GPUImage源码解读(五)

  • GPUImageFramebufferCache

    GPUImageFramebufferCache类核心的职责是管理GPUImageFramebuffer对象。

  • 方法列表 主要涉及到在缓存中查找 GPUImageFramebuffer,将 GPUImageFramebuffer 加入缓存,清空缓存等相关方法。

/**
从cache中获取一个GPUImageFramebuffer对象,如果获取失败,那么创建一个新的GPUImageFramebuffer对象。
@param framebufferSize 对象的大小
@param textureOptions 纹理的配置信息
@param onlyTexture 指示是否只为纹理,是否包含framebuffer对象
@return 返回framebuffer
*/
- (GPUImageFramebuffer *)fetchFramebufferForSize:(CGSize)framebufferSize textureOptions:(GPUTextureOptions)textureOptions onlyTexture:(BOOL)onlyTexture;
- (GPUImageFramebuffer *)fetchFramebufferForSize:(CGSize)framebufferSize onlyTexture:(BOOL)onlyTexture;
  • 实现方法

- (GPUImageFramebuffer *)fetchFramebufferForSize:(CGSize)framebufferSize textureOptions:(GPUTextureOptions)textureOptions onlyTexture:(BOOL)onlyTexture;
{
__block GPUImageFramebuffer *framebufferFromCache = nil;
// dispatch_sync(framebufferCacheQueue, ^{
runSynchronouslyOnVideoProcessingQueue(^{
// 创建查找字符串
NSString *lookupHash = [self hashForSize:framebufferSize textureOptions:textureOptions onlyTexture:onlyTexture];
// 获取GPUImageFramebuffer在缓存中的数量
NSNumber *numberOfMatchingTexturesInCache = [framebufferTypeCounts objectForKey:lookupHash];
NSInteger numberOfMatchingTextures = [numberOfMatchingTexturesInCache integerValue];
// 缓存中如果没有,则创建framebufferFromCache
if ([numberOfMatchingTexturesInCache integerValue] < 1)
{
// Nothing in the cache, create a new framebuffer to use
framebufferFromCache = [[GPUImageFramebuffer alloc] initWithSize:framebufferSize textureOptions:textureOptions onlyTexture:onlyTexture];
}
else
{
// Something found, pull the old framebuffer and decrement the count
NSInteger currentTextureID = (numberOfMatchingTextures - 1);
while ((framebufferFromCache == nil) && (currentTextureID >= 0))
{
// 根据数量构建带数量的textureHash字符串
NSString *textureHash = [NSString stringWithFormat:@"%@-%ld", lookupHash, (long)currentTextureID];
// 查找以textureHash为key的GPUImageFramebuffer是否存在
framebufferFromCache = [framebufferCache objectForKey:textureHash];
// Test the values in the cache first, to see if they got invalidated behind our back
if (framebufferFromCache != nil)
{
// Withdraw this from the cache while it's in use
[framebufferCache removeObjectForKey:textureHash];
}
currentTextureID--;
}
currentTextureID++;
// 更新framebufferTypeCounts中相同类型(纹理属性GPUTextureOptions)GPUImageFramebuffer的数量
[framebufferTypeCounts setObject:[NSNumber numberWithInteger:currentTextureID] forKey:lookupHash];
// 还是没有则创建
if (framebufferFromCache == nil)
{
framebufferFromCache = [[GPUImageFramebuffer alloc] initWithSize:framebufferSize textureOptions:textureOptions onlyTexture:onlyTexture];
}
}
});
// 引用计数加1,返回
[framebufferFromCache lock];
return framebufferFromCache;
}
- (GPUImageFramebuffer *)fetchFramebufferForSize:(CGSize)framebufferSize onlyTexture:(BOOL)onlyTexture;
{
//默认的GPUTextureOptions查找
GPUTextureOptions defaultTextureOptions;
defaultTextureOptions.minFilter = GL_LINEAR;
defaultTextureOptions.magFilter = GL_LINEAR;
defaultTextureOptions.wrapS = GL_CLAMP_TO_EDGE;
defaultTextureOptions.wrapT = GL_CLAMP_TO_EDGE;
defaultTextureOptions.internalFormat = GL_RGBA;
defaultTextureOptions.format = GL_BGRA;
defaultTextureOptions.type = GL_UNSIGNED_BYTE;
return [self fetchFramebufferForSize:framebufferSize textureOptions:defaultTextureOptions onlyTexture:onlyTexture];
}
  • 添加缓存

/**
向GPUImageFramebuffer缓存加添加GPUImageFramebuffer对象
@param framebuffer 需要添加的对象
*/
- (void)returnFramebufferToCache:(GPUImageFramebuffer *)framebuffer;
  • 实现方法

- (void)returnFramebufferToCache:(GPUImageFramebuffer *)framebuffer;
{
// 清除引用计数
[framebuffer clearAllLocks];
// dispatch_async(framebufferCacheQueue, ^{
runAsynchronouslyOnVideoProcessingQueue(^{
CGSize framebufferSize = framebuffer.size;
GPUTextureOptions framebufferTextureOptions = framebuffer.textureOptions;
// 常见查找hash字符串
NSString *lookupHash = [self hashForSize:framebufferSize textureOptions:framebufferTextureOptions onlyTexture:framebuffer.missingFramebuffer];
// 获取当前同类型缓存的数量
NSNumber *numberOfMatchingTexturesInCache = [framebufferTypeCounts objectForKey:lookupHash];
NSInteger numberOfMatchingTextures = [numberOfMatchingTexturesInCache integerValue];
// 对相同类型的GPUImageFramebuffer,存放在framebufferCache中时,key值由lookupHash加上数量避免覆盖相同的GPUImageFramebuffer。
NSString *textureHash = [NSString stringWithFormat:@"%@-%ld", lookupHash, (long)numberOfMatchingTextures];
// [framebufferCache setObject:framebuffer forKey:textureHash cost:round(framebufferSize.width * framebufferSize.height * 4.0)];
[framebufferCache setObject:framebuffer forKey:textureHash];
// framebufferTypeCounts中的key没有加数量
[framebufferTypeCounts setObject:[NSNumber numberWithInteger:(numberOfMatchingTextures + 1)] forKey:lookupHash];
});
}
  • 清空缓存, 内存警告的时候, 清理缓存中的纹理缓存,清理framebufferCache中的所有对象,在init中方法监听memoryWarningObserver

//收到 memory warning 时触发释放内存
- (void)purgeAllUnassignedFramebuffers;
{
runAsynchronouslyOnVideoProcessingQueue(^{
// dispatch_async(framebufferCacheQueue, ^{
[framebufferCache removeAllObjects];
[framebufferTypeCounts removeAllObjects];
#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
CVOpenGLESTextureCacheFlush([[GPUImageContext sharedImageProcessingContext] coreVideoTextureCache], 0);
#else
#endif
});
}
  • 帧缓存持有与释放。在读取帧缓存图像数据时,需要保持对 GPUImageFramebuffer 的引用。并且读取完数据后,需要对其进行释放。详细见 GPUImageFramebuffer 的 newCGImageFromFramebufferContents 方法。

- (void)addFramebufferToActiveImageCaptureList:(GPUImageFramebuffer *)framebuffer;
{
runAsynchronouslyOnVideoProcessingQueue(^{
// dispatch_async(framebufferCacheQueue, ^{
[activeImageCaptureList addObject:framebuffer];
});
}
- (void)removeFramebufferFromActiveImageCaptureList:(GPUImageFramebuffer *)framebuffer;
{
runAsynchronouslyOnVideoProcessingQueue(^{
// dispatch_async(framebufferCacheQueue, ^{
[activeImageCaptureList removeObject:framebuffer];
});
}