Solved

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

Posted on 2009-03-31
4
908 Views
Last Modified: 2013-12-17
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

0
Comment
Question by:tedunni
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
4 Comments
 
LVL 14

Expert Comment

by:jjardine
ID: 24033807
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?
0
 

Author Comment

by:tedunni
ID: 24033891
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.
0
 
LVL 86

Accepted Solution

by:
Mike Tomlinson earned 250 total points
ID: 24034376
Here is a simple example...
Imports System.Drawing.Drawing2D
Public Class Form1
 
    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(25, 100), _
            New Point(275, 350), _
            New Point(275, 100), _
            New Point(25, 350) _
        }
 
        Dim gp As New GraphicsPath
        gp.AddPolygon(polypoints)
        Dim rgn As New Region(gp)
        e.Graphics.ExcludeClip(rgn)
        e.Graphics.FillRectangle(Brushes.Red, Me.ClientRectangle)
    End Sub
 
End Class

Open in new window

FillOutsidePolygon.jpg
0
 

Author Closing Comment

by:tedunni
ID: 31565067
Thanks, another perfect solution.
0

Featured Post

Visualize your virtual and backup environments

Create well-organized and polished visualizations of your virtual and backup environments when planning VMware vSphere, Microsoft Hyper-V or Veeam deployments. It helps you to gain better visibility and valuable business insights.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In my previous article (http://www.experts-exchange.com/Programming/Languages/.NET/.NET_Framework_3.x/A_4362-Serialization-in-NET-1.html) we saw the basics of serialization and how types/objects can be serialized to Binary format. In this blog we wi…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
Do you want to know how to make a graph with Microsoft Access? First, create a query with the data for the chart. Then make a blank form and add a chart control. This video also shows how to change what data is displayed on the graph as well as form…

622 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question