流程图
屏幕快照 2017-05-10 17.10.38.png
- (void)_updateSource {
switch (_type) {
case YYImageTypeWebP: {
[self _updateSourceWebP];
} break;
case YYImageTypePNG: {
[self _updateSourceAPNG];
} break;
default: {
[self _updateSourceImageIO];
} break;
}
}
一、 研究一下_updateSourceImageIO
- (void)_updateSourceImageIO {
_width = 0;
_height = 0;
_orientation = UIImageOrientationUp;
_loopCount = 0;
dispatch_semaphore_wait(_framesLock, DISPATCH_TIME_FOREVER);
_frames = nil;
dispatch_semaphore_signal(_framesLock);
/*
* 加载动态图资源
* CGImageSourceCreateWithData 需传入data
* CGImageSourceCreateIncremental 不需要先传入data 创建后可以使用
CGImageSourceUpdateData 更新
*/
if (!_source) {
if (_finalized) {
_source = CGImageSourceCreateWithData((__bridge CFDataRef)_data, NULL);
} else {
_source = CGImageSourceCreateIncremental(NULL);
if (_source) CGImageSourceUpdateData(_source, (__bridge CFDataRef)_data, false);
}
} else {
CGImageSourceUpdateData(_source, (__bridge CFDataRef)_data, _finalized);
}
if (!_source) return;
/*
* CGImageSourceGetCount获取动图图中资源个数
*/
_frameCount = CGImageSourceGetCount(_source);
if (_frameCount == 0) return;
if (!_finalized) { // ignore multi-frame before finalized
_frameCount = 1;
} else {
if (_type == YYImageTypePNG) { // use custom apng decoder and ignore multi-frame
_frameCount = 1;
}
if (_type == YYImageTypeGIF) { // get gif loop count
/*
* CGImageSourceCopyProperties 返回图片资源的属性列表
* CFDictionaryGetValue 找到对应key的value
*/
CFDictionaryRef properties = CGImageSourceCopyProperties(_source, NULL);
if (properties) {
CFDictionaryRef gif = CFDictionaryGetValue(properties, kCGImagePropertyGIFDictionary);
if (gif) {
CFTypeRef loop = CFDictionaryGetValue(gif, kCGImagePropertyGIFLoopCount);
if (loop) CFNumberGetValue(loop, kCFNumberNSIntegerType, &_loopCount);
}
CFRelease(properties);
}
}
}
/*
ICO, GIF, APNG may contains multi-frame.
*/
NSMutableArray *frames = [NSMutableArray new];
for (NSUInteger i = 0; i < _frameCount; i++) {
_YYImageDecoderFrame *frame = [_YYImageDecoderFrame new];
frame.index = i;
frame.blendFromIndex = i;
frame.hasAlpha = YES;
frame.isFullSize = YES;
[frames addObject:frame];
CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(_source, i, NULL);
if (properties) {
NSTimeInterval duration = 0;
NSInteger orientationValue = 0, width = 0, height = 0;
CFTypeRef value = NULL;
value = CFDictionaryGetValue(properties, kCGImagePropertyPixelWidth);
if (value) CFNumberGetValue(value, kCFNumberNSIntegerType, &width);
value = CFDictionaryGetValue(properties, kCGImagePropertyPixelHeight);
if (value) CFNumberGetValue(value, kCFNumberNSIntegerType, &height);
if (_type == YYImageTypeGIF) {
CFDictionaryRef gif = CFDictionaryGetValue(properties, kCGImagePropertyGIFDictionary);
if (gif) {
// Use the unclamped frame delay if it exists.
value = CFDictionaryGetValue(gif, kCGImagePropertyGIFUnclampedDelayTime);
if (!value) {
// Fall back to the clamped frame delay if the unclamped frame delay does not exist.
value = CFDictionaryGetValue(gif, kCGImagePropertyGIFDelayTime);
}
if (value) CFNumberGetValue(value, kCFNumberDoubleType, &duration);
}
}
frame.width = width;
frame.height = height;
frame.duration = duration;
if (i == 0 && _width + _height == 0) { // init first frame
_width = width;
_height = height;
value = CFDictionaryGetValue(properties, kCGImagePropertyOrientation);
if (value) {
CFNumberGetValue(value, kCFNumberNSIntegerType, &orientationValue);
_orientation = YYUIImageOrientationFromEXIFValue(orientationValue);
}
}
CFRelease(properties);
}
}
dispatch_semaphore_wait(_framesLock, DISPATCH_TIME_FOREVER);
_frames = frames;
dispatch_semaphore_signal(_framesLock);
}
二、Image传入ImageView
1、 imageChanged
- (void)imageChanged {
YYAnimatedImageType newType = [self currentImageType];
/*
* 获取当前YYImage
* 找到所有帧数
* 初始化参数
*/
id newVisibleImage = [self imageForType:newType];
NSUInteger newImageFrameCount = 0;
BOOL hasContentsRect = NO;
if ([newVisibleImage isKindOfClass:[UIImage class]] &&
[newVisibleImage conformsToProtocol:@protocol(YYAnimatedImage)]) {
newImageFrameCount = ((UIImage<YYAnimatedImage> *) newVisibleImage).animatedImageFrameCount;
if (newImageFrameCount > 1) {
hasContentsRect = [((UIImage<YYAnimatedImage> *) newVisibleImage) respondsToSelector:@selector(animatedImageContentsRectAtIndex:)];
}
}
if (!hasContentsRect && _curImageHasContentsRect) {
if (!CGRectEqualToRect(self.layer.contentsRect, CGRectMake(0, 0, 1, 1)) ) {
[CATransaction begin];
[CATransaction setDisableActions:YES];
self.layer.contentsRect = CGRectMake(0, 0, 1, 1);
[CATransaction commit];
}
}
_curImageHasContentsRect = hasContentsRect;
if (hasContentsRect) {
CGRect rect = [((UIImage<YYAnimatedImage> *) newVisibleImage) animatedImageContentsRectAtIndex:0];
[self setContentsRect:rect forImage:newVisibleImage];
}
if (newImageFrameCount > 1) {
[self resetAnimated];
_curAnimatedImage = newVisibleImage;
_curFrame = newVisibleImage;
_totalLoop = _curAnimatedImage.animatedImageLoopCount;
_totalFrameCount = _curAnimatedImage.animatedImageFrameCount;
//计算内存
[self calcMaxBufferCount];
}
[self setNeedsDisplay];
[self didMoved];
}
2、 resetAnimated
// init the animated params.
/*
* 初始化动画
*/
- (void)resetAnimated {
dispatch_once(&_onceToken, ^{
_lock = dispatch_semaphore_create(1);
_buffer = [NSMutableDictionary new];
_requestQueue = [[NSOperationQueue alloc] init];
_requestQueue.maxConcurrentOperationCount = 1;
_link = [CADisplayLink displayLinkWithTarget:[YYWeakProxy proxyWithTarget:self] selector:@selector(step:)];
if (_runloopMode) {
[_link addToRunLoop:[NSRunLoop mainRunLoop] forMode:_runloopMode];
}
_link.paused = YES;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didReceiveMemoryWarning:) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
});
[_requestQueue cancelAllOperations];
LOCK(
if (_buffer.count) {
NSMutableDictionary *holder = _buffer;
_buffer = [NSMutableDictionary new];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
// Capture the dictionary to global queue,
// release these images in background to avoid blocking UI thread.
[holder class];
});
}
);
_link.paused = YES;
_time = 0;
if (_curIndex != 0) {
[self willChangeValueForKey:@"currentAnimatedImageIndex"];
_curIndex = 0;
[self didChangeValueForKey:@"currentAnimatedImageIndex"];
}
_curAnimatedImage = nil;
_curFrame = nil;
_curLoop = 0;
_totalLoop = 0;
_totalFrameCount = 1;
_loopEnd = NO;
_bufferMiss = NO;
_incrBufferCount = 0;
}
3、 step 核心方法
- (void)step:(CADisplayLink *)link {
//当前image
UIImage <YYAnimatedImage> *image = _curAnimatedImage;
//存储的是{@(index):image}每一帧的索引以及对应image
NSMutableDictionary *buffer = _buffer;
UIImage *bufferedImage = nil;
NSUInteger nextIndex = (_curIndex + 1) % _totalFrameCount;
BOOL bufferIsFull = NO;
if (!image) return;
if (_loopEnd) { // view will keep in last frame
[self stopAnimating];
return;
}
NSTimeInterval delay = 0;
if (!_bufferMiss) {
//对于每次切换帧的控制
_time += link.duration;
delay = [image animatedImageDurationAtIndex:_curIndex];
if (_time < delay) return;
_time -= delay;
if (nextIndex == 0) {
_curLoop++;
if (_curLoop >= _totalLoop && _totalLoop != 0) {
_loopEnd = YES;
[self stopAnimating];
[self.layer setNeedsDisplay]; // let system call `displayLayer:` before runloop sleep
return; // stop at last frame
}
}
delay = [image animatedImageDurationAtIndex:nextIndex];
if (_time > delay) _time = delay; // do not jump over frame
}
LOCK(
bufferedImage = buffer[@(nextIndex)];
if (bufferedImage) {
if ((int)_incrBufferCount < _totalFrameCount) {
[buffer removeObjectForKey:@(nextIndex)];
}
[self willChangeValueForKey:@"currentAnimatedImageIndex"];
_curIndex = nextIndex;
[self didChangeValueForKey:@"currentAnimatedImageIndex"];
_curFrame = bufferedImage == (id)[NSNull null] ? nil : bufferedImage;
if (_curImageHasContentsRect) {
_curContentsRect = [image animatedImageContentsRectAtIndex:_curIndex];
[self setContentsRect:_curContentsRect forImage:_curFrame];
}
nextIndex = (_curIndex + 1) % _totalFrameCount;
_bufferMiss = NO;
if (buffer.count == _totalFrameCount) {
bufferIsFull = YES;
}
} else {
_bufferMiss = YES;
}
)//LOCK
if (!_bufferMiss) {
[self.layer setNeedsDisplay]; // let system call `displayLayer:` before runloop sleep
}
if (!bufferIsFull && _requestQueue.operationCount == 0) { // if some work not finished, wait for next opportunity
//获取buffer数据
_YYAnimatedImageViewFetchOperation *operation = [_YYAnimatedImageViewFetchOperation new];
operation.view = self;
operation.nextIndex = nextIndex;
operation.curImage = image;
[_requestQueue addOperation:operation];
}
}
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