How to scale image to frame?

Question

Is it possible to scale UIImage to the frame size? Take a large image and “force it” into a smaller box.

Please provide an example.

Answer 1

If you are really talking about changing the UIImage, and not just changing the display frame, which can be done, as described in Mark, by changing the UIViewContentMode UIImageView, you can resize the actual image using the following UIImage extension (taken from this source )

 - (UIImage*)imageByScalingAndCroppingForSize:(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) == NO) { CGFloat widthFactor = targetWidth / width; CGFloat heightFactor = targetHeight / height; if (widthFactor > heightFactor) scaleFactor = widthFactor; // scale to fit height else scaleFactor = heightFactor; // scale to fit width 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; } } UIGraphicsBeginImageContext(targetSize); // this will crop CGRect thumbnailRect = CGRectZero; thumbnailRect.origin = thumbnailPoint; thumbnailRect.size.width = scaledWidth; thumbnailRect.size.height = scaledHeight; [sourceImage drawInRect:thumbnailRect]; newImage = UIGraphicsGetImageFromCurrentImageContext(); if(newImage == nil) NSLog(@"could not scale image"); //pop the context to get back to the default UIGraphicsEndImageContext(); return newImage; } 

Answer 2

possible deception of this question: How to scale UIImageView proportionally?

I will also copy the text of the accepted answer. Suppose your frame is a uiview:

imageView.contentMode = UIViewContentModeScaleAspectFit; will do what you want.

from documents, here are other scaling options

 UIViewContentMode Specifies how a view adjusts its content when its size changes. typedef enum { UIViewContentModeScaleToFill, UIViewContentModeScaleAspectFit, UIViewContentModeScaleAspectFill, UIViewContentModeRedraw, UIViewContentModeCenter, UIViewContentModeTop, UIViewContentModeBottom, UIViewContentModeLeft, UIViewContentModeRight, UIViewContentModeTopLeft, UIViewContentModeTopRight, UIViewContentModeBottomLeft, UIViewContentModeBottomRight, } UIViewContentMode; 

apple Documentation here: http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIImageView_Class/Reference/Reference.html