GDI+: GdipRotateLineTransform

[José Roca]

The following example creates a linear gradient brush and uses it to fill a rectangle. Next, the code modifies the brush's transformation matrix, applying a composite transformation, and then fills a rectangle with the transformed brush.

C++

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VOID Example_RotateTrans(HDC hdc)
{
   Graphics myGraphics(hdc);

   LinearGradientBrush linGrBrush(
      Rect(0, 0, 80, 40),
      Color(255, 255, 0, 0),  // red
      Color(255, 0, 0, 255),  // blue
      LinearGradientModeHorizontal);

   // Fill a large area with the linear gradient brush (no transformation).
   myGraphics.FillRectangle(&linGrBrush, 0, 0, 800, 150);

   // Apply a composite transformation: first scale, then rotate.
   linGrBrush.ScaleTransform(2, 1);                    // horizontal doubling
   linGrBrush.RotateTransform(20, MatrixOrderAppend);  // 20-degree rotation

   // Fill a large area with the transformed linear gradient brush.
   myGraphics.FillRectangle(&linGrBrush, 0, 200, 800, 150); 
}


PowerBASIC

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SUB GDIP_RotateLineTransform (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pLinBrush AS DWORD
   LOCAL rc AS RECTF
   LOCAL colorRed AS DWORD
   LOCAL colorBlue AS DWORD

   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   rc.x = 0 : rc.y = 0 : rc.Width = 80 : rc.Height = 40
   colorRed = GDIP_ARGB(255, 255, 0, 0)
   colorBlue = GDIP_ARGB(255, 0, 0, 255)
   hStatus = GdipCreateLineBrushFromRect(rc, colorRed, colorBlue, %LinearGradientModeHorizontal, %WrapModeTile, pLinBrush)

   ' // Fill a large area using the gradient brush with the default wrap mode.
   hStatus = GdipFillRectangle(pGraphics, pLinBrush, 0, 0, 800, 150)

   ' // Apply a composite transformation: first scale, then rotate.
   hStatus = GdipScaleLineTransform(pLinBrush, 2, 1, %MatrixOrderPrepend)   ' // horizontal doubling
   hStatus = GdipRotateLineTransform(pLinBrush, 20, %MatrixOrderAppend)     ' // 20-degree rotation

   ' // Fill a large area with the transformed linear gradient brush.
   hStatus = GdipFillRectangle(pGraphics, pLinBrush, 0, 200, 800, 150)

   ' // Cleanup
   IF pLinBrush THEN GdipDeleteBrush(pLinBrush)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB