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react-native/React/Layout/Layout.c

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/**
*
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* !! This file is a check-in from github! !!
* !! !!
* !! You should not modify this file directly. Instead: !!
* !! 1) Go to https://github.com/facebook/css-layout !!
* !! 2) Make a pull request and get it merged !!
* !! 3) Copy the file from github to here !!
* !! (don't forget to keep this header) !!
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* @generated
*
* Copyright (c) 2014, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// in concatenated header, don't include Layout.h it's already at the top
#ifndef CSS_LAYOUT_IMPLEMENTATION
#include "Layout.h"
#endif
#ifdef _MSC_VER
#include <float.h>
#define isnan _isnan
/* define fmaxf if < VC12 */
#if _MSC_VER < 1800
__forceinline const float fmaxf(const float a, const float b) {
return (a > b) ? a : b;
}
#endif
#endif
#define POSITIVE_FLEX_IS_AUTO 0
int gCurrentGenerationCount = 0;
bool layoutNodeInternal(css_node_t* node, float availableWidth, float availableHeight, css_direction_t parentDirection,
css_measure_mode_t widthMeasureMode, css_measure_mode_t heightMeasureMode, bool performLayout, char* reason);
bool isUndefined(float value) {
return isnan(value);
}
static bool eq(float a, float b) {
if (isUndefined(a)) {
return isUndefined(b);
}
return fabs(a - b) < 0.0001;
}
void init_css_node(css_node_t* node) {
node->style.align_items = CSS_ALIGN_STRETCH;
node->style.align_content = CSS_ALIGN_FLEX_START;
node->style.direction = CSS_DIRECTION_INHERIT;
node->style.flex_direction = CSS_FLEX_DIRECTION_COLUMN;
node->style.overflow = CSS_OVERFLOW_VISIBLE;
// Some of the fields default to undefined and not 0
node->style.dimensions[CSS_WIDTH] = CSS_UNDEFINED;
node->style.dimensions[CSS_HEIGHT] = CSS_UNDEFINED;
node->style.minDimensions[CSS_WIDTH] = CSS_UNDEFINED;
node->style.minDimensions[CSS_HEIGHT] = CSS_UNDEFINED;
node->style.maxDimensions[CSS_WIDTH] = CSS_UNDEFINED;
node->style.maxDimensions[CSS_HEIGHT] = CSS_UNDEFINED;
node->style.position[CSS_LEFT] = CSS_UNDEFINED;
node->style.position[CSS_TOP] = CSS_UNDEFINED;
node->style.position[CSS_RIGHT] = CSS_UNDEFINED;
node->style.position[CSS_BOTTOM] = CSS_UNDEFINED;
node->style.margin[CSS_START] = CSS_UNDEFINED;
node->style.margin[CSS_END] = CSS_UNDEFINED;
node->style.padding[CSS_START] = CSS_UNDEFINED;
node->style.padding[CSS_END] = CSS_UNDEFINED;
node->style.border[CSS_START] = CSS_UNDEFINED;
node->style.border[CSS_END] = CSS_UNDEFINED;
node->layout.dimensions[CSS_WIDTH] = CSS_UNDEFINED;
node->layout.dimensions[CSS_HEIGHT] = CSS_UNDEFINED;
// Such that the comparison is always going to be false
node->layout.last_parent_direction = (css_direction_t)-1;
node->layout.should_update = true;
node->layout.next_cached_measurements_index = 0;
node->layout.measured_dimensions[CSS_WIDTH] = CSS_UNDEFINED;
node->layout.measured_dimensions[CSS_HEIGHT] = CSS_UNDEFINED;
node->layout.cached_layout.width_measure_mode = (css_measure_mode_t)-1;
node->layout.cached_layout.height_measure_mode = (css_measure_mode_t)-1;
}
css_node_t* new_css_node() {
css_node_t* node = (css_node_t*)calloc(1, sizeof(*node));
init_css_node(node);
return node;
}
void free_css_node(css_node_t* node) {
free(node);
}
static void indent(int n) {
for (int i = 0; i < n; ++i) {
printf(" ");
}
}
static void print_number_0(const char* str, float number) {
if (!eq(number, 0)) {
printf("%s: %g, ", str, number);
}
}
static void print_number_nan(const char* str, float number) {
if (!isnan(number)) {
printf("%s: %g, ", str, number);
}
}
static bool four_equal(float four[4]) {
return
eq(four[0], four[1]) &&
eq(four[0], four[2]) &&
eq(four[0], four[3]);
}
static void print_css_node_rec(
css_node_t* node,
css_print_options_t options,
int level
) {
indent(level);
printf("{");
if (node->print) {
node->print(node->context);
}
if (options & CSS_PRINT_LAYOUT) {
printf("layout: {");
printf("width: %g, ", node->layout.dimensions[CSS_WIDTH]);
printf("height: %g, ", node->layout.dimensions[CSS_HEIGHT]);
printf("top: %g, ", node->layout.position[CSS_TOP]);
printf("left: %g", node->layout.position[CSS_LEFT]);
printf("}, ");
}
if (options & CSS_PRINT_STYLE) {
if (node->style.flex_direction == CSS_FLEX_DIRECTION_COLUMN) {
printf("flexDirection: 'column', ");
} else if (node->style.flex_direction == CSS_FLEX_DIRECTION_COLUMN_REVERSE) {
printf("flexDirection: 'column-reverse', ");
} else if (node->style.flex_direction == CSS_FLEX_DIRECTION_ROW) {
printf("flexDirection: 'row', ");
} else if (node->style.flex_direction == CSS_FLEX_DIRECTION_ROW_REVERSE) {
printf("flexDirection: 'row-reverse', ");
}
if (node->style.justify_content == CSS_JUSTIFY_CENTER) {
printf("justifyContent: 'center', ");
} else if (node->style.justify_content == CSS_JUSTIFY_FLEX_END) {
printf("justifyContent: 'flex-end', ");
} else if (node->style.justify_content == CSS_JUSTIFY_SPACE_AROUND) {
printf("justifyContent: 'space-around', ");
} else if (node->style.justify_content == CSS_JUSTIFY_SPACE_BETWEEN) {
printf("justifyContent: 'space-between', ");
}
if (node->style.align_items == CSS_ALIGN_CENTER) {
printf("alignItems: 'center', ");
} else if (node->style.align_items == CSS_ALIGN_FLEX_END) {
printf("alignItems: 'flex-end', ");
} else if (node->style.align_items == CSS_ALIGN_STRETCH) {
printf("alignItems: 'stretch', ");
}
if (node->style.align_content == CSS_ALIGN_CENTER) {
printf("alignContent: 'center', ");
} else if (node->style.align_content == CSS_ALIGN_FLEX_END) {
printf("alignContent: 'flex-end', ");
} else if (node->style.align_content == CSS_ALIGN_STRETCH) {
printf("alignContent: 'stretch', ");
}
if (node->style.align_self == CSS_ALIGN_FLEX_START) {
printf("alignSelf: 'flex-start', ");
} else if (node->style.align_self == CSS_ALIGN_CENTER) {
printf("alignSelf: 'center', ");
} else if (node->style.align_self == CSS_ALIGN_FLEX_END) {
printf("alignSelf: 'flex-end', ");
} else if (node->style.align_self == CSS_ALIGN_STRETCH) {
printf("alignSelf: 'stretch', ");
}
print_number_nan("flex", node->style.flex);
if (node->style.overflow == CSS_OVERFLOW_HIDDEN) {
printf("overflow: 'hidden', ");
} else if (node->style.overflow == CSS_OVERFLOW_VISIBLE) {
printf("overflow: 'visible', ");
}
if (four_equal(node->style.margin)) {
print_number_0("margin", node->style.margin[CSS_LEFT]);
} else {
print_number_0("marginLeft", node->style.margin[CSS_LEFT]);
print_number_0("marginRight", node->style.margin[CSS_RIGHT]);
print_number_0("marginTop", node->style.margin[CSS_TOP]);
print_number_0("marginBottom", node->style.margin[CSS_BOTTOM]);
print_number_0("marginStart", node->style.margin[CSS_START]);
print_number_0("marginEnd", node->style.margin[CSS_END]);
}
if (four_equal(node->style.padding)) {
print_number_0("padding", node->style.padding[CSS_LEFT]);
} else {
print_number_0("paddingLeft", node->style.padding[CSS_LEFT]);
print_number_0("paddingRight", node->style.padding[CSS_RIGHT]);
print_number_0("paddingTop", node->style.padding[CSS_TOP]);
print_number_0("paddingBottom", node->style.padding[CSS_BOTTOM]);
print_number_0("paddingStart", node->style.padding[CSS_START]);
print_number_0("paddingEnd", node->style.padding[CSS_END]);
}
if (four_equal(node->style.border)) {
print_number_0("borderWidth", node->style.border[CSS_LEFT]);
} else {
print_number_0("borderLeftWidth", node->style.border[CSS_LEFT]);
print_number_0("borderRightWidth", node->style.border[CSS_RIGHT]);
print_number_0("borderTopWidth", node->style.border[CSS_TOP]);
print_number_0("borderBottomWidth", node->style.border[CSS_BOTTOM]);
print_number_0("borderStartWidth", node->style.border[CSS_START]);
print_number_0("borderEndWidth", node->style.border[CSS_END]);
}
print_number_nan("width", node->style.dimensions[CSS_WIDTH]);
print_number_nan("height", node->style.dimensions[CSS_HEIGHT]);
print_number_nan("maxWidth", node->style.maxDimensions[CSS_WIDTH]);
print_number_nan("maxHeight", node->style.maxDimensions[CSS_HEIGHT]);
print_number_nan("minWidth", node->style.minDimensions[CSS_WIDTH]);
print_number_nan("minHeight", node->style.minDimensions[CSS_HEIGHT]);
if (node->style.position_type == CSS_POSITION_ABSOLUTE) {
printf("position: 'absolute', ");
}
print_number_nan("left", node->style.position[CSS_LEFT]);
print_number_nan("right", node->style.position[CSS_RIGHT]);
print_number_nan("top", node->style.position[CSS_TOP]);
print_number_nan("bottom", node->style.position[CSS_BOTTOM]);
}
if (options & CSS_PRINT_CHILDREN && node->children_count > 0) {
printf("children: [\n");
for (int i = 0; i < node->children_count; ++i) {
print_css_node_rec(node->get_child(node->context, i), options, level + 1);
}
indent(level);
printf("]},\n");
} else {
printf("},\n");
}
}
void print_css_node(css_node_t* node, css_print_options_t options) {
print_css_node_rec(node, options, 0);
}
static css_position_t leading[4] = {
/* CSS_FLEX_DIRECTION_COLUMN = */ CSS_TOP,
/* CSS_FLEX_DIRECTION_COLUMN_REVERSE = */ CSS_BOTTOM,
/* CSS_FLEX_DIRECTION_ROW = */ CSS_LEFT,
/* CSS_FLEX_DIRECTION_ROW_REVERSE = */ CSS_RIGHT
};
static css_position_t trailing[4] = {
/* CSS_FLEX_DIRECTION_COLUMN = */ CSS_BOTTOM,
/* CSS_FLEX_DIRECTION_COLUMN_REVERSE = */ CSS_TOP,
/* CSS_FLEX_DIRECTION_ROW = */ CSS_RIGHT,
/* CSS_FLEX_DIRECTION_ROW_REVERSE = */ CSS_LEFT
};
static css_position_t pos[4] = {
/* CSS_FLEX_DIRECTION_COLUMN = */ CSS_TOP,
/* CSS_FLEX_DIRECTION_COLUMN_REVERSE = */ CSS_BOTTOM,
/* CSS_FLEX_DIRECTION_ROW = */ CSS_LEFT,
/* CSS_FLEX_DIRECTION_ROW_REVERSE = */ CSS_RIGHT
};
static css_dimension_t dim[4] = {
/* CSS_FLEX_DIRECTION_COLUMN = */ CSS_HEIGHT,
/* CSS_FLEX_DIRECTION_COLUMN_REVERSE = */ CSS_HEIGHT,
/* CSS_FLEX_DIRECTION_ROW = */ CSS_WIDTH,
/* CSS_FLEX_DIRECTION_ROW_REVERSE = */ CSS_WIDTH
};
static bool isRowDirection(css_flex_direction_t flex_direction) {
return flex_direction == CSS_FLEX_DIRECTION_ROW ||
flex_direction == CSS_FLEX_DIRECTION_ROW_REVERSE;
}
static bool isColumnDirection(css_flex_direction_t flex_direction) {
return flex_direction == CSS_FLEX_DIRECTION_COLUMN ||
flex_direction == CSS_FLEX_DIRECTION_COLUMN_REVERSE;
}
static bool isFlexBasisAuto(css_node_t* node) {
#if POSITIVE_FLEX_IS_AUTO
// All flex values are auto.
(void) node;
return true;
#else
// A flex value > 0 implies a basis of zero.
return node->style.flex <= 0;
#endif
}
static float getFlexGrowFactor(css_node_t* node) {
// Flex grow is implied by positive values for flex.
if (node->style.flex > 0) {
return node->style.flex;
}
return 0;
}
static float getFlexShrinkFactor(css_node_t* node) {
#if POSITIVE_FLEX_IS_AUTO
// A flex shrink factor of 1 is implied by non-zero values for flex.
if (node->style.flex != 0) {
return 1;
}
#else
// A flex shrink factor of 1 is implied by negative values for flex.
if (node->style.flex < 0) {
return 1;
}
#endif
return 0;
}
static float getLeadingMargin(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) && !isUndefined(node->style.margin[CSS_START])) {
return node->style.margin[CSS_START];
}
return node->style.margin[leading[axis]];
}
static float getTrailingMargin(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) && !isUndefined(node->style.margin[CSS_END])) {
return node->style.margin[CSS_END];
}
return node->style.margin[trailing[axis]];
}
static float getLeadingPadding(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) &&
!isUndefined(node->style.padding[CSS_START]) &&
node->style.padding[CSS_START] >= 0) {
return node->style.padding[CSS_START];
}
if (node->style.padding[leading[axis]] >= 0) {
return node->style.padding[leading[axis]];
}
return 0;
}
static float getTrailingPadding(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) &&
!isUndefined(node->style.padding[CSS_END]) &&
node->style.padding[CSS_END] >= 0) {
return node->style.padding[CSS_END];
}
if (node->style.padding[trailing[axis]] >= 0) {
return node->style.padding[trailing[axis]];
}
return 0;
}
static float getLeadingBorder(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) &&
!isUndefined(node->style.border[CSS_START]) &&
node->style.border[CSS_START] >= 0) {
return node->style.border[CSS_START];
}
if (node->style.border[leading[axis]] >= 0) {
return node->style.border[leading[axis]];
}
return 0;
}
static float getTrailingBorder(css_node_t* node, css_flex_direction_t axis) {
if (isRowDirection(axis) &&
!isUndefined(node->style.border[CSS_END]) &&
node->style.border[CSS_END] >= 0) {
return node->style.border[CSS_END];
}
if (node->style.border[trailing[axis]] >= 0) {
return node->style.border[trailing[axis]];
}
return 0;
}
static float getLeadingPaddingAndBorder(css_node_t* node, css_flex_direction_t axis) {
return getLeadingPadding(node, axis) + getLeadingBorder(node, axis);
}
static float getTrailingPaddingAndBorder(css_node_t* node, css_flex_direction_t axis) {
return getTrailingPadding(node, axis) + getTrailingBorder(node, axis);
}
static float getMarginAxis(css_node_t* node, css_flex_direction_t axis) {
return getLeadingMargin(node, axis) + getTrailingMargin(node, axis);
}
static float getPaddingAndBorderAxis(css_node_t* node, css_flex_direction_t axis) {
return getLeadingPaddingAndBorder(node, axis) + getTrailingPaddingAndBorder(node, axis);
}
static css_align_t getAlignItem(css_node_t* node, css_node_t* child) {
if (child->style.align_self != CSS_ALIGN_AUTO) {
return child->style.align_self;
}
return node->style.align_items;
}
static css_direction_t resolveDirection(css_node_t* node, css_direction_t parentDirection) {
css_direction_t direction = node->style.direction;
if (direction == CSS_DIRECTION_INHERIT) {
direction = parentDirection > CSS_DIRECTION_INHERIT ? parentDirection : CSS_DIRECTION_LTR;
}
return direction;
}
static css_flex_direction_t getFlexDirection(css_node_t* node) {
return node->style.flex_direction;
}
static css_flex_direction_t resolveAxis(css_flex_direction_t flex_direction, css_direction_t direction) {
if (direction == CSS_DIRECTION_RTL) {
if (flex_direction == CSS_FLEX_DIRECTION_ROW) {
return CSS_FLEX_DIRECTION_ROW_REVERSE;
} else if (flex_direction == CSS_FLEX_DIRECTION_ROW_REVERSE) {
return CSS_FLEX_DIRECTION_ROW;
}
}
return flex_direction;
}
static css_flex_direction_t getCrossFlexDirection(css_flex_direction_t flex_direction, css_direction_t direction) {
if (isColumnDirection(flex_direction)) {
return resolveAxis(CSS_FLEX_DIRECTION_ROW, direction);
} else {
return CSS_FLEX_DIRECTION_COLUMN;
}
}
static float getFlex(css_node_t* node) {
return node->style.flex;
}
static bool isFlex(css_node_t* node) {
return (
node->style.position_type == CSS_POSITION_RELATIVE &&
getFlex(node) != 0
);
}
static bool isFlexWrap(css_node_t* node) {
return node->style.flex_wrap == CSS_WRAP;
}
static float getDimWithMargin(css_node_t* node, css_flex_direction_t axis) {
return node->layout.measured_dimensions[dim[axis]] +
getLeadingMargin(node, axis) +
getTrailingMargin(node, axis);
}
static bool isStyleDimDefined(css_node_t* node, css_flex_direction_t axis) {
float value = node->style.dimensions[dim[axis]];
return !isUndefined(value) && value >= 0.0;
}
static bool isLayoutDimDefined(css_node_t* node, css_flex_direction_t axis) {
float value = node->layout.measured_dimensions[dim[axis]];
return !isUndefined(value) && value >= 0.0;
}
static bool isPosDefined(css_node_t* node, css_position_t position) {
return !isUndefined(node->style.position[position]);
}
static bool isMeasureDefined(css_node_t* node) {
return node->measure;
}
static float getPosition(css_node_t* node, css_position_t position) {
float result = node->style.position[position];
if (!isUndefined(result)) {
return result;
}
return 0;
}
static float boundAxisWithinMinAndMax(css_node_t* node, css_flex_direction_t axis, float value) {
float min = CSS_UNDEFINED;
float max = CSS_UNDEFINED;
if (isColumnDirection(axis)) {
min = node->style.minDimensions[CSS_HEIGHT];
max = node->style.maxDimensions[CSS_HEIGHT];
} else if (isRowDirection(axis)) {
min = node->style.minDimensions[CSS_WIDTH];
max = node->style.maxDimensions[CSS_WIDTH];
}
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(css_node_t* node, css_flex_direction_t axis, float value) {
return fmaxf(boundAxisWithinMinAndMax(node, axis, value), getPaddingAndBorderAxis(node, axis));
}
static void setTrailingPosition(css_node_t* node, css_node_t* child, css_flex_direction_t axis) {
float size = child->style.position_type == CSS_POSITION_ABSOLUTE ?
0 :
child->layout.measured_dimensions[dim[axis]];
child->layout.position[trailing[axis]] = node->layout.measured_dimensions[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(css_node_t* node, css_flex_direction_t axis) {
float lead = node->style.position[leading[axis]];
if (!isUndefined(lead)) {
return lead;
}
return -getPosition(node, trailing[axis]);
}
static void setPosition(css_node_t* node, css_direction_t direction) {
css_flex_direction_t mainAxis = resolveAxis(getFlexDirection(node), direction);
css_flex_direction_t 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 CSS_UNDEFINED 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.measured_dimensions fields for the input node as well
// as the layout.position and layout.line_index fields for its child nodes. The
// layout.measured_dimensions 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):
// - CSS_MEASURE_MODE_UNDEFINED: max content
// - CSS_MEASURE_MODE_EXACTLY: fill available
// - CSS_MEASURE_MODE_AT_MOST: 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 CSS_MEASURE_MODE_UNDEFINED in that dimension.
//
static void layoutNodeImpl(css_node_t* node, float availableWidth, float availableHeight,
css_direction_t parentDirection, css_measure_mode_t widthMeasureMode, css_measure_mode_t heightMeasureMode, bool performLayout) {
/** START_GENERATED **/
assert(isUndefined(availableWidth) ? widthMeasureMode == CSS_MEASURE_MODE_UNDEFINED : true); // availableWidth is indefinite so widthMeasureMode must be CSS_MEASURE_MODE_UNDEFINED
assert(isUndefined(availableHeight) ? heightMeasureMode == CSS_MEASURE_MODE_UNDEFINED : true); // availableHeight is indefinite so heightMeasureMode must be CSS_MEASURE_MODE_UNDEFINED
float paddingAndBorderAxisRow = getPaddingAndBorderAxis(node, CSS_FLEX_DIRECTION_ROW);
float paddingAndBorderAxisColumn = getPaddingAndBorderAxis(node, CSS_FLEX_DIRECTION_COLUMN);
float marginAxisRow = getMarginAxis(node, CSS_FLEX_DIRECTION_ROW);
float marginAxisColumn = getMarginAxis(node, CSS_FLEX_DIRECTION_COLUMN);
// Set the resolved resolution in the node's layout.
css_direction_t 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 == CSS_MEASURE_MODE_EXACTLY && heightMeasureMode == CSS_MEASURE_MODE_EXACTLY) {
// Don't bother sizing the text if both dimensions are already defined.
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, availableWidth - marginAxisRow);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, availableHeight - marginAxisColumn);
} else if (innerWidth <= 0 || innerHeight <= 0) {
// Don't bother sizing the text if there's no horizontal or vertical space.
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, 0);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, 0);
} else {
// Measure the text under the current constraints.
css_dim_t measureDim = node->measure(
node->context,
innerWidth,
widthMeasureMode,
innerHeight,
heightMeasureMode
);
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW,
(widthMeasureMode == CSS_MEASURE_MODE_UNDEFINED || widthMeasureMode == CSS_MEASURE_MODE_AT_MOST) ?
measureDim.dimensions[CSS_WIDTH] + paddingAndBorderAxisRow :
availableWidth - marginAxisRow);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN,
(heightMeasureMode == CSS_MEASURE_MODE_UNDEFINED || heightMeasureMode == CSS_MEASURE_MODE_AT_MOST) ?
measureDim.dimensions[CSS_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->children_count;
if (childCount == 0) {
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW,
(widthMeasureMode == CSS_MEASURE_MODE_UNDEFINED || widthMeasureMode == CSS_MEASURE_MODE_AT_MOST) ?
paddingAndBorderAxisRow :
availableWidth - marginAxisRow);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN,
(heightMeasureMode == CSS_MEASURE_MODE_UNDEFINED || heightMeasureMode == CSS_MEASURE_MODE_AT_MOST) ?
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 == CSS_MEASURE_MODE_AT_MOST && availableWidth <= 0 &&
heightMeasureMode == CSS_MEASURE_MODE_AT_MOST && availableHeight <= 0) {
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, 0);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, 0);
return;
}
if (widthMeasureMode == CSS_MEASURE_MODE_AT_MOST && availableWidth <= 0) {
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, 0);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, isUndefined(availableHeight) ? 0 : (availableHeight - marginAxisColumn));
return;
}
if (heightMeasureMode == CSS_MEASURE_MODE_AT_MOST && availableHeight <= 0) {
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, isUndefined(availableWidth) ? 0 : (availableWidth - marginAxisRow));
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, 0);
return;
}
// If we're being asked to use an exact width/height, there's no need to measure the children.
if (widthMeasureMode == CSS_MEASURE_MODE_EXACTLY && heightMeasureMode == CSS_MEASURE_MODE_EXACTLY) {
node->layout.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, availableWidth - marginAxisRow);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, availableHeight - marginAxisColumn);
return;
}
}
// STEP 1: CALCULATE VALUES FOR REMAINDER OF ALGORITHM
css_flex_direction_t mainAxis = resolveAxis(getFlexDirection(node), direction);
css_flex_direction_t crossAxis = getCrossFlexDirection(mainAxis, direction);
bool isMainAxisRow = isRowDirection(mainAxis);
css_justify_t justifyContent = node->style.justify_content;
bool isNodeFlexWrap = isFlexWrap(node);
css_node_t* firstAbsoluteChild = NULL;
css_node_t* 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);
css_measure_mode_t measureModeMainDim = isMainAxisRow ? widthMeasureMode : heightMeasureMode;
css_measure_mode_t 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
css_node_t* child;
int i;
float childWidth;
float childHeight;
css_measure_mode_t childWidthMeasureMode;
css_measure_mode_t childHeightMeasureMode;
for (i = 0; i < childCount; i++) {
child = node->get_child(node->context, i);
if (performLayout) {
// Set the initial position (relative to the parent).
css_direction_t 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.position_type == CSS_POSITION_ABSOLUTE) {
// 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->next_child = child;
}
currentAbsoluteChild = child;
child->next_child = NULL;
} else {
if (isMainAxisRow && isStyleDimDefined(child, CSS_FLEX_DIRECTION_ROW)) {
// The width is definite, so use that as the flex basis.
child->layout.flex_basis = fmaxf(child->style.dimensions[CSS_WIDTH], getPaddingAndBorderAxis(child, CSS_FLEX_DIRECTION_ROW));
} else if (!isMainAxisRow && isStyleDimDefined(child, CSS_FLEX_DIRECTION_COLUMN)) {
// The height is definite, so use that as the flex basis.
child->layout.flex_basis = fmaxf(child->style.dimensions[CSS_HEIGHT], getPaddingAndBorderAxis(child, CSS_FLEX_DIRECTION_COLUMN));
} else if (!isFlexBasisAuto(child) && !isUndefined(availableInnerMainDim)) {
// If the basis isn't 'auto', it is assumed to be zero.
child->layout.flex_basis = fmaxf(0, getPaddingAndBorderAxis(child, mainAxis));
} else {
// Compute the flex basis and hypothetical main size (i.e. the clamped flex basis).
childWidth = CSS_UNDEFINED;
childHeight = CSS_UNDEFINED;
childWidthMeasureMode = CSS_MEASURE_MODE_UNDEFINED;
childHeightMeasureMode = CSS_MEASURE_MODE_UNDEFINED;
if (isStyleDimDefined(child, CSS_FLEX_DIRECTION_ROW)) {
childWidth = child->style.dimensions[CSS_WIDTH] + getMarginAxis(child, CSS_FLEX_DIRECTION_ROW);
childWidthMeasureMode = CSS_MEASURE_MODE_EXACTLY;
}
if (isStyleDimDefined(child, CSS_FLEX_DIRECTION_COLUMN)) {
childHeight = child->style.dimensions[CSS_HEIGHT] + getMarginAxis(child, CSS_FLEX_DIRECTION_COLUMN);
childHeightMeasureMode = CSS_MEASURE_MODE_EXACTLY;
}
// 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 = CSS_MEASURE_MODE_AT_MOST;
}
// 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 == CSS_OVERFLOW_HIDDEN) {
if (isMainAxisRow && isUndefined(childHeight) && !isUndefined(availableInnerHeight)) {
childHeight = availableInnerHeight;
childHeightMeasureMode = CSS_MEASURE_MODE_AT_MOST;
}
}
// Measure the child
layoutNodeInternal(child, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, false, "measure");
child->layout.flex_basis = fmaxf(isMainAxisRow ? child->layout.measured_dimensions[CSS_WIDTH] : child->layout.measured_dimensions[CSS_HEIGHT], 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.
css_node_t* firstRelativeChild = NULL;
css_node_t* currentRelativeChild = NULL;
// Add items to the current line until it's full or we run out of items.
while (i < childCount) {
child = node->get_child(node->context, i);
child->line_index = lineCount;
if (child->style.position_type != CSS_POSITION_ABSOLUTE) {
float outerFlexBasis = child->layout.flex_basis + 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.flex_basis;
}
// Store a private linked list of children that need to be layed out.
if (firstRelativeChild == NULL) {
firstRelativeChild = child;
}
if (currentRelativeChild != NULL) {
currentRelativeChild->next_child = child;
}
currentRelativeChild = child;
child->next_child = NULL;
}
i++;
endOfLineIndex++;
}
// If we don't need to measure the cross axis, we can skip the entire flex step.
bool canSkipFlex = !performLayout && measureModeCrossDim == CSS_MEASURE_MODE_EXACTLY;
// 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.flex_basis;
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->next_child;
}
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.flex_basis;
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, CSS_FLEX_DIRECTION_ROW);
childWidthMeasureMode = CSS_MEASURE_MODE_EXACTLY;
if (!isStyleDimDefined(currentRelativeChild, CSS_FLEX_DIRECTION_COLUMN)) {
childHeight = availableInnerCrossDim;
childHeightMeasureMode = isUndefined(childHeight) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_AT_MOST;
} else {
childHeight = currentRelativeChild->style.dimensions[CSS_HEIGHT] + getMarginAxis(currentRelativeChild, CSS_FLEX_DIRECTION_COLUMN);
childHeightMeasureMode = CSS_MEASURE_MODE_EXACTLY;
}
} else {
childHeight = updatedMainSize + getMarginAxis(currentRelativeChild, CSS_FLEX_DIRECTION_COLUMN);
childHeightMeasureMode = CSS_MEASURE_MODE_EXACTLY;
if (!isStyleDimDefined(currentRelativeChild, CSS_FLEX_DIRECTION_ROW)) {
childWidth = availableInnerCrossDim;
childWidthMeasureMode = isUndefined(childWidth) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_AT_MOST;
} else {
childWidth = currentRelativeChild->style.dimensions[CSS_WIDTH] + getMarginAxis(currentRelativeChild, CSS_FLEX_DIRECTION_ROW);
childWidthMeasureMode = CSS_MEASURE_MODE_EXACTLY;
}
}
bool requiresStretchLayout = !isStyleDimDefined(currentRelativeChild, crossAxis) &&
getAlignItem(node, currentRelativeChild) == CSS_ALIGN_STRETCH;
// 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->next_child;
}
}
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 == CSS_MEASURE_MODE_AT_MOST) {
remainingFreeSpace = 0;
}
// Use justifyContent to figure out how to allocate the remaining space
// available in the main axis.
if (justifyContent != CSS_JUSTIFY_FLEX_START) {
if (justifyContent == CSS_JUSTIFY_CENTER) {
leadingMainDim = remainingFreeSpace / 2;
} else if (justifyContent == CSS_JUSTIFY_FLEX_END) {
leadingMainDim = remainingFreeSpace;
} else if (justifyContent == CSS_JUSTIFY_SPACE_BETWEEN) {
remainingFreeSpace = fmaxf(remainingFreeSpace, 0);
if (itemsOnLine > 1) {
betweenMainDim = remainingFreeSpace / (itemsOnLine - 1);
} else {
betweenMainDim = 0;
}
} else if (justifyContent == CSS_JUSTIFY_SPACE_AROUND) {
// 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->get_child(node->context, i);
if (child->style.position_type == CSS_POSITION_ABSOLUTE &&
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.position_type == CSS_POSITION_RELATIVE) {
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.flex_basis;
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 == CSS_MEASURE_MODE_UNDEFINED || measureModeCrossDim == CSS_MEASURE_MODE_AT_MOST) {
// Compute the cross axis from the max cross dimension of the children.
containerCrossAxis = boundAxis(node, crossAxis, crossDim + paddingAndBorderAxisCross) - paddingAndBorderAxisCross;
if (measureModeCrossDim == CSS_MEASURE_MODE_AT_MOST) {
containerCrossAxis = fminf(containerCrossAxis, availableInnerCrossDim);
}
}
// If there's no flex wrap, the cross dimension is defined by the container.
if (!isNodeFlexWrap && measureModeCrossDim == CSS_MEASURE_MODE_EXACTLY) {
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->get_child(node->context, i);
if (child->style.position_type == CSS_POSITION_ABSOLUTE) {
// 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
css_align_t 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 == CSS_ALIGN_STRETCH) {
childWidth = child->layout.measured_dimensions[CSS_WIDTH] + getMarginAxis(child, CSS_FLEX_DIRECTION_ROW);
childHeight = child->layout.measured_dimensions[CSS_HEIGHT] + getMarginAxis(child, CSS_FLEX_DIRECTION_COLUMN);
bool isCrossSizeDefinite = false;
if (isMainAxisRow) {
isCrossSizeDefinite = isStyleDimDefined(child, CSS_FLEX_DIRECTION_COLUMN);
childHeight = crossDim;
} else {
isCrossSizeDefinite = isStyleDimDefined(child, CSS_FLEX_DIRECTION_ROW);
childWidth = crossDim;
}
// If the child defines a definite size for its cross axis, there's no need to stretch.
if (!isCrossSizeDefinite) {
childWidthMeasureMode = isUndefined(childWidth) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
childHeightMeasureMode = isUndefined(childHeight) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
layoutNodeInternal(child, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, true, "stretch");
}
} else if (alignItem != CSS_ALIGN_FLEX_START) {
float remainingCrossDim = containerCrossAxis - getDimWithMargin(child, crossAxis);
if (alignItem == CSS_ALIGN_CENTER) {
leadingCrossDim += remainingCrossDim / 2;
} else { // CSS_ALIGN_FLEX_END
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;
css_align_t alignContent = node->style.align_content;
if (alignContent == CSS_ALIGN_FLEX_END) {
currentLead += remainingAlignContentDim;
} else if (alignContent == CSS_ALIGN_CENTER) {
currentLead += remainingAlignContentDim / 2;
} else if (alignContent == CSS_ALIGN_STRETCH) {
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->get_child(node->context, j);
if (child->style.position_type != CSS_POSITION_RELATIVE) {
continue;
}
if (child->line_index != i) {
break;
}
if (isLayoutDimDefined(child, crossAxis)) {
lineHeight = fmaxf(lineHeight,
child->layout.measured_dimensions[dim[crossAxis]] + getMarginAxis(child, crossAxis));
}
}
endIndex = j;
lineHeight += crossDimLead;
if (performLayout) {
for (j = startIndex; j < endIndex; ++j) {
child = node->get_child(node->context, j);
if (child->style.position_type != CSS_POSITION_RELATIVE) {
continue;
}
css_align_t alignContentAlignItem = getAlignItem(node, child);
if (alignContentAlignItem == CSS_ALIGN_FLEX_START) {
child->layout.position[pos[crossAxis]] = currentLead + getLeadingMargin(child, crossAxis);
} else if (alignContentAlignItem == CSS_ALIGN_FLEX_END) {
child->layout.position[pos[crossAxis]] = currentLead + lineHeight - getTrailingMargin(child, crossAxis) - child->layout.measured_dimensions[dim[crossAxis]];
} else if (alignContentAlignItem == CSS_ALIGN_CENTER) {
childHeight = child->layout.measured_dimensions[dim[crossAxis]];
child->layout.position[pos[crossAxis]] = currentLead + (lineHeight - childHeight) / 2;
} else if (alignContentAlignItem == CSS_ALIGN_STRETCH) {
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.measured_dimensions[CSS_WIDTH] = boundAxis(node, CSS_FLEX_DIRECTION_ROW, availableWidth - marginAxisRow);
node->layout.measured_dimensions[CSS_HEIGHT] = boundAxis(node, CSS_FLEX_DIRECTION_COLUMN, availableHeight - marginAxisColumn);
// If the user didn't specify a width or height for the node, set the
// dimensions based on the children.
if (measureModeMainDim == CSS_MEASURE_MODE_UNDEFINED) {
// 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.measured_dimensions[dim[mainAxis]] = boundAxis(node, mainAxis, maxLineMainDim);
} else if (measureModeMainDim == CSS_MEASURE_MODE_AT_MOST) {
node->layout.measured_dimensions[dim[mainAxis]] = fmaxf(
fminf(availableInnerMainDim + paddingAndBorderAxisMain,
boundAxisWithinMinAndMax(node, mainAxis, maxLineMainDim)),
paddingAndBorderAxisMain);
}
if (measureModeCrossDim == CSS_MEASURE_MODE_UNDEFINED) {
// 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.measured_dimensions[dim[crossAxis]] = boundAxis(node, crossAxis, totalLineCrossDim + paddingAndBorderAxisCross);
} else if (measureModeCrossDim == CSS_MEASURE_MODE_AT_MOST) {
node->layout.measured_dimensions[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 == CSS_FLEX_DIRECTION_ROW_REVERSE ||
mainAxis == CSS_FLEX_DIRECTION_COLUMN_REVERSE) {
needsMainTrailingPos = true;
}
if (crossAxis == CSS_FLEX_DIRECTION_ROW_REVERSE ||
crossAxis == CSS_FLEX_DIRECTION_COLUMN_REVERSE) {
needsCrossTrailingPos = true;
}
// Set trailing position if necessary.
if (needsMainTrailingPos || needsCrossTrailingPos) {
for (i = 0; i < childCount; ++i) {
child = node->get_child(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 = CSS_UNDEFINED;
childHeight = CSS_UNDEFINED;
if (isStyleDimDefined(currentAbsoluteChild, CSS_FLEX_DIRECTION_ROW)) {
childWidth = currentAbsoluteChild->style.dimensions[CSS_WIDTH] + getMarginAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_ROW);
} 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, CSS_LEFT) && isPosDefined(currentAbsoluteChild, CSS_RIGHT)) {
childWidth = node->layout.measured_dimensions[CSS_WIDTH] -
(getLeadingBorder(node, CSS_FLEX_DIRECTION_ROW) + getTrailingBorder(node, CSS_FLEX_DIRECTION_ROW)) -
(currentAbsoluteChild->style.position[CSS_LEFT] + currentAbsoluteChild->style.position[CSS_RIGHT]);
childWidth = boundAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_ROW, childWidth);
}
}
if (isStyleDimDefined(currentAbsoluteChild, CSS_FLEX_DIRECTION_COLUMN)) {
childHeight = currentAbsoluteChild->style.dimensions[CSS_HEIGHT] + getMarginAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_COLUMN);
} 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, CSS_TOP) && isPosDefined(currentAbsoluteChild, CSS_BOTTOM)) {
childHeight = node->layout.measured_dimensions[CSS_HEIGHT] -
(getLeadingBorder(node, CSS_FLEX_DIRECTION_COLUMN) + getTrailingBorder(node, CSS_FLEX_DIRECTION_COLUMN)) -
(currentAbsoluteChild->style.position[CSS_TOP] + currentAbsoluteChild->style.position[CSS_BOTTOM]);
childHeight = boundAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_COLUMN, childHeight);
}
}
// If we're still missing one or the other dimension, measure the content.
if (isUndefined(childWidth) || isUndefined(childHeight)) {
childWidthMeasureMode = isUndefined(childWidth) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
childHeightMeasureMode = isUndefined(childHeight) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
// 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 = CSS_MEASURE_MODE_AT_MOST;
}
// 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 == CSS_OVERFLOW_HIDDEN) {
if (isMainAxisRow && isUndefined(childHeight) && !isUndefined(availableInnerHeight)) {
childHeight = availableInnerHeight;
childHeightMeasureMode = CSS_MEASURE_MODE_AT_MOST;
}
}
layoutNodeInternal(currentAbsoluteChild, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, false, "abs-measure");
childWidth = currentAbsoluteChild->layout.measured_dimensions[CSS_WIDTH] + getMarginAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_ROW);
childHeight = currentAbsoluteChild->layout.measured_dimensions[CSS_HEIGHT] + getMarginAxis(currentAbsoluteChild, CSS_FLEX_DIRECTION_COLUMN);
}
layoutNodeInternal(currentAbsoluteChild, childWidth, childHeight, direction, CSS_MEASURE_MODE_EXACTLY, CSS_MEASURE_MODE_EXACTLY, true, "abs-layout");
if (isPosDefined(currentAbsoluteChild, trailing[CSS_FLEX_DIRECTION_ROW]) &&
!isPosDefined(currentAbsoluteChild, leading[CSS_FLEX_DIRECTION_ROW])) {
currentAbsoluteChild->layout.position[leading[CSS_FLEX_DIRECTION_ROW]] =
node->layout.measured_dimensions[dim[CSS_FLEX_DIRECTION_ROW]] -
currentAbsoluteChild->layout.measured_dimensions[dim[CSS_FLEX_DIRECTION_ROW]] -
getPosition(currentAbsoluteChild, trailing[CSS_FLEX_DIRECTION_ROW]);
}
if (isPosDefined(currentAbsoluteChild, trailing[CSS_FLEX_DIRECTION_COLUMN]) &&
!isPosDefined(currentAbsoluteChild, leading[CSS_FLEX_DIRECTION_COLUMN])) {
currentAbsoluteChild->layout.position[leading[CSS_FLEX_DIRECTION_COLUMN]] =
node->layout.measured_dimensions[dim[CSS_FLEX_DIRECTION_COLUMN]] -
currentAbsoluteChild->layout.measured_dimensions[dim[CSS_FLEX_DIRECTION_COLUMN]] -
getPosition(currentAbsoluteChild, trailing[CSS_FLEX_DIRECTION_COLUMN]);
}
}
currentAbsoluteChild = currentAbsoluteChild->next_child;
}
/** END_GENERATED **/
}
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(css_measure_mode_t mode, bool performLayout) {
const char* kMeasureModeNames[CSS_MEASURE_MODE_COUNT] = {
"UNDEFINED",
"EXACTLY",
"AT_MOST"
};
const char* kLayoutModeNames[CSS_MEASURE_MODE_COUNT] = {
"LAY_UNDEFINED",
"LAY_EXACTLY",
"LAY_AT_MOST"
};
if (mode >= CSS_MEASURE_MODE_COUNT) {
return "";
}
return performLayout? kLayoutModeNames[mode] : kMeasureModeNames[mode];
}
static bool canUseCachedMeasurement(float availableWidth, float availableHeight,
float marginRow, float marginColumn,
css_measure_mode_t widthMeasureMode, css_measure_mode_t heightMeasureMode,
css_cached_measurement_t cachedLayout) {
// Is it an exact match?
if (eq(cachedLayout.available_width, availableWidth) &&
eq(cachedLayout.available_height, availableHeight) &&
cachedLayout.width_measure_mode == widthMeasureMode &&
cachedLayout.height_measure_mode == heightMeasureMode) {
return true;
}
// If the width is an exact match, try a fuzzy match on the height.
if (cachedLayout.width_measure_mode == widthMeasureMode &&
eq(cachedLayout.available_width, availableWidth) &&
heightMeasureMode == CSS_MEASURE_MODE_EXACTLY &&
eq(availableHeight - marginColumn, cachedLayout.computed_height)) {
return true;
}
// If the height is an exact match, try a fuzzy match on the width.
if (cachedLayout.height_measure_mode == heightMeasureMode &&
eq(cachedLayout.available_height, availableHeight) &&
widthMeasureMode == CSS_MEASURE_MODE_EXACTLY &&
eq(availableWidth - marginRow, cachedLayout.computed_width)) {
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(css_node_t* node, float availableWidth, float availableHeight,
css_direction_t parentDirection, css_measure_mode_t widthMeasureMode, css_measure_mode_t heightMeasureMode, bool performLayout, char* reason) {
css_layout_t* layout = &node->layout;
gDepth++;
bool needToVisitNode = (node->is_dirty(node->context) && layout->generation_count != gCurrentGenerationCount) ||
layout->last_parent_direction != parentDirection;
if (needToVisitNode) {
// Invalidate the cached results.
layout->next_cached_measurements_index = 0;
layout->cached_layout.width_measure_mode = (css_measure_mode_t)-1;
layout->cached_layout.height_measure_mode = (css_measure_mode_t)-1;
}
css_cached_measurement_t* 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, CSS_FLEX_DIRECTION_ROW);
float marginAxisColumn = getMarginAxis(node, CSS_FLEX_DIRECTION_COLUMN);
// First, try to use the layout cache.
if (canUseCachedMeasurement(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->next_cached_measurements_index; i++) {
if (canUseCachedMeasurement(availableWidth, availableHeight, marginAxisRow, marginAxisColumn,
widthMeasureMode, heightMeasureMode, layout->cached_measurements[i])) {
cachedResults = &layout->cached_measurements[i];
break;
}
}
}
} else if (performLayout) {
if (eq(layout->cached_layout.available_width, availableWidth) &&
eq(layout->cached_layout.available_height, availableHeight) &&
layout->cached_layout.width_measure_mode == widthMeasureMode &&
layout->cached_layout.height_measure_mode == heightMeasureMode) {
cachedResults = &layout->cached_layout;
}
} else {
for (int i = 0; i < layout->next_cached_measurements_index; i++) {
if (eq(layout->cached_measurements[i].available_width, availableWidth) &&
eq(layout->cached_measurements[i].available_height, availableHeight) &&
layout->cached_measurements[i].width_measure_mode == widthMeasureMode &&
layout->cached_measurements[i].height_measure_mode == heightMeasureMode) {
cachedResults = &layout->cached_measurements[i];
break;
}
}
}
if (!needToVisitNode && cachedResults != NULL) {
layout->measured_dimensions[CSS_WIDTH] = cachedResults->computed_width;
layout->measured_dimensions[CSS_HEIGHT] = cachedResults->computed_height;
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->computed_width, cachedResults->computed_height, 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->measured_dimensions[CSS_WIDTH], layout->measured_dimensions[CSS_HEIGHT], reason);
}
layout->last_parent_direction = parentDirection;
if (cachedResults == NULL) {
if (layout->next_cached_measurements_index == CSS_MAX_CACHED_RESULT_COUNT) {
if (gPrintChanges) {
printf("Out of cache entries!\n");
}
layout->next_cached_measurements_index = 0;
}
css_cached_measurement_t* newCacheEntry;
if (performLayout) {
// Use the single layout cache entry.
newCacheEntry = &layout->cached_layout;
} else {
// Allocate a new measurement cache entry.
newCacheEntry = &layout->cached_measurements[layout->next_cached_measurements_index];
layout->next_cached_measurements_index++;
}
newCacheEntry->available_width = availableWidth;
newCacheEntry->available_height = availableHeight;
newCacheEntry->width_measure_mode = widthMeasureMode;
newCacheEntry->height_measure_mode = heightMeasureMode;
newCacheEntry->computed_width = layout->measured_dimensions[CSS_WIDTH];
newCacheEntry->computed_height = layout->measured_dimensions[CSS_HEIGHT];
}
}
if (performLayout) {
node->layout.dimensions[CSS_WIDTH] = node->layout.measured_dimensions[CSS_WIDTH];
node->layout.dimensions[CSS_HEIGHT] = node->layout.measured_dimensions[CSS_HEIGHT];
layout->should_update = true;
}
gDepth--;
layout->generation_count = gCurrentGenerationCount;
return (needToVisitNode || cachedResults == NULL);
}
void layoutNode(css_node_t* node, float availableWidth, float availableHeight, css_direction_t 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++;
// If the caller didn't specify a height/width, use the dimensions
// specified in the style.
if (isUndefined(availableWidth) && isStyleDimDefined(node, CSS_FLEX_DIRECTION_ROW)) {
availableWidth = node->style.dimensions[CSS_WIDTH] + getMarginAxis(node, CSS_FLEX_DIRECTION_ROW);
}
if (isUndefined(availableHeight) && isStyleDimDefined(node, CSS_FLEX_DIRECTION_COLUMN)) {
availableHeight = node->style.dimensions[CSS_HEIGHT] + getMarginAxis(node, CSS_FLEX_DIRECTION_COLUMN);
}
css_measure_mode_t widthMeasureMode = isUndefined(availableWidth) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
css_measure_mode_t heightMeasureMode = isUndefined(availableHeight) ? CSS_MEASURE_MODE_UNDEFINED : CSS_MEASURE_MODE_EXACTLY;
if (layoutNodeInternal(node, availableWidth, availableHeight, parentDirection, widthMeasureMode, heightMeasureMode, true, "initial")) {
setPosition(node, node->layout.direction);
if (gPrintTree) {
print_css_node(node, CSS_PRINT_LAYOUT | CSS_PRINT_CHILDREN | CSS_PRINT_STYLE);
}
}
}
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