GdiComment

The GdiComment function copies a comment from a buffer into a specified enhanced-format metafile. 

BOOL GdiComment(
  HDC hdc,             // handle to a device context
  UINT cbSize,         // size of text buffer
  CONST BYTE *lpData   // pointer to text buffer
);

Parameters

hdc
Handle to an enhanced-metafile device context.
cbSize
Specifies the length of the comment buffer, in bytes.
lpData
Pointer to the buffer that contains the comment.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT: To get extended error information, call GetLastError.

Remarks

A comment can include any kind of private information — for example, the source of a picture and the date it was created. A comment should begin with an application signature, followed by the data.

Comments should not contain application-specific or position-specific data. Position-specific data specifies the location of a record, and it should not be included because one metafile may be embedded within another metafile.

A public comment is a comment that begins with the comment signature identifier GDICOMMENT_IDENTIFIER. The following public comments are defined:

GDICOMMENT_WINDOWS_METAFILE
The GDICOMMENT_WINDOWS_METAFILE public comment contains a Windows-format metafile that is equivalent to an enhanced-format metafile. This comment is written only by the SetWinMetaFileBits function. The comment record, if given, follows the ENHMETAHEADER metafile record. The comment has the following form: 

DWORD ident;         // This contains GDICOMMENT_IDENTIFIER. 
DWORD iComment;      // This contains GDICOMMENT_WINDOWS_METAFILE. 
DWORD nVersion;      // This contains the version number of the 
                     // Windows-format metafile. 
DWORD nChecksum;     // This is the additive DWORD checksum for 
                     // the enhanced metafile.  The checksum 
                     // for the enhanced metafile data including 
                     // this comment record must be zero. 
                     // Otherwise, the enhanced metafile has been 
                     //  modified and the Windows-format 
                     // metafile is no longer valid. 
DWORD fFlags;        // This must be zero. 
DWORD cbWinMetaFile; // This is the size, in bytes. of the 
                     // Windows-format metafile data that follows.
GDICOMMENT_BEGINGROUP
The GDICOMMENT_BEGINGROUP public comment identifies the beginning of a group of drawing records. It identifies an object within an enhanced metafile. The comment has the following form: 

DWORD   ident;         // This contains GDICOMMENT_IDENTIFIER. 
DWORD   iComment;      // This contains GDICOMMENT_BEGINGROUP. 
RECTL   rclOutput;     // This is the bounding rectangle for the 
                       // object in logical coordinates. 
DWORD   nDescription;  // This is the number of characters in the 
                       // optional Unicode description string that 
                       // follows. This is zero if there is no 
                       // description string.
GDICOMMENT_ENDGROUP
The GDICOMMENT_ENDGROUP public comment identifies the end of a group of drawing records. The GDICOMMENT_BEGINGROUP comment and the GDICOMMENT_ENDGROUP comment must be included in a pair and may be nested. The comment has the following form: 

DWORD   ident;       // This contains GDICOMMENT_IDENTIFIER. 
DWORD   iComment;    // This contains GDICOMMENT_ENDGROUP.
GDICOMMENT_MULTIFORMATS
The GDICOMMENT_MULTIFORMATS public comment allows multiple definitions of a picture to be included in an enhanced metafile. Using this comment, for example, an application can include an encapsulated PostScript definition as well as an enhanced metafile definition of a picture. When the record is played back, GDI selects and renders the first format recognized by the device. The comment has the following form: 

DWORD   ident;          // This contains GDICOMMENT_IDENTIFIER. 
DWORD   iComment;       // This contains GDICOMMENT_MULTIFORMATS. 
RECTL   rclOutput;      // This is the bounding rectangle for the 
                        // picture in logical coordinates. 
DWORD   nFormats;       // This contains the number of formats in 
                        // the comment. 
EMRFORMAT aemrformat[1];// This is an array of EMRFORMAT structures 
                        // in the order of preference.  The data 
                        // for each format follows the last 
                        // EMRFORMAT structure.

The EMRFORMAT structure has the following form: 

typedef struct tagEMRFORMAT   { 
    DWORD   dSignature; 
    DWORD   nVersion; 
    DWORD   cbData; 
    DWORD   offData; 
} EMRFORMAT;

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in wingdi.h.
  Import Library: Use gdi32.lib.

See Also

Metafiles Overview, Metafile Functions, CreateEnhMetaFile, EMRFORMAT, SetWinMetaFileBits