Question

是否有任何解决方案可以“动态”创建具有良好性能的照片？？我已经看过了here，但这并不是那么高效。

目的是创建像苹果photoapp这样的快速照片浏览器。因此，我需要根据从应用程序创建或下载到应用程序的照片创建切片。

Answer 1

您最好的选择可能是使用Core Graphics和ImageI / O

CGImageRef image = ...; // the big image to slice, don't draw with this image or it will decompress and might chew up all your memory
NSURL *url = ...; // the url for this slice
NSString *uti = @"public.jpeg"; // just an example, you should get the correct one for your images
CGSize sliceSize = 256.0; // for example
size_t column = 0;
size_t row = 0; // row and column should vary across your image
CGFloat colWidth = 256.0; // should account for the final column not being 256
CGFloat rowWidth = 256.0; // should account for the final row not being 256
CGRect sliceRect = CGRectMake(floor(column * sliceSize), floor(row * sliceSize),
                                    floor(colWidth), floor(rowHeight));
CGImageRef slicedImage = CGImageCreateWithImageInRect(image, sliceRect);
if(NULL == slicedImage) {
    NSLog(@"hosed image");
}
CGImageDestinationRef destination = CGImageDestinationCreateWithURL((CFURLRef)url, (CFStringRef)uti, 1, NULL);
CGImageDestinationAddImage(destination, slicedImage, NULL);
if(!CGImageDestinationFinalize(destination)) {
    NSLog(@"hosed write of %@", [url path]);
}
CFRelease(destination);
CGImageRelease(slicedImage);

谨慎一点，这是从记忆中拼凑而成的，可能是错误的。请阅读文档，看看我搞砸了。

以下是有关此技术的文档。

http://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CGImage/Reference/reference.html#//apple_ref/c/func/CGImageCreateWithImageInRect

http://developer.apple.com/library/ios/#documentation/GraphicsImaging/Conceptual/ImageIOGuide/imageio_basics/ikpg_basics.html

“动态”创建瓷砖

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