L_CompressRows

#include "l_bitmap.h"

L_LTKRN_API L_INT L_CompressRows(pRunBuffer, pBuffer, nWidth, nRows)

L_UINT16* pRunBuffer;

pointer to the output buffer

L_UCHAR* pBuffer;

pointer to the input buffer

L_UINT nWidth;

number of pixels in each row

L_UINT nRows;

number of rows

Does buffer-to-buffer RLE compression of 1-bit image data. Use this function to process multiple lines of image data.

Parameter

Description

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) * nRows.

pBuffer

Pointer to the input buffer, which contains the 1-bit image data to be compressed. The size of each row must be rounded up to a multiple of 4 bytes. Use integer math to calculate the required size of this buffer as follows: bytes required = (((nWidth + 31) &~31)/ 8) * nRows.

nWidth

The number of pixels in each row.

nRows

The number of rows to process.

Returns

> 0

The number of pixels processed.

< 1

An error occurred. Refer to Return Codes.

Comments

The output buffer must be larger than the input buffer to accommodate the worst possible case with run-length encoding, where there are alternating black and white pixels. In most cases, however, the actual compressed data will be much smaller than the input data.

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.

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