Question

i am trying to scale down a image i get from photo library on touchesmoved by user in a similar way like when we take picture with camera using UIImagepicker setEditing to Yes method(or like the camera app).

I am trying to use the following method passing in some parameters based on touchesmoved but i am not getting the desired effect? what am i possibly doing wrong??

-(UIImage*)scaleToSize:(UIImage *)img:(CGSize)size
{


// Create a bitmap graphics context
    // This will also set it as the current context
    UIGraphicsBeginImageContext(size);

// Draw the scaled image in the current context
[img drawInRect:CGRectMake(0, 0, size.width, size.height)];

// Create a new image from current context
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

// Pop the current context from the stack
UIGraphicsEndImageContext();

// Return our new scaled image
return scaledImage;
}

-(void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIImage *img = [self scaleToSize:imgView.image:CGSizeMake(touch1.x,touch1.y)];
        imgView.image=img;
}

also how can i save the scaled image once somehow i scale it??

Answer 1

Building on your comment, the image will distort as it will draw the image into the rectangle specified and if the new dimensions are not the same aspect ratio (the width / height) as the original image then it will appear distorted.

You need some logic to ensure that your new width and height have the same aspect ratio, for example:

CGFloat newHeight = imageView.frame.size.height * size.width / imageView.frame.size.width;

If you make your Graphics context size.width and newHeight and then draw your image into this rect it will maintain the aspect ratio.

You will likely want to put some extra logic in there to either create a new width given the height or new height given the width, depending on which dimension was the largest change.

Hope this helps,

Dave