将UIButton中的图像缩放到AspectFit？
将UIButton中的图像缩放到AspectFit？
提问于 2010-01-08 11:34:59
我想添加一个图像到一个UIButton，还想缩放我的图像以适应UIButton (使图像更小)。请教我怎么做。
这是我尝试过的方法，但它不起作用：
使用setContentMode向按钮添加图像的
[self.itemImageButton setImage:stretchImage forState:UIControlStateNormal];
[self.itemImageButton setContentMode:UIViewContentModeScaleAspectFit];- 制作“拉伸图像”：
UIImage *stretchImage = [updatedItem.thumbnail stretchableImageWithLeftCapWidth:0 topCapHeight:0];回答 16
Stack Overflow用户
回答已采纳
发布于 2010-01-08 12:00:19
如果您确实想缩放图像，请执行此操作，但您应该在使用它之前调整它的大小。在运行时调整它的大小只会损失CPU周期。
这是我用来缩放图像的类别：
UIImage+Extra.h
@interface UIImage (Extras)
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;
@end;UIImage+Extra.m
@implementation UIImage (Extras)
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize {
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (!CGSizeEqualToSize(imageSize, targetSize)) {
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor < heightFactor)
scaleFactor = widthFactor;
else
scaleFactor = heightFactor;
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor < heightFactor) {
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
} else if (widthFactor > heightFactor) {
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
// this is actually the interesting part:
UIGraphicsBeginImageContextWithOptions(targetSize, NO, 0);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;
}
@end你可以按你想要的大小使用它。像这样：
[self.itemImageButton setImage:[stretchImage imageByScalingProportionallyToSize:CGSizeMake(20,20)]];Stack Overflow用户
发布于 2010-07-19 21:22:45
我也有同样的问题。只需设置UIButton中ImageView的ContentMode即可。
[[self.itemImageButton imageView] setContentMode: UIViewContentModeScaleAspectFit];
[self.itemImageButton setImage:[UIImage imageNamed:stretchImage] forState:UIControlStateNormal];希望这能有所帮助。
Stack Overflow用户
发布于 2015-07-15 19:51:57
这里的答案对我都不起作用，我用下面的代码解决了这个问题：
button.contentMode = UIViewContentModeScaleToFill;
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
button.contentVerticalAlignment = UIControlContentVerticalAlignmentFill;您也可以在Interface Builder中执行此操作。
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原文链接：
https://stackoverflow.com/questions/2025319
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