从SpriteSheet加速UIImage创建 [英] Speed up UIImage creation from SpriteSheet

问题描述

我不太确定标题是否正确，但是我不确定我的问题在哪里。

我需要加载一个数组Spritesheet中的UIImage，然后将其用作UIImageView中的动画。

Spritesheet由TexturePacker生成，TexturePacker生成巨大的地图集（2048x2048）和json

直到现在，我的工作一直没有问题，甚至只用了0.5-0.8秒就加载了100帧，这我真的很满意。 / p>

现在的问题是我需要从Documents文件夹中加载Spritesheets（因为它们已下载，因此无法集成到应用程序中），所以我必须使用 UIImage imageWithContentsOfFile ，而不是 UIImage imagenamed 。
这使我的加载时间增加了5-15秒，具体取决于动画中的帧数。
我猜是问题所在，因为图像没有被缓存，正在为每一帧加载图像，但是我不明白为什么。

这是代码：

  //在这一行中，完善
 // UIImage * atlas = [UIImage imageNamed： @ media/spritesheets/[e-mail]]； 
 // //但是，这非常令人难以置信的加载时间
 UIImage * atlas = [UIImage imageWithContentsOfFile：[[NSBundle mainBundle] pathForResource：@ media / spritesheets / default-pro7 @ 2x ofType：@ png]]; 
 
 CGImageRef atlasCGI = [atlas CGImage]; 
 
 for（NSDictionary * dict以帧为单位）{
 
 NSDictionary * frame = [dict objectForKey：@ frame]; 
 int x = [[frame objectForKey：@ x] intValue]; 
 int y = [[frame objectForKey：@ y] intValue]; 
 int width = [[frame objectForKey：@ w] intValue]; 
 int height = [[frame objectForKey：@ h] intValue]; 
 
 NSDictionary * spriteSize = [dict objectForKey：@ spriteSourceSize]; 
 int realx = [[spriteSize objectForKey：@ x] intValue]; 
 
 NSDictionary * size = [dict objectForKey：@ sourceSize]; 
 int realWidth = [[size objectForKey：@ w] intValue]; 
 int realHeight = [[size objectForKey：@ h] intValue]; 
 
 //初始化画布尺寸！ 
 canvasSize = CGSizeMake（realWidth，realHeight）; 
 
 bitmapBytesPerRow =（canvasSize.width * 4）; 
 bitmapByteCount =（bitmapBytesPerRow * canvasSize.height）; 
 
 bitmapData = malloc（bitmapByteCount）; 
 
 //创建上下文
 context = CGBitmapContextCreate（bitmapData，canvasSize.width，canvasSize.height，8，bitmapBytesPerRow，colorSpace，kCGImageAlphaPremultipliedLast）; 
 
 //清除背景
 CGContextClearRect（context，CGRectMake（0.0f，0.0f，canvasSize.width，canvasSize.height））; 
 
 //获取spriteRect 
 CGRect cropRect = CGRectMake（x，y，width，height）; 
 CGImageRef imageRef = CGImageCreateWithImageInRect（atlasCGI，cropRect）; 
 
 //将图像绘制到位图上下文中
 CGContextDrawImage（context，CGRectMake（realx，0，width，height），imageRef）; 
 
 //获取结果图像
 resultImage = CGBitmapContextCreateImage（context）; 
 
 UIImage * result =结果= [UIImage imageWithCGImage：resultImage]; 
 
 [images addObject：result]; 
 
 //清理
 free（bitmapData）; 
 CGImageRelease（resultImage）; 
 CGImageRelease（imageRef）; 
} 
  

我什至可以尝试一个上传系统分析器会话，该会话显示了花费了很多的时间时间加载

解决方案

好吧，我终于弄清楚了问题出在哪里。在使用Instruments Time profiler仔细查看之后，我注意到在copyImageBlockSetPNG中花费了很多时间，这使我首先相信我从磁盘上为每一帧加载图像。原来，有人已经遇到了这个问题 CGContextDrawImage是否在，这是真的，我是每帧都加载内存，而不是从磁盘加载内存，而是每帧以png格式从内存中解压缩。

在那篇文章中有一个解决方案，包括将图像写到上下文中并从中获取图像的未压缩副本。

但是我发现了另一种方法，我相信它更有效率

  NSDictionary * dict = [NSDictionary dictionaryWithObject：[NSNumber numberWithBool：是] 
 forKey：（id）kCGImageSourceShouldCache]; 
 NSData * imageData = [NSData dataWithContentsOfFile：@ path / to / image.png]]; 
 CGImageSourceRef source = CGImageSourceCreateWithData（（__ bridge CFDataRef）（imageData），NULL）; 
 CGImageRef atlasCGI = CGImageSourceCreateImageAtIndex（source，0，（__bridge CFDictionaryRef）dict）; 
 CFRelease（来源）； 
  

希望有帮助！

I'm not really sure I got the title exactly right, but I'm not sure where my problem is exactly.

I need to load an array of UIImages from an spritesheet, which I'll then use as animations in a UIImageView.

The spritesheet is generated with TexturePacker, which generates the huge atlas (2048x2048) and a json with the sprites descriptions.

Until now, I've had it working without issues, even loading 100 frames in just 0.5-0.8 secs which I was really happy with.

The problem is now I need to load the spritesheets from the Documents folder (they are downloaded, so can't be integrated in the app), so I have to use UIImage imageWithContentsOfFile instead of UIImage imagenamed. This makes my loading time increase by 5-15 seconds depending the number of frames in the animation. I'm guessing the problem is that because the image isn't being cached, is loading it for every frame, but I don't see why

This is the code:

// With this line, perfect
//UIImage *atlas = [UIImage imageNamed:@"media/spritesheets/[e-mail]"];
// But with this one, incredibly looooong loading times
UIImage *atlas = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"media/spritesheets/default-pro7@2x" ofType:@"png"]];

CGImageRef atlasCGI = [atlas CGImage];

for( NSDictionary* dict in frames) {

    NSDictionary *frame = [dict objectForKey:@"frame"];
    int x = [[frame objectForKey:@"x"] intValue];
    int y = [[frame objectForKey:@"y"] intValue];
    int width = [[frame objectForKey:@"w"] intValue];
    int height = [[frame objectForKey:@"h"] intValue];

    NSDictionary *spriteSize = [dict objectForKey:@"spriteSourceSize"];
    int realx = [[spriteSize objectForKey:@"x"] intValue];

    NSDictionary *size = [dict objectForKey:@"sourceSize"];
    int realWidth = [[size objectForKey:@"w"] intValue];
    int realHeight = [[size objectForKey:@"h"] intValue];

    //Initialize the canvas size!
    canvasSize = CGSizeMake(realWidth, realHeight);

    bitmapBytesPerRow   = (canvasSize.width * 4);
    bitmapByteCount     = (bitmapBytesPerRow * canvasSize.height);

    bitmapData = malloc( bitmapByteCount );

    //Create the context
    context = CGBitmapContextCreate(bitmapData, canvasSize.width, canvasSize.height, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);

    // Clear background
    CGContextClearRect(context,CGRectMake(0.0f,0.0f,canvasSize.width,canvasSize.height));

    // Get spriteRect
    CGRect cropRect = CGRectMake(x, y, width, height);
    CGImageRef imageRef = CGImageCreateWithImageInRect(atlasCGI, cropRect);

    //Draw the image into the bitmap context
    CGContextDrawImage(context, CGRectMake(realx, 0, width, height), imageRef);

    //Get the result image
    resultImage = CGBitmapContextCreateImage(context);

    UIImage *result = result = [UIImage imageWithCGImage:resultImage];

    [images addObject:result];

    //Cleanup
    free(bitmapData);
    CGImageRelease(resultImage);
    CGImageRelease(imageRef);
}

I can even try an upload system profiler sessions which show where is taking so much time loading

解决方案

Well, I finally figured out where the problem was. After looking more carefully with Instruments Time profiler, I noticed a lot of time was spent in copyImageBlockSetPNG , which was what made me believe first that I was loading the image from disk for every frame. turn out, somebody already had this problem Does CGContextDrawImage decompress PNG on the fly?, and it ended being true that I was loading the memory each frame, but not from disk, instead it was being uncompressed from memory in png format for every frame.

In that post theres a solution, which consists in writing the image to a context and getting from it an uncompressed copy of the image.

That works, but I found other way which I believe It's a little bit more efficient

NSDictionary *dict = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
                                             forKey:(id)kCGImageSourceShouldCache];
NSData *imageData = [NSData dataWithContentsOfFile:@"path/to/image.png"]];
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)(imageData), NULL);
CGImageRef atlasCGI = CGImageSourceCreateImageAtIndex(source, 0, (__bridge CFDictionaryRef)dict);
CFRelease(source);

Hope it helps!

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