How do I scale a UIButton's imageView?

问题:

I created a UIButton instance named "button" with an image using [UIButton setImage:forState:]. The button.frame is larger than the image's size.

Now I want to scale this button's image smaller. I tried changing button.imageView.frame, button.imageView.bounds and button.imageView.contentMode, but all seem ineffective.

Can anyone help me scale a UIButton's imageView?

I created the UIButton like this:

UIButton *button = [[UIButton alloc] init];
[button setImage:image forState:UIControlStateNormal];

I tried to scale the image like this:

button.imageView.contentMode = UIViewContentModeScaleAspectFit;
button.imageView.bounds = CGRectMake(0, 0, 70, 70);

and this:

button.imageView.contentMode = UIViewContentModeScaleAspectFit;
button.imageView.frame = CGRectMake(0, 0, 70, 70);

回答1:

For the original poster, here is the solution I found:

commentButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;

This will allow your button to scale horizontally. There is a vertical setting as well.

Took me several hours to figure that one out (the naming of the property is very unintuitive) so figured I'd share.

回答2:

I'd faced similar problem, where I've a background Image (one with border) and an image (flag) for a custom button. I wanted flag to be scaled down and in center. I tried changing imageView's attribute but didn't succeed and was seeing this image --

During my experiments, I tried :

button.imageEdgeInsets = UIEdgeInsetsMake(kTop,kLeft,kBottom,kRight)

I achieved expected result as :

回答3:

An Addition Way for config in XIB file. You can choose this option if you want text or image is Scale full fill in UIButton. It's will be the same with code.

UIButton *btn = [UIButton new];

btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
btn.contentVerticalAlignment   = UIControlContentVerticalAlignmentFill;

回答4:

use

button.contentMode = UIViewContentModeScaleToFill;

not

button.imageView.contentMode = UIViewContentModeScaleAspectFit;

Update:

As @Chris commented,

To get this to work for setImage:forState:, you need to do the following to scale horizontally: myButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;

回答5:

    UIButton *button= [[UIButton alloc] initWithFrame:CGRectMake(0,0,70,70)];
    button.buttonType = UIButtonTypeCustom;
    UIImage *buttonImage = [UIImage imageNamed:@"image.png"];

    UIImage *stretchableButtonImage = [buttonImage stretchableImageWithLeftCapWidth:12 topCapHeight:0]; 
    [button setBackgroundImage:stretchableButtonImage forState:UIControlStateNormal]; 

回答6:

I found this solution.

1) Subclass the following methods of UIButton

+ (id)buttonWithType:(UIButtonType)buttonType {
    MyButton *toReturn = [super buttonWithType:buttonType];
    toReturn.imageView.contentMode = UIViewContentModeScaleAspectFit;
    return toReturn;
}

- (CGRect)imageRectForContentRect:(CGRect)contentRect {
    return contentRect;
}

And it works well.

回答7:

Strange, the only combo that worked for me (iOS 5.1) is...

button.imageView.contentMode = UIViewContentModeScaleAspectFit;

and

[button setImage:newImage forState:UIControlStateNormal];

回答8:

I just ran into this same problem, and there's a possible answer in this question:

Why does a custom UIButton image does not resize in Interface Builder?

Essentially, use the backgroundimage property instead, which does get scaled.

回答9:

Just do (From Design OR From Code):

From Design

1. Open your xib OR Storyboard.
2. Select button
3. Inside Attribute Inspector (Right side) > In "Control" section > select last 4th option for both Horizontal and Verical.

[For Point#3: Change Horizontal and vertical Align to UIControlContentHorizontalAlignmentFill and UIControlContentVericalAlignmentFill]

From Code

button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
button.contentVerticalAlignment =  UIControlContentVerticalAlignmentFill;

回答10:

like this can solve your problem:

+ (UIImage*)resizedImage:(UIImage*)image
{
 CGRect frame = CGRectMake(0, 0, 60, 60);
 UIGraphicsBeginImageContext(frame.size);
 [image drawInRect:frame];
 UIImage* resizedImage = UIGraphicsGetImageFromCurrentImageContext();
 UIGraphicsEndImageContext();

 return resizedImage;
}

回答11:

From small test I just did after reading here, depends if you use setImage or setBackgroundImage, both did the same result and strech the image

//for setBackgroundImage
 self.imageButton.contentMode = UIViewContentModeScaleAspectFill;
        [self.imageButton setBackgroundImage:[UIImage imageNamed:@"imgFileName"] forState:UIControlStateNormal];

//for setImage
 self.imageButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
        self.imageButton.contentVerticalAlignment = UIControlContentVerticalAlignmentFill;
    [self.imageButton setImage:[UIImage imageNamed:@"imgFileName"] forState:UIControlStateNormal];

回答12:

button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;
button.contentVerticalAlignment =  UIControlContentVerticalAlignmentFill;

回答13:

I can't get a solution use by _imageView, but I can use a CGContextRef to solve it. It use the UIGraphicsGetCurrentContext to get the currentContextRef and draw a image in currentContextRef, and then scale or rotate the image and create a new image. But it's not perfect.

the code:

-(UIImage*) scaleAndRotateImage:(UIImage*)photoimage width:(CGFloat)bounds_width height:(CGFloat)bounds_height;
{
    CGImageRef imgRef = photoimage.CGImage;

    CGFloat width = CGImageGetWidth(imgRef);
    CGFloat height = CGImageGetHeight(imgRef);

    CGAffineTransform transform = CGAffineTransformIdentity;
    CGRect bounds = CGRectMake(0, 0, width, height);

    bounds.size.width = bounds_width;
    bounds.size.height = bounds_height;

    CGFloat scaleRatio = bounds.size.width / width;
    CGFloat scaleRatioheight = bounds.size.height / height;
    CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef));
    CGFloat boundHeight;
    UIImageOrientation orient = photoimage.imageOrientation;
    switch(orient)
    {
        case UIImageOrientationUp: //EXIF = 1
            transform = CGAffineTransformIdentity;
            break;

        case UIImageOrientationUpMirrored: //EXIF = 2
            transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0);
            transform = CGAffineTransformScale(transform, -1.0, 1.0);
            break;

        case UIImageOrientationDown: //EXIF = 3
            transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationDownMirrored: //EXIF = 4
            transform = CGAffineTransformMakeTranslation(0.0, imageSize.height);
            transform = CGAffineTransformScale(transform, 1.0, -1.0);
            break;

        case UIImageOrientationLeftMirrored: //EXIF = 5
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width);
            transform = CGAffineTransformScale(transform, -1.0, 1.0);
            transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
            break;

        case UIImageOrientationLeft: //EXIF = 6
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(0.0, imageSize.width);
            transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
            break;

        case UIImageOrientationRightMirrored: //EXIF = 7
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeScale(-1.0, 1.0);
            transform = CGAffineTransformRotate(transform, M_PI / 2.0);
            break;

        case UIImageOrientationRight: //EXIF = 8
            boundHeight = bounds.size.height;
            bounds.size.height = bounds.size.width;
            bounds.size.width = boundHeight;
            transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
            transform = CGAffineTransformRotate(transform, M_PI / 2.0);
            break;

        default:
            [NSException raise:NSInternalInconsistencyException format:@"Invalid?image?orientation"];
            break;
    }

    UIGraphicsBeginImageContext(bounds.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft)
    {
        CGContextScaleCTM(context, -scaleRatio, scaleRatioheight);
        CGContextTranslateCTM(context, -height, 0);
    }
    else
    {
        CGContextScaleCTM(context, scaleRatio, -scaleRatioheight);
        CGContextTranslateCTM(context, 0, -height);
    }

    CGContextConcatCTM(context, transform);

    CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef);
    UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return imageCopy;
}

回答14:

This will also work, as the backgroundImage automatically scales

[button setBackgroundImage:image forState:UIControlStateNormal];

回答15:

Storyboard

You must define specific property in Runtime Attributes of Identity inspector – imageView.contentModel, where you set value relatively to rawValue position of enum UIViewContentMode. 1 means scaleAspectFit.

And button's alignment, in Attributes inspector:

回答16:

At the bottom left of screenshot, you can see Stretching properties. Try using those.

回答17:

Every UIButton has one hidden UIImageView of its own. So we have to set the content mode like the way given below...

[[btn imageView] setContentMode: UIViewContentModeScaleAspectFit];
[btn setImage:[UIImage imageNamed:imageName] forState:UIControlStateNormal];