各位高手显卡,我想知道这两个方法之一是调整一个UIImage更好:调整UIImage大小的方法更好,为什么?
第一个我遇到简单,流行,如下:
-(UIImage *)resizeImage:(UIImage *)image width:(CGFloat)resizedWidth height:(CGFloat)resizedHeight
{
UIGraphicsBeginImageContext(CGSizeMake(resizedWidth ,resizedHeight));
[image drawInRect:CGRectMake(0, 0, resizedWidth, resizedHeight)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
,我发现这个链接http://iphonesdksnippets.com/post/2009/05/06/Resize-image-and-keep-aspect-ratio.aspx,似乎完成了与上述相同,但更复杂的(我真的不明白是怎么回事)第二种方法:
-(UIImage *)resizeImage:(UIImage *)image width:(CGFloat)resizedWidth height:(CGFloat)resizedHeight
{
CGImageRef imageRef = [image CGImage];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bitmap = CGBitmapContextCreate(NULL, resizedWidth, resizedHeight, 8, 4 * resizedWidth, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(bitmap, CGRectMake(0, 0, resizedWidth, resizedHeight), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
UIImage *result = [UIImage imageWithCGImage:ref];
CGContextRelease(bitmap);
CGImageRelease(ref);
return result;
}
所以米问题是,哪种方式更好,为什么?
低级方法=在调整大小后保持质量更好吗? @tom –
我想UIImage的drawInRect方法将在内部使用CGContextDrawImage ... – Tom