I have a closed path defined as a CGPath (actually, CGMutablePath).
I want to color burn a specific region of a UIImage defined by the path. I've been fiddling around with Core Graphics, but currently my only options are to color tint a rectangular area defined by a CGRect, not a path.
Can anyone point me in the right direction?
--Update
Using the help of Rob I managed to rotate the image I got from the camera 90 deg to let it appear correctly in the UIImageview..
Only problem I have left is the PATH i need to draw is still 90 degrees of, and out of scale. The code i currently use is as following:
- (UIImage*)applyColorFillWithPath:(CGMutablePathRef) path withColor:(UIColor*)color {
CGFloat targetWidth = self.size.width;
CGFloat targetHeight = self.size.height;
CGImageRef imageRef = [self CGImage];
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
if (bitmapInfo == kCGImageAlphaNone) {
bitmapInfo = kCGImageAlphaNoneSkipLast;
}
CGContextRef context;
if (self.imageOrientation == UIImageOrientationUp || self.imageOrientation == UIImageOrientationDown) {
//UIGraphicsBeginImageContext(CGSizeMake(targetWidth, targetHeight));
context = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
} else {
//UIGraphicsBeginImageContext(CGSizeMake(targetHeight, targetWidth));
context = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
}
// set the fill color
//[color setFill];
if (self.imageOrientation == UIImageOrientationLeft) {
CGContextRotateCTM(context, radians(90));
CGContextTranslateCTM (context, 0, -targetHeight);
} else if (self.imageOrientation == UIImageOrientationRight) {
CGContextRotateCTM (context, radians(-90));
CGContextTranslateCTM (context, -targetWidth, 0);
} else if (self.imageOrientation == UIImageOrientationUp) {
// NOTHING
} else if (self.imageOrientation == UIImageOrientationDown) {
CGContextTranslateCTM (context, targetWidth, targetHeight);
CGContextRotateCTM (context, radians(-180));
}
CGContextDrawImage(context, CGRectMake(0, 0, targetWidth, targetHeight),imageRef);
CGContextBeginPath(context);
CGContextAddPath(context, path);
CGContextSaveGState(context);
CGContextClip(context);
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillRect(context, CGPathGetBoundingBox(path));
CGContextRestoreGState(context);
// Turn the bitmap context into a UIImage.
CGImageRef cgImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
UIImage *coloredImg = [UIImage imageWithCGImage:cgImage scale:1 orientation:UIImageOrientationUp];
CGImageRelease(cgImage);
//return the color-burned image
return coloredImg;
}
The following image is the result. De red rectangle is a representation of the CGPATH. The white square is actually the result of the above method on the path.
http://i41.tinypic.com/f1zbdi.png
I suppose I need to manually rotate the CGPATH 90 degrees using COS math's and what not.. Although I might oversee something.. ?
Set the context's clipping path to your path to constrain the affected pixels.