L_GetBitmapRowColCompressed (original) (raw)

Summary

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

Syntax

#include "l_bitmap.h"

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

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to get the image data from.

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 output buffer, which will be filled with 1-bit compressed image data. Calculate the required size of this buffer as follows: bytes required = (nWidth + 3) * 2.

L_INT nRow

The number of the row to retrieve. 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 retrieve. The first column offset is 0, and the last column offset is 1 less than the bitmap width.

L_SIZE_T 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

For an example, refer to L_PutBitmapRowColCompressed.