IG_file_IO_register

In This Topic

This function registers your own functions to be called to do Reads, Writes, and Seeks during image file transfers.

Declaration:

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AT_ERRCOUNT ACCUAPI IG_file_IO_register ( LPFNIG_READ lpfnReadFunc, LPFNIG_WRITE lpfnWriteFunc, LPFNIG_SEEK lpfnSeekFunc );

Arguments:

Name	Type	Description
lpfnReadFunc	LPFNIG_READ	Far pointer to your function to be called for READs.
lpfnWriteFunc	LPFNIG_WRITE	Far pointer to your function to be called for WRITEs.
lpfnSeekFunc	LPFNIG_SEEK	Far pointer to your function to be called for SEEKs.

Return Value:

Returns the number of ImageGear errors that occurred during this function call.

Supported Raster Image Formats:

This function does not process image pixels.

Sample:

File IO

Example:

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LPFNIG_READ MyReadFunc; /* To be called for file READs / { HIGEAR hIGear; / Will hold HIGEAR handle of image / ... IG_file_IO_register ( MyReadFunc, NULL, NULL );/ Register it / ... IG_load_file ( "picture.bmp", &hIGear ); ... } / This will be called for each read during the above Load: / LONG ACCUAPI MyReadFunc ( LONG fd, LPBYTE lpBuffer, LONG lNumToRead ) { LONG nNumActuallyRead; ... / May transfer bytes to buffer in any way / return nNumActuallyRead; / Return count, or -1 for error */ }

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LPFNIG_READ               MyReadFunc;      /* To be called for file READs */
{
HIGEAR           hIGear;     /* Will hold HIGEAR handle of image  */
 ...
IG_file_IO_register ( MyReadFunc, NULL, NULL );/* Register it */
 ...
IG_load_file ( "picture.bmp", &hIGear );
 ...
}
/* This will be called for each read during the above Load:   */
LONG  ACCUAPI MyReadFunc ( LONG fd, LPBYTE lpBuffer, 
        LONG lNumToRead )
{
LONG     nNumActuallyRead;
 ...   /* May transfer bytes to buffer in any way     */
return  nNumActuallyRead; /* Return count, or -1 for error  */
}

Remarks:

An argument should be NULL if you want ImageGear to perform that operation. See also the descriptions for typedefs LPFNIG_READ, LPFNIG_WRITE, and LPFNIG_SEEK.

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