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
66 lines
1.8 KiB
C++
66 lines
1.8 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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#pragma once
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#include <memory>
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#include <react/attributedstring/AttributedString.h>
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#include <react/attributedstring/AttributedStringBox.h>
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#include <react/attributedstring/ParagraphAttributes.h>
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#include <react/core/LayoutConstraints.h>
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#include <react/utils/ContextContainer.h>
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#include <react/utils/SimpleThreadSafeCache.h>
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namespace facebook {
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namespace react {
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class TextLayoutManager;
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using SharedTextLayoutManager = std::shared_ptr<const TextLayoutManager>;
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/*
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* Cross platform facade for Android-specific TextLayoutManager.
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*/
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class TextLayoutManager {
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public:
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TextLayoutManager(const ContextContainer::Shared &contextContainer)
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: contextContainer_(contextContainer){};
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~TextLayoutManager();
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/*
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* Measures `attributedString` using native text rendering infrastructure.
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*/
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Size measure(
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AttributedStringBox attributedStringBox,
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ParagraphAttributes paragraphAttributes,
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LayoutConstraints layoutConstraints) const;
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/*
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* Returns an opaque pointer to platform-specific TextLayoutManager.
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* Is used on a native views layer to delegate text rendering to the manager.
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*/
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void *getNativeTextLayoutManager() const;
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private:
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Size doMeasure(
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AttributedString attributedString,
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ParagraphAttributes paragraphAttributes,
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LayoutConstraints layoutConstraints) const;
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using MeasureCacheKey =
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std::tuple<AttributedString, ParagraphAttributes, LayoutConstraints>;
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using MeasureCache = SimpleThreadSafeCache<MeasureCacheKey, Size, 256>;
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void *self_;
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ContextContainer::Shared contextContainer_;
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MeasureCache measureCache_{};
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};
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} // namespace react
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} // namespace facebook
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