在我的iPhone应用程序中,我用相机拍了一张照片,然后我想把它调整为290*390像素。我用这个方法来调整图像的大小:
UIImage *newImage = [image _imageScaledToSize:CGSizeMake(290, 390)
interpolationQuality:1];
它工作得很好,但它是一个没有记录的功能,所以我不能再在iPhone OS4上使用它了。
所以…调整UIImage大小最简单的方法是什么?
给我的萨玛瑞恩同胞们,这是萨玛琳。iOS c#版本的@Paul Lynch回答。
private UIImage ResizeImage(UIImage image, CGSize newSize)
{
UIGraphics.BeginImageContextWithOptions(newSize, false, 0.0f);
image.Draw(new CGRect(0, 0, newSize.Width, newSize.Height));
UIImage newImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return newImage;
}
最简单的方法是设置UIImageView的框架,并将contentMode设置为其中一个调整大小的选项。
或者你可以使用这个实用工具方法,如果你真的需要调整图像的大小:
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
// In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
// Pass 1.0 to force exact pixel size.
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
使用示例:
#import "MYUtil.h"
…
UIImage *myIcon = [MYUtil imageWithImage:myUIImageInstance scaledToSize:CGSizeMake(20, 20)];
这里是我的一些冗长的Swift代码
func scaleImage(image:UIImage, toSize:CGSize) -> UIImage {
UIGraphicsBeginImageContextWithOptions(toSize, false, 0.0);
let aspectRatioAwareSize = self.aspectRatioAwareSize(image.size, boxSize: toSize, useLetterBox: false)
let leftMargin = (toSize.width - aspectRatioAwareSize.width) * 0.5
let topMargin = (toSize.height - aspectRatioAwareSize.height) * 0.5
image.drawInRect(CGRectMake(leftMargin, topMargin, aspectRatioAwareSize.width , aspectRatioAwareSize.height))
let retVal = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return retVal
}
func aspectRatioAwareSize(imageSize: CGSize, boxSize: CGSize, useLetterBox: Bool) -> CGSize {
// aspect ratio aware size
// http://stackoverflow.com/a/6565988/8047
let imageWidth = imageSize.width
let imageHeight = imageSize.height
let containerWidth = boxSize.width
let containerHeight = boxSize.height
let imageAspectRatio = imageWidth/imageHeight
let containerAspectRatio = containerWidth/containerHeight
let retVal : CGSize
// use the else at your own risk: it seems to work, but I don't know
// the math
if (useLetterBox) {
retVal = containerAspectRatio > imageAspectRatio ? CGSizeMake(imageWidth * containerHeight / imageHeight, containerHeight) : CGSizeMake(containerWidth, imageHeight * containerWidth / imageWidth)
} else {
retVal = containerAspectRatio < imageAspectRatio ? CGSizeMake(imageWidth * containerHeight / imageHeight, containerHeight) : CGSizeMake(containerWidth, imageHeight * containerWidth / imageWidth)
}
return retVal
}