GDI+: GdipWidenPath

[José Roca]

The following example creates a GraphicsPath object and adds a closed curve to the path. The code creates a green pen that has a width of 10, changes its style to DashStyleDash, and passes the address of that pen to the GdipWidenPath function. Then the code draws the path with a blue pen of width 1.

C++

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VOID WidenExample(HDC hdc)
{
   Graphics graphics(hdc);
   Pen bluePen(Color(255, 0, 0, 255));
   Pen greenPen(Color(255, 0, 255,  0), 10);

   PointF points[] = {
      PointF(20.0f, 20.0f),
      PointF(160.0f, 100.0f),
      PointF(140.0f, 60.0f),
      PointF(60.0f, 100.0f)};

   GraphicsPath path;
   path.AddClosedCurve(points, 4);
   path.Widen(&greenPen);
   graphics.DrawPath(&bluePen, &path);
}


PowerBASIC

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SUB GDIP_WidenPath (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pPath AS DWORD
   LOCAL pBluePen AS DWORD
   LOCAL pGreenPen AS DWORD
   DIM   pts(3) AS POINTF

   ' // Create the Graphics object.
   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   ' // Create the pens.
   hStatus = GdipCreatePen1(GDIP_ARGB(255, 0, 0, 255), 1, %UnitWorld, pBluePen)
   hStatus = GdipCreatePen1(GDIP_ARGB(255, 255, 255, 0), 10, %UnitWorld, pGreenPen)

   ' // Create the Path object.
   hStatus = GdipCreatePath(%FillModeAlternate, pPath)

   ' // Add a closed curve.
   pts(0).x = 20  : pts(0).y = 20
   pts(1).x = 160 : pts(1).y = 100
   pts(2).x = 140 : pts(2).y = 60
   pts(3).x = 60  : pts(3).y = 100
   hStatus = GdipAddPathClosedCurve(pPath, pts(0), 4)

   ' // The GdipWidenPath function respects the dash style of the specified pen
   ' // (the green pen in this case). The following instruction changes it.
   hStatus = GdipSetPenDashStyle(pGreenPen, %DashStyleDash)

   ' // Widen tha path.
   hStatus = GdipWidenPath(pPath, pGreenPen, %NULL, FlatnessDefault)

   ' // Draw the path.
   hStatus = GdipDrawPath(pGraphics, pBluePen, pPath)

   ' // Cleanup
   IF pBluePen THEN GdipDeletePen(pBluePen)
   IF pGreenPen THEN GdipDeletePen(pGreenPen)
   IF pPath THEN GdipDeletePath(pPath)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB