LFileSettings::GetTag

#include "ltwrappr.h"

static L_INT32 LFileSettings::GetTag(uTag, pType, pCount, pData)

L_UINT16 uTag;	/* tag to identify data in a TIFF file */
L_UINT16 L_FAR * pType;	/* data type of the tagged data */
L_UINT32 L_FAR * pCount;	/* number of data items */
L_VOID L_FAR * pData;	/* pointer to a buffer */

Parameter	Description
uTag	Tag to identify the data in the TIFF file. Use the same tag that you specified in the LFileSettings::SetTag function.
pType	Address of the variable to be updated with the tagged data type. The following are possible values:
	Value	Meaning
	TAG_BYTE	[1] Byte.
	TAG_ASCII	[2] Byte in the range of 0 to 255.
	TAG_SBYTE	[6] Byte used as signed number in the range of -128 to +127.
	TAG_UNDEFINED	[7] Byte, with application-defined usage.
	TAG_SHORT	[3] Two bytes, unsigned.
	TAG_SSHORT	[8] Two bytes, signed.
	TAG_LONG	[4] Four bytes, unsigned.
	TAG_SLONG	[9] Four bytes, signed.
	TAG_RATIONAL	[5] Eight bytes, used as a pair of unsigned long integers, where the first number is the numerator and the second is the denominator of a fraction.
	TAG_SRATIONAL	[10] Eight bytes, used as a pair of signed long integers, where the first number is the numerator and the second is the denominator of a fraction.
	TAG_FLOAT	[11] Four bytes used as a floating point number.
	TAG_DOUBLE	[12] Eight bytes used as a double-precision floating point number.
pCount	Address of the variable to be updated with the count of data items. The count is based on the tagged data type. For example, if the count is 2 and the data type is TAG_DOUBLE, the required buffer size is 16.
pData	Pointer to the buffer to be updated with the data. You can pass NULL if you want to use this function's return value to determine the required buffer size.

Returns

>0	Length of the tagged data, in bytes.
<= 0	An error occurred. Refer to Return Codes.

Comments

It is often convenient to call this function twice, as follows:

1.	Call the function the first time, specifying NULL in the pData parameter, and using the return value to determine the required size of the buffer.
2.	Allocate the buffer.
3.	Call the function the second time, passing a pointer to your buffer in the pData parameter.

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

To detect whether a file has annotation information, you should call LFileSettings::GetTag and see if ANNTAG_TYPE is present.

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.

See Also

Functions:	LFile::DeleteTag, LFileSettings::SetTag, Class Members
Topics:	Implementing TIFF Comments and Tags

Example

L_VOID TestGetSetTag()
{
   L_TCHAR msgbuf[80]; /* buffer for the message string */
   L_UINT16 LogoPosition = 0x8001; /* my private tag */
   L_UINT16 TagType = TAG_SSHORT; /* tagged data type */
   L_UINT32 TagCount = 4; /* count of data items */
   L_INT TagData[] = {5, 5, 24, 37};
   L_VOID L_FAR * pTagData = &TagData; /* pointer to the buffer containing the data */

   LBitmap LeadBitmap;
   LFileSettings fileSettings;

   /* Set the tag data to be saved */
   fileSettings.SetTag(LogoPosition, TagType, TagCount, pTagData);
   /* Clear the variables so that we can validate the data */
   TagType = 0;
   TagCount = 0;
   TagData[0] = 0;
   TagData[1] = 0;
   TagData[2] = 0;
   TagData[3] = 0;
   /* Get the tag data that is ready to be saved */
   fileSettings.GetTag(LogoPosition, &TagType, &TagCount, pTagData);
   /* Display a message showing the data */
   if ((TagType == TAG_SSHORT) && (TagCount == 4))
   {
      wsprintf(msgbuf, TEXT("X = %d\nY= %d\nWidth = %d\nHeight = %d"),
            ((L_INT L_FAR *)pTagData)[0],
            ((L_INT L_FAR *)pTagData)[1],
            ((L_INT L_FAR *)pTagData)[2],
            ((L_INT L_FAR *)pTagData)[3]);

      MessageBox (NULL, msgbuf, TEXT("Logo Position"), MB_OK);
   }
   /* Save the file with the tag */
   LeadBitmap.SetFileName(TEXT("Test.tif"));
   LeadBitmap.Save(FILE_TIF, LeadBitmap.GetBitsPerPixel(), 0, 0);
   /* Clear the tag from memory */
   fileSettings.SetTag(0, 0, 0, NULL);
   return;
}