Flood filling in iPad too slow

Question

I am using flood Filling for one of my coloring apps on iPad.

The app basically fills color within the black line of the image and I am able to do this with no problem, but it's too slow.

I first used recursive flood fill and its performance is the worst (due to Stack Overflow), then I was able to convert it to iterative using Stack with the following code but this is too slow

-(void)floodFillAtPoint:(CGPoint)atPoint
 {
Stack *stack = [[Stack alloc] init];

[stack push:[StackPoint pointWithPoint:atPoint]];
StackPoint *currentPoint = nil;
int counter = 0;
while ((currentPoint = [stack pop])) 
{
    CGPoint aPoint = currentPoint.point;//CGPointMake(pointPixel.x, pointPixel.y);
    [self setColorAtPoint:aPoint];
    CGPoint bPoint = aPoint;
    bPoint.x+=1;
    if([self checkForValidRegionAtPoint:bPoint])
        [stack push:[StackPoint pointWithPoint:bPoint]];
    bPoint = aPoint;
    bPoint.x-=1;
    if([self checkForValidRegionAtPoint:bPoint])
        [stack push:[StackPoint pointWithPoint:bPoint]];
    bPoint = aPoint;
    bPoint.y+=1;
    if([self checkForValidRegionAtPoint:bPoint])
        [stack push:[StackPoint pointWithPoint:bPoint]];
    bPoint = aPoint;
    bPoint.y-=1;
    if([self checkForValidRegionAtPoint:bPoint])
        [stack push:[StackPoint pointWithPoint:bPoint]];        
    counter++;
}
[stack release];

}

Would anyone suggest an alternative method which works best on iPad device?

Answer 1

Using an Objective-C object to represent each and every pixel is going to be extremely slow and add little benefit.

Use a different data structure to represent your bitmap, like one of the various CG* bitmap encapsulation mechanisms. Then twiddle the bits in the bitmap directly. It'll be tons and tons faster.