react-native/React/Modules/RCTUIManagerObserverCoordin...

82 lines
2.6 KiB
Objective-C

/**
* 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.
*/
#import <UIKit/UIKit.h>
#import <React/RCTViewManager.h>
typedef dispatch_block_t RCTUIManagerMountingBlock;
/**
* Allows hooking into UIManager internals. This can be used to execute code at
* specific points during the view updating process.
* New observers must not be added inside observer handlers.
* The particular order of handler invocation is not guaranteed.
* All observer handlers are called on UIManager queue.
*/
@protocol RCTUIManagerObserver <NSObject>
@optional
/**
* Called just before the UIManager layout views.
* It allows performing some operation for components which contain custom
* layout logic right before regular Yoga based layout. So, for instance,
* some components which have own React-independent state can compute and cache
* own intrinsic content size (which will be used by Yoga) at this point.
*/
- (void)uiManagerWillPerformLayout:(RCTUIManager *)manager;
/**
* Called just after the UIManager layout views.
* It allows performing custom layout logic right after regular Yoga based layout.
* So, for instance, this can be used for computing final layout for a component,
* since it has its final frame set by Yoga at this point.
*/
- (void)uiManagerDidPerformLayout:(RCTUIManager *)manager;
/**
* Called before flushing UI blocks at the end of a batch.
* This is called from the UIManager queue. Can be used to add UI operations in that batch.
*/
- (void)uiManagerWillPerformMounting:(RCTUIManager *)manager;
/**
* Called right before flushing UI blocks and allows to intercept the mounting process.
* Return `YES` to cancel default execution of the `block` (and perform the
* execution later).
*/
- (BOOL)uiManager:(RCTUIManager *)manager performMountingWithBlock:(RCTUIManagerMountingBlock)block;
/**
* Called just after flushing UI blocks.
* This is called from the UIManager queue.
*/
- (void)uiManagerDidPerformMounting:(RCTUIManager *)manager;
@end
/**
* Simple helper which take care of RCTUIManager's observers.
*/
@interface RCTUIManagerObserverCoordinator : NSObject <RCTUIManagerObserver>
/**
* Add a UIManagerObserver. See the `RCTUIManagerObserver` protocol for more info.
* References to observers are held weakly.
* This method can be called safely from any queue.
*/
- (void)addObserver:(id<RCTUIManagerObserver>)observer;
/**
* Remove a `UIManagerObserver`.
* This method can be called safely from any queue.
*/
- (void)removeObserver:(id<RCTUIManagerObserver>)observer;
@end