我有一个大小为 (1008、669) 的 UIImage,如何根据我的设备大小调整它的大小(因此,例如,如果我在 iPhone4s 中查看它,它的宽度将为 640 x 960((320 * retina_scale) x (480 * retina_scale))。我使用以下方法来执行此操作,但我的图像只是在UIImageView
中拉伸.如何处理?如何使它动态化,以便它可以在所有类型的图像中工作?
- (UIImage *) hResizeImage:(UIImage *)image withTargetSize:(CGSize)targetSize {
CGSize size = image.size;
CGFloat widthRatio = targetSize.width / image.size.width;
CGFloat heightRatio = targetSize.height / image.size.height;
// Figure out what our orientation is, and use that to form the rectangle
CGSize newSize;
if(widthRatio > heightRatio) {
newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio);
} else {
newSize = CGSizeMake(size.width * widthRatio, size.height * widthRatio);
}
// This is the rect that we've calculated out and this is what is actually used below
CGRect scaledRect = CGRectMake(0, 0, newSize.width * [UIScreen mainScreen].scale, newSize.height * [UIScreen mainScreen].scale);
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, [UIScreen mainScreen].scale);
[image drawInRect:scaledRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
由于比例因子是在 UIGraphicsBeginImageContextWithOptions 中指定的,因此在计算 scaledRect 时不需要将宽度和高度乘以屏幕比例。
如果在 UIGraphicsBeginImageContextWithOptions 中指定值 0.0,则比例因子将自动设置为设备主屏幕的比例因子。
- (UIImage *)hResizeImage:(UIImage *)image withTargetSize:(CGSize)targetSize {
CGSize size = image.size;
CGFloat widthRatio = targetSize.width / image.size.width;
CGFloat heightRatio = targetSize.height / image.size.height;
// Figure out what our orientation is, and use that to form the rectangle
CGSize newSize;
if(widthRatio > heightRatio) {
newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio);
} else {
newSize = CGSizeMake(size.width * widthRatio, size.height * widthRatio);
}
// This is the rect that we've calculated out and this is what is actually used below
CGRect scaledRect = CGRectMake(0, 0, newSize.width, newSize.height);
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, 0.0f);
[image drawInRect:scaledRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}