LFile::CreateThumbnailCallBack

#include "ltwrappr.h"

virtual L_INT LFile::CreateThumbnailCallBack (pFileInfo, pLBitmap, pLBuffer, uFlags, nRow, nLines)

pFILEINFO pFileInfo;

pointer to the file information handle

LBitmapBase * pLBitmap;

pointer to the bitmap handle

LBuffer * pLBuffer;

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.
pLBitmap The pointer to the bitmap handle referencing the bitmap that contains the image information.
pLBuffer 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.
FILEREAD_CLIPVERT [0x0020] Internal flag.
FILEREAD_CLIPHORZ [0x0040] Internal flag.
FILEREAD_UPDATELUT [0x0080] Internal flag.
nRow The current bitmap row number of the first line in the buffer.
nLines The number of lines in the pLBuffer 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 pLBuffer 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.

Platforms

Win32, x64.

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