REDIRECTWRITE Callback Function

#include "l_bitmap.h"

L_INT L_FAR L_EXPORT YourWrite(FD, pBuf, nCount, pUserData)

L_INT FD;	/* file handle */
L_CHAR L_FAR *pBuf;	/* address of buffer for write data */
L_UINT nCount;	/* length of data buffer */
L_VOID L_FAR *pUserData;	/* pointer to additional parameters */

Replaces the normal LEADTOOLS function for writing a file.

Parameter	Description
FD	Identifies the file to be written. The file handle is returned by the REDIRECTOPEN callback function.
pBuf	Points to a buffer that contains data to be written to the file.
nCount	Specifies the number of bytes to be written to the file.
pUserData	A void pointer that you can use to access a variable or structure containing data that your callback function needs. This gives you a way to receive data indirectly from the function that uses this callback function. (This is the same pointer that you pass in the pUserData parameter of the calling function.)
	Keep in mind that this is a void pointer, which must be cast to the appropriate data type within your callback function.

Returns

>0	The number of bytes that the function wrote to the file.
-1	The function failed.

Comments

For information about using this type of callback, refer to L_RedirectIO.

When nCount is 0, the file should be truncated. That is, mark the current write position as the last position in the file. Please note that previous operating system write functions automatically truncated a file when 0 bytes were written. However, the WIN32 WriteFile function does not truncate the file.

Example

To see how the following function is defined and called, refer to L_RedirectIO.

/* This procedure is a replacement to the built in Write procedure.
In this example no I/O operation will be done, so we do nothing. */
L_UINT L_FAR L_EXPORT WindowsWrite (L_INT FD, L_CHAR L_FAR * pBuf, L_UINT uCount)
{
   UNREFERENCED_PARAMETER (FD);
   UNREFERENCED_PARAMETER (pBuf);
   return (uCount);
}