Resize UIImage and change the size of UIImageView
Solution 1
When you get the width and height of a resized image Get width of a resized image after UIViewContentModeScaleAspectFit, you can resize your imageView:
imageView.frame = CGRectMake(0, 0, resizedWidth, resizedHeight);
imageView.center = imageView.superview.center;
I haven't checked if it works, but I think all should be OK
Solution 2
- (UIImage *)image:(UIImage*)originalImage scaledToSize:(CGSize)size
{
//avoid redundant drawing
if (CGSizeEqualToSize(originalImage.size, size))
{
return originalImage;
}
//create drawing context
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
//draw
[originalImage drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];
//capture resultant image
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//return image
return image;
}
Solution 3
This is the Swift equivalent for Rajneesh071's answer, using extensions
UIImage {
func scaleToSize(aSize :CGSize) -> UIImage {
if (CGSizeEqualToSize(self.size, aSize)) {
return self
}
UIGraphicsBeginImageContextWithOptions(aSize, false, 0.0)
self.drawInRect(CGRectMake(0.0, 0.0, aSize.width, aSize.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}
Usage:
let image = UIImage(named: "Icon")
item.icon = image?.scaleToSize(CGSize(width: 30.0, height: 30.0))
Solution 4
Use the category below and then apply border from Quartz into your image:
[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];
The category: UIImage+AutoScaleResize.h
#import <Foundation/Foundation.h>
@interface UIImage (AutoScaleResize)
- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;
@end
UIImage+AutoScaleResize.m
#import "UIImage+AutoScaleResize.h"
@implementation UIImage (AutoScaleResize)
- (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;
}
@end
Solution 5
If you have the size of the image, why don't you set the frame.size
of the image view to be of this size?
EDIT----
Ok, so seeing your comment I propose this:
UIImageView *imageView;
//so let's say you're image view size is set to the maximum size you want
CGFloat maxWidth = imageView.frame.size.width;
CGFloat maxHeight = imageView.frame.size.height;
CGFloat viewRatio = maxWidth / maxHeight;
CGFloat imageRatio = image.size.height / image.size.width;
if (imageRatio > viewRatio) {
CGFloat imageViewHeight = round(maxWidth * imageRatio);
imageView.frame = CGRectMake(0, ceil((self.bounds.size.height - imageViewHeight) / 2.f), maxWidth, imageViewHeight);
}
else if (imageRatio < viewRatio) {
CGFloat imageViewWidth = roundf(maxHeight / imageRatio);
imageView.frame = CGRectMake(ceil((maxWidth - imageViewWidth) / 2.f), 0, imageViewWidth, maxHeight);
} else {
//your image view is already at the good size
}
This code will resize your image view to its image ratio, and also position the image view to the same centre as your "default" position.
PS: I hope you're setting imageView.layer.shouldRasterise = YES
and imageView.layer.rasterizationScale = [UIScreen mainScreen].scale;
if you're using CALayer shadow effect ;) It will greatly improve the performance of your UI.
Related videos on Youtube
Sergey Grischyov
St. Petersburg State University graduate. Cocoa Controls contributor.
Updated on March 01, 2020Comments
-
Sergey Grischyov about 4 years
I have this
UIImageView
and I have the values of its max height and max width. What I want to achieve is that I want to take the image (with any aspect ratio and any resolution) and I want it to fit in the borders, so the picture does not exceed them, but it can shrink them as it wants. (marked red in the picture):Right now the image fits the necessary size properly, but I have 2 worries: 1. The
UIImageView
is not equal the size of the resized image, thus leaving red background (and I don't want that) 2. If the image is smaller that the height of myUIImageView
it is not resized to be smaller, it stays the same height.Here's my code and I know its wrong:
UIImage *actualImage = [attachmentsArray lastObject]; UIImageView *attachmentImageNew = [[UIImageView alloc] initWithFrame:CGRectMake(5.5, 6.5, 245, 134)]; attachmentImageNew.image = actualImage; attachmentImageNew.backgroundColor = [UIColor redColor]; attachmentImageNew.contentMode = UIViewContentModeScaleAspectFit;
So how do I dynamically change the size not only of the
UIImageView.image
, but of the wholeUIImageView
, thus making its size totally adjustable to its content. Any help would be much appreciated, thanks! -
Sergey Grischyov about 11 yearsWhy do you think I'm resizing it with
attachmentImageNew.contentMode = UIViewContentModeScaleAspectFit
? Because the image is too big. I can't set the size of theimageView
to be the exact of the size of its image, because I have the max value for its height and width. And pretty much 90% of the images have to be resized. -
Sergey Grischyov about 11 yearsI tried that and it goes beyond the limits of my
UIImageView
into the galaxy far far away -
tiguero about 11 yearsThat sounds like a star wars bug then :-)
-
Sergey Grischyov about 11 yearsWell, it's no bug, it just behaves like that, I don't think I need
contentMode
at all, I need something more powerful -
tiguero about 11 yearsThere is always a default mode for the contentMode it is not as if you don't need one. The default is UIViewContentModeScaleToFill
-
Alex over 8 yearsif after superview I don't add '!' it give me error 'value of optional type 'UIView?' not unwrapped' is fixed if I use '!' : imageView.center = imageView.superview!.center;
-
Rob over 6 yearsWhat if you're using auto layout? Shouldn't you not be setting
frame
? -
TheTravloper about 5 yearshow to use it btw
-
Wei over 3 yearsThanks you save me a day to change image inside an uibutton.