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Drawing a Polygon in a VCL Forms Application

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This procedure draws a polygon in a VCL form.

  1. Create a VCL form.
  2. Code the form's OnPaint event handler to draw a polygon.
  3. Build and run the application.

To create a VCL form

  1. Choose File > New > Other > Delphi Projects or C++Builder Projects and double-click the VCL Forms Application icon.The VCL Forms Designer is displayed.
  2. In the form view, click the form, if necessary, to display Form1 in the Object Inspector.

To write the OnPaint event handler

  1. In the Object Inspector, click the Events tab.
  2. Double-click the OnPaint event.The Code Editor displays with the cursor in the TForm1.FormPaint (Delphi) or TForm1::FormPaint (C++) event handler block.
  3. Enter the following event handling code:
Canvas.Polygon ([Point(0,0), Point(0, ClientHeight),
Point(ClientWidth, ClientHeight)]); TPoint points[] = { Point(0,0),
                    Point(0, ClientHeight),
                    Point(ClientWidth, ClientHeight) };
Canvas->Polygon( points, 3 );

To run the program

  1. Select Run > Run .
  2. The applications executes, displaying a right triangle in the lower left half of the form.

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