LFile::EnumGeoKeys

#include "ltwrappr.h"

virtual L_INT LFile::EnumGeoKeys(uFlags, pLoadOptions)

L_UINT uFlags;	/* reserved for future use. */
pLOADFILEOPTION pLoadOptions;	/* pointer to optional extended load options */

Enumerates all the GeoKeys in a GeoTIFF file.

Parameter	Description
uFlags	Flags parameter reserved for future use. Pass 0.
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

For multipage GeoTIFF files, you can enumerate the tags from a particular page. Specify the page number on which to enumerate the keys using the pLoadOptions parameter.

The callback is called for each GeoKey value stored in the three standard GeoTIFF tags (34735, 34736 and 34737). For enumerating the other standard GeoTIFF data stored as separate tags, you can use LFile::EnumTags. Or you can call LFile::ReadTag for each of these tags (since there are not that many of them to warrant the use of LFile::EnumTags).

For more information about GeoKeys tags, refer to Implementing GeoKeys (GeoTIFF tags).

Required DLLs and Libraries

LTFIL

LFTIF

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

See Also

Functions:	LFile::SetGeoKey, LFile::GetGeoKey, LFile::WriteGeoKey, LFile::WriteMetaData, LFile::EnumGeoKeys, LFile::SaveFile, LFile::SaveBitmap, LFile::EnumGeoKeysCallBack
Topics:	Implementing GeoKeys (GeoTIFF tags)
	Implementing TIFF Comments and Tags
	Raster Image Functions: Working with GeoKeys

Example

/* Displays a GeoKey in a message box*/
static L_VOID DisplayKey(L_UINT16 uTag,L_UINT16 uType,L_UINT32 uCount,L_VOID L_FAR*pData)
{
   L_TCHAR s[500];
   wsprintf(s, TEXT("Key = %d, Type = %s, Count = %d"), uTag,
uType == TAG_ASCII ? TEXT("ASCII") : (uType == TAG_SHORT ? TEXT("SHORT") : TEXT("DOUBLE")),uCount);
   MessageBox(NULL, s, TEXT("Key Info"), MB_OK);
   /* LEADTOOLS makes the string null-terminated, so it is OK to pass it to MessageBox. Note
   that for Unicode builds you will need to convert this array of bytes to array of WCHAR*/
   if(uType == TAG_ASCII)
      MessageBox(NULL, (LPSTR)pData, TEXT("Key Value"), MB_OK);
   else
   {
      if(uType == TAG_SHORT)
      {
         if(uCount == 1)
            wsprintf(s, TEXT("%d"), *(L_UINT16 L_FAR*)pData);
         else
            wsprintf(s, TEXT("{%d, ...}"), *(L_UINT16 L_FAR*)pData);
      }
      else
      {
         if(uCount == 1)
            sprintf(s, TEXT("%g"), *(L_DOUBLE L_FAR*)pData);
         else
            sprintf(s, TEXT("{%g, ...}"), *(L_DOUBLE L_FAR*)pData);
      }
      MessageBox(NULL, s, TEXT("Key Value"), MB_OK);
   }
}
class LFileChild : public LFile
{
   L_INT EnumGeoKeysCallBack(L_UINT16 uTag,L_UINT16 uType,L_UINT32 uCount,
L_VOID L_FAR*pData);
};

L_INT LFileChild::EnumGeoKeysCallBack(L_UINT16 uTag,L_UINT16 uType,L_UINT32 uCount,
L_VOID L_FAR*pData)
{
   DisplayKey(uTag,uType,uCount,pData) ;
   return SUCCESS ;
}

L_VOID EnumGeoKeysExample(LFileChild& file)
{
   file.SetFileName(TEXT("C:\\GeoTIFF.tif"));
   file.EnableCallBack(TRUE) ;
   L_INT nRet = file.EnumGeoKeys( 0, NULL);
   if(nRet != SUCCESS)
      MessageBox(NULL, TEXT("Error enumerating GeoKeys"), TEXT("ERROR"), MB_OK);
   else
      MessageBox(NULL, TEXT("Enumeration SUCCEEDED!"), TEXT("SUCCESS"), MB_OK);
}