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L_PutBitmapRowColCompressed

Summary

Puts a row (or part of a row) of 1-bit compressed data from a buffer to a bitmap that is maintained in its compressed format.

Syntax

#include "l_bitmap.h"

L_LTKRN_API L_SSIZE_T L_PutBitmapRowColCompressed(pBitmap, pWorkBuffer, pRunBuffer, nRow, nCol, uWidth)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to be updated.

L_UCHAR* pWorkBuffer

NULL or a pointer to an optional work buffer. Allocating the work buffer speeds processing if you call this function more than once, because if you do not allocate a work buffer, the function allocates and frees a temporary buffer each time it is called. The size of this buffer should be the same as the bitmap handle's BytesPerLine field.

L_UINT16* pRunBuffer

Pointer to the input buffer, which contains 1-bit compressed image data.

L_INT nRow

The number of the row to update. The first row is 0, and the last row is 1 less than the bitmap height.

L_INT nCol

The column offset within the row to update. The first column offset is 0, and the last column offset is 1 less than the bitmap width.

L_UINT uWidth

The number of pixels to retrieve.

Returns

Value	Meaning
> 0	The number of pixels processed.
< 1	An error occurred. Refer to Return Codes.

Comments

This function is useful for working with 1-bit images that are loaded in their compressed formats for faster loading and display. For more information, refer to Speeding Up 1-Bit Documents.

Required DLLs and Libraries

LTKRN
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64, Linux.

Example

This example demonstrates the low-level functions for accessing
1-bit compressed bitmap data. It demonstrates the ability to get and put
partial rows, and the ability to process partial rows in buffer-to-buffer
processing. The result of the function is an inverted rectangle in the
middle of the image.

L_INT PutBitmapRowColCompressedExample(L_TCHAR*      pszFilename, 
                                                       HWND          hWnd, 
                                                       pBITMAPHANDLE pLeadBitmap) 
{ 
   L_INT nRet; 
   L_INT     XOffset;      /* Column offset of the rectangle to process */ 
   L_INT     XSize;        /* Pixel width of the rectangle to process */ 
   L_INT     YOffset;      /* Row offset of the rectangle to process */ 
   L_INT     YSize;        /* Pixel height of the rectangle to process */ 
   L_UCHAR*  pBuffer;      /* Buffer to hold the expanded row */ 
   L_UINT16* pRunBuffer;   /* Buffer to hold the compressed row */ 
   L_UCHAR*  pWorkBuffer;  /* Work buffer */ 
   HGLOBAL   hBuffer;      /* Handle to the pBuffer */ 
   HGLOBAL   hRunBuffer;   /* Handle to the pRunBuffer */ 
   HGLOBAL   hWorkBuffer;  /* Handle to the pWorkBuffer */ 
   L_INT     i, n;         /* Counters */ 
 
   /* Load the bitmap, at 1 bit per pixel */ 
   if(pLeadBitmap->Flags.Allocated) 
      L_FreeBitmap(pLeadBitmap); 
   nRet = L_LoadFile( pszFilename, pLeadBitmap, sizeof(BITMAPHANDLE),1,0, 
                     LOADFILE_COMPRESSED | LOADFILE_ALLOCATE | LOADFILE_STORE, 
                     NULL, NULL, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* This example does not work with rotated view perspectives */ 
   if ( (pLeadBitmap->ViewPerspective != TOP_LEFT) || (pLeadBitmap->ViewPerspective != BOTTOM_LEFT) ) 
   { 
      nRet = L_ChangeBitmapViewPerspective ( NULL, pLeadBitmap, sizeof(BITMAPHANDLE), TOP_LEFT ); 
      if(nRet != SUCCESS) 
      { 
         L_FreeBitmap(pLeadBitmap); 
         return nRet; 
      } 
   } 
   /* Specify a rectangle in the middle right part of the displayed image */ 
   XOffset = pLeadBitmap->Width / 3; 
   XSize = pLeadBitmap->Width * 2 / 3; 
   YOffset = pLeadBitmap->Height / 3; 
   YSize = pLeadBitmap->Height / 3; 
   /* Adjust the YOffset if the view perspective is bottom left */ 
   if (pLeadBitmap->ViewPerspective == BOTTOM_LEFT) 
   { 
      YOffset = pLeadBitmap->Height - YOffset - YSize; 
   } 
   /* Allocate the buffers */ 
   hBuffer = GlobalAlloc(GMEM_MOVEABLE, ( XSize + 7) / 8); 
   pBuffer = (L_UCHAR*)GlobalLock( hBuffer ); 
   hRunBuffer = GlobalAlloc(GMEM_MOVEABLE, (XSize + 3) * 2); 
   pRunBuffer = (L_UINT16*)GlobalLock( hRunBuffer ); 
   hWorkBuffer = GlobalAlloc(GMEM_MOVEABLE, pLeadBitmap->BytesPerLine); 
   pWorkBuffer = (L_UCHAR* )GlobalLock( hWorkBuffer ); 
   /* Invert the colors of pixels in the left half of the rectangle. */ 
   /* Notice that we get the whole rectangle, but process only half of it. */ 
   L_AccessBitmap(pLeadBitmap); 
   for(i=YOffset; i < (YOffset + YSize); i++) 
   { 
      nRet = (L_INT)L_GetBitmapRowColCompressed(pLeadBitmap, pWorkBuffer, 
                                          pRunBuffer, i, XOffset, XSize); 
      if(nRet < 1) 
      { 
         L_FreeBitmap(pLeadBitmap); 
         return nRet; 
      } 
      nRet = L_ExpandRow(pRunBuffer, pBuffer, 0, XSize/2); 
      if(nRet != SUCCESS) 
      { 
         L_FreeBitmap(pLeadBitmap); 
         return nRet; 
      } 
      for(n=0; n < (XSize /16); n++) 
         pBuffer[n] = pBuffer[n] ^ 0xFF; 
      nRet = L_CompressRow(pRunBuffer, pBuffer, 0, XSize/2); 
      if(nRet < 1 ) 
      { 
         L_FreeBitmap(pLeadBitmap); 
         return nRet; 
      } 
      nRet =(L_INT)L_PutBitmapRowColCompressed(pLeadBitmap, pWorkBuffer, pRunBuffer, i,  
                                                XOffset, XSize/ 2); 
      if(nRet < 1) 
      { 
         L_FreeBitmap(pLeadBitmap); 
         return nRet; 
      } 
   } 
   L_ReleaseBitmap(pLeadBitmap); 
   /* Free memory that we no longer need */ 
   GlobalFree(hBuffer); 
   GlobalFree(hRunBuffer); 
   GlobalFree(hWorkBuffer); 
   /* Update the paint palette to force a repaint */ 
   SendMessage (hWnd, WM_QUERYNEWPALETTE, 0, 0L); 
   return SUCCESS; 
}