WmfPlaceableFileHeader structure (gdiplusmetaheader.h)

The WmfPlaceableFileHeader structure defines the fields of a placeable metafile header. Placeable metafiles were created as a way of specifying how a metafile is mapped and scaled on a display device.

Syntax

typedef struct {
  UINT32     Key;
  INT16      Hmf;
  PWMFRect16 BoundingBox;
  INT16      Inch;
  UINT32     Reserved;
  INT16      Checksum;
} WmfPlaceableFileHeader;

Members

Key

Type: UINT32

Identification value that indicates the presence of a placeable metafile header. This value is always 0x9AC6CDD7.

Hmf

Type: INT16

Handle to the metafile in memory. When written to disk, this field is not used and will always contains the value 0.

BoundingBox

Type: PWMFRect16

Destination rectangle, measured in twips, for displaying the metafile.

Inch

Type: INT16

Number of twips per inch used to represent the image.

Normally, there are 1440 twips per inch; however, this number can be changed to scale the image.

• A value of 720 specifies that the image is twice its normal size.
• A value of 360 specifies that the image is four times its normal size.
• A value of 2880 specifies that the image is half its normal size.

Reserved

Type: UINT32

Not used and is always set to 0.

Checksum

Type: INT16

Checksum for the previous 10 WORDs in the header. This value can be used to determine whether the metafile has become corrupted.

Remarks

Although placeable metafiles are quite common, they are not directly supported by the Windows API. To display a placeable metafile using the Windows API, you must first strip the placeable metafile header from the file. This is typically performed by copying the metafile to a temporary file starting at file offset 22 (0x16). This is because each placeable metafile begins with a 22-byte header that is followed by a standard metafile.

Requirements

See also

PWMFRect16