static public Bitmap UseFilter(Bitmap bitmap, int[,] filter, double divisor, int displacement, IBrush brush)
{
int width = bitmap.Width;
int height = bitmap.Height;
PixelMap copy = new PixelMap(bitmap);
PixelMap map = new PixelMap(width, height);
for (int i = 0; i < width; i++)
{
map[i, 0] = copy[i, 0];
map[i, height - 1] = copy[i, height - 1];
}
for (int j = 0; j < height; j++)
{
map[0, j] = copy[0, j];
map[width - 1, j] = copy[width - 1, j];
}
for (int x = 1; x < width - 1; x++)
{
for (int y = 1; y < height - 1; y++)
{
//use filter
if (brush.PointInBrush(x, y))
{
int R = 0;
int G = 0;
int B = 0;
for (int i = -1; i <= 1; i++)
{
for (int j = -1; j <= 1; j++)
{
R += copy[x + i, y + j].R * filter[i + 1, j + 1];
G += copy[x + i, y + j].G * filter[i + 1, j + 1];
B += copy[x + i, y + j].B * filter[i + 1, j + 1];
}
}
R = (int)Math.Round(R / divisor) + displacement;
G = (int)Math.Round(G / divisor) + displacement;
B = (int)Math.Round(B / divisor) + displacement;
R = Math.Max(Math.Min(255, R), 0);
G = Math.Max(Math.Min(255, G), 0);
B = Math.Max(Math.Min(255, B), 0);
map[x, y] = new Pixel(R, G, B);
}
else
{
map[x, y] = copy[x, y];
}
}
}
return(map.GetBitmap());
}