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Drawing a Custom Dashed Line

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Windows GDI+ provides several dash styles that are listed in the DashStyle enumeration. If those standard dash styles don't suit your needs, you can create a custom dash pattern.

To draw a custom dashed line, put the lengths of the dashes and spaces in an array and pass the address of the array as an argument to the Pen::SetDashPattern method of a Pen object. The following example draws a custom dashed line based on the array {5, 2, 15, 4}. If you multiply the elements of the array by the pen width of 5, you get {25, 10, 75, 20}. The displayed dashes alternate in length between 25 and 75, and the spaces alternate in length between 10 and 20.

REAL dashValues[4] = {5, 2, 15, 4};
Pen blackPen(Color(255, 0, 0, 0), 5);
blackPen.SetDashPattern(dashValues, 4);
stat = graphics.DrawLine(&blackPen, Point(5, 5), Point(405, 5));

The following illustration shows the resulting dashed line. Note that the final dash has to be shorter than 25 units so that the line can end at (405, 5).

illustration showing a dashed line; each segment is a short line followed by a long one