Available in LEADTOOLS Imaging Pro, Vector, Document, and Medical Imaging toolkits. |
#include "ltwrappr.h"
virtual L_INT LFile::ReadFileExtensions(ppExtensionList, pLoadOptions=NULL)
pEXTENSIONLIST * ppExtensionList; |
/* pointer to a pointer to a structure */ |
pLOADFILEOPTION pLoadOptions; |
/* pointer to optional extended load options */ |
Loads extensions from an Exif file. Please note that not all Exif files have extensions.
Parameter |
Description |
ppExtensionList |
Pointer to a pointer to an EXTENSIONLIST structure to be updated with the extensions read from the specified Exif file. |
pLoadOptions |
Pointer to optional extended load options. Pass NULL to use the default load options. |
Returns
>=0 |
Length of the comment field. |
< 0 |
An error occurred. Refer to Return Codes. |
Comments
Currently, this function works only with Exif files. Exif files can contain extra data stored as "FlashPix extensions". This function can be used to access this extra data. LEADTOOLS refers to this extra data as "extensions".
The LFile::LoadExtensionStampfunction can be used to load a stamp from the extension and LFile::GetExtensionAudio can be used to get embedded audio data.
When the memory allocated by this function is no longer needed, call LFile::FreeExtensions to free the memory.
Required DLLs and Libraries
LTFIL For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application. |
Win32, x64.
See Also
Functions: |
LFile::LoadExtensionStamp, LFile::GetExtensionAudio, LFile::FreeExtensions, LFile::ReadStamp, Class Members |
Topics: |
Raster Image Functions: Getting and Setting File Information |
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Example
#include <stdio.h> L_INT LFile__ReadFileExtensionsExample(L_TCHAR * pszFile, L_TCHAR * pszInfoFile) { L_INT nRet; LFile File; pEXTENSIONLIST pExtensionList; L_TCHAR szBuffer[512]; L_TCHAR szText[1024]; L_CHAR szName[128]; L_CHAR szCLSID[64]; HANDLE fd; DWORD dwSizeWrite; File.SetFileName(pszFile); nRet = File.ReadFileExtensions(&pExtensionList); if(nRet != SUCCESS) { MessageBox(NULL, TEXT("Error getting extensions!"), TEXT("Getting Extensions"), MB_OK); return nRet; } // Open the info .txt file fd = CreateFile(pszInfoFile, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0); if(!fd) { MessageBox(NULL, TEXT("Error opening info file!"), TEXT("Getting Extensions"), MB_OK); return FAILURE; } // Do we have a stamp, audio, or both? switch(pExtensionList->uFlags & (EXTENSION_STAMP | EXTENSION_AUDIO)) { case 0: lstrcpy(szBuffer, TEXT("")); break; case EXTENSION_STAMP: lstrcpy(szBuffer, TEXT(", EXTENSION_STAMP")); break; case EXTENSION_AUDIO: lstrcpy(szBuffer, TEXT(", EXTENSION_AUDIO")); break; case EXTENSION_STAMP | EXTENSION_AUDIO: lstrcpy(szBuffer, TEXT(", EXTENSION_STAMP | EXTENSION_AUDIO")); break; } wsprintf(szText, TEXT("Extension count: %d%s\n"), pExtensionList->uCount, szBuffer); WriteFile(fd, szText, 1024, &dwSizeWrite, NULL); for (L_UINT u = 0; u < pExtensionList->uCount; u++) { // Translate the Unicode string to multibyte if (!WideCharToMultiByte(CP_ACP, // Code page 0, // Performance and mapping flags pExtensionList->aList[u].pName, // Wide-character string -1, // Number of chars in string szName, // Buffer for new string sizeof(szName), // Size of buffer NULL, // Default for unmappable chars NULL)) // Sset when default char used { strcpy_s(szName, "ERROR decoding the Unicode string"); } if (pExtensionList->aList[u].pClsid) { StringFromGUID2((REFGUID) pExtensionList->aList[u].pClsid, (LPWSTR) szBuffer, sizeof(szBuffer)); WideCharToMultiByte(CP_ACP, // Code page 0, // Performance and mapping flags (LPWSTR) szBuffer, // Wide-character string -1, // Number of chars in string szCLSID, // Buffer for new string sizeof(szCLSID), // Size of buffer NULL, // Default for unmappable chars NULL); // Set when default char used } else strcpy_s(szCLSID, "NULL"); // Write information about stream 'u' wsprintf(szText, TEXT("[%d]: Name = %s, DataSize = %d, CLSID = %s\n"), u, szName, pExtensionList->aList[u].uDataSize, szCLSID); WriteFile(fd, szText, 1024, &dwSizeWrite, NULL); } CloseHandle(fd); // Run notepad to show the info file wsprintf(szBuffer, TEXT("notepad %s"), pszInfoFile); WinExec((LPCSTR)szBuffer, SW_SHOW); nRet = File.FreeExtensions(pExtensionList); if(nRet != SUCCESS) return nRet; return SUCCESS; }