In This Topic ▼

LBitmapBase::PutRowCol

Summary

Copies data from a buffer into a class objects bitmap, with an offset to the bitmap. The data is copied exactly as it is stored in the buffer. The buffer contains uncompressed data.

Syntax

#include "ltwrappr.h"

virtual L_SSIZE_T LBitmapBase::PutRowCol (LBuff, nRow, nCol)

Parameters

LBuffer& LBuff

An LBuffer object that contains the 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.

Returns

Value	Meaning
>=1	The number of bytes put.
< 1	An error occurred. Refer to Return Codes.

Comments

Copies data from a buffer to the class object's bitmap, with an offset to the bitmap. The buffer to which contains uncompressed data.

By using this low-level function to update any part of a row, you can write a procedure that updates a single pixel or a rectangular area within the bitmap.

You must consider the bits per pixel of the bitmap when specifying the parameters. The following table describes the rules:

Bits Per Pixel	Column Offset (in Pixels)	Bytes to Update
1	Must be a multiple of 8 (such as 0, 8, or 16).	Should not go past the end of the row. Consider that there are 8 pixels per byte.
4	Must be an even number (such as 0, 2, or 4).	Should not go past the end of the row. Consider that there are 2 pixels per byte.
8	Can be any column within the bitmap.	Should not go past the end of the row. Consider that there is 1 pixel per byte.
16	Can be any column within the bitmap.	Must be a multiple of 2 (such as 2, 4, or 6), because there are 2 bytes per pixel. Also, it should not go past the end of the row.
24	Can be any column within the bitmap.	Must be a multiple of 3 (such as 3, 6, or 9), because there are 3 bytes per pixel. Also, it should not go past the end of the row.
32	Can be any column within the bitmap.	Must be a multiple of 4 (such as 4, 8, or 12), because there are 4 bytes per pixel. Also, it should not go past the end of the row.To speed up the operation then lock the bitmap memory when you use this function a lot. Normally, you can call LBitmapBase::Access to lock the memory before starting an operation that uses this function, then call LBitmapBase::Release when the operation is finished.

Color order of the target bitmap is determined by the Order field in the bitmap handle. This value can be ORDER_RGB, ORDER_BGR, ORDER_GRAY or ORDER_ROMM

NOTE: To calculate the correct size for a single row of image data:

(((Width * BitsPerPixel) + 31) >> 3)) &~3