Swiftgram/Source/Details/ASGraphicsContext.h
Adlai Holler 1d105c2056
Add an experimental "no-copy" renderer (#741)
* Add "ASGraphicsContext" to skip copying our rendered images

* Zero the buffer before making a context

* Update license header

* Update dangerfile

* Make it a runtime flag

* Restore GState for good measure

* Free buffer if end without image

* Enable the experiment, and cut out the middle-man

* Fix typo
2018-01-13 19:19:08 -08:00

63 lines
1.8 KiB
Objective-C

//
// ASGraphicsContext.h
// Texture
//
// Copyright (c) 2018-present, Pinterest, Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
#import <Foundation/Foundation.h>
#import <AsyncDisplayKit/ASBaseDefines.h>
#import <CoreGraphics/CoreGraphics.h>
@class UIImage;
/**
* Functions for creating one-shot graphics contexts that do not have to copy
* their contents when an image is generated from them. This is efficient
* for our use, since we do not reuse graphics contexts.
*
* The API mirrors the UIGraphics API, with the exception that forming an image
* ends the context as well.
*/
NS_ASSUME_NONNULL_BEGIN
ASDISPLAYNODE_EXTERN_C_BEGIN
/**
* Call this to enable the experimental no-copy rendering.
*
* Returns YES if it was enabled, or NO + assert if it's too late because
* rendering has already started. In practice it's fine to call this
* during -didFinishLaunchingWithOptions:.
*/
extern BOOL ASEnableNoCopyRendering(void);
/**
* Creates a one-shot context.
*
* Behavior is the same as UIGraphicsBeginImageContextWithOptions.
*/
extern void ASGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale);
/**
* Generates and image and ends the current one-shot context.
*
* Behavior is the same as UIGraphicsGetImageFromCurrentImageContext followed by UIGraphicsEndImageContext.
*/
extern UIImage * _Nullable ASGraphicsGetImageAndEndCurrentContext(void);
/**
* Call this if you want to end the current context without making an image.
*
* Behavior is the same as UIGraphicsEndImageContext.
*/
extern void ASGraphicsEndImageContext(void);
ASDISPLAYNODE_EXTERN_C_END
NS_ASSUME_NONNULL_END