How to Use a Matrix to Transform Objects in VB.NET

The Visual Basic .NET (VB.NET) Matrix class contains a Translate method that can help you transform a 2D drawing such as an ellipse or a rectangle. This lets you move a GraphicsPath object across the screen without having to create multiple versions of the object. A GraphicsPath object contains a series of curves and lines. Utilize the GraphicsPath object's Transform method and a Matrix object's Translate method to transform your object.

Instructions

1. Open your Visual Basic .NET file in an editor, such as Microsoft Visual Studio.

2. Create a new subroutine to perform the matrix transformation and pass it the "PaintEventArgs" data by adding the following code in your file:

   Public Sub TransformRectangle(ByVal e As PaintEventArgs)

3. Create new GraphicsPath, RectangleF and Matrix objects by adding the following code at the top of the subroutine:

   Dim gpath As New GraphicsPath
   Dim rectf As RectangleF = New RectangleF(0,0,75,75)
   Dim transmatrix As New Matrix

   The rectangle will appear in the top-left corner at the coordinates (0,0) with a width of 75 units and a height of 75 units.

4. Draw the initial position of the rectangle on the screen with the following code:

   e.Graphics.DrawPath(Pens.Black, gpath)

5. Translate and then transform the object with this code:

   transmatrix.Translate(200,0)
   gpath.Transform(transmatrix)

6. Draw the transformed rectangle on the user's screen with the code:

   e.Graphics.DrawPath(Pens.Black, gpath)

   End Sub

   The transformed rectangle will appear 200 units to the right of the initial rectangle.

7. Save your VB.NET file, and compile and run the program to view the transformed rectangle.

References

• Microsoft: MSDN: GraphicsPath.Transform Method
• Microsoft: MSDN: Matrix Class
• Java2s: Path Transform Matrix Demo