Editing Windows Metafile (section)

==History==
The original [[16 bit]] WMF file format was fully specified in volume 4 of the 1992 [[Windows 3.1]] SDK documentation<ref>Microsoft Windows 3.1 Programmers Reference, Volume 4 Resources, Microsoft Press 1992, {{ISBN|1-55615-494-1}}, chapter 3 pp. 21-45</ref> (at least if combined with the descriptions of the individual functions and structures in the other volumes), but that specification was vague about a few details. These manuals were published as printed books available in bookstores with no [[clickwrap|click through]] [[End-user license agreement|EULA]] or other unusual licensing restrictions (just a general warning that if purchased as part of a software bundle, the software would be subject to one).

Over time the existence of that historic specification was largely forgotten and some alternative implementations resorted to reverse engineering to figure out the file format from existing WMF files, which was difficult and error prone.<ref>{{cite web | url=http://wvware.sourceforge.net/caolan/support.html | title=Window Metafile (wmf) Reference | quote=''These opcodes are unimplemented, for the reason that i dont know what they are, no known documentation'' | author=Caolan McNamara | access-date=2008-06-01}}</ref> In September 2006, Microsoft again published the WMF file format specification in a more complete form<ref>{{cite web | url=http://msdn.microsoft.com/en-us/library/cc215212.aspx | title=<nowiki>[MS-WMF]:</nowiki> Windows Metafile Format Specification | access-date=2008-06-01 }}</ref> in the context of the [[Microsoft Open Specification Promise]], promising to not assert patent rights to file format implementors.<ref name="osp">{{cite web | url=http://www.microsoft.com/interop/osp/ | title=Microsoft Open Specification Promise | website=[[Microsoft]] | access-date=2008-06-01 }}</ref>

Microsoft later deprecated WMF files in favour of [[32-bit]] EMF files as WMF files had real issues with device independence, despite the use of a "placeable" file header which provided basic device independence. Microsoft found that developers who use the format were "[embedding] application, location, or scaling comments in the metafiles... Others added headers to the metafile that provided various application-specific information", causing major compatibility issues.<ref name="ENHMETA_technote">{{citation|title=Enhanced Metafiles in Win32|publisher=Microsoft Developer Network Technology Group|date=June 10, 1993|url=http://www.massmind.org/techref/fileext/emf/enh_meta.htm}}</ref> Thus, in 1992 with [[Windows NT 3.1]], Microsoft introduced the Enhanced Metafile format (EMF)<ref name="rfc7903">{{cite IETF|title = Windows Image Media Types|rfc = 7903|sectionname = Windows Metafiles|page = 1|last1 = Leonard|first1 = Sean|date = September 2016|publisher = [[Internet Engineering Task Force|IETF]]|access-date = February 8, 2020|issn = 2070-1721|doi = 10.17487/RFC7903}}</ref> &mdash; a format which was based on the [[Win32]] API and with which they built-in device independence.<ref name="emfintroduced">{{citation|url=https://wiki.fileformat.com/image/emf/|title=EMF|work=FileFormat|date=11 October 2019|publisher=Aspose Pty Ltd|access-date=2020-01-20}}</ref><ref name="ENHMETA_technote"/> &mdash; these were also known as NT metafiles.<ref>{{citation|title=NT Metafiles and GDI Objects|first=Charles|last=Petzold|author-link=Charles Petzold|work=[[PC Magazine]]|date=October 11, 1994|pages=343–347|url=https://books.google.com/books?id=fy_G-xlQbE8C&pg=PA345}}</ref> With the release of [[Windows XP]] and GDI+, the set of records had to be significantly increased and so Microsoft released EMF+ as an extension to the existing EMF file format.<ref name="rfc7903"/><ref>{{cite book|title=Graphics Programming with GDI+ & DirectX|publisher=A-List Publishing|page=68|year=2005|first1=Alex|last1=Polyakov|first2=Vitaly|last2=Brusentsev|isbn=1-931769-39-7|url=https://books.google.com/books?id=MJ_VAwAAQBAJ&pg=PA68}}</ref>