Windows Metafiles (WMF) is a native vector graphics file format used by Windows to store bitmaps, text, and complex graphics functions. Two versions of WMF are available – 16-bit and 32-bit. GDI calls are used to create graphics effectively and promptly. Metafiles are used by programs to save data between sessions and temporarily store data in the Clipboard. WMF has two variants – Placeable and Standard Versions. The former is used to position images on the page, while the latter is used to create clipboard metafiles. The first GDI command record in Enhanced Metafile (EMF) files contains all header information, including Placeable and Clipboard data.
FAQ: Understanding Windows Metafiles (WMF) and Enhanced Metafiles (EMF)
If you frequently work with graphics, you must have come across Windows Metafiles (WMF) and Enhanced Metafiles (EMF). These are widely used file formats designed specifically for vector graphics, bitmap, and text storage. Here are the answers to some of the frequently asked questions about WMFs and EMFs.
What is WMF and EMF?
Windows Metafile (WMF) is a proprietary vector graphics file format used by native Windows programs for graphic storage. WMFs are usually less complex than their successors, Enhanced Metafile (EMF) format. EMF is a 32-bit extension of the original WMF that supports more complex graphics functions.
What are GDI Calls?
GDI or Graphics Device Interface is a programming interface that enables applications to use graphics and formatted text on both video display and printer output. The building blocks of WMF and EMF files are Windows Drawing Commands or GDI calls. These calls control how and where graphical data is displayed on the screen or printed on paper.
How do WMFs and EMFs work?
WMF and EMF formats are effective formats that produce graphics rapidly because they store commands for drawing rather than the graphical data itself. These commands are issued by GDI calls, a system library that enables Windows to manage graphical elements. In other words, the WMF/EMF file stores a script (commands) that instructs Windows how to draw the graphic.
Are there different variants of WMF?
Yes, there are two different variants of WMF, Standard WMF and Placeable WMF. In a standard WMF file, GDI command records follow an 18-byte header. For Placeable WMF, a 22-byte header is added in front of the standard 18-byte header. This header contains information that positions the picture on the page. So, if you want to place an image in a specific place on the page, you should use the Placeable WMF format.
What are the differences between standard WMF and EMF?
EMF is a more advanced and extended version of WMF format. The first difference between the two formats is the number of bits used. WMF is a 16-bit format that uses less memory than EMF, which is a 32-bit format. As a result, EMF files are generally larger than WMF files. Another difference is that EMFs can store more complex graphics functions than WMFs, which makes them more suitable for advanced graphics. Additionally, EMF files can support multiple image resolutions, making it easy to export graphics from one program to another without losing quality.
What is the Clipboard Metafile?
Windows uses metafiles to save temporary data when users cut or copy a graphic from one program and then paste it into another program. When you copy or cut a graphic, Windows stores it temporarily in the clipboard. This data is stored as a clipboard metafile, which uses a different header format than WMF or EMF files.
WMF and EMF are essential file formats used in graphics programming to store vector graphics, bitmap, and text data. While WMFs are simpler than EMFs, EMFs can support more advanced graphic functions and offer more flexibility in exporting graphics between programs. Understanding these file formats and how they work can help you work more efficiently with graphics in your projects.