Definition: Windows Metafile

The native vector graphics file format in Windows. Windows Metafiles also can hold bitmaps and text. The original 16-bit format uses the .WMF file extension. The subsequent 32-bit format, which supports more sophisticated graphics functions, generates .EMF (Enhanced MetaFile) files.

Actual Drawing Commands
WMF and EMF files are made up of Windows drawing commands (GDI calls), which results in an efficient format that renders illustrations very quickly. Metafiles are also used by programs to hold data between sessions, and Windows uses it for temporary storage in the Clipboard.

Standard and Placeable Versions
The standard WMF file uses an 18-byte header followed by GDI command records. There are two additional WMF variations that place another header in front of the standard header. A Placeable Metafile uses a 22-byte header containing x-y coordinates for positioning the image on the page. A Clipboard Metafile uses an 8- or 16-byte header. In an EMF file, all header information, including Placeable and Clipboard data, is stored in the first GDI command record.