Soft Paint Bucket Fill: Colour Equality
- by Bart van Heukelom
I'm making a small app where children can fill preset illustrations with colours. I've succesfully implemented an MS-paint style paint bucket using the flood fill argorithm. However, near the edges of image elements pixels are left unfilled, because the lines are anti-aliased. This is because the current condition on whether to fill is colourAtCurrentPixel == colourToReplace
(the colours are RGB uints)
I'd like to add a smoothing/treshold option like in Photoshop and other sophisticated tools, but what's the algorithm to determine the equality/distance between two colours?
if (match(pixel(x,y), colourToReplace) setpixel(x,y,colourToReplaceWith)
How to fill in match()?
Here's my current full code:
var b:BitmapData = settings.background;
b.lock();
var from:uint = b.getPixel(x,y);
var q:Array = [];
var xx:int;
var yy:int;
var w:int = b.width;
var h:int = b.height;
q.push(y*w + x);
while (q.length != 0) {
var xy:int = q.shift();
xx = xy % w;
yy = (xy - xx) / w;
if (b.getPixel(xx,yy) == from) {
b.setPixel(xx,yy,to);
if (xx != 0) q.push(xy-1);
if (xx != w-1) q.push(xy+1);
if (yy != 0) q.push(xy-w);
if (yy != h-1) q.push(xy+w);
}
}
b.unlock(null);
