Metafile

Metafile is a file that records graphical commands rather than storing pixel data. It describes how to render an image or page by a sequence of drawing instructions, enabling device‑independent interchange of vector graphics and layout descriptions. A metafile usually begins with a header containing metadata such as version and bounding box, followed by a series of records that encode operations like moving the drawing cursor, drawing lines and curves, rendering text, or placing embedded images. A renderer interprets the record stream to reproduce the image on screen or on a printer.

In the Windows environment the term is common for Windows Metafile WMF and Enhanced Metafile EMF. WMF is an older 16‑bit format that records graphical commands using GDI. EMF, introduced later, stores a more robust, device‑independent record stream and is generally preferred; EMF+ adds further capabilities from GDI+ for gradients, transparency, and complex objects.

Metafiles are used to exchange vector graphics between applications, embed graphics in documents, and drive printers or rendering pipelines. They are often more compact than bitmaps for simple drawings and retain scalability since they describe geometry rather than pixels.

Limitations include portability issues across platforms and software, potential vendor-specific command sets, and editing difficulty. Some operations are not fully supported by all viewers, and complex raster content may require conversion to bitmaps. For web and cross‑platform use, newer formats such as SVG or PDF are commonly favored, though metafile formats persist in legacy workflows.