1 Building and Installing Emacs on MS-Windows
2 using the MSYS and MinGW tools
4 Copyright (C) 2013 Free Software Foundation, Inc.
5 See the end of the file for license conditions.
7 The MSYS/MinGW build described here is supported on versions of
8 Windows starting with Windows 2000 and newer. Windows 9X are not
9 supported (but the Emacs binary produced by this build will run on
12 * For the brave (a.k.a. "impatient"):
14 For those who have a working MSYS/MinGW development environment and
15 are comfortable with running Posix configure scripts, here are the
16 concise instructions for configuring and building the native Windows
17 binary of Emacs with these tools.
19 Do not use this recipe with Cygwin. For building on Cygwin, use the
20 normal installation instructions, ../INSTALL.
22 0. Start the MSYS Bash window. Everything else below is done from
23 that window's Bash prompt.
25 0a. If you are building from the development trunk (as opposed to a
26 release tarball), produce the configure script, by typing from
27 the top-level Emacs source directory:
31 1. If you want to build Emacs outside of the source tree
32 (recommended), create the build directory and chdir there.
34 2. Invoke the MSYS-specific configure script:
36 - If you are building outside the source tree:
38 /PATH/TO/EMACS/SOURCE/TREE/nt/msysconfig.sh --prefix=PREFIX ...
40 - If you are building in-place, i.e. inside the source tree:
42 ./nt/msysconfig.sh --prefix=PREFIX ...
44 It is always preferable to use --prefix to configure Emacs for
45 some specific location of its installed tree; the default
46 /usr/local is not suitable for Windows (see the detailed
47 instructions for the reasons).
49 You can pass other options to the configure script. Here's a
50 typical example (for an in-place debug build):
52 CPPFLAGS='-DGLYPH_DEBUG=1' CFLAGS='-O0 -g3' ./nt/msysconfig.sh --prefix=/d/usr/emacs --enable-checking
54 3. After the configure script finishes, it should display the
55 resulting configuration. After that, type
59 Use "make -j N" if your MSYS Make supports parallel execution;
60 the build will take significantly less time in that case. Here N
61 is the number of simultaneous parallel jobs; use the number of
62 the cores on your system.
64 4. Install the produced binaries:
68 If you want the installation tree to go to a place that is
69 different from the one specified by --prefix, say
71 make install prefix=/where/ever/you/want
75 If these short instructions somehow fail, read the rest of this
78 * Installing MinGW and MSYS
80 Make sure you carefully read the following two sections in their
81 entirety and install/configure the various packages as instructed.
82 A correct installation makes all the rest almost trivial; a botched
83 installation will likely make you miserable for quite some time.
85 There are two alternative to installing MinGW + MSYS: using the GUI
86 installer, called mingw-get, provided by the MinGW project, or
87 manual installation. The next two sections describe each one of
90 ** Installing MinGW and MSYS using mingw-get
92 A nice installer, called mingw-get, is available for those who don't
93 like to mess with manual installations. You can download it from
96 https://sourceforge.net/projects/mingw/files/Installer/mingw-get/
98 (This installer only supports packages downloaded from the MinGW
99 site; for the rest you will still need the manual method.)
101 After installing mingw-get, invoke it to install the packages that
102 are already selected by default on the "Select Components" screen of
105 After that, use "mingw-get install PACKAGE" to install the following
109 . mingw-developer-toolkit
111 (We recommend that you refrain from installing the MSYS Texinfo
112 package, which is part of msys-base, because it might produce mixed
113 EOL format when installing Info files. Instead, install the MinGW
114 port of Texinfo, see the ezwinports URL below. To uninstall the
115 MSYS Texinfo, after installing it as part of msys-base, invoke the
116 command "mingw-get remove msys-texinfo".)
118 At this point, you should be ready to configure and build Emacs in
119 its basic configuration. Skip to the "Generating the configure
120 script" section for the build instructions. If you want to build it
121 with image support and other optional libraries, read about the
122 optional libraries near the end of this document, before you start
123 the build. Also, consider installing additional MinGW packages that
124 are required/recommended, especially if you are building from the
125 Bazaar repository, as described in the next section.
127 ** Installing MinGW and MSYS manually
131 You will need to install the MinGW port of GCC and Binutils, and the
132 MinGW runtime and Windows API distributions, to compile Emacs. You
133 can find these on the MinGW download/Base page:
135 https://sourceforge.net/projects/mingw/files/MinGW/Base/
137 In general, install the latest stable versions of the following
138 MinGW packages from that page: gcc, binutils, mingw-rt, w32api. You
139 only need the 'bin' and the 'dll' tarballs of each of the above.
141 MinGW packages are distributed as .tar.lzma compressed archives. To
142 install the packages manually, we recommend to use the Windows port
143 of the 'bsdtar' program to unpack the tarballs. 'bsdtar' is
144 available as part of the 'libarchive' package from here:
146 http://sourceforge.net/projects/ezwinports/files/
148 The recommended place to install these packages is a single tree
149 starting from some directory on a drive other than the system drive
150 C:. A typical example would be D:\usr, with D:\usr\bin holding the
151 binaries and DLLs (should be added to your Path environment
152 variable), D:\usr\include holding the include files, D:\usr\lib
153 holding the static and import libraries, D:\usr\share holding docs,
154 message catalogs, and package-specific subdirectories, etc.
156 Having all the headers and libraries in a single place will greatly
157 reduce the number of -I and -L flags you will have to pass to the
158 configure script (see below), as these files will be right where the
159 compiler expects them.
161 We specifically do NOT recommend installing packages below
162 "C:\Program Files" or "C:\Program Files (x86)". These directories
163 are protected on versions of Windows from Vista and on, and you will
164 have difficulties updating and maintaining your installation later,
165 due to UAC elevation prompts, file virtualization, etc. You *have*
168 Additional MinGW packages are required/recommended, especially if
169 you are building from the Bazaar repository:
171 . Texinfo (needed to produce the Info manuals when building from
172 bzr, and for "make install")
174 Available from http://sourceforge.net/projects/ezwinports/files/.
176 . gzip (needed to compress files during "make install")
178 Available from http://gnuwin32.sourceforge.net/packages/gzip.htm.
180 . pkg-config (needed for building with some optional libraries,
181 such as GnuTLS and libxml2)
183 Available from http://www.gtk.org/download/win32.php
185 Each package might list other packages as prerequisites on its
186 download page (under "Runtime requirements"); download those as
187 well. (Using the mingw-get installer will fetch those prerequisites
188 automatically for you.) A missing prerequisite will manifest itself
189 by the program failing to run and presenting a pop-up dialog that
190 states the missing or incompatible DLL; be sure to find and install
193 Once you think you have MinGW installed, test the installation by
194 building a trivial "hello, world!" program, and make sure that it
195 builds without any error messages and the binary works when run.
199 You will need a reasonably full MSYS installation. MSYS is an
200 environment needed to run the Posix configure scripts and the
201 resulting Makefile's, in order to produce native Windows binaries
202 using the MinGW compiler and runtime libraries. Here's the list of
203 MSYS packages that are required:
205 . All the packages from the MSYS Base distribution, listed here:
207 https://sourceforge.net/projects/mingw/files/MSYS/Base/
209 . Additional packages listed below, from the MSYS Extension
212 https://sourceforge.net/projects/mingw/files/MSYS/Extension/
220 These should only be needed if you intend to build development
221 versions of Emacs from the Bazaar repository.
223 . Additional packages (needed only if building from the Bazaar
224 repository): Automake and Autoconf. They are available from
227 http://sourceforge.net/projects/ezwinports/files/automake-1.11.6-msys-bin.zip/download
228 http://sourceforge.net/projects/ezwinports/files/autoconf-2.65-msys-bin.zip/download
230 MSYS packages are distributed as .tar.lzma compressed archives. To
231 install the packages manually, we recommend to use the Windows port
232 of the 'bsdtar' program, already mentioned above.
234 If/when you are confident in your MinGW/MSYS installation, and want
235 to speed up the builds, we recommend installing a pre-release
236 version of Make from here:
238 https://sourceforge.net/projects/mingwbuilds/files/external-binary-packages/
240 These are snapshot builds of many packages, but you only need
241 make.exe from there. The advantage of this make.exe is that it
242 supports parallel builds, so you can use "make -j N" to considerably
243 speed up your builds.
245 Several users reported that MSYS 1.0.18 causes Make to hang in
246 parallel builds. If you bump into this, we suggest to downgrade to
247 MSYS 1.0.17, which doesn't have that problem.
249 For each of these packages, install the 'bin' and 'dll' tarballs of
250 their latest stable releases. If there's an 'ext' tarball (e.g.,
251 msysCORE and Coreutils have it), download and install those as well.
253 Each package might list other packages as prerequisites on its
254 download page (under "Runtime requirements"); download those as
255 well. (Using the mingw-get installer will fetch those prerequisites
256 automatically for you.) A missing prerequisite will manifest itself
257 by the program failing to run and presenting a pop-up dialog that
258 states the missing or incompatible DLL; be sure to find and install
261 MSYS packages should be installed in a separate tree from MinGW.
262 For example, use D:\MSYS or D:\usr\MSYS as the top-level directory
263 from which you unpack all of the MSYS packages.
265 Do NOT add the MSYS bin directory to your Windows Path! Only the
266 MinGW bin directory should be on Path. When you install MSYS, it
267 creates a shortcut on your desktop that invokes the MSYS Bash shell
268 in a Command Prompt window; that shell is already set up so that the
269 MSYS bin directory is on PATH ahead of any other directory. Thus,
270 Bash will find MSYS executables first, which is exactly what you
273 At this point, you are ready to build Emacs in its basic
274 configuration. If you want to build it with image support and other
275 optional libraries, read about that near the end of this document.
277 * Generating the configure script
279 If you are building a release or pretest tarball, skip this section,
280 because the configure script is already present in the tarball.
282 To build a development snapshot from the Emacs Bazaar repository,
283 you will first need to generate the configure script and a few other
284 auto-generated files. (If this step, described below, somehow
285 fails, you can use the files in the autogen/ directory instead, but
286 they might be outdated, and, most importantly, you are well advised
287 not to disregard any failures in your local build procedures, as
288 these are likely to be symptoms of incorrect installation that will
289 bite you down the road.)
291 To generate the configure script, type this at the MSYS Bash prompt
292 from the top-level directory of the Emacs tree:
296 If successful, this command should produce the following output:
299 Checking whether you have the necessary tools...
300 (Read INSTALL.BZR for more details on building Emacs)
302 Checking for autoconf (need at least version 2.65)...
304 Checking for automake (need at least version 1.11)...
306 Your system has the required tools, running autoreconf...
307 You can now run `./configure'.
309 * Configuring Emacs for MinGW:
311 Now it's time to run the configure script. You can do that either
312 from a separate build directory that is outside of the Emacs source
313 tree (recommended), or from inside the source tree. The former is
314 recommended because it allows you to have several different builds,
315 e.g., an optimized build and an unoptimized one, of the same
316 revision of the source tree; the source tree will be left in its
317 pristine state, without any build products.
319 You invoke the configure script like this:
321 /PATH/TO/EMACS/SOURCE/TREE/nt/msysconfig.sh --prefix=PREFIX ...
323 or, if you are building in-place, i.e. inside the source tree:
325 ./nt/msysconfig.sh --prefix=PREFIX ...
327 Here PREFIX is the place where you eventually want to install Emacs
328 once built, e.g. /d/usr. We recommend to always use --prefix when
329 building Emacs on Windows, because the default '/usr/local' is not
330 appropriate for Windows: it will be mapped by MSYS to something like
331 C:\MSYS\local, and it will defeat the purpose of PREFIX, which is to
332 install programs in a single coherent tree resembling Posix systems.
333 Such a single-tree installation makes sure all the other programs
334 and packages ported from GNU or Unix systems will work seamlessly
335 together. Where exactly is the root of that tree on your system is
336 something only you, the user who builds Emacs, can know, and the
337 Emacs build process cannot guess, because usually there's no
338 '/usr/local' directory on any drive on Windows systems.
340 Do NOT use Windows-style x:/foo/bar file names on the configure
341 script command line; use the MSYS-style /x/foo/bar instead. Using
342 Windows-style file names was reported to cause subtle and hard to
343 figure out problems during the build. This applies both to the
344 command switches, such as --prefix=, and to the absolute file name
345 of msysconfig.sh, if you are building outside of the source tree.
347 You can pass additional options to the configure script, for the
350 ./nt/msysconfig.sh --help
352 As explained in the help text, you may need to tell the script what
353 are the optional flags to invoke the compiler. This is needed if
354 some of your headers and libraries, e.g., those belonging to
355 optional image libraries, are installed in places where the compiler
356 normally doesn't look for them. (Remember that advice above to
357 avoid such situations? here's is where you will start paying for
358 disregarding that recommendation.) For example, if you have libpng
359 headers in C:\emacs\libs\libpng-1.2.37-lib\include and jpeg library
360 headers in C:\emacs\libs\jpeg-6b-4-lib\include, you will need to say
363 CPPFLAGS='-I/c/emacs/libs/libpng-1.2.37-lib/include -I/c/emacs/libs/jpeg-6b-4-lib/include' ./nt/msysconfig.sh --prefix=PREFIX
365 which is quite a mouth-full, especially if you have more directories
366 to specify... Perhaps you may wish to revisit your installation
369 If you have a global site-lisp directory from previous Emacs
370 installation, and you want Emacs to continue using it, specify it
371 via the --enable-locallisppath switch to msysconfig.sh, like this:
373 ./nt/msysconfig.sh --prefix=PREFIX --enable-locallisppath="/d/usr/share/emacs/VERSION/site-lisp:/d/wherever/site-lisp"
375 Use the normal MSYS /d/foo/bar style to specify directories by their
378 A few frequently used options are needed when you want to produce an
379 unoptimized binary with runtime checks enabled:
381 CPPFLAGS='-DGLYPH_DEBUG=1' CFLAGS='-O0 -g3' ./nt/msysconfig.sh --prefix=PREFIX --enable-checking
383 Once invoked, the configure script will run for some time, and, if
384 successful, will eventually produce a summary of the configuration
387 Configured for `i686-pc-mingw32'.
389 Where should the build process find the source code? /path/to/emacs/sources
390 What compiler should emacs be built with? gcc -std=gnu99 -O0 -g3
391 Should Emacs use the GNU version of malloc? yes
392 Should Emacs use a relocating allocator for buffers? yes
393 Should Emacs use mmap(2) for buffer allocation? no
394 What window system should Emacs use? w32
395 What toolkit should Emacs use? none
396 Where do we find X Windows header files? NONE
397 Where do we find X Windows libraries? NONE
398 Does Emacs use -lXaw3d? no
399 Does Emacs use -lXpm? yes
400 Does Emacs use -ljpeg? yes
401 Does Emacs use -ltiff? yes
402 Does Emacs use a gif library? yes
403 Does Emacs use -lpng? yes
404 Does Emacs use -lrsvg-2? no
405 Does Emacs use imagemagick? no
406 Does Emacs use -lgpm? no
407 Does Emacs use -ldbus? no
408 Does Emacs use -lgconf? no
409 Does Emacs use GSettings? no
410 Does Emacs use -lselinux? no
411 Does Emacs use -lgnutls? yes
412 Does Emacs use -lxml2? yes
413 Does Emacs use -lfreetype? no
414 Does Emacs use -lm17n-flt? no
415 Does Emacs use -lotf? no
416 Does Emacs use -lxft? no
417 Does Emacs use toolkit scroll bars? yes
419 You are almost there, hang on.
421 If the output is significantly different, or if configure finishes
422 prematurely and displays some error message, you should examine the
423 configuration log in config.log and find the reason for the failure.
425 Once you succeeded in configuring Emacs, and just want to rebuild it
426 after updating your local repository from the main repository, you
427 don't need to re-run the configure script manually, unless you want
428 to change the configure-time options. Just typing "make" will
429 re-run configure if necessary with the exact same options you
430 specified originally, and then go on to invoking Make, described
435 This is simple: just type "make" and sit back, watching the fun.
437 If you installed a snapshot build of Make, the build will be much
438 faster if you type "make -j N" instead, where N is the number of
439 independent processing units on your machine. E.g., on a core i7
440 system try using N of 6 or even 8. (If this hangs, see the notes
441 above about downgrading to MSYS 1.0.17.)
443 When Make finishes, you can install the produced binaries:
447 or, if you want the installed tree to go in a place different from
448 the configured one, type
450 make install prefix=WHEREVER
452 Congrats! You have built and installed your own Emacs!
456 The following make targets may be used by users building the source
457 distribution, or users who have checked out of Bazaar after
458 an initial bootstrapping.
461 Builds Emacs from the available sources and pre-compiled lisp files.
464 Installs the built programs and the auxiliary files.
467 Removes object and executable files produced by the build process in
468 the current configuration. After "make clean", you can rebuild with
469 the same configuration using make. useful when you want to be sure
470 that all of the products are built from coherent sources.
473 In addition to the files removed by make clean, this also removes
474 Makefiles and other generated files to get back to the state of a
475 freshly unpacked source distribution. After make distclean, it is
476 necessary to run the configure script followed by "make", in order
479 The following targets are intended only for use with the Bazaar sources.
482 Removes all the auto-generated files and all the *.elc byte-compiled
483 files, and builds Emacs from scratch. Useful when some change in
484 basic Emacs functionality makes byte compilation of updated files
487 make maintainer-clean
488 Removes everything that can be recreated, including compiled Lisp
489 files, to get back to the state of a fresh Bazaar tree. After make
490 maintainer-clean, it is necessary to run configure and "make" or
491 "make bootstrap" to rebuild. Occasionally it may be necessary to
492 run this target after an update.
494 * Optional image library support
496 In addition to its "native" image formats (pbm and xbm), Emacs can
497 handle other image types: xpm, tiff, gif, png, jpeg and experimental
500 To build Emacs with support for them, the corresponding headers must
501 be in the include path and libraries should be where the linker
502 looks for them, when the configure script is run. If needed, this
503 can be set up using the CPPFLAGS and CFLAGS variable specified on
504 the configure command line. The configure script will report
505 whether it was able to detect the headers and libraries. If the
506 results of this testing appear to be incorrect, please look for
507 details in the file config.log: it will show the failed test
508 programs and compiler error messages that should explain what is
509 wrong. (Usually, any such failures happen because some headers are
510 missing due to bad packaging of the image support libraries.)
512 Note that any file path passed to the compiler or linker must use
513 forward slashes, or double each backslash, as that is how Bash
516 If the configure script finds the necessary headers and libraries,
517 but they are for some reason incompatible, or if you want to omit
518 support for some image library that is installed on your system for
519 some other reason, use the --without-PACKAGE option to configure,
520 such as --without-gif to omit GIF, --without-tiff to omit TIFF, etc.
521 Passing the --help option to the configure script displays all of
522 the supported --without-PACKAGE options.
524 To use the external image support, the DLLs implementing the
525 functionality must be found when Emacs first needs them, either on the
526 PATH, or in the same directory as emacs.exe. Failure to find a
527 library is not an error; the associated image format will simply be
528 unavailable. Note that once Emacs has determined that a library can
529 not be found, there's no way to force it to try again, other than
530 restarting. See the variable `dynamic-library-alist' to configure the
531 expected names of the libraries.
533 Some image libraries have dependencies on one another, or on zlib.
534 For example, tiff support depends on the jpeg library. If you did not
535 compile the libraries yourself, you must make sure that any dependency
536 is in the PATH or otherwise accessible and that the binaries are
537 compatible (for example, that they were built with the same compiler).
539 For PNG images, we recommend to use versions 1.4.x and later of
540 libpng, because previous versions had security issues. You can find
541 precompiled libraries and headers on the GTK download page for
542 Windows (http://www.gtk.org/download/win32.php).
544 Versions 1.4.0 and later of libpng are binary incompatible with
545 earlier versions, so Emacs will only look for libpng libraries which
546 are compatible with the version it was compiled against. That
547 version is given by the value of the Lisp variable `libpng-version';
548 e.g., 10403 means version 1.4.3. The variable `dynamic-library-alist'
549 is automatically set to name only those DLL names that are known to
550 be compatible with the version given by `libpng-version'. If PNG
551 support does not work for you even though you have the support DLL
552 installed, check the name of the installed DLL against
553 `dynamic-library-alist' and the value of `libpng-version', and
554 download compatible DLLs if needed.
556 For GIF images, we recommend to use versions 5.0.0 or later of
557 giflib, as it is much enhanced wrt previous versions. You can find
558 precompiled binaries and headers for giflib on the ezwinports site,
559 http://sourceforge.net/projects/ezwinports/files/.
561 Version 5.0.0 and later of giflib are binary incompatible with
562 previous versions (the signatures of several functions have
563 changed), so Emacs will only look for giflib libraries that are
564 compatible with the version it was compiled against. Similar to
565 libpng, that version is given by the value of the Lisp variable
566 `libgif-version'; e.g., 50005 means version 5.0.5. The variable
567 `dynamic-library-alist' is automatically set to name only those DLL
568 libraries that are known to be compatible with the version given by
571 Binaries for the other image libraries can be found at the GnuWin32
572 project. Note specifically that, due to some packaging snafus in
573 the GnuWin32-supplied image libraries, you will need to download
574 _source_ packages for some of the libraries in order to get the
575 header files necessary for building Emacs with image support.
577 * Optional GnuTLS support
579 To compile with GnuTLS, you will need pkg-config to be installed, as
580 the configure script invokes pkg-config to find out which compiler
581 switches to use for GnuTLS. See above for the URL where you can
582 find pkg-config for Windows.
584 You will also need to install the p11-kit package, which is a
585 dependency of GnuTLS, and its header files are needed for
586 compilation of programs that use GnuTLS. You can find p11-kit on
587 the same site as GnuTLS, see the URL below.
589 If the configure script finds the GnuTLS header files and libraries
590 on your system, Emacs is built with GnuTLS support by default; to
591 avoid that you can pass the argument --without-gnutls.
593 In order to support GnuTLS at runtime, a GnuTLS-enabled Emacs must
594 be able to find the relevant DLLs during startup; failure to do so
595 is not an error, but GnuTLS won't be available to the running
598 You can get pre-built binaries (including any required DLL and the
599 header files) at http://sourceforge.net/projects/ezwinports/files/.
601 * Optional libxml2 support
603 To compile with libxml2, you will need pkg-config to be installed,
604 as the configure script invokes pkg-config to find out which
605 compiler switches to use for libxml2. See above for the URL where
606 you can find pkg-config for Windows.
608 If the configure script finds the libxml2 header files and libraries
609 on your system, Emacs is built with libxml2 support by default; to
610 avoid that you can pass the argument --without-libxml2.
612 In order to support libxml2 at runtime, a libxml2-enabled Emacs must
613 be able to find the relevant DLLs during startup; failure to do so
614 is not an error, but libxml2 features won't be available to the
617 One place where you can get pre-built Windows binaries of libxml2
618 (including any required DLL and the header files) is here:
620 http://sourceforge.net/projects/ezwinports/files/
622 For runtime support of libxml2, you will also need to install the
623 libiconv "development" tarball, because the libiconv headers need to
624 be available to the compiler when you compile with libxml2 support.
625 A MinGW port of libiconv can be found on the MinGW site:
627 http://sourceforge.net/projects/mingw/files/MinGW/Base/libiconv/
629 You need the libiconv-X.Y.Z-N-mingw32-dev.tar.lzma tarball from that
632 * Experimental SVG support
634 To compile with SVG, you will need pkg-config to be installed, as
635 the configure script invokes pkg-config to find out which compiler
636 switches to use for SVG. See above for the URL where you can find
637 pkg-config for Windows.
639 SVG support is currently experimental, and not built by default.
640 Specify --with-rsvg and ensure you have all the dependencies in your
641 include path. Unless you have built a minimalist librsvg yourself
642 (untested), librsvg depends on a significant chunk of GTK+ to build,
643 plus a few Gnome libraries, libxml2, libbz2 and zlib at runtime. The
644 easiest way to obtain the dependencies required for building is to
645 download a pre-bundled GTK+ development environment for Windows.
647 To use librsvg at runtime, ensure that librsvg and its dependencies
648 are on your PATH. If you didn't build librsvg yourself, you will
649 need to check with where you downloaded it from for the
650 dependencies, as there are different build options. If it is a
651 short list, then it most likely only lists the immediate
652 dependencies of librsvg, but the dependencies themselves have
653 dependencies - so don't download individual libraries from GTK+,
654 download and install the whole thing. If you think you've got all
655 the dependencies and SVG support is still not working, check your
656 PATH for other libraries that shadow the ones you downloaded.
657 Libraries of the same name from different sources may not be
658 compatible, this problem was encountered with libbzip2 from GnuWin32
659 with libcroco from gnome.org.
661 If you can see etc/images/splash.svg, then you have managed to get
662 SVG support working. Congratulations for making it through DLL hell
663 to this point. You'll probably find that some SVG images crash
664 Emacs. Problems have been observed in some images that contain
665 text, they seem to be a problem in the Windows port of Pango, or
666 maybe a problem with the way Cairo or librsvg is using it that
667 doesn't show up on other platforms.
670 This file is part of GNU Emacs.
672 GNU Emacs is free software: you can redistribute it and/or modify
673 it under the terms of the GNU General Public License as published by
674 the Free Software Foundation, either version 3 of the License, or
675 (at your option) any later version.
677 GNU Emacs is distributed in the hope that it will be useful,
678 but WITHOUT ANY WARRANTY; without even the implied warranty of
679 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
680 GNU General Public License for more details.
682 You should have received a copy of the GNU General Public License
683 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.