//
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// YYTextAsyncLayer.m
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// YYText <https://github.com/ibireme/YYText>
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//
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// Created by ibireme on 15/4/11.
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// Copyright (c) 2015 ibireme.
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//
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// This source code is licensed under the MIT-style 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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#import "YYTextAsyncLayer.h"
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#import <libkern/OSAtomic.h>
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/// Global display queue, used for content rendering.
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static dispatch_queue_t YYTextAsyncLayerGetDisplayQueue() {
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#define MAX_QUEUE_COUNT 16
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static int queueCount;
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static dispatch_queue_t queues[MAX_QUEUE_COUNT];
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static dispatch_once_t onceToken;
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static int32_t counter = 0;
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dispatch_once(&onceToken, ^{
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queueCount = (int)[NSProcessInfo processInfo].activeProcessorCount;
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queueCount = queueCount < 1 ? 1 : queueCount > MAX_QUEUE_COUNT ? MAX_QUEUE_COUNT : queueCount;
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if ([UIDevice currentDevice].systemVersion.floatValue >= 8.0) {
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for (NSUInteger i = 0; i < queueCount; i++) {
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dispatch_queue_attr_t attr = dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_SERIAL, QOS_CLASS_USER_INITIATED, 0);
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queues[i] = dispatch_queue_create("com.ibireme.text.render", attr);
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}
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} else {
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for (NSUInteger i = 0; i < queueCount; i++) {
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queues[i] = dispatch_queue_create("com.ibireme.text.render", DISPATCH_QUEUE_SERIAL);
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dispatch_set_target_queue(queues[i], dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0));
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}
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}
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});
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uint32_t cur = (uint32_t)OSAtomicIncrement32(&counter);
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return queues[(cur) % queueCount];
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#undef MAX_QUEUE_COUNT
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}
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static dispatch_queue_t YYTextAsyncLayerGetReleaseQueue() {
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#ifdef YYDispatchQueuePool_h
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return YYDispatchQueueGetForQOS(NSQualityOfServiceDefault);
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#else
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return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
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#endif
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}
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/// a thread safe incrementing counter.
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@interface _YYTextSentinel : NSObject
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/// Returns the current value of the counter.
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@property (atomic, readonly) int32_t value;
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/// Increase the value atomically. @return The new value.
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- (int32_t)increase;
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@end
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@implementation _YYTextSentinel {
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int32_t _value;
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}
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- (int32_t)value {
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return _value;
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}
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- (int32_t)increase {
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return OSAtomicIncrement32(&_value);
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}
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@end
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@implementation YYTextAsyncLayerDisplayTask
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@end
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@implementation YYTextAsyncLayer {
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_YYTextSentinel *_sentinel;
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}
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#pragma mark - Override
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+ (id)defaultValueForKey:(NSString *)key {
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if ([key isEqualToString:@"displaysAsynchronously"]) {
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return @(YES);
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} else {
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return [super defaultValueForKey:key];
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}
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}
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- (instancetype)init {
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self = [super init];
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static CGFloat scale; //global
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static dispatch_once_t onceToken;
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dispatch_once(&onceToken, ^{
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scale = [UIScreen mainScreen].scale;
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});
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self.contentsScale = scale;
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_sentinel = [_YYTextSentinel new];
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_displaysAsynchronously = YES;
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return self;
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}
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- (void)dealloc {
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[_sentinel increase];
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}
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- (void)setNeedsDisplay {
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[self _cancelAsyncDisplay];
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[super setNeedsDisplay];
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}
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- (void)display {
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super.contents = super.contents;
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[self _displayAsync:_displaysAsynchronously];
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}
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#pragma mark - Private
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- (void)_displayAsync:(BOOL)async {
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__strong id<YYTextAsyncLayerDelegate> delegate = (id)self.delegate;
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YYTextAsyncLayerDisplayTask *task = [delegate newAsyncDisplayTask];
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if (!task.display) {
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if (task.willDisplay) task.willDisplay(self);
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self.contents = nil;
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if (task.didDisplay) task.didDisplay(self, YES);
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return;
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}
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if (async) {
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if (task.willDisplay) task.willDisplay(self);
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_YYTextSentinel *sentinel = _sentinel;
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int32_t value = sentinel.value;
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BOOL (^isCancelled)() = ^BOOL() {
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return value != sentinel.value;
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};
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CGSize size = self.bounds.size;
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BOOL opaque = self.opaque;
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CGFloat scale = self.contentsScale;
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CGColorRef backgroundColor = (opaque && self.backgroundColor) ? CGColorRetain(self.backgroundColor) : NULL;
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if (size.width < 1 || size.height < 1) {
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CGImageRef image = (__bridge_retained CGImageRef)(self.contents);
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self.contents = nil;
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if (image) {
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dispatch_async(YYTextAsyncLayerGetReleaseQueue(), ^{
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CFRelease(image);
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});
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}
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if (task.didDisplay) task.didDisplay(self, YES);
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CGColorRelease(backgroundColor);
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return;
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}
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dispatch_async(YYTextAsyncLayerGetDisplayQueue(), ^{
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if (isCancelled()) {
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CGColorRelease(backgroundColor);
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return;
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}
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UIGraphicsBeginImageContextWithOptions(size, opaque, scale);
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CGContextRef context = UIGraphicsGetCurrentContext();
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if (opaque) {
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CGContextSaveGState(context); {
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if (!backgroundColor || CGColorGetAlpha(backgroundColor) < 1) {
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CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
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CGContextAddRect(context, CGRectMake(0, 0, size.width * scale, size.height * scale));
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CGContextFillPath(context);
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}
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if (backgroundColor) {
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CGContextSetFillColorWithColor(context, backgroundColor);
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CGContextAddRect(context, CGRectMake(0, 0, size.width * scale, size.height * scale));
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CGContextFillPath(context);
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}
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} CGContextRestoreGState(context);
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CGColorRelease(backgroundColor);
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}
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task.display(context, size, isCancelled);
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if (isCancelled()) {
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UIGraphicsEndImageContext();
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dispatch_async(dispatch_get_main_queue(), ^{
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if (task.didDisplay) task.didDisplay(self, NO);
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});
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return;
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}
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UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
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UIGraphicsEndImageContext();
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if (isCancelled()) {
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dispatch_async(dispatch_get_main_queue(), ^{
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if (task.didDisplay) task.didDisplay(self, NO);
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});
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return;
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}
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dispatch_async(dispatch_get_main_queue(), ^{
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if (isCancelled()) {
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if (task.didDisplay) task.didDisplay(self, NO);
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} else {
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self.contents = (__bridge id)(image.CGImage);
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if (task.didDisplay) task.didDisplay(self, YES);
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}
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});
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});
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} else {
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[_sentinel increase];
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if (task.willDisplay) task.willDisplay(self);
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UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.opaque, self.contentsScale);
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CGContextRef context = UIGraphicsGetCurrentContext();
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if (self.opaque) {
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CGSize size = self.bounds.size;
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size.width *= self.contentsScale;
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size.height *= self.contentsScale;
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CGContextSaveGState(context); {
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if (!self.backgroundColor || CGColorGetAlpha(self.backgroundColor) < 1) {
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CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
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CGContextAddRect(context, CGRectMake(0, 0, size.width, size.height));
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CGContextFillPath(context);
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}
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if (self.backgroundColor) {
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CGContextSetFillColorWithColor(context, self.backgroundColor);
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CGContextAddRect(context, CGRectMake(0, 0, size.width, size.height));
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CGContextFillPath(context);
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}
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} CGContextRestoreGState(context);
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}
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task.display(context, self.bounds.size, ^{return NO;});
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UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
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UIGraphicsEndImageContext();
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self.contents = (__bridge id)(image.CGImage);
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if (task.didDisplay) task.didDisplay(self, YES);
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}
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}
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- (void)_cancelAsyncDisplay {
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[_sentinel increase];
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}
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@end
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