LBitmapBase::GetRowCompressed

#include "ltwrappr.h"

virtual L_INT32 LBitmapBase::GetRowCompressed(pLRunBuffer, nRow, nLines=1, pWorkBuffer=NULL)

LBuffer L_FAR * pLRunBuffer;	/* pointer to an LBuffer object */
L_INT nRow;	/* number of the first row to retrieve */
L_INT nLines;	/* the number of rows to retrieve */
LBuffer L_FAR * pWorkBuffer;	/* pointer to an optional work buffer */

Retrieves one or more rows of 1-bit compressed data from a class object’s bitmap that has been loaded in its compressed format. This function is available in the Document/Medical toolkits only.

Parameter	Description
pLRunBuffer	Pointer to an LBuffer object that will receive the retrieved row(s).
nRow	The number of the row to retrieve. The first row is 0 and the last row is 1 less than the bitmap height.
nLines	The number of lines to retrieve.
pWorkBuffer	A pointer to an optional work buffer. You can also pass NULL. 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 value returned by LBitmapBase::GetBytesPerLine.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Retrieves a row (or part of a row) of 1-bit compressed data from a class objects bitmap that has been loaded in its compressed format.

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

LTDIS
LTFIL

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

See Also

Elements:	LBitmapBase::PutRow, LBitmapBase::PutRowCol, LBitmapBase::PutRowCompressed, LBitmapBase::GetRow, LBitmapBase::PutRowColCompressed, LBitmapBase::GetRowCol, LBitmapBase::GetRowColCompressed, Class Members
Topics:	Speeding Up 1-Bit Documents

Example

/* This example demonstrates the low-level functions for accessing
1-bit compressed bitmap data. It demonstrates the ability to get and put
rows, and the ability to process rows in buffer-to-buffer processing.
The result of the function is the first 50 lines are inverted. */
void TestLoad(L_TCHAR L_FAR * pszFilename, HWND hWnd)
{
   LBitmapBase LeadBitmap;   /* Bitmap handle for the image */
   LBuffer Buffer;
   LBuffer RunBuffer;
   L_INT nRow = 0;            /* first row to get */
   L_INT nYSize = 50;         /* # of rows to get */

   /* Load the bitmap, as compressed */
   LeadBitmap.File()->SetFileName(pszFilename);
   LeadBitmap.File()->LoadFile(1,0,LOADFILE_COMPRESSED | LOADFILE_ALLOCATE | LOADFILE_STORE);

   /* if the ViewPerspective is not TOP_LEFT or BOTTOM_LEFT, make it TOP_LEFT */
   /* Get/PutRow functions only work with TOP_LEFT or BOTTOM_LEFT */
   if ( (LeadBitmap. GetViewPerspective() != TOP_LEFT)|| (LeadBitmap.GetViewPerspective() != BOTTOM_LEFT) )
      LeadBitmap.ChangeViewPerspective (TOP_LEFT );

   if (LeadBitmap.GetViewPerspective()== BOTTOM_LEFT)
      nRow = LeadBitmap.GetHeight() - nRow - nYSize;
   /* Allocate the buffers */
   Buffer.Reallocate((((LeadBitmap.GetWidth() + 31) &~31)/ 8) * nYSize);
   RunBuffer.Reallocate((L_UINT32)((LeadBitmap.GetWidth() + 3) * 2) * nYSize);
   /* Access the bitmap */
   LeadBitmap.Access();
   /* Get the top nRow lines */
   LeadBitmap.GetRowCompressed (&RunBuffer, nRow, nYSize,0);
   LeadBitmap.PutRowCompressed (RunBuffer, nRow, nYSize,0);
   LeadBitmap.Release();
}