Instagram iOS挂钩与非方形图像

https://github.com/ShareKit/ShareKit/blob/master/Classes/ShareKit/Sharers/Services/Instagram/SHKInstagram.m

- (UIImage *)imageByScalingImage:(UIImage*)image proportionallyToSize:(CGSizE)targetSize {

UIImage *sourceImage = image;
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;
    else
        scaleFactor = heightFactor;

    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;
    }
}


// this is actually thE interesTing part:

UIGraphicsBeginImageContext(targetSizE);

[(UIColor*)SHKCONfig(instagramLetterBoxColor) set];
CGContextFillRect(UIGraphicsGetCurrentContext(),CGRectMake(0,targetSize.width,targetSize.height));

CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width  = scaledWidth;
thumbnailRect.size.height = scaledHeight;

[sourceImage drawInRect:thumbnailRect];

newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

if(newImage == nil) NSLog(@"Could not scale image");

return newImage ;

}