GDI+: GdipGetImageAttributesAdjustedPalette

[José Roca]

The following example initializes a ColorPalette structure with four colors: aqua, black, red, and green. The code also creates an ImageAttributes object and sets its bitmap remap table so that green will be converted to blue. Then the code adjusts the palette colors by passing the address of the palette to the GdipGetAdjustedPalette function. The code displays the four palette colors twice: once before the adjustment and once after the adjustment.

C++

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VOID Example_GetAdjustedPalette(HDC hdc)
{
   Graphics graphics(hdc);
   INT j;

   // Create a palette that has four entries.
   ColorPalette* palette =
      (ColorPalette*)malloc(sizeof(ColorPalette) + 3 * sizeof(ARGB));
   palette->Flags = 0;
   palette->Count = 4;

   palette->Entries[0] = 0xFF00FFFF;   // aqua
   palette->Entries[1] = 0xFF000000;   // black
   palette->Entries[2] = 0xFFFF0000;   // red
   palette->Entries[3] = 0xFF00FF00;   // green
 
   // Display the four palette colors with no adjustment.
   SolidBrush brush(Color());
   for(j = 0; j < 4; ++j)
   {
      brush.SetColor(palette->Entries[j]);
      graphics.FillRectangle(&brush, 30*j, 0, 20, 20);
   }

   // Create a remap table that converts green to blue.
   ColorMap map;
      map.oldColor = Color(255, 0, 255, 0);  // green
      map.newColor = Color(255, 0, 0, 255);  // blue

   // Create an ImageAttributes object, and set its bitmap remap table.
   ImageAttributes imAtt;
   imAtt.SetRemapTable(1, &map, ColorAdjustTypeBitmap);

   // Adjust the palette.
   imAtt.GetAdjustedPalette(palette, ColorAdjustTypeBitmap);

   // Display the four palette colors after the adjustment.
   for(j = 0; j < 4; ++j)
   {
      brush.SetColor(palette->Entries[j]);
      graphics.FillRectangle(&brush, 30*j, 30, 20, 20);
   }
}


PowerBASIC

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SUB GDIP_GetAdjustedPalette (BYVAL hdc AS DWORD)

   LOCAL hStatus AS LONG
   LOCAL pGraphics AS DWORD
   LOCAL pBrush AS DWORD

   hStatus = GdipCreateFromHDC(hdc, pGraphics)

   ' // Create a palette that has four entries.
   LOCAL palette AS COLORPALETTE
   palette.Flags = 0
   palette.Count = 4

   palette.Entries(0) = &HFF00FFFF  ' // aqua
   palette.Entries(1) = &HFF000000  ' // black
   palette.Entries(2) = &HFFFF0000  ' // red
   palette.Entries(3) = &HFF00FF00  ' // green

   ' // Create a SolidBrush
   hStatus = GdipCreateSolidFill(GDIP_ARGB(255, 0, 0, 0), pBrush)
   
   ' // Display the four palette colors with no adjustment.
   LOCAL j AS LONG
   FOR j = 0 TO 3
      hStatus = GdipSetSolidFillColor(pBrush, palette.Entries(j))
      hStatus = GdipFillRectangle (pGraphics, pBrush, 30*j, 0, 20, 20)
   NEXT
   
   ' // Create a remap table that converts green to blue.
   LOCAL map AS GDIP_ColorMap
   map.oldColor = GDIP_ARGB(255, 0, 255, 0)  ' // green
   map.newColor = GDIP_ARGB(255, 0, 0, 255)  ' // blue

   ' // Create an ImageAttributes object, and set its bitmap remap table.
   LOCAL pImgAttr AS DWORD
   hStatus = GdipCreateImageAttributes(pImgAttr)
   hStatus = GdipSetImageAttributesRemapTable(pImgAttr, _
             %ColorAdjustTypeBitmap, %TRUE, 1, map)

   ' // Adjust the palette.
   hStatus = GdipGetImageAttributesAdjustedPalette(pImgAttr, palette, %ColorAdjustTypeBitmap)

   ' // Display the four palette colors after the adjustment.
   FOR j = 0 TO 3
      hStatus = GdipSetSolidFillColor(pBrush, palette.Entries(j))
      hStatus = GdipFillRectangle (pGraphics, pBrush, 30*j, 30, 20, 20)
   NEXT

   ' // Cleanup
   IF pImgAttr THEN GdipDisposeImageAttributes(pImgAttr)
   IF pBrush THEN GdipDeleteBrush(pBrush)
   IF pGraphics THEN GdipDeleteGraphics(pGraphics)

END SUB


The following illustration shows the output of the preceding code. Note that the green in the original palette was changed to blue.