#pragma mark image scale utility 《完整！！！！》

- (UIImage *)imageByScalingToMaxSize:(UIImage *)sourceImage {

if (sourceImage.size.width < ORIGINAL_MAX_WIDTH) return sourceImage;

CGFloat btWidth = 0.0f;

CGFloat btHeight = 0.0f;

if (sourceImage.size.width > sourceImage.size.height) {

btHeight = ORIGINAL_MAX_WIDTH;

btWidth = sourceImage.size.width * (ORIGINAL_MAX_WIDTH / sourceImage.size.height);

} else {

btWidth = ORIGINAL_MAX_WIDTH;

btHeight = sourceImage.size.height * (ORIGINAL_MAX_WIDTH / sourceImage.size.width);

}

CGSize targetSize = CGSizeMake(btWidth, btHeight);

return [self imageByScalingAndCroppingForSourceImage:sourceImage targetSize:targetSize];

}

- (UIImage *)imageByScalingAndCroppingForSourceImage:(UIImage *)sourceImage targetSize:(CGSize)targetSize {

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;

}