GDI+: GdipDrawCurve

[José Roca]

The following example defines a polygon and fills it.

C++

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VOID Example_DrawCurve5(HDC hdc)
{
   Graphics graphics(hdc);

   // Define a Pen object and an array of PointF objects.
   Pen greenPen(Color::Green, 3);
   PointF point1(100.0f, 100.0f);
   PointF point2(200.0f, 50.0f);
   PointF point3(400.0f, 10.0f);
   PointF point4(500.0f, 100.0f);

   PointF curvePoints[4] = {
   point1,
   point2,
   point3,
   point4};

   PointF* pcurvePoints = curvePoints;

   // Specify offset, number of segments to draw, and tension.
   int offset = 1;
   int segments = 2;
   REAL tension = 1.0f;

   // Draw the curve.
   graphics.DrawCurve(&greenPen, curvePoints, 4, offset, segments, tension);

   //Draw the points in the curve.
   SolidBrush redBrush(Color::Red);
   graphics.FillEllipse(&redBrush, Rect(95, 95, 10, 10));
   graphics.FillEllipse(&redBrush, Rect(195, 45, 10, 10));
   graphics.FillEllipse(&redBrush, Rect(395, 5, 10, 10));
   graphics.FillEllipse(&redBrush, Rect(495, 95, 10, 10));
}


PowerBASIC

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SUB GDIP_DrawCurve (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pGreenPen AS DWORD
   LOCAL pRedBrush AS DWORD
   LOCAL offset AS LONG
   LOCAL segments AS LONG
   LOCAL tension AS SINGLE
   LOCAL point1 AS POINTF
   LOCAL point2 AS POINTF
   LOCAL point3 AS POINTF
   LOCAL point4 AS POINTF
   DIM   curvePoints(3) AS POINTF

   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   ' // Create a green Pen
   hStatus = GdipCreatePen1(GDIP_ARGB(255, 0, 255, 0), 1.0!, %UnitWorld, pGreenPen)

   point1.x = 100.0 : point1.y = 100.0
   point2.x = 200.0 : point2.y = 50.0
   point3.x = 400.0 : point3.y = 10.0
   point4.x = 500.0 : point4.y = 100.0

   curvePoints(0) = point1
   curvePoints(1) = point2
   curvePoints(2) = point3
   curvePoints(3) = point4

   ' // Specify offset, number of segments to draw, and tension.
   offset = 1
   segments = 2
   tension = 1.0!

   ' // Draw the curve
   hStatus = GdipDrawCurve3(pGraphics, pGreenPen, curvePoints(0), 4, offset, segments, tension)

  ' // Create the brush
   hStatus = GdipCreateSolidFill(GDIP_ARGB(255, 255, 0, 0), pRedBrush)

   ' //Draw the points in the curve
   hStatus = GdipFillEllipse(pGraphics, pRedBrush, 95, 95, 10, 10)
   hStatus = GdipFillEllipse(pGraphics, pRedBrush, 195, 45, 10, 10)
   hStatus = GdipFillEllipse(pGraphics, pRedBrush, 395, 5, 10, 10)
   hStatus = GdipFillEllipse(pGraphics, pRedBrush, 495, 95, 10, 10)

   ' // Cleanup
   IF pRedBrush THEN GdipDeleteBrush(pRedBrush)
   IF pGreenPen THEN GdipDeletePen(pGreenPen)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB


[José Roca]

The following example draws an antialised cardinal spline.

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SUB GDIP_DrawCurve (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pPen AS DWORD
   DIM   curvePoints(4) AS POINTL

   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   ' // Array of Point structures
   curvePoints(0).x = 0   : curvePoints(0).y = 100
   curvePoints(1).x = 50  : curvePoints(1).y = 80
   curvePoints(2).x = 100 : curvePoints(2).y = 20
   curvePoints(3).x = 150 : curvePoints(3).y = 80
   curvePoints(4).x = 200 : curvePoints(4).y = 100

   ' // Create a Pen
   hStatus = GdipCreatePen1(GDIP_ARGB(255, 0, 0, 255), 4, %UnitPixel, pPen)

   ' Gamma correction is nice, though slower...
   hStatus = GdipSetCompositingQuality(pGraphics, %CompositingQualityGammaCorrected)

   ' Draw the curve with anti-aliasing
   hStatus = GdipSetSmoothingMode(pGraphics, %SmoothingModeAntiAlias)
   hStatus = GdipDrawCurveI(pGraphics, pPen, curvePoints(0), 5)

   ' // Cleanup
   IF pPen THEN GdipDeletePen(pPen)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB