在Visual Studio C#中的PictureBox中填写Function？

Question

Is there any function to automatically fill in one of these states in brazil with a certain color, but without their neighbour state? So as an example, i have the coordinate 150x and 200y for the picturebox in c# Visual Studio. And i want that from this point everything grey that surrounds this point should turn into blue, but it should stop at the white border. Is there any function to do that, without declaring specific polygons for each state? Thanks for all Answers!

Answer 1

Here I have an idea that you can use recursion to traverse the pixels and modify their color.

Bitmap bmp;
private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
    int x = e.X;
    int y = e.Y;

    bmp = (Bitmap)pictureBox1.Image;
    ModifyMap(x, y);
    pictureBox1.Image = bmp;
}

// Recursion
private void ModifyMap(int x, int y)
{
    // the color info of gray part "Color [A=255, R=153, G=153, B=153]"
    if (bmp.GetPixel(x, y).ToString() == "Color [A=255, R=153, G=153, B=153]")
    {
        bmp.SetPixel(x, y, Color.Blue);
        ModifyMap(x + 1, y);
        ModifyMap(x - 1, y);
        ModifyMap(x, y + 1);
        ModifyMap(x, y - 1);
    }
}

The test result,