scale Image in an UIButton to AspectFit?

Question

I want to add an image to a UIButton, and also want to scale my image to fit with the UIButton (make image smaller). Please show me how to do it.

This is what I have try, but it does't work:

1. Add image to button and setContentView

   [self.itemImageButton setImage:stretchImage forState:UIControlStateNormal]; [self.itemImageButton setContentMode:UIViewContentModeScaleAspectFit];

2. Try to make a stretchImage:

   UIImage *stretchImage = [updatedItem.thumbnail stretchableImageWithLeftCapWidth:0 topCapHeight:0];

Thank for your help

Answer 1

If you really want to scale an image, do it, but you should resize it before using it. Resizing it at run time will just lose CPU cycles.

This is the category I'm using to scale an image :

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:

UIGraphicsBeginImageContext(targetSize);

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

You can use it to the size you want. Like :

[self.itemImageButton setImage:[stretchImage imageByScalingProportionallyToSize:CGSizeMake(20,20)]];

Answer 2

I had the same problem. Just set the ContentMode of the ImageView that is inside the UIButton.

[[self.itemImageButton imageView] setContentMode: UIViewContentModeScaleAspectFit];
[self.itemImageButton setImage:[UIImage imageNamed:stretchImage] forState:UIControlStateNormal];

Hope this helps.