GDI+: GdipGetImagePalette

[José Roca]

The following example creates an Image object based on a BMP file. The image in that file uses 8 bits per pixel. The code calls the GdipGetImagePaletteSize function to determine the size of the image's palette. The call to GdipGetImagePalette fills the ColorPalette structure. The code displays the number of colors in the palette and then displays the ARGB values of the first five colors in the palette.

C++

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#include <windows.h>
#include <gdiplus.h>
#include <stdio.h>
using namespace Gdiplus;

INT main()
{
   GdiplusStartupInput gdiplusStartupInput;
   ULONG_PTR gdiplusToken;
   GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

   Image* image = new Image(L"Stripes8Bit.bmp");

   UINT size = image->GetPaletteSize();
   printf("The size of the palette is %d bytes.\n", size);
   ColorPalette* palette = (ColorPalette*)malloc(size);

   image->GetPalette(palette, size);

   if(size > 0)
   {
      printf("There are %u colors in the palette.\n", palette->Count);
      printf("The first five colors in the palette are as follows:\n");

      for(INT j = 0; j <= 4; ++j)
         printf("%x\n", palette->Entries[j]);
   }

   delete(image);
   free(palette);
   GdiplusShutdown(gdiplusToken);
   return 0;
}


PowerBASIC

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#COMPILE EXE
#DIM ALL
#INCLUDE "GDIPLUS.INC"

' ========================================================================================
' Main
' ========================================================================================
FUNCTION WINMAIN (BYVAL hInstance AS DWORD, BYVAL hPrevInstance AS DWORD, BYVAL lpszCmdLine AS ASCIIZ PTR, BYVAL nCmdShow AS LONG) AS LONG

   LOCAL hStatus AS LONG
   LOCAL token AS DWORD
   LOCAL StartupInput AS GdiplusStartupInput
   LOCAL pImage AS DWORD
   LOCAL strFileName AS STRING
   LOCAL nSize AS LONG
   LOCAL i AS LONG
   LOCAL clrpalette AS COLORPALETTE

   ' Initialize GDI+
   StartupInput.GdiplusVersion = 1
   hStatus = GdiplusStartup(token, StartupInput, BYVAL %NULL)
   IF hStatus THEN
      PRINT "Error initializing GDI+"
      EXIT FUNCTION
   END IF

   ' // Create an Image object, and then clone it.
   strFileName = UCODE$("climber8bit.bmp")
   hStatus = GdipLoadImageFromFile(STRPTR(strFileName), pImage)

   hStatus = GdipGetImagePaletteSize(pImage, nSize)
   PRINT "The size of the palette is" & STR$(nSize) & " bytes."
   IF nSize THEN
      hStatus = GdipGetImagePalette(pImage, clrPalette, nSize)
      IF hStatus = %StatusOk THEN
         PRINT "There are" & STR$(clrPalette.count) & " colors in the palette."
         FOR i = 0 TO 4
            PRINT HEX$(clrPalette.Entries(i))
         NEXT
      END IF
   END IF

   ' // Cleanup
   IF pImage THEN GdipDisposeImage(pImage)

   ' Shutdown GDI+
   GdiplusShutdown token

   WAITKEY$

END FUNCTION
' ========================================================================================