LFile::ReadTags

#include "ltwrappr.h"

L_INT LFile::ReadTags(uFlags, puTagCount, ppTags, puDataSize, ppData, pLoadOptions)

L_UINT uFlags;	control flags
L_UINT * puTagCount;	number of tags found
pLEADFILETAG * ppTags;	address of the variable for tags data
L_SIZE_T * puDataSize;	the overall size of the tags data
L_UCHAR ** ppData;	the overall tags data
pLOADFILEOPTION pLoadOptions;	pointer to optional extended load options

Gets all the tags stored in a file.

Parameter	Description
uFlags	Flag that determines whether to read the tag overall data. You can combine values when appropriate by using a bitwise OR ( \| ):
	Flag	Meaning
	READFILEMETADATA_NOMEMORY	[0x01] Do not read the tag overall data. If this flag is set, then puDataSize and ppData will not be used and the function will not read the tag overall data.
puTagCount	Address of the variable to be updated with the number of tags found in the file.
ppTags	Pointer to an array of pLEADFILETAG structures. Each element of the array contains data for one tag found in the file. The number of elements in ppTags is puTagCount. When this array is no longer needed pass it to the LFile::FreeTags function to free the allocated memory.
puDataSize	Address of the variable to be updated with the size in bytes of the overall tags data.
ppData	Address of the variable to be updated with a pointer to the overall tags data. The size of this pointer in bytes is puDataSize. Each LEADFILETAG item found contains an offset to where the data for this item is stored in ppData.
pLoadOptions	Pointer to optional extended load options. Pass NULL to use the default load options.

Returns

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

Comments

You must free the data allocated with this function using the LFile::FreeTags function.

For general information about TIFF tags, refer to Implementing TIFF Comments and Tags.

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.

Example

L_INT LFile__ReadFileTagsExample() 
{ 
   LFile LeadFile; 
   L_INT nRet; 
   L_UINT i = 0, uTagCount = 0, uCommentCount = 0, uGeoKeyCount = 0; 
   pLEADFILETAG pTags = NULL, pCurrentTag, pGeoKeys = NULL, pCurrentGeoKey; 
   L_SIZE_T uTagDataSize = 0, uCommentDataSize = 0, uGeoKeyDataSize = 0; 
   L_UCHAR *pTagData = NULL, *pCommentData = NULL, *pGeoKeyData = NULL; 
   L_CHAR *pszAscii = NULL; 
   pLEADFILECOMMENT pComments = NULL, pCurrentComment; 
   LeadFile.SetFileName(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\image1.jpg")); 
   // read all the tags from the file 
   nRet = LeadFile.ReadTags(0, &uTagCount, &pTags, &uTagDataSize, &pTagData, NULL); 
   // Read all the comments in the file 
   if(nRet == SUCCESS) 
   { 
      // Yes, read all the comments from the file 
      nRet = LeadFile.ReadComments(0, &uCommentCount, &pComments, &uCommentDataSize, &pCommentData, NULL); 
   } 
   // Read all the geo keys in the file 
   if(nRet == SUCCESS) 
   { 
      // Yes, read all the geo keys from the file 
      nRet = LeadFile.ReadGeoKeys(0, &uGeoKeyCount, &pGeoKeys, &uGeoKeyDataSize, &pGeoKeyData, NULL); 
   } 
   if(nRet == SUCCESS) 
   { 
      if(uTagCount > 0) 
      { 
         // Show the tags 
         wprintf(L"Tags\n"); 
         for(i = 0; i < uTagCount; i++) 
         { 
            pCurrentTag = &pTags[i]; 
            // If this tag is of type ASCII, get its data 
            if(pCurrentTag->uType == TAG_ASCII) 
            { 
               pszAscii = (L_CHAR*)malloc(pCurrentTag->uDataSize + 1); 
               ZeroMemory(pszAscii, pCurrentTag->uDataSize + 1); 
               CopyMemory(pszAscii, pTagData + pCurrentTag->uDataOffset, pCurrentTag->uDataSize); 
            } 
            else 
            { 
               pszAscii = NULL; 
            } 
            printf("Id: 0x%X, data length: %u, data: %s\n", pCurrentTag->uTag, pCurrentTag->uDataSize, pszAscii != NULL ? pszAscii : "Binary data"); 
         } 
         LeadFile.FreeTags(uTagCount, pTags, uTagDataSize, pTagData); 
      } 
      if(uCommentCount > 0) 
      { 
         // Show the Comments 
         wprintf(L"Comments\n"); 
         for(i = 0; i < uCommentCount; i++) 
         { 
            pCurrentComment = &pComments[i]; 
            // If this comment is of type ASCII, get its data 
            printf("Id: 0x%X, data length: %u\n", pCurrentComment->uType, pCurrentComment->uDataSize); 
         } 
         LeadFile.FreeComments(uCommentCount, pComments, uCommentDataSize, pCommentData); 
      } 
      if(uGeoKeyCount > 0) 
      { 
         // Show the geo keys 
         wprintf(L"GeoKeys\n"); 
         for(i = 0; i < uGeoKeyCount; i++) 
         { 
            pCurrentGeoKey = &pGeoKeys[i]; 
            // If this geo key is of type ASCII, get its data 
            if(pCurrentGeoKey->uType == TAG_ASCII) 
            { 
               pszAscii = (L_CHAR*)malloc(pCurrentGeoKey->uDataSize + 1); 
               ZeroMemory(pszAscii, pCurrentGeoKey->uDataSize + 1); 
               CopyMemory(pszAscii, pGeoKeyData + pCurrentGeoKey->uDataOffset, pCurrentGeoKey->uDataSize); 
            } 
            else 
            { 
               pszAscii = NULL; 
            } 
            printf("Id: 0x%X, data length: %u, data: %s\n", pCurrentGeoKey->uTag, pCurrentGeoKey->uDataSize, pszAscii != NULL ? pszAscii : "Binary data"); 
         } 
         LeadFile.FreeTags(uGeoKeyCount, pGeoKeys, uGeoKeyDataSize, pGeoKeyData); 
      } 
   } 
   return SUCCESS; 
}

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Summary of Features

Functions:	LFile::FreeTags, LFile::ReadComments, LFile::ReadGeoKeys, Class Members
Topics:	Implementing TIFF Comments and Tags