Scan-line flood-fill

        private void floodFill(Bitmap buffer, int x, int y, Color start, Color end) {
            // Scan-line method -- Thanks to Runer112 for providing me with the link
            // to Lode's tutorial (and thanks to Lode for writing said tutorial), which
            // served as the basis for this, and jacobly for helping to fix it.

            // areColorValuesEqual(Color,Color): compares ARGB values
            if (areColorValuesEqual(start, end)) return;
            if (areColorValuesEqual(buffer.GetPixel(x, y), end)) return;

            // Line from current position to bottom
            int y1 = y;
            while (y1 < buffer.Height && areColorValuesEqual(buffer.GetPixel(x, y1), start)) {
                buffer.SetPixel(x, y1, end);
                y1++;
            }
            int maxY = y1 - 1;                                                          //Store the maximum Y value

            // Line from current position to top
            y1 = y - 1;
            while (y1 >= 0 && areColorValuesEqual(buffer.GetPixel(x, y1), start)) {
                buffer.SetPixel(x, y1, end);
                y1--;
            }
            int minY = y1 + 1;                                                          //Store the minimum Y value

            for (int i = minY; i < maxY; i++) {                                         //From the minimum to the maximum
                if (x > 0 && areColorValuesEqual(buffer.GetPixel(x - 1, i), start)) {   //If we can check left and it hasn't been filled left,
                    floodFill(buffer, x - 1, i, start, end);                            //Fill to the left
                }
                if (x < buffer.Width - 1 && areColorValuesEqual(buffer.GetPixel(x + 1, i), start)) {//If we can go right and it hasn't been filled right,
                    floodFill(buffer, x + 1, i, start, end);                            //Fill to the right
                }
            }
        }