Retrieves one or more rows of 1-bit compressed data from a class objects bitmap that has been loaded in its compressed format.
virtual L_INT LBitmapBase::GetRowCompressed(pLRunBuffer, nRow, nLines=1, pWorkBuffer=NULL)
Pointer to an LBuffer object that will receive the retrieved row(s).
The number of the row to retrieve. The first row is 0 and the last row is 1 less than the bitmap height.
The number of lines to retrieve.
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.
|SUCCESS||The function was successful.|
|< 1||An error occurred. Refer to Return Codes.|
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.
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.
L_INT LBitmapBase__GetRowCompressedExample(L_TCHAR * pszFilename, HWND hWnd)
LBitmapBase LeadBitmap; /* Bitmap handle for the image */
L_INT nRow = 0; /* first row to get */
L_INT nYSize = 50; /* # of rows to get */
/* Load the bitmap, as compressed */
nRet =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) )
nRet =LeadBitmap.ChangeViewPerspective (TOP_LEFT );
if (LeadBitmap.GetViewPerspective()== BOTTOM_LEFT)
nRow = LeadBitmap.GetHeight() - nRow - nYSize;
/* Allocate the buffers */
nRet =Buffer.Reallocate((((LeadBitmap.GetWidth() + 31) &~31)/ 8) * nYSize);
nRet =RunBuffer.Reallocate((L_UINT32)((LeadBitmap.GetWidth() + 3) * 2) * nYSize);
/* Access the bitmap */
/* Get the top nRow lines */
nRet =LeadBitmap.GetRowCompressed (&RunBuffer, nRow, nYSize,0);
nRet =LeadBitmap.PutRowCompressed (RunBuffer, nRow, nYSize,0);
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