asked on

Fill the area outside a Polygon (opposite of Graphics.FillPolygon)

The code snippet below will draw a polygon and then fill the area inside of that polygon. I would like to draw a polygon (an array of points) and fill the area OUTSIDE of that polygon with a color - basically blank the area outside of a polygon with a color

Thanks

Private Sub Form1_Paint(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.PaintEventArgs) Handles _
      MyBase.Paint
    Dim polypoints() As Point
 
    ' Draw a polygon.
    polypoints = New Point() { _
        New Point(20, 110), _
        New Point(90, 150), _
        New Point(90, 100), _
        New Point(20, 150) _
    }
    e.Graphics.FillPolygon(Brushes.Red, polypoints)
    e.Graphics.DrawPolygon(Pens.Green, polypoints)
  End Sub

Open in new window

jjardine

Could you not just draw a box or rectangle over the entire screen and fill it with your color, then draw the polygon and fill it as white?

tedunni

ASKER

What I receive first is a bitmap image with colors and shapes already on it. I also receive the polygon as an input. I then take that bitmap and then draw a polygon on it. At that point I want to color the area outside of the polygon.

I don't believe I can do what you are suggesting jjardine because I would lose the image data that is inside the polygon.

ASKER CERTIFIED SOLUTION

Mike Tomlinson

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

tedunni

ASKER

Thanks, another perfect solution.