = node->style.dimensions[dim[axis]];
|
|
return !isUndefined(value) && value >= 0.0;
|
|
}
|
|
|
|
static bool isLayoutDimDefined(CSSNode* node, CSSFlexDirection axis) {
|
|
float value = node->layout.measuredDimensions[dim[axis]];
|
|
return !isUndefined(value) && value >= 0.0;
|
|
}
|
|
|
|
static bool isPosDefined(CSSNode* node, CSSPosition position) {
|
|
return !isUndefined(node->style.position[position]);
|
|
}
|
|
|
|
static bool isMeasureDefined(CSSNode* node) {
|
|
return node->measure;
|
|
}
|
|
|
|
static float getPosition(CSSNode* node, CSSPosition position) {
|
|
float result = node->style.position[position];
|
|
if (!isUndefined(result)) {
|
|
return result;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static float boundAxisWithinMinAndMax(CSSNode* node, CSSFlexDirection axis, float value) {
|
|
float min = CSSUndefined;
|
|
float max = CSSUndefined;
|
|
|
|
if (isColumnDirection(axis)) {
|
|
min = node->style.minDimensions[CSSDimensionHeight];
|
|
max = node->style.maxDimensions[CSSDimensionHeight];
|
|
} else if (isRowDirection(axis)) {
|
|
min = node->style.minDimensions[CSSDimensionWidth];
|
|
max = node->style.maxDimensions[CSSDimensionWidth];
|
|
}
|
|
|
|
float boundValue = value;
|
|
|
|
if (!isUndefined(max) && max >= 0.0 && boundValue > max) {
|
|
boundValue = max;
|
|
}
|
|
if (!isUndefined(min) && min >= 0.0 && boundValue < min) {
|
|
boundValue = min;
|
|
}
|
|
|
|
return boundValue;
|
|
}
|
|
|
|
// Like boundAxisWithinMinAndMax but also ensures that the value doesn't go below the
|
|
// padding and border amount.
|
|
static float boundAxis(CSSNode* node, CSSFlexDirection axis, float value) {
|
|
return fmaxf(boundAxisWithinMinAndMax(node, axis, value), getPaddingAndBorderAxis(node, axis));
|
|
}
|
|
|
|
static void setTrailingPosition(CSSNode* node, CSSNode* child, CSSFlexDirection axis) {
|
|
float size = child->style.positionType == CSSPositionTypeAbsolute ?
|
|
0 :
|
|
child->layout.measuredDimensions[dim[axis]];
|
|
child->layout.position[trailing[axis]] = node->layout.measuredDimensions[dim[axis]] - size - child->layout.position[pos[axis]];
|
|
}
|
|
|
|
// If both left and right are defined, then use left. Otherwise return
|
|
// +left or -right depending on which is defined.
|
|
static float getRelativePosition(CSSNode* node, CSSFlexDirection axis) {
|
|
float lead = node->style.position[leading[axis]];
|
|
if (!isUndefined(lead)) {
|
|
return lead;
|
|
}
|
|
return -getPosition(node, trailing[axis]);
|
|
}
|
|
|
|
static void setPosition(CSSNode* node, CSSDirection direction) {
|
|
CSSFlexDirection mainAxis = resolveAxis(getFlexDirection(node), direction);
|
|
CSSFlexDirection crossAxis = getCrossFlexDirection(mainAxis, direction);
|
|
|
|
node->layout.position[leading[mainAxis]] = getLeadingMargin(node, mainAxis) +
|
|
getRelativePosition(node, mainAxis);
|
|
node->layout.position[trailing[mainAxis]] = getTrailingMargin(node, mainAxis) +
|
|
getRelativePosition(node, mainAxis);
|
|
node->layout.position[leading[crossAxis]] = getLeadingMargin(node, crossAxis) +
|
|
getRelativePosition(node, crossAxis);
|
|
node->layout.position[trailing[crossAxis]] = getTrailingMargin(node, crossAxis) +
|
|
getRelativePosition(node, crossAxis);
|
|
}
|
|
|
|
//
|
|
// This is the main routine that implements a subset of the flexbox layout algorithm
|
|
// described in the W3C CSS documentation: https://www.w3.org/TR/css3-flexbox/.
|
|
//
|
|
// Limitations of this algorithm, compared to the full standard:
|
|
// * Display property is always assumed to be 'flex' except for Text nodes, which
|
|
// are assumed to be 'inline-flex'.
|
|
// * The 'zIndex' property (or any form of z ordering) is not supported. Nodes are
|
|
// stacked in document order.
|
|
// * The 'order' property is not supported. The order of flex items is always defined
|
|
// by document order.
|
|
// * The 'visibility' property is always assumed to be 'visible'. Values of 'collapse'
|
|
// and 'hidden' are not supported.
|
|
// * The 'wrap' property supports only 'nowrap' (which is the default) or 'wrap'. The
|
|
// rarely-used 'wrap-reverse' is not supported.
|
|
// * Rather than allowing arbitrary combinations of flexGrow, flexShrink and
|
|
// flexBasis, this algorithm supports only the three most common combinations:
|
|
// flex: 0 is equiavlent to flex: 0 0 auto
|
|
// flex: n (where n is a positive value) is equivalent to flex: n 1 auto
|
|
// If POSITIVE_FLEX_IS_AUTO is 0, then it is equivalent to flex: n 0 0
|
|
// This is faster because the content doesn't need to be measured, but it's
|
|
// less flexible because the basis is always 0 and can't be overriden with
|
|
// the width/height attributes.
|
|
// flex: -1 (or any negative value) is equivalent to flex: 0 1 auto
|
|
// * Margins cannot be specified as 'auto'. They must be specified in terms of pixel
|
|
// values, and the default value is 0.
|
|
// * The 'baseline' value is not supported for alignItems and alignSelf properties.
|
|
// * Values of width, maxWidth, minWidth, height, maxHeight and minHeight must be
|
|
// specified as pixel values, not as percentages.
|
|
// * There is no support for calculation of dimensions based on intrinsic aspect ratios
|
|
// (e.g. images).
|
|
// * There is no support for forced breaks.
|
|
// * It does not support vertical inline directions (top-to-bottom or bottom-to-top text).
|
|
//
|
|
// Deviations from standard:
|
|
// * Section 4.5 of the spec indicates that all flex items have a default minimum
|
|
// main size. For text blocks, for example, this is the width of the widest word.
|
|
// Calculating the minimum width is expensive, so we forego it and assume a default
|
|
// minimum main size of 0.
|
|
// * Min/Max sizes in the main axis are not honored when resolving flexible lengths.
|
|
// * The spec indicates that the default value for 'flexDirection' is 'row', but
|
|
// the algorithm below assumes a default of 'column'.
|
|
//
|
|
// Input parameters:
|
|
// - node: current node to be sized and layed out
|
|
// - availableWidth & availableHeight: available size to be used for sizing the node
|
|
// or CSSUndefined if the size is not available; interpretation depends on layout
|
|
// flags
|
|
// - parentDirection: the inline (text) direction within the parent (left-to-right or
|
|
// right-to-left)
|
|
// - widthMeasureMode: indicates the sizing rules for the width (see below for explanation)
|
|
// - heightMeasureMode: indicates the sizing rules for the height (see below for explanation)
|
|
// - performLayout: specifies whether the caller is interested in just the dimensions
|
|
// of the node or it requires the entire node and its subtree to be layed out
|
|
// (with final positions)
|
|
//
|
|
// Details:
|
|
// This routine is called recursively to lay out subtrees of flexbox elements. It uses the
|
|
// information in node.style, which is treated as a read-only input. It is responsible for
|
|
// setting the layout.direction and layout.measuredDimensions fields for the input node as well
|
|
// as the layout.position and layout.lineIndex fields for its child nodes. The
|
|
// layout.measuredDimensions field includes any border or padding for the node but does
|
|
// not include margins.
|
|
//
|
|
// The spec describes four different layout modes: "fill available", "max content", "min content",
|
|
// and "fit content". Of these, we don't use "min content" because we don't support default
|
|
// minimum main sizes (see above for details). Each of our measure modes maps to a layout mode
|
|
// from the spec (https://www.w3.org/TR/css3-sizing/#terms):
|
|
// - CSSMeasureModeUndefined: max content
|
|
// - CSSMeasureModeExactly: fill available
|
|
// - CSSMeasureModeAtMost: fit content
|
|
//
|
|
// When calling layoutNodeImpl and layoutNodeInternal, if the caller passes an available size of
|
|
// undefined then it must also pass a measure mode of CSSMeasureModeUndefined in that dimension.
|
|
//
|
|
static void layoutNodeImpl(CSSNode* node, float availableWidth, float availableHeight,
|
|
CSSDirection parentDirection, CSSMeasureMode widthMeasureMode, CSSMeasureMode heightMeasureMode, bool performLayout) {
|
|
|
|
assert(isUndefined(availableWidth) ? widthMeasureMode == CSSMeasureModeUndefined : true); // availableWidth is indefinite so widthMeasureMode must be CSSMeasureModeUndefined
|
|
assert(isUndefined(availableHeight) ? heightMeasureMode == CSSMeasureModeUndefined : true); // availableHeight is indefinite so heightMeasureMode must be CSSMeasureModeUndefined
|
|
|
|
float paddingAndBorderAxisRow = getPaddingAndBorderAxis(node, CSSFlexDirectionRow);
|
|
float paddingAndBorderAxisColumn = getPaddingAndBorderAxis(node, CSSFlexDirectionColumn);
|
|
float marginAxisRow = getMarginAxis(node, CSSFlexDirectionRow);
|
|
float marginAxisColumn = getMarginAxis(node, CSSFlexDirectionColumn);
|
|
|
|
// Set the resolved resolution in the node's layout.
|
|
CSSDirection direction = resolveDirection(node, parentDirection);
|
|
node->layout.direction = direction;
|
|
|
|
// For content (text) nodes, determine the dimensions based on the text contents.
|
|
if (isMeasureDefined(node)) {
|
|
float innerWidth = availableWidth - marginAxisRow - paddingAndBorderAxisRow;
|
|
float innerHeight = availableHeight - marginAxisColumn - paddingAndBorderAxisColumn;
|
|
|
|
if (widthMeasureMode == CSSMeasureModeExactly && heightMeasureMode == CSSMeasureModeExactly) {
|
|
|
|
// Don't bother sizing the text if both dimensions are already defined.
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, availableWidth - marginAxisRow);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, availableHeight - marginAxisColumn);
|
|
} else if (innerWidth <= 0 || innerHeight <= 0) {
|
|
|
|
// Don't bother sizing the text if there's no horizontal or vertical space.
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, 0);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, 0);
|
|
} else {
|
|
|
|
// Measure the text under the current constraints.
|
|
CSSSize measuredSize = node->measure(
|
|
node->context,
|
|
|
|
innerWidth,
|
|
widthMeasureMode,
|
|
innerHeight,
|
|
heightMeasureMode
|
|
);
|
|
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow,
|
|
(widthMeasureMode == CSSMeasureModeUndefined || widthMeasureMode == CSSMeasureModeAtMost) ?
|
|
measuredSize.width + paddingAndBorderAxisRow :
|
|
availableWidth - marginAxisRow);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn,
|
|
(heightMeasureMode == CSSMeasureModeUndefined || heightMeasureMode == CSSMeasureModeAtMost) ?
|
|
measuredSize.height + paddingAndBorderAxisColumn :
|
|
availableHeight - marginAxisColumn);
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
// For nodes with no children, use the available values if they were provided, or
|
|
// the minimum size as indicated by the padding and border sizes.
|
|
int childCount = node->childCount;
|
|
if (childCount == 0) {
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow,
|
|
(widthMeasureMode == CSSMeasureModeUndefined || widthMeasureMode == CSSMeasureModeAtMost) ?
|
|
paddingAndBorderAxisRow :
|
|
availableWidth - marginAxisRow);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn,
|
|
(heightMeasureMode == CSSMeasureModeUndefined || heightMeasureMode == CSSMeasureModeAtMost) ?
|
|
paddingAndBorderAxisColumn :
|
|
availableHeight - marginAxisColumn);
|
|
return;
|
|
}
|
|
|
|
// If we're not being asked to perform a full layout, we can handle a number of common
|
|
// cases here without incurring the cost of the remaining function.
|
|
if (!performLayout) {
|
|
// If we're being asked to size the content with an at most constraint but there is no available width,
|
|
// the measurement will always be zero.
|
|
if (widthMeasureMode == CSSMeasureModeAtMost && availableWidth <= 0 &&
|
|
heightMeasureMode == CSSMeasureModeAtMost && availableHeight <= 0) {
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, 0);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, 0);
|
|
return;
|
|
}
|
|
|
|
if (widthMeasureMode == CSSMeasureModeAtMost && availableWidth <= 0) {
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, 0);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, isUndefined(availableHeight) ? 0 : (availableHeight - marginAxisColumn));
|
|
return;
|
|
}
|
|
|
|
if (heightMeasureMode == CSSMeasureModeAtMost && availableHeight <= 0) {
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, isUndefined(availableWidth) ? 0 : (availableWidth - marginAxisRow));
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, 0);
|
|
return;
|
|
}
|
|
|
|
// If we're being asked to use an exact width/height, there's no need to measure the children.
|
|
if (widthMeasureMode == CSSMeasureModeExactly && heightMeasureMode == CSSMeasureModeExactly) {
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, availableWidth - marginAxisRow);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, availableHeight - marginAxisColumn);
|
|
return;
|
|
}
|
|
}
|
|
|
|
// STEP 1: CALCULATE VALUES FOR REMAINDER OF ALGORITHM
|
|
CSSFlexDirection mainAxis = resolveAxis(getFlexDirection(node), direction);
|
|
CSSFlexDirection crossAxis = getCrossFlexDirection(mainAxis, direction);
|
|
bool isMainAxisRow = isRowDirection(mainAxis);
|
|
CSSJustify justifyContent = node->style.justifyContent;
|
|
bool isNodeFlexWrap = isFlexWrap(node);
|
|
|
|
CSSNode* firstAbsoluteChild = NULL;
|
|
CSSNode* currentAbsoluteChild = NULL;
|
|
|
|
float leadingPaddingAndBorderMain = getLeadingPaddingAndBorder(node, mainAxis);
|
|
float trailingPaddingAndBorderMain = getTrailingPaddingAndBorder(node, mainAxis);
|
|
float leadingPaddingAndBorderCross = getLeadingPaddingAndBorder(node, crossAxis);
|
|
float paddingAndBorderAxisMain = getPaddingAndBorderAxis(node, mainAxis);
|
|
float paddingAndBorderAxisCross = getPaddingAndBorderAxis(node, crossAxis);
|
|
|
|
CSSMeasureMode measureModeMainDim = isMainAxisRow ? widthMeasureMode : heightMeasureMode;
|
|
CSSMeasureMode measureModeCrossDim = isMainAxisRow ? heightMeasureMode : widthMeasureMode;
|
|
|
|
// STEP 2: DETERMINE AVAILABLE SIZE IN MAIN AND CROSS DIRECTIONS
|
|
float availableInnerWidth = availableWidth - marginAxisRow - paddingAndBorderAxisRow;
|
|
float availableInnerHeight = availableHeight - marginAxisColumn - paddingAndBorderAxisColumn;
|
|
float availableInnerMainDim = isMainAxisRow ? availableInnerWidth : availableInnerHeight;
|
|
float availableInnerCrossDim = isMainAxisRow ? availableInnerHeight : availableInnerWidth;
|
|
|
|
// STEP 3: DETERMINE FLEX BASIS FOR EACH ITEM
|
|
CSSNode* child;
|
|
int i;
|
|
float childWidth;
|
|
float childHeight;
|
|
CSSMeasureMode childWidthMeasureMode;
|
|
CSSMeasureMode childHeightMeasureMode;
|
|
for (i = 0; i < childCount; i++) {
|
|
child = node->getChild(node->context, i);
|
|
|
|
if (performLayout) {
|
|
// Set the initial position (relative to the parent).
|
|
CSSDirection childDirection = resolveDirection(child, direction);
|
|
setPosition(child, childDirection);
|
|
}
|
|
|
|
// Absolute-positioned children don't participate in flex layout. Add them
|
|
// to a list that we can process later.
|
|
if (child->style.positionType == CSSPositionTypeAbsolute) {
|
|
|
|
// Store a private linked list of absolutely positioned children
|
|
// so that we can efficiently traverse them later.
|
|
if (firstAbsoluteChild == NULL) {
|
|
firstAbsoluteChild = child;
|
|
}
|
|
if (currentAbsoluteChild != NULL) {
|
|
currentAbsoluteChild->nextChild = child;
|
|
}
|
|
currentAbsoluteChild = child;
|
|
child->nextChild = NULL;
|
|
} else {
|
|
|
|
if (isMainAxisRow && isStyleDimDefined(child, CSSFlexDirectionRow)) {
|
|
|
|
// The width is definite, so use that as the flex basis.
|
|
child->layout.flexBasis = fmaxf(child->style.dimensions[CSSDimensionWidth], getPaddingAndBorderAxis(child, CSSFlexDirectionRow));
|
|
} else if (!isMainAxisRow && isStyleDimDefined(child, CSSFlexDirectionColumn)) {
|
|
|
|
// The height is definite, so use that as the flex basis.
|
|
child->layout.flexBasis = fmaxf(child->style.dimensions[CSSDimensionHeight], getPaddingAndBorderAxis(child, CSSFlexDirectionColumn));
|
|
} else if (!isFlexBasisAuto(child) && !isUndefined(availableInnerMainDim)) {
|
|
|
|
// If the basis isn't 'auto', it is assumed to be zero.
|
|
child->layout.flexBasis = fmaxf(0, getPaddingAndBorderAxis(child, mainAxis));
|
|
} else {
|
|
|
|
// Compute the flex basis and hypothetical main size (i.e. the clamped flex basis).
|
|
childWidth = CSSUndefined;
|
|
childHeight = CSSUndefined;
|
|
childWidthMeasureMode = CSSMeasureModeUndefined;
|
|
childHeightMeasureMode = CSSMeasureModeUndefined;
|
|
|
|
if (isStyleDimDefined(child, CSSFlexDirectionRow)) {
|
|
childWidth = child->style.dimensions[CSSDimensionWidth] + getMarginAxis(child, CSSFlexDirectionRow);
|
|
childWidthMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
if (isStyleDimDefined(child, CSSFlexDirectionColumn)) {
|
|
childHeight = child->style.dimensions[CSSDimensionHeight] + getMarginAxis(child, CSSFlexDirectionColumn);
|
|
childHeightMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
|
|
// According to the spec, if the main size is not definite and the
|
|
// child's inline axis is parallel to the main axis (i.e. it's
|
|
// horizontal), the child should be sized using "UNDEFINED" in
|
|
// the main size. Otherwise use "AT_MOST" in the cross axis.
|
|
if (!isMainAxisRow && isUndefined(childWidth) && !isUndefined(availableInnerWidth)) {
|
|
childWidth = availableInnerWidth;
|
|
childWidthMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
|
|
// The W3C spec doesn't say anything about the 'overflow' property,
|
|
// but all major browsers appear to implement the following logic.
|
|
if (node->style.overflow == CSSOverflowHidden) {
|
|
if (isMainAxisRow && isUndefined(childHeight) && !isUndefined(availableInnerHeight)) {
|
|
childHeight = availableInnerHeight;
|
|
childHeightMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
}
|
|
|
|
// If child has no defined size in the cross axis and is set to stretch, set the cross
|
|
// axis to be measured exactly with the available inner width
|
|
if (!isMainAxisRow &&
|
|
!isUndefined(availableInnerWidth) &&
|
|
!isStyleDimDefined(child, CSSFlexDirectionRow) &&
|
|
widthMeasureMode == CSSMeasureModeExactly &&
|
|
getAlignItem(node, child) == CSSAlignStretch) {
|
|
childWidth = availableInnerWidth;
|
|
childWidthMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
if (isMainAxisRow &&
|
|
!isUndefined(availableInnerHeight) &&
|
|
!isStyleDimDefined(child, CSSFlexDirectionColumn) &&
|
|
heightMeasureMode == CSSMeasureModeExactly &&
|
|
getAlignItem(node, child) == CSSAlignStretch) {
|
|
childHeight = availableInnerHeight;
|
|
childHeightMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
|
|
// Measure the child
|
|
layoutNodeInternal(child, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, false, "measure");
|
|
|
|
child->layout.flexBasis = fmaxf(isMainAxisRow ? child->layout.measuredDimensions[CSSDimensionWidth] : child->layout.measuredDimensions[CSSDimensionHeight], getPaddingAndBorderAxis(child, mainAxis));
|
|
}
|
|
}
|
|
}
|
|
|
|
// STEP 4: COLLECT FLEX ITEMS INTO FLEX LINES
|
|
|
|
// Indexes of children that represent the first and last items in the line.
|
|
int startOfLineIndex = 0;
|
|
int endOfLineIndex = 0;
|
|
|
|
// Number of lines.
|
|
int lineCount = 0;
|
|
|
|
// Accumulated cross dimensions of all lines so far.
|
|
float totalLineCrossDim = 0;
|
|
|
|
// Max main dimension of all the lines.
|
|
float maxLineMainDim = 0;
|
|
|
|
while (endOfLineIndex < childCount) {
|
|
|
|
// Number of items on the currently line. May be different than the difference
|
|
// between start and end indicates because we skip over absolute-positioned items.
|
|
int itemsOnLine = 0;
|
|
|
|
// sizeConsumedOnCurrentLine is accumulation of the dimensions and margin
|
|
// of all the children on the current line. This will be used in order to
|
|
// either set the dimensions of the node if none already exist or to compute
|
|
// the remaining space left for the flexible children.
|
|
float sizeConsumedOnCurrentLine = 0;
|
|
|
|
float totalFlexGrowFactors = 0;
|
|
float totalFlexShrinkScaledFactors = 0;
|
|
|
|
i = startOfLineIndex;
|
|
|
|
// Maintain a linked list of the child nodes that can shrink and/or grow.
|
|
CSSNode* firstRelativeChild = NULL;
|
|
CSSNode* currentRelativeChild = NULL;
|
|
|
|
// Add items to the current line until it's full or we run out of items.
|
|
while (i < childCount) {
|
|
child = node->getChild(node->context, i);
|
|
child->lineIndex = lineCount;
|
|
|
|
if (child->style.positionType != CSSPositionTypeAbsolute) {
|
|
float outerFlexBasis = child->layout.flexBasis + getMarginAxis(child, mainAxis);
|
|
|
|
// If this is a multi-line flow and this item pushes us over the available size, we've
|
|
// hit the end of the current line. Break out of the loop and lay out the current line.
|
|
if (sizeConsumedOnCurrentLine + outerFlexBasis > availableInnerMainDim && isNodeFlexWrap && itemsOnLine > 0) {
|
|
break;
|
|
}
|
|
|
|
sizeConsumedOnCurrentLine += outerFlexBasis;
|
|
itemsOnLine++;
|
|
|
|
if (isFlex(child)) {
|
|
totalFlexGrowFactors += getFlexGrowFactor(child);
|
|
|
|
// Unlike the grow factor, the shrink factor is scaled relative to the child
|
|
// dimension.
|
|
totalFlexShrinkScaledFactors += getFlexShrinkFactor(child) * child->layout.flexBasis;
|
|
}
|
|
|
|
// Store a private linked list of children that need to be layed out.
|
|
if (firstRelativeChild == NULL) {
|
|
firstRelativeChild = child;
|
|
}
|
|
if (currentRelativeChild != NULL) {
|
|
currentRelativeChild->nextChild = child;
|
|
}
|
|
currentRelativeChild = child;
|
|
child->nextChild = NULL;
|
|
}
|
|
|
|
i++;
|
|
endOfLineIndex++;
|
|
}
|
|
|
|
// If we don't need to measure the cross axis, we can skip the entire flex step.
|
|
bool canSkipFlex = !performLayout && measureModeCrossDim == CSSMeasureModeExactly;
|
|
|
|
// In order to position the elements in the main axis, we have two
|
|
// controls. The space between the beginning and the first element
|
|
// and the space between each two elements.
|
|
float leadingMainDim = 0;
|
|
float betweenMainDim = 0;
|
|
|
|
// STEP 5: RESOLVING FLEXIBLE LENGTHS ON MAIN AXIS
|
|
// Calculate the remaining available space that needs to be allocated.
|
|
// If the main dimension size isn't known, it is computed based on
|
|
// the line length, so there's no more space left to distribute.
|
|
float remainingFreeSpace = 0;
|
|
if (!isUndefined(availableInnerMainDim)) {
|
|
remainingFreeSpace = availableInnerMainDim - sizeConsumedOnCurrentLine;
|
|
} else if (sizeConsumedOnCurrentLine < 0) {
|
|
// availableInnerMainDim is indefinite which means the node is being sized based on its content.
|
|
// sizeConsumedOnCurrentLine is negative which means the node will allocate 0 pixels for
|
|
// its content. Consequently, remainingFreeSpace is 0 - sizeConsumedOnCurrentLine.
|
|
remainingFreeSpace = -sizeConsumedOnCurrentLine;
|
|
}
|
|
|
|
float originalRemainingFreeSpace = remainingFreeSpace;
|
|
float deltaFreeSpace = 0;
|
|
|
|
if (!canSkipFlex) {
|
|
float childFlexBasis;
|
|
float flexShrinkScaledFactor;
|
|
float flexGrowFactor;
|
|
float baseMainSize;
|
|
float boundMainSize;
|
|
|
|
// Do two passes over the flex items to figure out how to distribute the remaining space.
|
|
// The first pass finds the items whose min/max constraints trigger, freezes them at those
|
|
// sizes, and excludes those sizes from the remaining space. The second pass sets the size
|
|
// of each flexible item. It distributes the remaining space amongst the items whose min/max
|
|
// constraints didn't trigger in pass 1. For the other items, it sets their sizes by forcing
|
|
// their min/max constraints to trigger again.
|
|
//
|
|
// This two pass approach for resolving min/max constraints deviates from the spec. The
|
|
// spec (https://www.w3.org/TR/css-flexbox-1/#resolve-flexible-lengths) describes a process
|
|
// that needs to be repeated a variable number of times. The algorithm implemented here
|
|
// won't handle all cases but it was simpler to implement and it mitigates performance
|
|
// concerns because we know exactly how many passes it'll do.
|
|
|
|
// First pass: detect the flex items whose min/max constraints trigger
|
|
float deltaFlexShrinkScaledFactors = 0;
|
|
float deltaFlexGrowFactors = 0;
|
|
currentRelativeChild = firstRelativeChild;
|
|
while (currentRelativeChild != NULL) {
|
|
childFlexBasis = currentRelativeChild->layout.flexBasis;
|
|
|
|
if (remainingFreeSpace < 0) {
|
|
flexShrinkScaledFactor = getFlexShrinkFactor(currentRelativeChild) * childFlexBasis;
|
|
|
|
// Is this child able to shrink?
|
|
if (flexShrinkScaledFactor != 0) {
|
|
baseMainSize = childFlexBasis +
|
|
remainingFreeSpace / totalFlexShrinkScaledFactors * flexShrinkScaledFactor;
|
|
boundMainSize = boundAxis(currentRelativeChild, mainAxis, baseMainSize);
|
|
if (baseMainSize != boundMainSize) {
|
|
// By excluding this item's size and flex factor from remaining, this item's
|
|
// min/max constraints should also trigger in the second pass resulting in the
|
|
// item's size calculation being identical in the first and second passes.
|
|
deltaFreeSpace -= boundMainSize - childFlexBasis;
|
|
deltaFlexShrinkScaledFactors -= flexShrinkScaledFactor;
|
|
}
|
|
}
|
|
} else if (remainingFreeSpace > 0) {
|
|
flexGrowFactor = getFlexGrowFactor(currentRelativeChild);
|
|
|
|
// Is this child able to grow?
|
|
if (flexGrowFactor != 0) {
|
|
baseMainSize = childFlexBasis +
|
|
remainingFreeSpace / totalFlexGrowFactors * flexGrowFactor;
|
|
boundMainSize = boundAxis(currentRelativeChild, mainAxis, baseMainSize);
|
|
if (baseMainSize != boundMainSize) {
|
|
// By excluding this item's size and flex factor from remaining, this item's
|
|
// min/max constraints should also trigger in the second pass resulting in the
|
|
// item's size calculation being identical in the first and second passes.
|
|
deltaFreeSpace -= boundMainSize - childFlexBasis;
|
|
deltaFlexGrowFactors -= flexGrowFactor;
|
|
}
|
|
}
|
|
}
|
|
|
|
currentRelativeChild = currentRelativeChild->nextChild;
|
|
}
|
|
|
|
totalFlexShrinkScaledFactors += deltaFlexShrinkScaledFactors;
|
|
totalFlexGrowFactors += deltaFlexGrowFactors;
|
|
remainingFreeSpace += deltaFreeSpace;
|
|
|
|
// Second pass: resolve the sizes of the flexible items
|
|
deltaFreeSpace = 0;
|
|
currentRelativeChild = firstRelativeChild;
|
|
while (currentRelativeChild != NULL) {
|
|
childFlexBasis = currentRelativeChild->layout.flexBasis;
|
|
float updatedMainSize = childFlexBasis;
|
|
|
|
if (remainingFreeSpace < 0) {
|
|
flexShrinkScaledFactor = getFlexShrinkFactor(currentRelativeChild) * childFlexBasis;
|
|
|
|
// Is this child able to shrink?
|
|
if (flexShrinkScaledFactor != 0) {
|
|
updatedMainSize = boundAxis(currentRelativeChild, mainAxis, childFlexBasis +
|
|
remainingFreeSpace / totalFlexShrinkScaledFactors * flexShrinkScaledFactor);
|
|
}
|
|
} else if (remainingFreeSpace > 0) {
|
|
flexGrowFactor = getFlexGrowFactor(currentRelativeChild);
|
|
|
|
// Is this child able to grow?
|
|
if (flexGrowFactor != 0) {
|
|
updatedMainSize = boundAxis(currentRelativeChild, mainAxis, childFlexBasis +
|
|
remainingFreeSpace / totalFlexGrowFactors * flexGrowFactor);
|
|
}
|
|
}
|
|
|
|
deltaFreeSpace -= updatedMainSize - childFlexBasis;
|
|
|
|
if (isMainAxisRow) {
|
|
childWidth = updatedMainSize + getMarginAxis(currentRelativeChild, CSSFlexDirectionRow);
|
|
childWidthMeasureMode = CSSMeasureModeExactly;
|
|
|
|
if (!isUndefined(availableInnerCrossDim) &&
|
|
!isStyleDimDefined(currentRelativeChild, CSSFlexDirectionColumn) &&
|
|
heightMeasureMode == CSSMeasureModeExactly &&
|
|
getAlignItem(node, currentRelativeChild) == CSSAlignStretch) {
|
|
childHeight = availableInnerCrossDim;
|
|
childHeightMeasureMode = CSSMeasureModeExactly;
|
|
} else if (!isStyleDimDefined(currentRelativeChild, CSSFlexDirectionColumn)) {
|
|
childHeight = availableInnerCrossDim;
|
|
childHeightMeasureMode = isUndefined(childHeight) ? CSSMeasureModeUndefined : CSSMeasureModeAtMost;
|
|
} else {
|
|
childHeight = currentRelativeChild->style.dimensions[CSSDimensionHeight] + getMarginAxis(currentRelativeChild, CSSFlexDirectionColumn);
|
|
childHeightMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
} else {
|
|
childHeight = updatedMainSize + getMarginAxis(currentRelativeChild, CSSFlexDirectionColumn);
|
|
childHeightMeasureMode = CSSMeasureModeExactly;
|
|
|
|
if (!isUndefined(availableInnerCrossDim) &&
|
|
!isStyleDimDefined(currentRelativeChild, CSSFlexDirectionRow) &&
|
|
widthMeasureMode == CSSMeasureModeExactly &&
|
|
getAlignItem(node, currentRelativeChild) == CSSAlignStretch) {
|
|
childWidth = availableInnerCrossDim;
|
|
childWidthMeasureMode = CSSMeasureModeExactly;
|
|
} else if (!isStyleDimDefined(currentRelativeChild, CSSFlexDirectionRow)) {
|
|
childWidth = availableInnerCrossDim;
|
|
childWidthMeasureMode = isUndefined(childWidth) ? CSSMeasureModeUndefined : CSSMeasureModeAtMost;
|
|
} else {
|
|
childWidth = currentRelativeChild->style.dimensions[CSSDimensionWidth] + getMarginAxis(currentRelativeChild, CSSFlexDirectionRow);
|
|
childWidthMeasureMode = CSSMeasureModeExactly;
|
|
}
|
|
}
|
|
|
|
bool requiresStretchLayout = !isStyleDimDefined(currentRelativeChild, crossAxis) &&
|
|
getAlignItem(node, currentRelativeChild) == CSSAlignStretch;
|
|
|
|
// Recursively call the layout algorithm for this child with the updated main size.
|
|
layoutNodeInternal(currentRelativeChild, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, performLayout && !requiresStretchLayout, "flex");
|
|
|
|
currentRelativeChild = currentRelativeChild->nextChild;
|
|
}
|
|
}
|
|
|
|
remainingFreeSpace = originalRemainingFreeSpace + deltaFreeSpace;
|
|
|
|
// STEP 6: MAIN-AXIS JUSTIFICATION & CROSS-AXIS SIZE DETERMINATION
|
|
|
|
// At this point, all the children have their dimensions set in the main axis.
|
|
// Their dimensions are also set in the cross axis with the exception of items
|
|
// that are aligned "stretch". We need to compute these stretch values and
|
|
// set the final positions.
|
|
|
|
// If we are using "at most" rules in the main axis, we won't distribute
|
|
// any remaining space at this point.
|
|
if (measureModeMainDim == CSSMeasureModeAtMost) {
|
|
remainingFreeSpace = 0;
|
|
}
|
|
|
|
// Use justifyContent to figure out how to allocate the remaining space
|
|
// available in the main axis.
|
|
if (justifyContent != CSSJustifyFlexStart) {
|
|
if (justifyContent == CSSJustifyCenter) {
|
|
leadingMainDim = remainingFreeSpace / 2;
|
|
} else if (justifyContent == CSSJustifyFlexEnd) {
|
|
leadingMainDim = remainingFreeSpace;
|
|
} else if (justifyContent == CSSJustifySpaceBetween) {
|
|
remainingFreeSpace = fmaxf(remainingFreeSpace, 0);
|
|
if (itemsOnLine > 1) {
|
|
betweenMainDim = remainingFreeSpace / (itemsOnLine - 1);
|
|
} else {
|
|
betweenMainDim = 0;
|
|
}
|
|
} else if (justifyContent == CSSJustifySpaceAround) {
|
|
// Space on the edges is half of the space between elements
|
|
betweenMainDim = remainingFreeSpace / itemsOnLine;
|
|
leadingMainDim = betweenMainDim / 2;
|
|
}
|
|
}
|
|
|
|
float mainDim = leadingPaddingAndBorderMain + leadingMainDim;
|
|
float crossDim = 0;
|
|
|
|
for (i = startOfLineIndex; i < endOfLineIndex; ++i) {
|
|
child = node->getChild(node->context, i);
|
|
|
|
if (child->style.positionType == CSSPositionTypeAbsolute &&
|
|
isPosDefined(child, leading[mainAxis])) {
|
|
if (performLayout) {
|
|
// In case the child is position absolute and has left/top being
|
|
// defined, we override the position to whatever the user said
|
|
// (and margin/border).
|
|
child->layout.position[pos[mainAxis]] = getPosition(child, leading[mainAxis]) +
|
|
getLeadingBorder(node, mainAxis) +
|
|
getLeadingMargin(child, mainAxis);
|
|
}
|
|
} else {
|
|
if (performLayout) {
|
|
// If the child is position absolute (without top/left) or relative,
|
|
// we put it at the current accumulated offset.
|
|
child->layout.position[pos[mainAxis]] += mainDim;
|
|
}
|
|
|
|
// Now that we placed the element, we need to update the variables.
|
|
// We need to do that only for relative elements. Absolute elements
|
|
// do not take part in that phase.
|
|
if (child->style.positionType == CSSPositionTypeRelative) {
|
|
if (canSkipFlex) {
|
|
// If we skipped the flex step, then we can't rely on the measuredDims because
|
|
// they weren't computed. This means we can't call getDimWithMargin.
|
|
mainDim += betweenMainDim + getMarginAxis(child, mainAxis) + child->layout.flexBasis;
|
|
crossDim = availableInnerCrossDim;
|
|
} else {
|
|
// The main dimension is the sum of all the elements dimension plus
|
|
// the spacing.
|
|
mainDim += betweenMainDim + getDimWithMargin(child, mainAxis);
|
|
|
|
// The cross dimension is the max of the elements dimension since there
|
|
// can only be one element in that cross dimension.
|
|
crossDim = fmaxf(crossDim, getDimWithMargin(child, crossAxis));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
mainDim += trailingPaddingAndBorderMain;
|
|
|
|
float containerCrossAxis = availableInnerCrossDim;
|
|
if (measureModeCrossDim == CSSMeasureModeUndefined || measureModeCrossDim == CSSMeasureModeAtMost) {
|
|
// Compute the cross axis from the max cross dimension of the children.
|
|
containerCrossAxis = boundAxis(node, crossAxis, crossDim + paddingAndBorderAxisCross) - paddingAndBorderAxisCross;
|
|
|
|
if (measureModeCrossDim == CSSMeasureModeAtMost) {
|
|
containerCrossAxis = fminf(containerCrossAxis, availableInnerCrossDim);
|
|
}
|
|
}
|
|
|
|
// If there's no flex wrap, the cross dimension is defined by the container.
|
|
if (!isNodeFlexWrap && measureModeCrossDim == CSSMeasureModeExactly) {
|
|
crossDim = availableInnerCrossDim;
|
|
}
|
|
|
|
// Clamp to the min/max size specified on the container.
|
|
crossDim = boundAxis(node, crossAxis, crossDim + paddingAndBorderAxisCross) - paddingAndBorderAxisCross;
|
|
|
|
// STEP 7: CROSS-AXIS ALIGNMENT
|
|
// We can skip child alignment if we're just measuring the container.
|
|
if (performLayout) {
|
|
for (i = startOfLineIndex; i < endOfLineIndex; ++i) {
|
|
child = node->getChild(node->context, i);
|
|
|
|
if (child->style.positionType == CSSPositionTypeAbsolute) {
|
|
// If the child is absolutely positioned and has a top/left/bottom/right
|
|
// set, override all the previously computed positions to set it correctly.
|
|
if (isPosDefined(child, leading[crossAxis])) {
|
|
child->layout.position[pos[crossAxis]] = getPosition(child, leading[crossAxis]) +
|
|
getLeadingBorder(node, crossAxis) +
|
|
getLeadingMargin(child, crossAxis);
|
|
} else {
|
|
child->layout.position[pos[crossAxis]] = leadingPaddingAndBorderCross +
|
|
getLeadingMargin(child, crossAxis);
|
|
}
|
|
} else {
|
|
float leadingCrossDim = leadingPaddingAndBorderCross;
|
|
|
|
// For a relative children, we're either using alignItems (parent) or
|
|
// alignSelf (child) in order to determine the position in the cross axis
|
|
CSSAlign alignItem = getAlignItem(node, child);
|
|
|
|
// If the child uses align stretch, we need to lay it out one more time, this time
|
|
// forcing the cross-axis size to be the computed cross size for the current line.
|
|
if (alignItem == CSSAlignStretch) {
|
|
childWidth = child->layout.measuredDimensions[CSSDimensionWidth] + getMarginAxis(child, CSSFlexDirectionRow);
|
|
childHeight = child->layout.measuredDimensions[CSSDimensionHeight] + getMarginAxis(child, CSSFlexDirectionColumn);
|
|
bool isCrossSizeDefinite = false;
|
|
|
|
if (isMainAxisRow) {
|
|
isCrossSizeDefinite = isStyleDimDefined(child, CSSFlexDirectionColumn);
|
|
childHeight = crossDim;
|
|
} else {
|
|
isCrossSizeDefinite = isStyleDimDefined(child, CSSFlexDirectionRow);
|
|
childWidth = crossDim;
|
|
}
|
|
|
|
// If the child defines a definite size for its cross axis, there's no need to stretch.
|
|
if (!isCrossSizeDefinite) {
|
|
childWidthMeasureMode = isUndefined(childWidth) ? CSSMeasureModeUndefined : CSSMeasureModeExactly;
|
|
childHeightMeasureMode = isUndefined(childHeight) ? CSSMeasureModeUndefined : CSSMeasureModeExactly;
|
|
layoutNodeInternal(child, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, true, "stretch");
|
|
}
|
|
} else if (alignItem != CSSAlignFlexStart) {
|
|
float remainingCrossDim = containerCrossAxis - getDimWithMargin(child, crossAxis);
|
|
|
|
if (alignItem == CSSAlignCenter) {
|
|
leadingCrossDim += remainingCrossDim / 2;
|
|
} else { // CSSAlignFlexEnd
|
|
leadingCrossDim += remainingCrossDim;
|
|
}
|
|
}
|
|
|
|
// And we apply the position
|
|
child->layout.position[pos[crossAxis]] += totalLineCrossDim + leadingCrossDim;
|
|
}
|
|
}
|
|
}
|
|
|
|
totalLineCrossDim += crossDim;
|
|
maxLineMainDim = fmaxf(maxLineMainDim, mainDim);
|
|
|
|
// Reset variables for new line.
|
|
lineCount++;
|
|
startOfLineIndex = endOfLineIndex;
|
|
endOfLineIndex = startOfLineIndex;
|
|
}
|
|
|
|
// STEP 8: MULTI-LINE CONTENT ALIGNMENT
|
|
if (lineCount > 1 && performLayout && !isUndefined(availableInnerCrossDim)) {
|
|
float remainingAlignContentDim = availableInnerCrossDim - totalLineCrossDim;
|
|
|
|
float crossDimLead = 0;
|
|
float currentLead = leadingPaddingAndBorderCross;
|
|
|
|
CSSAlign alignContent = node->style.alignContent;
|
|
if (alignContent == CSSAlignFlexEnd) {
|
|
currentLead += remainingAlignContentDim;
|
|
} else if (alignContent == CSSAlignCenter) {
|
|
currentLead += remainingAlignContentDim / 2;
|
|
} else if (alignContent == CSSAlignStretch) {
|
|
if (availableInnerCrossDim > totalLineCrossDim) {
|
|
crossDimLead = (remainingAlignContentDim / lineCount);
|
|
}
|
|
}
|
|
|
|
int endIndex = 0;
|
|
for (i = 0; i < lineCount; ++i) {
|
|
int startIndex = endIndex;
|
|
int j;
|
|
|
|
// compute the line's height and find the endIndex
|
|
float lineHeight = 0;
|
|
for (j = startIndex; j < childCount; ++j) {
|
|
child = node->getChild(node->context, j);
|
|
if (child->style.positionType != CSSPositionTypeRelative) {
|
|
continue;
|
|
}
|
|
if (child->lineIndex != i) {
|
|
break;
|
|
}
|
|
if (isLayoutDimDefined(child, crossAxis)) {
|
|
lineHeight = fmaxf(lineHeight,
|
|
child->layout.measuredDimensions[dim[crossAxis]] + getMarginAxis(child, crossAxis));
|
|
}
|
|
}
|
|
endIndex = j;
|
|
lineHeight += crossDimLead;
|
|
|
|
if (performLayout) {
|
|
for (j = startIndex; j < endIndex; ++j) {
|
|
child = node->getChild(node->context, j);
|
|
if (child->style.positionType != CSSPositionTypeRelative) {
|
|
continue;
|
|
}
|
|
|
|
CSSAlign alignContentAlignItem = getAlignItem(node, child);
|
|
if (alignContentAlignItem == CSSAlignFlexStart) {
|
|
child->layout.position[pos[crossAxis]] = currentLead + getLeadingMargin(child, crossAxis);
|
|
} else if (alignContentAlignItem == CSSAlignFlexEnd) {
|
|
child->layout.position[pos[crossAxis]] = currentLead + lineHeight - getTrailingMargin(child, crossAxis) - child->layout.measuredDimensions[dim[crossAxis]];
|
|
} else if (alignContentAlignItem == CSSAlignCenter) {
|
|
childHeight = child->layout.measuredDimensions[dim[crossAxis]];
|
|
child->layout.position[pos[crossAxis]] = currentLead + (lineHeight - childHeight) / 2;
|
|
} else if (alignContentAlignItem == CSSAlignStretch) {
|
|
child->layout.position[pos[crossAxis]] = currentLead + getLeadingMargin(child, crossAxis);
|
|
// TODO(prenaux): Correctly set the height of items with indefinite
|
|
// (auto) crossAxis dimension.
|
|
}
|
|
}
|
|
}
|
|
|
|
currentLead += lineHeight;
|
|
}
|
|
}
|
|
|
|
// STEP 9: COMPUTING FINAL DIMENSIONS
|
|
node->layout.measuredDimensions[CSSDimensionWidth] = boundAxis(node, CSSFlexDirectionRow, availableWidth - marginAxisRow);
|
|
node->layout.measuredDimensions[CSSDimensionHeight] = boundAxis(node, CSSFlexDirectionColumn, availableHeight - marginAxisColumn);
|
|
|
|
// If the user didn't specify a width or height for the node, set the
|
|
// dimensions based on the children.
|
|
if (measureModeMainDim == CSSMeasureModeUndefined) {
|
|
// Clamp the size to the min/max size, if specified, and make sure it
|
|
// doesn't go below the padding and border amount.
|
|
node->layout.measuredDimensions[dim[mainAxis]] = boundAxis(node, mainAxis, maxLineMainDim);
|
|
} else if (measureModeMainDim == CSSMeasureModeAtMost) {
|
|
node->layout.measuredDimensions[dim[mainAxis]] = fmaxf(
|
|
fminf(availableInnerMainDim + paddingAndBorderAxisMain,
|
|
boundAxisWithinMinAndMax(node, mainAxis, maxLineMainDim)),
|
|
paddingAndBorderAxisMain);
|
|
}
|
|
|
|
if (measureModeCrossDim == CSSMeasureModeUndefined) {
|
|
// Clamp the size to the min/max size, if specified, and make sure it
|
|
// doesn't go below the padding and border amount.
|
|
node->layout.measuredDimensions[dim[crossAxis]] = boundAxis(node, crossAxis, totalLineCrossDim + paddingAndBorderAxisCross);
|
|
} else if (measureModeCrossDim == CSSMeasureModeAtMost) {
|
|
node->layout.measuredDimensions[dim[crossAxis]] = fmaxf(
|
|
fminf(availableInnerCrossDim + paddingAndBorderAxisCross,
|
|
boundAxisWithinMinAndMax(node, crossAxis, totalLineCrossDim + paddingAndBorderAxisCross)),
|
|
paddingAndBorderAxisCross);
|
|
}
|
|
|
|
// STEP 10: SETTING TRAILING POSITIONS FOR CHILDREN
|
|
if (performLayout) {
|
|
bool needsMainTrailingPos = false;
|
|
bool needsCrossTrailingPos = false;
|
|
|
|
if (mainAxis == CSSFlexDirectionRowReverse ||
|
|
mainAxis == CSSFlexDirectionColumnReverse) {
|
|
needsMainTrailingPos = true;
|
|
}
|
|
|
|
if (crossAxis == CSSFlexDirectionRowReverse ||
|
|
crossAxis == CSSFlexDirectionColumnReverse) {
|
|
needsCrossTrailingPos = true;
|
|
}
|
|
|
|
// Set trailing position if necessary.
|
|
if (needsMainTrailingPos || needsCrossTrailingPos) {
|
|
for (i = 0; i < childCount; ++i) {
|
|
child = node->getChild(node->context, i);
|
|
|
|
if (needsMainTrailingPos) {
|
|
setTrailingPosition(node, child, mainAxis);
|
|
}
|
|
|
|
if (needsCrossTrailingPos) {
|
|
setTrailingPosition(node, child, crossAxis);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// STEP 11: SIZING AND POSITIONING ABSOLUTE CHILDREN
|
|
currentAbsoluteChild = firstAbsoluteChild;
|
|
while (currentAbsoluteChild != NULL) {
|
|
// Now that we know the bounds of the container, perform layout again on the
|
|
// absolutely-positioned children.
|
|
if (performLayout) {
|
|
|
|
childWidth = CSSUndefined;
|
|
childHeight = CSSUndefined;
|
|
|
|
if (isStyleDimDefined(currentAbsoluteChild, CSSFlexDirectionRow)) {
|
|
childWidth = currentAbsoluteChild->style.dimensions[CSSDimensionWidth] + getMarginAxis(currentAbsoluteChild, CSSFlexDirectionRow);
|
|
} else {
|
|
// If the child doesn't have a specified width, compute the width based on the left/right offsets if they're defined.
|
|
if (isPosDefined(currentAbsoluteChild, CSSPositionLeft) && isPosDefined(currentAbsoluteChild, CSSPositionRight)) {
|
|
childWidth = node->layout.measuredDimensions[CSSDimensionWidth] -
|
|
(getLeadingBorder(node, CSSFlexDirectionRow) + getTrailingBorder(node, CSSFlexDirectionRow)) -
|
|
(currentAbsoluteChild->style.position[CSSPositionLeft] + currentAbsoluteChild->style.position[CSSPositionRight]);
|
|
childWidth = boundAxis(currentAbsoluteChild, CSSFlexDirectionRow, childWidth);
|
|
}
|
|
}
|
|
|
|
if (isStyleDimDefined(currentAbsoluteChild, CSSFlexDirectionColumn)) {
|
|
childHeight = currentAbsoluteChild->style.dimensions[CSSDimensionHeight] + getMarginAxis(currentAbsoluteChild, CSSFlexDirectionColumn);
|
|
} else {
|
|
// If the child doesn't have a specified height, compute the height based on the top/bottom offsets if they're defined.
|
|
if (isPosDefined(currentAbsoluteChild, CSSPositionTop) && isPosDefined(currentAbsoluteChild, CSSPositionBottom)) {
|
|
childHeight = node->layout.measuredDimensions[CSSDimensionHeight] -
|
|
(getLeadingBorder(node, CSSFlexDirectionColumn) + getTrailingBorder(node, CSSFlexDirectionColumn)) -
|
|
(currentAbsoluteChild->style.position[CSSPositionTop] + currentAbsoluteChild->style.position[CSSPositionBottom]);
|
|
childHeight = boundAxis(currentAbsoluteChild, CSSFlexDirectionColumn, childHeight);
|
|
}
|
|
}
|
|
|
|
// If we're still missing one or the other dimension, measure the content.
|
|
if (isUndefined(childWidth) || isUndefined(childHeight)) {
|
|
childWidthMeasureMode = isUndefined(childWidth) ? CSSMeasureModeUndefined : CSSMeasureModeExactly;
|
|
childHeightMeasureMode = isUndefined(childHeight) ? CSSMeasureModeUndefined : CSSMeasureModeExactly;
|
|
|
|
// According to the spec, if the main size is not definite and the
|
|
// child's inline axis is parallel to the main axis (i.e. it's
|
|
// horizontal), the child should be sized using "UNDEFINED" in
|
|
// the main size. Otherwise use "AT_MOST" in the cross axis.
|
|
if (!isMainAxisRow && isUndefined(childWidth) && !isUndefined(availableInnerWidth)) {
|
|
childWidth = availableInnerWidth;
|
|
childWidthMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
|
|
// The W3C spec doesn't say anything about the 'overflow' property,
|
|
// but all major browsers appear to implement the following logic.
|
|
if (node->style.overflow == CSSOverflowHidden) {
|
|
if (isMainAxisRow && isUndefined(childHeight) && !isUndefined(availableInnerHeight)) {
|
|
childHeight = availableInnerHeight;
|
|
childHeightMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
}
|
|
|
|
layoutNodeInternal(currentAbsoluteChild, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, false, "abs-measure");
|
|
childWidth = currentAbsoluteChild->layout.measuredDimensions[CSSDimensionWidth] + getMarginAxis(currentAbsoluteChild, CSSFlexDirectionRow);
|
|
childHeight = currentAbsoluteChild->layout.measuredDimensions[CSSDimensionHeight] + getMarginAxis(currentAbsoluteChild, CSSFlexDirectionColumn);
|
|
}
|
|
|
|
layoutNodeInternal(currentAbsoluteChild, childWidth, childHeight, direction, CSSMeasureModeExactly, CSSMeasureModeExactly, true, "abs-layout");
|
|
|
|
if (isPosDefined(currentAbsoluteChild, trailing[CSSFlexDirectionRow]) &&
|
|
!isPosDefined(currentAbsoluteChild, leading[CSSFlexDirectionRow])) {
|
|
currentAbsoluteChild->layout.position[leading[CSSFlexDirectionRow]] =
|
|
node->layout.measuredDimensions[dim[CSSFlexDirectionRow]] -
|
|
currentAbsoluteChild->layout.measuredDimensions[dim[CSSFlexDirectionRow]] -
|
|
getPosition(currentAbsoluteChild, trailing[CSSFlexDirectionRow]);
|
|
}
|
|
|
|
if (isPosDefined(currentAbsoluteChild, trailing[CSSFlexDirectionColumn]) &&
|
|
!isPosDefined(currentAbsoluteChild, leading[CSSFlexDirectionColumn])) {
|
|
currentAbsoluteChild->layout.position[leading[CSSFlexDirectionColumn]] =
|
|
node->layout.measuredDimensions[dim[CSSFlexDirectionColumn]] -
|
|
currentAbsoluteChild->layout.measuredDimensions[dim[CSSFlexDirectionColumn]] -
|
|
getPosition(currentAbsoluteChild, trailing[CSSFlexDirectionColumn]);
|
|
}
|
|
}
|
|
|
|
currentAbsoluteChild = currentAbsoluteChild->nextChild;
|
|
}
|
|
}
|
|
|
|
int gDepth = 0;
|
|
bool gPrintTree = false;
|
|
bool gPrintChanges = false;
|
|
bool gPrintSkips = false;
|
|
|
|
static const char* spacer = " ";
|
|
|
|
static const char* getSpacer(unsigned long level) {
|
|
unsigned long spacerLen = strlen(spacer);
|
|
if (level > spacerLen) {
|
|
level = spacerLen;
|
|
}
|
|
return &spacer[spacerLen - level];
|
|
}
|
|
|
|
static const char* getModeName(CSSMeasureMode mode, bool performLayout) {
|
|
const char* kMeasureModeNames[CSSMeasureModeCount] = {
|
|
"UNDEFINED",
|
|
"EXACTLY",
|
|
"AT_MOST"
|
|
};
|
|
const char* kLayoutModeNames[CSSMeasureModeCount] = {
|
|
"LAY_UNDEFINED",
|
|
"LAY_EXACTLY",
|
|
"LAY_AT_MOST"
|
|
};
|
|
|
|
if (mode >= CSSMeasureModeCount) {
|
|
return "";
|
|
}
|
|
|
|
return performLayout? kLayoutModeNames[mode] : kMeasureModeNames[mode];
|
|
}
|
|
|
|
static bool canUseCachedMeasurement(
|
|
bool isTextNode,
|
|
float availableWidth,
|
|
float availableHeight,
|
|
float margin_row,
|
|
float margin_column,
|
|
CSSMeasureMode widthMeasureMode,
|
|
CSSMeasureMode heightMeasureMode,
|
|
CSSCachedMeasurement cached_layout) {
|
|
|
|
bool is_height_same =
|
|
(cached_layout.heightMeasureMode == CSSMeasureModeUndefined && heightMeasureMode == CSSMeasureModeUndefined) ||
|
|
(cached_layout.heightMeasureMode == heightMeasureMode && eq(cached_layout.availableHeight, availableHeight));
|
|
|
|
bool is_width_same =
|
|
(cached_layout.widthMeasureMode == CSSMeasureModeUndefined && widthMeasureMode == CSSMeasureModeUndefined) ||
|
|
(cached_layout.widthMeasureMode == widthMeasureMode && eq(cached_layout.availableWidth, availableWidth));
|
|
|
|
if (is_height_same && is_width_same) {
|
|
return true;
|
|
}
|
|
|
|
bool is_height_valid =
|
|
(cached_layout.heightMeasureMode == CSSMeasureModeUndefined && heightMeasureMode == CSSMeasureModeAtMost && cached_layout.computedHeight <= (availableHeight - margin_column)) ||
|
|
(heightMeasureMode == CSSMeasureModeExactly && eq(cached_layout.computedHeight, availableHeight - margin_column));
|
|
|
|
if (is_width_same && is_height_valid) {
|
|
return true;
|
|
}
|
|
|
|
bool is_width_valid =
|
|
(cached_layout.widthMeasureMode == CSSMeasureModeUndefined && widthMeasureMode == CSSMeasureModeAtMost && cached_layout.computedWidth <= (availableWidth - margin_row)) ||
|
|
(widthMeasureMode == CSSMeasureModeExactly && eq(cached_layout.computedWidth, availableWidth - margin_row));
|
|
|
|
if (is_height_same && is_width_valid) {
|
|
return true;
|
|
}
|
|
|
|
if (is_height_valid && is_width_valid) {
|
|
return true;
|
|
}
|
|
|
|
// We know this to be text so we can apply some more specialized heuristics.
|
|
if (isTextNode) {
|
|
if (is_width_same) {
|
|
if (heightMeasureMode == CSSMeasureModeUndefined) {
|
|
// Width is the same and height is not restricted. Re-use cahced value.
|
|
return true;
|
|
}
|
|
|
|
if (heightMeasureMode == CSSMeasureModeAtMost &&
|
|
cached_layout.computedHeight < (availableHeight - margin_column)) {
|
|
// Width is the same and height restriction is greater than the cached height. Re-use cached value.
|
|
return true;
|
|
}
|
|
|
|
// Width is the same but height restriction imposes smaller height than previously measured.
|
|
// Update the cached value to respect the new height restriction.
|
|
cached_layout.computedHeight = availableHeight - margin_column;
|
|
return true;
|
|
}
|
|
|
|
if (cached_layout.widthMeasureMode == CSSMeasureModeUndefined) {
|
|
if (widthMeasureMode == CSSMeasureModeUndefined ||
|
|
(widthMeasureMode == CSSMeasureModeAtMost &&
|
|
cached_layout.computedWidth <= (availableWidth - margin_row))) {
|
|
// Previsouly this text was measured with no width restriction, if width is now restricted
|
|
// but to a larger value than the previsouly measured width we can re-use the measurement
|
|
// as we know it will fit.
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
//
|
|
// This is a wrapper around the layoutNodeImpl function. It determines
|
|
// whether the layout request is redundant and can be skipped.
|
|
//
|
|
// Parameters:
|
|
// Input parameters are the same as layoutNodeImpl (see above)
|
|
// Return parameter is true if layout was performed, false if skipped
|
|
//
|
|
bool layoutNodeInternal(CSSNode* node, float availableWidth, float availableHeight,
|
|
CSSDirection parentDirection, CSSMeasureMode widthMeasureMode, CSSMeasureMode heightMeasureMode, bool performLayout, char* reason) {
|
|
CSSLayout* layout = &node->layout;
|
|
|
|
gDepth++;
|
|
|
|
bool needToVisitNode = (node->isDirty(node->context) && layout->generationCount != gCurrentGenerationCount) ||
|
|
layout->lastParentDirection != parentDirection;
|
|
|
|
if (needToVisitNode) {
|
|
// Invalidate the cached results.
|
|
layout->nextCachedMeasurementsIndex = 0;
|
|
layout->cached_layout.widthMeasureMode = (CSSMeasureMode)-1;
|
|
layout->cached_layout.heightMeasureMode = (CSSMeasureMode)-1;
|
|
}
|
|
|
|
CSSCachedMeasurement* cachedResults = NULL;
|
|
|
|
// Determine whether the results are already cached. We maintain a separate
|
|
// cache for layouts and measurements. A layout operation modifies the positions
|
|
// and dimensions for nodes in the subtree. The algorithm assumes that each node
|
|
// gets layed out a maximum of one time per tree layout, but multiple measurements
|
|
// may be required to resolve all of the flex dimensions.
|
|
// We handle nodes with measure functions specially here because they are the most
|
|
// expensive to measure, so it's worth avoiding redundant measurements if at all possible.
|
|
if (isMeasureDefined(node)) {
|
|
float marginAxisRow = getMarginAxis(node, CSSFlexDirectionRow);
|
|
float marginAxisColumn = getMarginAxis(node, CSSFlexDirectionColumn);
|
|
|
|
// First, try to use the layout cache.
|
|
if (canUseCachedMeasurement(node->isTextNode, availableWidth, availableHeight, marginAxisRow, marginAxisColumn,
|
|
widthMeasureMode, heightMeasureMode, layout->cached_layout)) {
|
|
cachedResults = &layout->cached_layout;
|
|
} else {
|
|
// Try to use the measurement cache.
|
|
for (int i = 0; i < layout->nextCachedMeasurementsIndex; i++) {
|
|
if (canUseCachedMeasurement(node->isTextNode, availableWidth, availableHeight, marginAxisRow, marginAxisColumn,
|
|
widthMeasureMode, heightMeasureMode, layout->cachedMeasurements[i])) {
|
|
cachedResults = &layout->cachedMeasurements[i];
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
} else if (performLayout) {
|
|
if (eq(layout->cached_layout.availableWidth, availableWidth) &&
|
|
eq(layout->cached_layout.availableHeight, availableHeight) &&
|
|
layout->cached_layout.widthMeasureMode == widthMeasureMode &&
|
|
layout->cached_layout.heightMeasureMode == heightMeasureMode) {
|
|
|
|
cachedResults = &layout->cached_layout;
|
|
}
|
|
} else {
|
|
for (int i = 0; i < layout->nextCachedMeasurementsIndex; i++) {
|
|
if (eq(layout->cachedMeasurements[i].availableWidth, availableWidth) &&
|
|
eq(layout->cachedMeasurements[i].availableHeight, availableHeight) &&
|
|
layout->cachedMeasurements[i].widthMeasureMode == widthMeasureMode &&
|
|
layout->cachedMeasurements[i].heightMeasureMode == heightMeasureMode) {
|
|
|
|
cachedResults = &layout->cachedMeasurements[i];
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!needToVisitNode && cachedResults != NULL) {
|
|
layout->measuredDimensions[CSSDimensionWidth] = cachedResults->computedWidth;
|
|
layout->measuredDimensions[CSSDimensionHeight] = cachedResults->computedHeight;
|
|
|
|
if (gPrintChanges && gPrintSkips) {
|
|
printf("%s%d.{[skipped] ", getSpacer(gDepth), gDepth);
|
|
if (node->print) {
|
|
node->print(node->context);
|
|
}
|
|
printf("wm: %s, hm: %s, aw: %f ah: %f => d: (%f, %f) %s\n",
|
|
getModeName(widthMeasureMode, performLayout),
|
|
getModeName(heightMeasureMode, performLayout),
|
|
availableWidth, availableHeight,
|
|
cachedResults->computedWidth, cachedResults->computedHeight, reason);
|
|
}
|
|
} else {
|
|
|
|
if (gPrintChanges) {
|
|
printf("%s%d.{%s", getSpacer(gDepth), gDepth, needToVisitNode ? "*" : "");
|
|
if (node->print) {
|
|
node->print(node->context);
|
|
}
|
|
printf("wm: %s, hm: %s, aw: %f ah: %f %s\n",
|
|
getModeName(widthMeasureMode, performLayout),
|
|
getModeName(heightMeasureMode, performLayout),
|
|
availableWidth, availableHeight, reason);
|
|
}
|
|
|
|
layoutNodeImpl(node, availableWidth, availableHeight, parentDirection, widthMeasureMode, heightMeasureMode, performLayout);
|
|
|
|
if (gPrintChanges) {
|
|
printf("%s%d.}%s", getSpacer(gDepth), gDepth, needToVisitNode ? "*" : "");
|
|
if (node->print) {
|
|
node->print(node->context);
|
|
}
|
|
printf("wm: %s, hm: %s, d: (%f, %f) %s\n",
|
|
getModeName(widthMeasureMode, performLayout),
|
|
getModeName(heightMeasureMode, performLayout),
|
|
layout->measuredDimensions[CSSDimensionWidth], layout->measuredDimensions[CSSDimensionHeight], reason);
|
|
}
|
|
|
|
layout->lastParentDirection = parentDirection;
|
|
|
|
if (cachedResults == NULL) {
|
|
if (layout->nextCachedMeasurementsIndex == CSS_MAX_CACHED_RESULT_COUNT) {
|
|
if (gPrintChanges) {
|
|
printf("Out of cache entries!\n");
|
|
}
|
|
layout->nextCachedMeasurementsIndex = 0;
|
|
}
|
|
|
|
CSSCachedMeasurement* newCacheEntry;
|
|
if (performLayout) {
|
|
// Use the single layout cache entry.
|
|
newCacheEntry = &layout->cached_layout;
|
|
} else {
|
|
// Allocate a new measurement cache entry.
|
|
newCacheEntry = &layout->cachedMeasurements[layout->nextCachedMeasurementsIndex];
|
|
layout->nextCachedMeasurementsIndex++;
|
|
}
|
|
|
|
newCacheEntry->availableWidth = availableWidth;
|
|
newCacheEntry->availableHeight = availableHeight;
|
|
newCacheEntry->widthMeasureMode = widthMeasureMode;
|
|
newCacheEntry->heightMeasureMode = heightMeasureMode;
|
|
newCacheEntry->computedWidth = layout->measuredDimensions[CSSDimensionWidth];
|
|
newCacheEntry->computedHeight = layout->measuredDimensions[CSSDimensionHeight];
|
|
}
|
|
}
|
|
|
|
if (performLayout) {
|
|
node->layout.dimensions[CSSDimensionWidth] = node->layout.measuredDimensions[CSSDimensionWidth];
|
|
node->layout.dimensions[CSSDimensionHeight] = node->layout.measuredDimensions[CSSDimensionHeight];
|
|
node->shouldUpdate = true;
|
|
}
|
|
|
|
gDepth--;
|
|
layout->generationCount = gCurrentGenerationCount;
|
|
return (needToVisitNode || cachedResults == NULL);
|
|
}
|
|
|
|
void CSSNodeCalculateLayout(CSSNode* node, float availableWidth, float availableHeight, CSSDirection parentDirection) {
|
|
// Increment the generation count. This will force the recursive routine to visit
|
|
// all dirty nodes at least once. Subsequent visits will be skipped if the input
|
|
// parameters don't change.
|
|
gCurrentGenerationCount++;
|
|
|
|
CSSMeasureMode widthMeasureMode = CSSMeasureModeUndefined;
|
|
CSSMeasureMode heightMeasureMode = CSSMeasureModeUndefined;
|
|
|
|
if (!isUndefined(availableWidth)) {
|
|
widthMeasureMode = CSSMeasureModeExactly;
|
|
} else if (isStyleDimDefined(node, CSSFlexDirectionRow)) {
|
|
availableWidth = node->style.dimensions[dim[CSSFlexDirectionRow]] + getMarginAxis(node, CSSFlexDirectionRow);
|
|
widthMeasureMode = CSSMeasureModeExactly;
|
|
} else if (node->style.maxDimensions[CSSDimensionWidth] >= 0.0) {
|
|
availableWidth = node->style.maxDimensions[CSSDimensionWidth];
|
|
widthMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
|
|
if (!isUndefined(availableHeight)) {
|
|
heightMeasureMode = CSSMeasureModeExactly;
|
|
} else if (isStyleDimDefined(node, CSSFlexDirectionColumn)) {
|
|
availableHeight = node->style.dimensions[dim[CSSFlexDirectionColumn]] + getMarginAxis(node, CSSFlexDirectionColumn);
|
|
heightMeasureMode = CSSMeasureModeExactly;
|
|
} else if (node->style.maxDimensions[CSSDimensionHeight] >= 0.0) {
|
|
availableHeight = node->style.maxDimensions[CSSDimensionHeight];
|
|
heightMeasureMode = CSSMeasureModeAtMost;
|
|
}
|
|
|
|
if (layoutNodeInternal(node, availableWidth, availableHeight, parentDirection, widthMeasureMode, heightMeasureMode, true, "initial")) {
|
|
|
|
setPosition(node, node->layout.direction);
|
|
|
|
if (gPrintTree) {
|
|
CSSNodePrint(node, CSSPrintOptionsLayout | CSSPrintOptionsChildren | CSSPrintOptionsStyle);
|
|
}
|
|
}
|
|
}
|