/** * Copyright (c) Facebook, Inc. and its affiliates. * * This source code is licensed under the MIT license found in the * LICENSE file in the root directory of this source tree. */ #pragma once #include "ParagraphMeasurementCache.h" #include "ParagraphShadowNode.h" #include #include #include #include namespace facebook { namespace react { /* * Descriptor for component. */ class ParagraphComponentDescriptor final : public ConcreteComponentDescriptor { public: ParagraphComponentDescriptor( SharedEventDispatcher eventDispatcher, const SharedContextContainer &contextContainer) : ConcreteComponentDescriptor(eventDispatcher) { // Every single `ParagraphShadowNode` will have a reference to // a shared `TextLayoutManager`. textLayoutManager_ = std::make_shared(contextContainer); // Every single `ParagraphShadowNode` will have a reference to // a shared `EvictingCacheMap`, a simple LRU cache for Paragraph // measurements. #ifdef ANDROID auto paramName = "react_fabric:enabled_paragraph_measure_cache_android"; #else auto paramName = "react_fabric:enabled_paragraph_measure_cache_ios"; #endif // TODO: T39927960 - get rid of this if statement bool enableCache = (contextContainer != nullptr ? contextContainer ->getInstance>( "ReactNativeConfig") ->getBool(paramName) : false); if (enableCache) { measureCache_ = std::make_unique(); } else { measureCache_ = nullptr; } } void adopt(UnsharedShadowNode shadowNode) const override { ConcreteComponentDescriptor::adopt(shadowNode); assert(std::dynamic_pointer_cast(shadowNode)); auto paragraphShadowNode = std::static_pointer_cast(shadowNode); // `ParagraphShadowNode` uses `TextLayoutManager` to measure text content // and communicate text rendering metrics to mounting layer. paragraphShadowNode->setTextLayoutManager(textLayoutManager_); // `ParagraphShadowNode` uses this to cache the results of text rendering // measurements. paragraphShadowNode->setMeasureCache( measureCache_ ? measureCache_.get() : nullptr); // All `ParagraphShadowNode`s must have leaf Yoga nodes with properly // setup measure function. paragraphShadowNode->enableMeasurement(); } private: SharedTextLayoutManager textLayoutManager_; std::unique_ptr measureCache_; }; } // namespace react } // namespace facebook