Shapes and Regions

• Download demo project - 22.7 Kb
• Download source - 52.3 Kb

Introduction

It is often a good idea to add irregular buttons to an application. This may be achieved by combining the use of Graphics.DrawPolygon and Region.

Background

I needed to plot city boundaries using VB.NET and I needed to make the plot interactive. The users would click on a city and the application should display information about that city. This led me to use Graphics.DrawPolygon to display the boundaries and apply a Region to make the shapes clickable.

Using the code

There are two forms in the project. Form1 contains the code below, the shape editor on the other hand can be used to generate x:y coordinates of a shape. One can draw the shape in the picture box and copy the points in the listbox.

Private Sub Button1_Click(ByVal sender As System.Object, _
              ByVal e As System.EventArgs) Handles Button1.Click
    Dim H(3) As Point
    Dim J As New Kring()

    ' make a square polygon

    H(0) = New Point(100, 100)
    H(1) = New Point(300, 100)
    H(2) = New Point(300, 400)
    H(3) = New Point(100, 400)
    'you can create a complex set of points

    J.KKline = H

    ' I don't know how to set the fillbrush during design time so just 

    '  specify other attributes via code

    J.FillBrush = New SolidBrush(Color.Blue)

    ' it is important that the objects size be equal to

    ' the canvas or this in this case the form.

    ' the canvas may also be a picturebox or other windows control

    ' example :

    ' Picturebox1.controls.add(J)

    ' j.size = picturebox1.size


    J.Size = Me.Size
    Me.Controls.Add(J)
End Sub

Points of Interest

I'm looking at developing a much faster and effective way to display clickable shapes. I've already used the same method (just applied geodetic formulas) to plot building footprints, road networks, and parcel vectors. But I cannot share those codes because they're my company properties.