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Share measured text layouts across unchanged Text clones instead of copying them #59357

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Share measured text layouts across unchanged Text clones instead of copying them #59357

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37 changes: 18 additions & 19 deletions packages/react-native/ReactCommon/react/renderer/components/text/ParagraphShadowNode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -258,9 +258,9 @@ void ParagraphShadowNode::updateStateIfNeeded(const Content& content) {
#endif
}

MeasuredPreparedTextLayout* ParagraphShadowNode::findUsableLayout(
const MeasuredPreparedTextLayout* ParagraphShadowNode::findUsableLayout(
Float pointScaleFactor) {
MeasuredPreparedTextLayout* ret = nullptr;
const MeasuredPreparedTextLayout* ret = nullptr;

if constexpr (TextLayoutManagerExtended::supportsPreparedTextLayout()) {
// We consider the layout to be reusable, if our content measurement,
Expand All @@ -274,7 +274,7 @@ MeasuredPreparedTextLayout* ParagraphShadowNode::findUsableLayout(
// equally sized one carried over from a previous revision.
for (auto it = measuredLayouts_.rbegin(); it != measuredLayouts_.rend();
++it) {
auto& prevLayout = *it;
const auto& prevLayout = **it;
if (prevLayout.pointScaleFactor == pointScaleFactor &&
floatEquality(
prevLayout.measurement.size.width, expectedSize.width) &&
Expand Down Expand Up @@ -312,9 +312,9 @@ Size ParagraphShadowNode::measureContent(
// Layouts carried over from a previous revision may have been prepared
// at another pixel density, which they can't be reused for.
for (const auto& layout : measuredLayouts_) {
if (layout.layoutConstraints == layoutConstraints &&
layout.pointScaleFactor == layoutContext.pointScaleFactor) {
return layout.measurement.size;
if (layout->layoutConstraints == layoutConstraints &&
layout->pointScaleFactor == layoutContext.pointScaleFactor) {
return layout->measurement.size;
}
}
}
Expand All @@ -340,13 +340,15 @@ Size ParagraphShadowNode::measureContent(
preparedLayout, textLayoutContext, layoutConstraints);

measuredLayouts_.push_back(
MeasuredPreparedTextLayout{
.layoutConstraints = layoutConstraints,
.pointScaleFactor = layoutContext.pointScaleFactor,
.measurement = measurement,
// PreparedTextLayout is not trivially copyable on all platforms
// NOLINTNEXTLINE(performance-move-const-arg)
.preparedTextLayout = std::move(preparedLayout)});
std::make_shared<const MeasuredPreparedTextLayout>(
MeasuredPreparedTextLayout{
.layoutConstraints = layoutConstraints,
.pointScaleFactor = layoutContext.pointScaleFactor,
.measurement = measurement,
// PreparedTextLayout is not trivially copyable on all
// platforms
// NOLINTNEXTLINE(performance-move-const-arg)
.preparedTextLayout = std::move(preparedLayout)}));
assert_valid_size(measurement.size, layoutConstraints);
return measurement.size;
}
Expand Down Expand Up @@ -427,12 +429,9 @@ void ParagraphShadowNode::layout(LayoutContext layoutContext) {

// Only this layout can be reused by a later revision (see the copy
// constructor), so drop the others measured for this one.
if (measuredLayouts_.size() > 1) {
auto usedLayout = std::move(*measuredLayout);
measuredLayouts_.clear();
measuredLayouts_.push_back(std::move(usedLayout));
measuredLayout = &measuredLayouts_.back();
}
std::erase_if(measuredLayouts_, [&](const auto& layout) {
return layout.get() != measuredLayout;
});

} else if (ReactNativeFeatureFlags::fixTextLayoutOnPixelDensityChange()) {
MeasuredPreparedTextLayout unpreparedLayout;
Expand Down
8 changes: 5 additions & 3 deletions packages/react-native/ReactCommon/react/renderer/components/text/ParagraphShadowNode.h
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Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ class ParagraphShadowNode
* may be used, given the currently assigned layout to the ShadowNode and
* the current pixel density
*/
MeasuredPreparedTextLayout *findUsableLayout(Float pointScaleFactor);
const MeasuredPreparedTextLayout *findUsableLayout(Float pointScaleFactor);

/**
* Returns the final measure of the content frame, before layout rounding
Expand All @@ -145,9 +145,11 @@ class ParagraphShadowNode

/*
* Intermediate layout results generated during measurement, that may be
* reused by the platform.
* reused by the platform. Layouts are immutable once measured, so a clone
* shares them instead of copying them (on Android, copying one creates a
* JNI global reference).
*/
mutable std::vector<MeasuredPreparedTextLayout> measuredLayouts_;
mutable std::vector<std::shared_ptr<const MeasuredPreparedTextLayout>> measuredLayouts_;
};

} // namespace facebook::react
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