Get width of a resized image after UIViewContentModeScaleAspectFit

Question

I have my UIImageView and I put an image into it that I resize like this:

UIImageView *attachmentImageNew = [[UIImageView alloc] initWithFrame:CGRectMake(5.5, 6.5, 245, 134)];
attachmentImageNew.image = actualImage;
attachmentImageNew.backgroundColor = [UIColor redColor];
attachmentImageNew.contentMode = UIViewContentModeScaleAspectFit;

I tried getting the width of the resized picture in my UIImageView by doing this:

NSLog(@"Size of pic is %f", attachmentImageNew.image.size.width);

But it actually returns me the width of the original picture. Any ideas on how do I get the frame of the picture that I see on screen?

EDIT: Here's how my UIImageView looks, red area is its backgroundColor

enter image description here

Just check update in my answer. – Bhavin Feb 01 '13 at 14:32 — Bhavin, Feb 01 '13 at 14:32

Mikhail · Accepted Answer · 2013-02-01T15:41:17.173

47

I don't know is there more clear solution, but this works:

float widthRatio = imageView.bounds.size.width / imageView.image.size.width;
float heightRatio = imageView.bounds.size.height / imageView.image.size.height;
float scale = MIN(widthRatio, heightRatio);
float imageWidth = scale * imageView.image.size.width;
float imageHeight = scale * imageView.image.size.height;

edited Feb 01 '13 at 15:41

answered Feb 01 '13 at 15:31

Mikhail

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For those who are wondering what MIN() function is, I believe you can replace with this line of code: float scale = widthRatio < heightRatio ? widthRatio : heightRatio; – Zhang Jul 09 '14 at 03:51
1

Copy paste function in swift, related to @Mikhail's answer: `func getScaledSizeOfImage(image: UIImage, toSize: CGSize) -> CGSize { var widthRatio = toSize.width/image.size.width var heightRatio = toSize.height/image.size.height var scale = min(widthRatio, heightRatio) var imageWidth = scale*image.size.width var imageHeight = scale*image.size.height return CGSizeMake(imageWidth, imageHeight) }` – Mr. T Jul 30 '15 at 10:17
Swift 3.0 Version: let widthRatio = imageView.bounds.size.width / (imageView.image?.size.width)! let heightRatio = imageView.bounds.size.height / (imageView.image?.size.height)! let scale = min(widthRatio, heightRatio) let imageWidth = scale * (imageView.image?.size.width)! let imageHeight = scale * (imageView.image?.size.height)! – SaundersB Nov 12 '16 at 18:56

score 1 · Answer 2 · answered Aug 01 '15 at 09:23

1

A solution in Swift:

let currentHeight = imageView.bounds.size.height
let currentWidth = imageView.bounds.size.width
let newWidth = UIScreen.mainScreen().bounds.width
let newHeight = (newWidth * currentHeight) / currentWidth

println(newHeight)

answered Aug 01 '15 at 09:23

iagomr

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score 0 · Answer 3 · answered Feb 01 '13 at 14:05

It has the reference of your original image, so always gives the same dimensions as of original image.

To get the dimensions of new image you have to check aspect ratio. I have derived a formula for my need using different images of different size using Preview that how it resizes image according to its aspect ratio.

Bhavin · Answer 4 · 2013-02-01T14:29:58.420

According to Apple's Documentation for UIViewContentModeScaleAspectFit

It Scales the content (In your case actualImage) to fit the size of the view (In your case attachmentImageNew) by maintaining the aspect ratio.

That means your image size ( after the scaling ) should be same as your UIImageView.

UPDATE :

One new Suggestion to you if you don't want to use UIViewContentModeScaleAspectFit and if you can fix the size of scaledImage then you can use below code to scale the image for fix newSize and then you can use the width to your code.

CGSize newSize = CGSizeMake(100.0,50.0);
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

score 0 · Answer 5 · answered Feb 01 '13 at 14:41

in your case:

float yourScaledImageWitdh =  attachmentImageNew.frame.size.height *  attachmentImageNew.image.size.width / attachmentImageNew.image.size.height
NSLog(@"width of resized pic is %f", yourScaledImageWitdh);

but you should also check, before, the original image proportion vs the imageView proportion, my line of code is good just in case the red area is added horizontally, not in case your original image proportion is wider than the imageView frame proportion

score 0 · Answer 6 · answered Nov 04 '15 at 10:23

For Swift 2, you can use this code snippet to align an aspectFitted image to the bottom of the screen (sampled from earlier answers to this question -> thanks to you, guys)

let screenSize: CGRect = UIScreen.mainScreen().bounds
let screenWidth = CGFloat(screenSize.width)
let screenHeight = CGFloat(screenSize.height)

imageView.frame = CGRectMake(0, screenHeight - (imageView.image?.size.height)! , screenWidth, (imageView.image?.size.height)!)

let newSize:CGSize = getScaledSizeOfImage(imageView.image!, toSize: self.view.frame.size)

imageView.frame = CGRectMake(0, screenHeight - (newSize.height) , screenWidth, newSize.height)

func getScaledSizeOfImage(image: UIImage, toSize: CGSize) -> CGSize       
{
    let widthRatio = toSize.width/image.size.width
    let heightRatio = toSize.height/image.size.height
    let scale = min(widthRatio, heightRatio)
    let imageWidth = scale*image.size.width
    let imageHeight = scale*image.size.height
    return CGSizeMake(imageWidth, imageHeight)
}

Get width of a resized image after UIViewContentModeScaleAspectFit

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