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HOWTO: How To Use LoadImage() to Read a BMP File

This article was previously published under Q158898
SUMMARY
The LoadImage API can be used to load a bitmap from a BMP file. However, it does not return palette information. This article provides sample code and describes how to retrieve the palette information for the bitmap with LoadImage.
MORE INFORMATION
The following code uses the LoadImage API to load the bitmap as aDIBSection, and then creates a palette from the DIBSection's color table.If no color table is present, a halftone palette is used:
   BOOL LoadBitmapFromBMPFile( LPTSTR szFileName, HBITMAP *phBitmap,   HPALETTE *phPalette )   {   BITMAP  bm;   *phBitmap = NULL;   *phPalette = NULL;   // Use LoadImage() to get the image loaded into a DIBSection   *phBitmap = (HBITMAP)LoadImage( NULL, szFileName, IMAGE_BITMAP, 0, 0,               LR_CREATEDIBSECTION | LR_DEFAULTSIZE | LR_LOADFROMFILE );   if( *phBitmap == NULL )     return FALSE;   // Get the color depth of the DIBSection   GetObject(*phBitmap, sizeof(BITMAP), &bm );   // If the DIBSection is 256 color or less, it has a color table   if( ( bm.bmBitsPixel * bm.bmPlanes ) <= 8 )   {   HDC           hMemDC;   HBITMAP       hOldBitmap;   RGBQUAD       rgb[256];   LPLOGPALETTE  pLogPal;   WORD          i;   // Create a memory DC and select the DIBSection into it   hMemDC = CreateCompatibleDC( NULL );   hOldBitmap = (HBITMAP)SelectObject( hMemDC, *phBitmap );   // Get the DIBSection's color table   GetDIBColorTable( hMemDC, 0, 256, rgb );   // Create a palette from the color tabl   pLogPal = (LOGPALETTE *)malloc( sizeof(LOGPALETTE) + (256*sizeof(PALETTEENTRY)) );   pLogPal->palVersion = 0x300;   pLogPal->palNumEntries = 256;   for(i=0;i<256;i++)   {     pLogPal->palPalEntry[i].peRed = rgb[i].rgbRed;     pLogPal->palPalEntry[i].peGreen = rgb[i].rgbGreen;     pLogPal->palPalEntry[i].peBlue = rgb[i].rgbBlue;     pLogPal->palPalEntry[i].peFlags = 0;   }   *phPalette = CreatePalette( pLogPal );   // Clean up   free( pLogPal );   SelectObject( hMemDC, hOldBitmap );   DeleteDC( hMemDC );   }   else   // It has no color table, so use a halftone palette   {   HDC    hRefDC;   hRefDC = GetDC( NULL );   *phPalette = CreateHalftonePalette( hRefDC );   ReleaseDC( NULL, hRefDC );   }   return TRUE;   }				
The following code demonstrates how to use the LoadBitmapFromBMPFilefunction:
   case WM_PAINT:   {     PAINTSTRUCT   ps;     HBITMAP       hBitmap, hOldBitmap;     HPALETTE      hPalette, hOldPalette;     HDC           hDC, hMemDC;     BITMAP        bm;   hDC = BeginPaint( hWnd, &ps );   if( LoadBitmapFromBMPFile( szFileName, &hBitmap, &hPalette ) )   {      GetObject( hBitmap, sizeof(BITMAP), &bm );      hMemDC = CreateCompatibleDC( hDC );      hOldBitmap = (HBITMAP)SelectObject( hMemDC, hBitmap );      hOldPalette = SelectPalette( hDC, hPalette, FALSE );      RealizePalette( hDC );      BitBlt( hDC, 0, 0, bm.bmWidth, bm.bmHeight,              hMemDC, 0, 0, SRCCOPY );      SelectObject( hMemDC, hOldBitmap );      DeleteObject( hBitmap );      SelectPalette( hDC, hOldPalette, FALSE );      DeleteObject( hPalette );   }   EndPaint( hWnd, &amp;ps );   }   break;				
4.00 kbdsd BITMAP DDB DIB BMP file LoadImage LoadBitmap
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Article ID: 158898 - Last Review: 11/21/2006 15:33:30 - Revision: 2.2

Microsoft Win32 Application Programming Interface

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