LFile::CreateThumbnailCallBack

#include "ltwrappr.h"

virtual L_INT LFile::CreateThumbnailCallBack (pFileInfo, pBitmap, pBuffer, uFlags, nRow, nLines)

pFILEINFO pFileInfo;	/* pointer to the file information handle */
pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UCHAR L_FAR * pBuffer;	/* pointer to a buffer of the caller's output data */
L_UINT uFlags;	/* flags for first and last row, and first and last pass */
L_INT nRow;	/* current row number of the first line in the buffer */
L_INT nLines;	/* number of lines in the buffer */

Handles the output image data that the calling function has written to a buffer.

Parameter	Description
pFileInfo	The pointer to the FILEINFO structure that contains image information.
pBitmap	The pointer to the bitmap handle referencing the bitmap that contains the image information.
pBuffer	A pointer to a buffer containing one or more lines of output image data that the calling function has already processed (read or decompressed).
uFlags	Flags that describe whether this is the first or last call of the callback, and whether the buffer contains first or last row of image data. Possible values are:
	Value	Meaning
	FILEREAD_FIRSTPASS	[0x0001] This is the first pass through a progressive JPEG or CMP file.
	FILEREAD_LASTPASS	[0x0002] This is the last pass through a progressive JPEG or CMP file.
	FILEREAD_FIRSTROW	[0x0004] The first row of the buffer is the first row of the bitmap.
	FILEREAD_LASTROW	[0x0008] The last row of the buffer is the last row of the bitmap.
	FILEREAD_COMPRESSED	[0x0010] The data in the buffer is 1-bit compressed data, which you can handle as explained in Speeding Up 1-Bit Documents.
nRow	The current bitmap row number of the first line in the buffer.
nLines	The number of lines in the pBuffer buffer.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Several LEADTOOLS functions use this type of callback function. In some cases, The pBuffer buffer contains data that your callback function must output in order for the calling function to accomplish anything. In other cases, where the callback is optional, the callback gets a copy of the data, and the callback's output is in addition to the calling function's output. Refer to the description of the calling function to see how it uses the callback.

The FILEINFO structure that gets passed to the LFile::CreateThumbnailCallBack function does not contain the total number of pages. To get the total number of pages, you should call LFile::GetInfo and set the FILEINFO_TOTALPAGES flag.

Required DLLs and Libraries

LTFIL
File format DLLs

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Functions:	LFile::LoadFile, LFile::BrowseDir, Class Members
Topics:	Raster Image Functions: Saving Files,
	Raster Image Functions: Loading and Saving Stamp Images,
	Loading and Saving Images