Filling Colors inside edges - iphone

Question

I am new to Iphone development.
Currently i am making coloring app.
I am using apple's paint app as ref to create my app.
I successfully create app where u can color on a screen with given texture image
What i did is
I create a custom UIView which extends opengl and i detect touches on it and draw accordingly.
I also kept background UIImageView which contain outline images, so it feels like your drawing above that Image.
Everything works fine
but i wanted to fill color inside black edges
Like if a image has four square which has black edges and inside of that square is blank and if i touch any square it should fill that square with selected color(mostly i am working on irregular shape)
Can anyone tell me how can i fill colors inside that square
The flood fill algo looks slow as i have some big images which will take time to fill the color
so is there any easy method by which i can fill color
A sample code will b very helpful as i am new to iPhone Dev

Answer 1

I implemnted this kind of feature in my recent project. The difference is: I filled color in border only.
Check my code over here, it might get helpful to you
// apply color to only border & return an image
+ (UIImage *)imageNamed:(NSString *)name withColor:(UIColor *)color
{
// load the image
UIImage *img = [UIImage imageNamed:name];
// begin a new image context, to draw our colored image onto
UIGraphicsBeginImageContext(img.size);
// get a reference to that context we created
CGContextRef context = UIGraphicsGetCurrentContext();
// set the fill color
[color setFill];
// translate/flip the graphics context (for transforming from CG* coords to UI* coords
CGContextTranslateCTM(context, 0, img.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// set the blend mode to color burn, and the original image
CGContextSetBlendMode(context, kCGBlendModeColorBurn);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, rect, img.CGImage);
// set a mask that matches the shape of the image, then draw (color burn) a colored rectangle
CGContextClipToMask(context, rect, img.CGImage);
CGContextAddRect(context, rect);
CGContextDrawPath(context,kCGPathFill);
// generate a new UIImage from the graphics context we drew onto
UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//return the color-burned image
return coloredImg;
}
Enjoy Programming !