.WMF

Introduction

A Windows Metafile is a recording of drawing commands from the 16-bit Windows graphics system (GDI). Playing the file back draws the picture again: lines, shapes, text and bitmaps, at whatever size is needed. It can hold vector drawing, bitmaps or both.

WMF was the usual way to move clip art and charts between Windows programs in the 1990s, and Office documents still embed it. Its 32-bit successor is the Enhanced Metafile (EMF).

Structure

A WMF file is a header followed by records. Each record is its size in 16-bit words (4 bytes), a 2-byte function number naming the GDI call, and that call's parameters. All numbers are little-endian. The last record is an end-of-file record of three words with function number 0.

Many files start with an extra 22-byte "placeable" header, added by Aldus, that gives the picture's bounding box and its units per inch. It begins with the key D7 CD C6 9A. The standard 18-byte header comes after it, or first in a file without it.

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