iphone - 缩放图像非常慢 - 帮助 [英] iphone - Scaling Images are very slow - Help

问题描述

我正在使用以下代码自行缩放图像。代码很好，图像缩放没有问题。

I am scaling images by myself using the following codes. The code is fine and the images are scaled without problem.

UIImage *originImg = img;
size = newSize;
if (originImg.size.width > originImg.size.height) {
    newSize = CGSizeMake(size.width, originImg.size.height * size.width / originImg.size.width);
} else {
    newSize = CGSizeMake(originImg.size.width * size.height / originImg.size.height, size.height);
}

UIGraphicsBeginImageContext(newSize);

CGContextRef context = CGContextRetain(UIGraphicsGetCurrentContext());
CGContextTranslateCTM(context, 0.0, newSize.height);
CGContextScaleCTM(context, 1.0, -1.0);

CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, newSize.width, newSize.height), originImg.CGImage);

UIImage* scaledImage = [UIGraphicsGetImageFromCurrentImageContext() retain];

UIGraphicsEndImageContext();
CGContextRelease(context);

唯一的问题是此代码的缩放过程非常慢。有人可以指出如何改进吗？

The only problem is that the scaling process from this code is very slow. Can someone point out how to improve it?

谢谢

推荐答案

您可以尝试：

CGContextSetInterpolationQuality(context, kCGInterpolationNone);

或

CGContextSetInterpolationQuality(context, kCGInterpolationLow);

并查看其中任何一个是否产生任何性能差异且质量水平可接受。

and see if either of those produce any performance differences with an acceptable quality level.

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