react-native/ReactCommon/fabric/view/yoga/YogaLayoutableShadowNode.cpp

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include "YogaLayoutableShadowNode.h"

#include <algorithm>
#include <memory>

#include <fabric/core/LayoutContext.h>
#include <fabric/core/LayoutConstraints.h>
#include <fabric/debug/DebugStringConvertibleItem.h>
#include <fabric/view/conversions.h>
#include <yoga/Yoga.h>

namespace facebook {
namespace react {

YogaLayoutableShadowNode::YogaLayoutableShadowNode(
  const SharedYogaStylableProps &props,
  const SharedShadowNodeSharedList &children
):
  yogaNode_({}),
  yogaConfig_(nullptr) {

  assert(props);
  assert(children);

  initializeYogaConfig(yogaConfig_);
  yogaNode_.setConfig(&yogaConfig_);
  yogaNode_.setStyle(props->yogaStyle);
  yogaNode_.setContext(this);
  yogaNode_.setDirty(true);

  YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(&yogaNode_, children);
}

YogaLayoutableShadowNode::YogaLayoutableShadowNode(
  const SharedYogaLayoutableShadowNode &shadowNode,
  const SharedYogaStylableProps &props,
  const SharedShadowNodeSharedList &children
):
  yogaNode_(shadowNode->yogaNode_),
  yogaConfig_(nullptr) {

  initializeYogaConfig(yogaConfig_);
  yogaNode_.setConfig(&yogaConfig_);
  yogaNode_.setContext(this);
  yogaNode_.setOwner(nullptr);
  yogaNode_.setDirty(true);

  if (props) {
    yogaNode_.setStyle(props->yogaStyle);
  }

  if (children) {
    YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(&yogaNode_, children);
  }
}

void YogaLayoutableShadowNode::cleanLayout() {
  yogaNode_.setDirty(false);
}

void YogaLayoutableShadowNode::dirtyLayout() {
  yogaNode_.markDirtyAndPropogate();
}

bool YogaLayoutableShadowNode::getIsLayoutClean() const {
  return !yogaNode_.isDirty();
}

bool YogaLayoutableShadowNode::getHasNewLayout() const {
  return yogaNode_.getHasNewLayout();
}

void YogaLayoutableShadowNode::setHasNewLayout(bool hasNewLayout) {
  yogaNode_.setHasNewLayout(hasNewLayout);
}

#pragma mark - Mutating Methods

void YogaLayoutableShadowNode::enableMeasurement() {
  ensureUnsealed();

  yogaNode_.setMeasureFunc(YogaLayoutableShadowNode::yogaNodeMeasureCallbackConnector);
}

void YogaLayoutableShadowNode::appendChild(SharedYogaLayoutableShadowNode child) {
  ensureUnsealed();

  auto yogaNodeRawPtr = &yogaNode_;
  auto childYogaNodeRawPtr = &child->yogaNode_;
  yogaNodeRawPtr->insertChild(childYogaNodeRawPtr, yogaNodeRawPtr->getChildrenCount());

  if (childYogaNodeRawPtr->getOwner() == nullptr) {
    child->ensureUnsealed();
    childYogaNodeRawPtr->setOwner(yogaNodeRawPtr);
  }
}

void YogaLayoutableShadowNode::layout(LayoutContext layoutContext) {
  if (!getIsLayoutClean()) {
    ensureUnsealed();

    /*
     * In Yoga, every single Yoga Node has to have a (non-null) pointer to
     * Yoga Config (this config can be shared between many nodes),
     * so every node can be individually configured. This does *not* mean
     * however that Yoga consults with every single Yoga Node Config for every
     * config parameter. Especially in case of `pointScaleFactor`,
     * the only value in the config of the root node is taken into account
     * (and this is by design).
     */
    yogaConfig_.pointScaleFactor = layoutContext.pointScaleFactor;
    YGNodeCalculateLayout(&yogaNode_, YGUndefined, YGUndefined, YGDirectionInherit);
  }

  LayoutableShadowNode::layout(layoutContext);
}

void YogaLayoutableShadowNode::layoutChildren(LayoutContext layoutContext) {
  for (auto child : getLayoutableChildNodes()) {
    auto yogaLayoutableChild = std::dynamic_pointer_cast<const YogaLayoutableShadowNode>(child);
    if (!yogaLayoutableChild) {
      continue;
    }

    auto nonConstYogaLayoutableChild = std::const_pointer_cast<YogaLayoutableShadowNode>(yogaLayoutableChild);

    LayoutMetrics childLayoutMetrics = layoutMetricsFromYogaNode(nonConstYogaLayoutableChild->yogaNode_);
    childLayoutMetrics.pointScaleFactor = layoutContext.pointScaleFactor;
    nonConstYogaLayoutableChild->setLayoutMetrics(childLayoutMetrics);
  }
}

#pragma mark - Yoga Connectors

YGNode *YogaLayoutableShadowNode::yogaNodeCloneCallbackConnector(YGNode *oldYogaNode, YGNode *parentYogaNode, int childIndex) {
  // We have only raw pointer to the parent shadow node, but that's enough for now.
  YogaLayoutableShadowNode *parentShadowNodeRawPtr = (YogaLayoutableShadowNode *)parentYogaNode->getContext();
  assert(parentShadowNodeRawPtr);

  // Old child shadow node already exists but we have only raw pointer to it...
  YogaLayoutableShadowNode *oldShadowNodeRawPtr = (YogaLayoutableShadowNode *)oldYogaNode->getContext();
  assert(oldShadowNodeRawPtr);

  // ... but we have to address this by `shared_ptr`. We cannot create a new `shared_ptr` for it because we will end up with two shared pointers to
  // single object which will cause preluminary destroyng the object.

  auto &&layoutableChildNodes = parentShadowNodeRawPtr->getLayoutableChildNodes();
  SharedLayoutableShadowNode oldShadowNode = nullptr;

  // We cannot rely on `childIndex` all the time because `childNodes` can
  // contain non-layoutable shadow nodes, however chances are good that
  // `childIndex` points to the right shadow node.

  // Optimistic attempt (in case if `childIndex` is valid):
  if (childIndex < layoutableChildNodes.size()) {
    oldShadowNode = layoutableChildNodes[childIndex];
    if (oldShadowNode.get() == oldShadowNodeRawPtr) {
      goto found;
    } else {
      oldShadowNode = nullptr;
    }
  }

  // General solution:
  for (auto child : layoutableChildNodes) {
    if (child.get() == oldShadowNodeRawPtr) {
      oldShadowNode = child;
      break;
    }
  }

  assert(oldShadowNode);

found:

  // The new one does not exist yet. So, we have to clone and replace this using `cloneAndReplaceChild`.
  SharedYogaLayoutableShadowNode newShadowNode =
    std::dynamic_pointer_cast<const YogaLayoutableShadowNode>(parentShadowNodeRawPtr->cloneAndReplaceChild(oldShadowNode));
  assert(newShadowNode);

  return &newShadowNode->yogaNode_;
}

YGSize YogaLayoutableShadowNode::yogaNodeMeasureCallbackConnector(YGNode *yogaNode, float width, YGMeasureMode widthMode, float height, YGMeasureMode heightMode) {
  YogaLayoutableShadowNode *shadowNodeRawPtr = (YogaLayoutableShadowNode *)yogaNode->getContext();
  assert(shadowNodeRawPtr);

  Size minimumSize = Size {0, 0};
  Size maximumSize = Size {kFloatMax, kFloatMax};

  switch (widthMode) {
    case YGMeasureModeUndefined:
      break;
    case YGMeasureModeExactly:
      minimumSize.width = fabricFloatFromYogaFloat(width);
      maximumSize.width = fabricFloatFromYogaFloat(width);
      break;
    case YGMeasureModeAtMost:
      maximumSize.width = fabricFloatFromYogaFloat(width);
      break;
  }

  switch (heightMode) {
    case YGMeasureModeUndefined:
      break;
    case YGMeasureModeExactly:
      minimumSize.height = fabricFloatFromYogaFloat(height);
      maximumSize.height = fabricFloatFromYogaFloat(height);
      break;
    case YGMeasureModeAtMost:
      maximumSize.height = fabricFloatFromYogaFloat(height);
      break;
  }

  Size size = shadowNodeRawPtr->measure(LayoutConstraints {minimumSize, maximumSize});

  return YGSize {
    yogaFloatFromFabricFloat(size.width),
    yogaFloatFromFabricFloat(size.height)
  };
}

void YogaLayoutableShadowNode::setYogaNodeChildrenBasedOnShadowNodeChildren(YGNode *yogaNodeRawPtr, const SharedShadowNodeSharedList &children) {
  auto yogaNodeChildren = YGVector();

  for (const SharedShadowNode &shadowNode : *children) {
    const SharedYogaLayoutableShadowNode yogaLayoutableShadowNode = std::dynamic_pointer_cast<const YogaLayoutableShadowNode>(shadowNode);

    if (!yogaLayoutableShadowNode) {
      continue;
    }

    auto &&childYogaNodeRawPtr = &yogaLayoutableShadowNode->yogaNode_;

    yogaNodeChildren.push_back(childYogaNodeRawPtr);

    if (childYogaNodeRawPtr->getOwner() == nullptr) {
      yogaLayoutableShadowNode->ensureUnsealed();
      childYogaNodeRawPtr->setOwner(yogaNodeRawPtr);
    }
  }

  yogaNodeRawPtr->setChildren(yogaNodeChildren);
}

void YogaLayoutableShadowNode::initializeYogaConfig(YGConfig &config) {
  config.cloneNodeCallback = YogaLayoutableShadowNode::yogaNodeCloneCallbackConnector;
}

} // namespace react
} // namespace facebook