dibhelp.c

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/*------------------------------------------
   DIBHELP.C -- DIB Section Helper Routines 
                (c) Charles Petzold, 1998
  ------------------------------------------*/

#define WINVER 0x0500
#include <windows.h>
#include "dibhelp.h"

#define HDIB_SIGNATURE (* (int *) "Dib ")

typedef struct
{
     PBYTE    * ppRow ;            // must be first field for macros!
     int        iSignature ;
     HBITMAP    hBitmap ;
     BYTE     * pBits ;
     DIBSECTION ds ;
     int        iRShift[3] ;
     int        iLShift[3] ;
}
DIBSTRUCT, * PDIBSTRUCT ;

/*---------------------------------------------------------------
   DibIsValid:  Returns TRUE if hdib points to a valid DIBSTRUCT
  ---------------------------------------------------------------*/

BOOL DibIsValid (HDIB hdib)
{
     PDIBSTRUCT pdib = hdib ;

     if (pdib == NULL)
          return FALSE ;

     if (IsBadReadPtr (pdib, sizeof (DIBSTRUCT)))
          return FALSE ;

     if (pdib->iSignature != HDIB_SIGNATURE)
          return FALSE ;

     return TRUE ;
}

/*-----------------------------------------------------------------------
   DibBitmapHandle:  Returns the handle to the DIB section bitmap object
  -----------------------------------------------------------------------*/

HBITMAP DibBitmapHandle (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return NULL ;
     
     return ((PDIBSTRUCT) hdib)->hBitmap ;
}

/*-------------------------------------------
   DibWidth:  Returns the bitmap pixel width
  -------------------------------------------*/

int DibWidth (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ;
     
     return ((PDIBSTRUCT) hdib)->ds.dsBm.bmWidth ;
}

/*---------------------------------------------
   DibHeight:  Returns the bitmap pixel height
  ---------------------------------------------*/

int DibHeight (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ; 
     
     return ((PDIBSTRUCT) hdib)->ds.dsBm.bmHeight ;
}

/*----------------------------------------------------
   DibBitCount:  Returns the number of bits per pixel
  ----------------------------------------------------*/

int DibBitCount (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ;
     
     return ((PDIBSTRUCT) hdib)->ds.dsBm.bmBitsPixel ;
}

/*--------------------------------------------------------------
   DibRowLength:  Returns the number of bytes per row of pixels
  --------------------------------------------------------------*/

int DibRowLength (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ;
     
     return 4 * ((DibWidth (hdib) * DibBitCount (hdib) + 31) / 32) ;
}

/*----------------------------------------------------------------
   DibNumColors:  Returns the number of colors in the color table
  ----------------------------------------------------------------*/

int DibNumColors (HDIB hdib)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib))
          return 0 ;

     if (pdib->ds.dsBmih.biClrUsed != 0)
     {
          return pdib->ds.dsBmih.biClrUsed ;
     }
     else if (DibBitCount (hdib) <= 8)
     {
          return 1 << DibBitCount (hdib) ;
     }
     return 0 ;
}

/*------------------------------------------
   DibMask:  Returns one of the color masks
  ------------------------------------------*/

DWORD DibMask (HDIB hdib, int i)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib) || i < 0 || i > 2)
          return 0 ;
     
     return pdib->ds.dsBitfields[i] ;
}

/*---------------------------------------------------
   DibRShift:  Returns one of the right-shift values
  ---------------------------------------------------*/

int DibRShift (HDIB hdib, int i)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib) || i < 0 || i > 2)
          return 0 ;
     
     return pdib->iRShift[i] ;
}

/*--------------------------------------------------
   DibLShift:  Returns one of the left-shift values
  --------------------------------------------------*/

int DibLShift (HDIB hdib, int i)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib) || i < 0 || i > 2)
          return 0 ;
     
     return pdib->iLShift[i] ;
}

/*---------------------------------------------------------------
   DibCompression:  Returns the value of the biCompression field
  ---------------------------------------------------------------*/

int DibCompression (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ;

     return ((PDIBSTRUCT) hdib)->ds.dsBmih.biCompression ;
}

/*--------------------------------------------------------------
   DibIsAddressable:  Returns TRUE if the DIB is not compressed
  --------------------------------------------------------------*/

BOOL DibIsAddressable (HDIB hdib)
{
     int iCompression ;

     if (!DibIsValid (hdib))
          return FALSE ;

     iCompression = DibCompression (hdib) ;

     if (iCompression == BI_RGB || iCompression == BI_BITFIELDS)
         return TRUE ;

     return FALSE ;
}

/*---------------------------------------------------------------------------
   These functions return the sizes of various components of the DIB section
     AS THEY WOULD APPEAR in a packed DIB. These functions aid in converting
     the DIB section to a packed DIB and in saving DIB files.
  ---------------------------------------------------------------------------*/

DWORD DibInfoHeaderSize (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return 0 ;

     return ((PDIBSTRUCT) hdib)->ds.dsBmih.biSize ;
}

DWORD DibMaskSize (HDIB hdib)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib))
          return 0 ;

     if (pdib->ds.dsBmih.biCompression == BI_BITFIELDS)
          return 3 * sizeof (DWORD) ;

     return 0 ;
}

DWORD DibColorSize (HDIB hdib)
{
     return DibNumColors (hdib) * sizeof (RGBQUAD) ;
} 

DWORD DibInfoSize (HDIB hdib)
{
     return DibInfoHeaderSize(hdib) + DibMaskSize(hdib) + DibColorSize(hdib) ;
}

DWORD DibBitsSize (HDIB hdib)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib))
          return 0 ;

     if (pdib->ds.dsBmih.biSizeImage != 0)
     {
          return pdib->ds.dsBmih.biSizeImage ;
     }
     return DibHeight (hdib) * DibRowLength (hdib) ;
}

DWORD DibTotalSize (HDIB hdib)
{
     return DibInfoSize (hdib) + DibBitsSize (hdib) ;
}

/*----------------------------------------------------------------------
   These functions return pointers to the various components of the DIB 
     section.
  ----------------------------------------------------------------------*/

BITMAPINFOHEADER * DibInfoHeaderPtr (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return NULL ;
     
     return & (((PDIBSTRUCT) hdib)->ds.dsBmih) ;
}

DWORD * DibMaskPtr (HDIB hdib)
{
     PDIBSTRUCT pdib = hdib ;

     if (!DibIsValid (hdib))
          return 0 ;

     return pdib->ds.dsBitfields ;
}

void * DibBitsPtr (HDIB hdib)
{
     if (!DibIsValid (hdib))
          return NULL ;
     
     return ((PDIBSTRUCT) hdib)->pBits ;
}

/*------------------------------------------------------
   DibSetColor:  Obtains entry from the DIB color table
  ------------------------------------------------------*/

BOOL DibGetColor (HDIB hdib, int index, RGBQUAD * prgb)
{
     PDIBSTRUCT pdib = hdib ;
     HDC        hdcMem ;
     int        iReturn ;

     if (!DibIsValid (hdib))
          return 0 ;

     hdcMem = CreateCompatibleDC (NULL) ;
     SelectObject (hdcMem, pdib->hBitmap) ;
     iReturn = GetDIBColorTable (hdcMem, index, 1, prgb) ;
     DeleteDC (hdcMem) ;

     return iReturn ? TRUE : FALSE ;
}

/*----------------------------------------------------
   DibGetColor:  Sets an entry in the DIB color table
  ----------------------------------------------------*/
 
BOOL DibSetColor (HDIB hdib, int index, RGBQUAD * prgb)
{
     PDIBSTRUCT pdib = hdib ;
     HDC        hdcMem ;
     int        iReturn ;

     if (!DibIsValid (hdib))
          return 0 ;

     hdcMem = CreateCompatibleDC (NULL) ;
     SelectObject (hdcMem, pdib->hBitmap) ;
     iReturn = SetDIBColorTable (hdcMem, index, 1, prgb) ;
     DeleteDC (hdcMem) ;

     return iReturn ? TRUE : FALSE ;
}

/*-----------------------------------------------------------------
   DibPixelPtr:  Returns a pointer to the pixel at position (x, y)
  -----------------------------------------------------------------*/

BYTE * DibPixelPtr (HDIB hdib, int x, int y)
{
     if (!DibIsAddressable (hdib))
          return NULL ;

     if (x < 0 || x >= DibWidth (hdib) || y < 0 || y >= DibHeight (hdib))
          return NULL ;

     return (((PDIBSTRUCT) hdib)->ppRow)[y] + (x * DibBitCount (hdib) >> 3) ;
}

/*-----------------------------------------------
   DibGetPixel:  Obtains a pixel value at (x, y)
  -----------------------------------------------*/

DWORD DibGetPixel (HDIB hdib, int x, int y)
{
     PBYTE pPixel ;

     if (!(pPixel = DibPixelPtr (hdib, x, y)))
          return 0 ;

     switch (DibBitCount (hdib))
     {
     case  1:  return 0x01 & (* pPixel >> (7 - (x & 7))) ;
     case  4:  return 0x0F & (* pPixel >> (x & 1 ? 0 : 4)) ;
     case  8:  return * pPixel ;
     case 16:  return * (WORD *) pPixel ;
     case 24:  return 0x00FFFFFF & * (DWORD *) pPixel ; 
     case 32:  return * (DWORD *) pPixel ;
     }
     return 0 ;
}

/*--------------------------------------------
   DibSetPixel:  Sets a pixel value at (x, y)
  --------------------------------------------*/

BOOL DibSetPixel (HDIB hdib, int x, int y, DWORD dwPixel)
{
     PBYTE pPixel ;

     if (!(pPixel = DibPixelPtr (hdib, x, y)))
          return FALSE ;