How to show black empty space in CGContext for iOS - iphone

Question

I have an image that is 640x480 pixels and I need to crop and center it into a 596x596 px UIImage. Any empty space should be black (it should be black above and below the image). Right now i'm cropping it like this...
-(UIImage*)cropImage:(UIImage *)theImage toFitSize:(CGSize)theSize
{
CGFloat CROP_X = floorf((theImage.size.width-theSize.width)/2);
CGFloat CROP_Y = floorf((theImage.size.height-theSize.height)/2);
CGRect imageRect = CGRectMake(CROP_X, CROP_Y, theSize.width, theSize.height);
UIGraphicsBeginImageContext(imageRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(context, 0, 0, 0, 1);
CGRect drawRect = CGRectMake(-imageRect.origin.x, -imageRect.origin.y, theImage.size.width, theImage.size.height);
CGContextClipToRect(context, CGRectMake(0, 0, imageRect.size.width, imageRect.size.height));
[theImage drawInRect:drawRect];
UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return finalImage;
}
And I also tried
- (UIImage *)croppedImage:(CGRect)bounds
{
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], bounds);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return croppedImage;
}
But the empty space comes out as transparent. How do i do this?
Thanks

Answer 1

Do you really need to alter the image? If you're just going to present the clipped image, you can configure the UIImageView backgroundColor property to get the desired effect.
CGRect largerRect = CGRectMake(/* larger rect */);
CGRect smallerRect = CGRectMake(/* smaller rect */);
UIImage *croppedImage = [self cropImage:largerImage toFitSize:smallerRect];
// make the view the original size
UIImageView *imageView = [[UIImageView alloc] initWithFrame:largerRect];
imageView.image = croppedImage;
// center the cropped image and give it a loud background color
imageView.contentMode = UIViewContentModeCenter;
imageView.backgroundColor = [UIColor redColor];

Answer 2

this is resize image working code you only use resizeimage function and image is resize as you want width height
-`-(UIImage *)resizeImage:(UIImage *)image{
float width = image.size.width;
float height = image.size.height;
float maxSide = 310;
if (width >= height && width > maxSide)
{
width = maxSide;
height = (height*(width/image.size.width));
}
else{
if (height > maxSide)
{
height = maxSide;
width = (width * (height/image.size.height));
}
}
if ((int)width % 2 != 0)
{
width-- ;
}
if ((int)height %2 !=0)
{
height-- ;
}
UIImage *newImage;
if (width != image.size.width)
newImage = [self scaleImage:image ToSize:CGSizeMake(width,height)];
else
newImage = image;
return newImage;}- (UIImage*)scaleImage:(UIImage*)image ToSize:(CGSize)targetSize{
if (image == nil)
return nil;
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; // 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)
{
}
UIGraphicsEndImageContext();
return newImage;
}
`