mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Valentin Shergin
c4876d0313
Summary: The diff implements a new class called `AttributedStringBox` that represents an object storing a shared `AttributedString` *or* a shared pointer to some opaque platform-specific object that can be used as an attributed string. The class serves two main purposes: - Represent type-erased attributed string entity (which can be platform-specific or platform-independent); - Represent a container that can be copied with constant complexity. Why? Several reasons: - Sometimes it makes sense to keep an attributed string as a shared resource. This way we don't need to pay for expensive copying and we also implement a copy-on-write semantics on top of that if needed. - We need to extend a TextLayoutMeasure API to support measuring some platform-specific attributed string implementation to remove the necessity of converting a string back and forth between representations. That's especially important for TextInput because we will need to measure that very efficiently (and the source of measuring, in this case, is a platform attributed string). In other words, we need something to store inside TextInputState to measure and update very efficiently. The source of this data might be a native TextInput control or a data from React, to represent that kinda object we need this data structure (and interfaces that deal with it). Changelog: [Internal] Fabric-specific internal change. Reviewed By: sammy-SC Differential Revision: D18670793 fbshipit-source-id: bc0164f801f28642f7c6da340af12acf33b85d24
78 lines
2.0 KiB
C++
78 lines
2.0 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "ParagraphShadowNode.h"
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#include <react/attributedstring/AttributedStringBox.h>
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#include "ParagraphState.h"
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namespace facebook {
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namespace react {
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char const ParagraphComponentName[] = "Paragraph";
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AttributedString ParagraphShadowNode::getAttributedString() const {
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if (!cachedAttributedString_.has_value()) {
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auto textAttributes = TextAttributes::defaultTextAttributes();
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textAttributes.apply(getProps()->textAttributes);
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cachedAttributedString_ =
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BaseTextShadowNode::getAttributedString(textAttributes, *this);
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}
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return cachedAttributedString_.value();
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}
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void ParagraphShadowNode::setTextLayoutManager(
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SharedTextLayoutManager textLayoutManager) {
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ensureUnsealed();
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textLayoutManager_ = textLayoutManager;
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}
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void ParagraphShadowNode::updateStateIfNeeded() {
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ensureUnsealed();
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auto attributedString = getAttributedString();
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auto const &state = getStateData();
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assert(textLayoutManager_);
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assert(
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(!state.layoutManager || state.layoutManager == textLayoutManager_) &&
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"`StateData` refers to a different `TextLayoutManager`");
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if (state.attributedString == attributedString &&
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state.layoutManager == textLayoutManager_) {
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return;
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}
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setStateData(ParagraphState{
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attributedString, getProps()->paragraphAttributes, textLayoutManager_});
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}
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#pragma mark - LayoutableShadowNode
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Size ParagraphShadowNode::measure(LayoutConstraints layoutConstraints) const {
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AttributedString attributedString = getAttributedString();
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if (attributedString.isEmpty()) {
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return {0, 0};
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}
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return textLayoutManager_->measure(
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AttributedStringBox{attributedString},
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getProps()->paragraphAttributes,
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layoutConstraints);
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}
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void ParagraphShadowNode::layout(LayoutContext layoutContext) {
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updateStateIfNeeded();
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ConcreteViewShadowNode::layout(layoutContext);
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}
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} // namespace react
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} // namespace facebook
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