libemf2svg

MS EMF (Enhanced Metafile) to SVG conversion library.

Motivation

By themselves, EMF/EMF+ files are rare in the wild. However, they are frequently embedded inside other MS file formats.

This project was started to properly convert Visio stencils (.VSS) to svg and be able to reuse public stencils in other environments than MS Visio (see libvisio2svg).

However this project could be use beyond its original motivations to handle emf blobs in any MS formats.

Output example

Dependencies

• libiconv
• libpng
• libfontconfig
• libfreetype

Installing the dependencies on Debian:

# compiler
apt-get install gcc g++ 
# or 
apt-get install clang

# build deps
apt-get install cmake pkg-config

# library deps with their headers
apt-get install libpng-dev libc6-dev libfontconfig1-dev libfreetype6-dev zlib1g-dev

Installing the dependencies on OS X:

$ brew install argp-standalone

Installing the dependencies on RHEL/CentOS/Fedora:

yum install cmake libpng-devel freetype-devel fontconfig-devel gcc-c++ gcc

Also note that in some rare cases, to properly handle text fields (ETO_GLYPH_INDEX flag), the ttf font used by the documents must be present and indexed (fontconfig) on your system.

Building

Commands to build this project:

# options: 
# * [-DUSE_CLANG=on]: use clang instead of gcc
# * [-DSTATIC=on]: build static library
# * [-DDEBUG=on]: compile with debugging symbols
#
# CMAKE_INSTALL_PREFIX is optional, default is /usr/local/
$ cmake . -DCMAKE_INSTALL_PREFIX=/usr/

# compilation
$ make

# installation
$ make install

Command line tool

$ ./emf2svg-conv --help
Usage: emf2svg-conv [OPTION...] -i FILE -o FILE
emf2svg -- Enhanced Metafile to SVG converter

  -h, --height=HEIGHT        Max height in px
  -i, --input=FILE           Input EMF file
  -o, --output=FILE          Output SVG file
  -p, --emfplus              Handle EMF+ records
  -v, --verbose              Produce verbose output
  -w, --width=WIDTH          Max width in px
  -?, --help                 Give this help list
      --usage                Give a short usage message
      --version              Print program version
  -V, --version              Print emf2svg version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

Report bugs to https://github.com/kakwa/libemf2svg/issues.

# usage example:
$ ./emf2svg-conv -i ./tests/resources/emf/test-037.emf -o example.svg -v

Library

Shorten examples:

Conversion from EMF to SVG (complete example here):

#include <emf2svg.h>
//[...]
int main(int argc, char *argv[]){

    /* emf content size */
    size_t emf_size;
    /* emf content */
    char * emf_content;
    /* svg output string */
    char *svg_out = NULL;
    /* svg output length */
    size_t svg_out_len = 0;

    //[...]

    /*************************** options settings **************************/

    /* allocate the options structure) */
    generatorOptions *options = (generatorOptions *)calloc(1, \
            sizeof(generatorOptions));
    /* debugging flag (prints the emf record in stdout if true) */
    options->verbose = true;
    /* emf+ flag (handles emf+ records if true) */
    options->emfplus = true;
    /* if a custom xml/svg namespace is needed (keep empty in doubt) */
    options->nameSpace = (char *)"svg";
    /* includes the svg start and stop tags (set to false if the result
     * of this call is meant to be used inside another svg) */
    options->svgDelimiter = true;
    /* image width in px (set to 0 to use the original emf device width) */
    options->imgWidth = 0;
    /* image height in px (set to 0 to use the original emf device height) */
    options->imgHeight = 0;

    /***************************** conversion ******************************/

    int ret = emf2svg(emf_content, emf_size, &svg_out, &svg_out_len, options);

    /***********************************************************************/

    //[...]
}

Check document for EMF+ record presence (complete example here):

int main(int argc, char *argv[]){

    /* emf content size */
    size_t emf_size;
    /* emf content */
    char * emf_content;
    /* svg output string */
    char *svg_out = NULL;
    /* svg output length */
    size_t svg_out_len = 0;

    bool emfplus;
    int ret = emf2svg_is_emfplus(emf_content, emf_size, &emfplus);
    if(emfplus)
        fprintf(stdout,"%s contains EMF+ records\n", file_name);
}

See ./src/conv/emf2svg.cpp for a real life example.

EMF/EMF+ record type coverage

EMF RECORDS:

Status	Count	Percent
Supported	37	[ 35%]
Partial	33	[ 31%]
Unused	2	[ 1%]
Ignored	33	[ 31%]
Total	105

EMF+ RECORDS:

Status	Count	Percent
Supported	0	[ 0%]
Partial	0	[ 0%]
Unused	0	[ 0%]
Ignored	85	[ 100%]
Total	85

ChangeLogs

1.1.0:

• add handling of font index encoding
• add fontconfig dependency
• add freetype dependency
• add common variables LIB_INSTALL_DIR, BIN_INSTALL_DIR, INCLUDE_INSTALL_DIR to set install directories

1.0.3:

• Fixing compilation on CentOS 7 (work around argp bug)

1.0.2:

• broken release, please don't use

1.0.1:

• cleaner handling of memstream on OSX (don't install libmemstream, just embed it)

1.0.0:

• better cmake regarding finding dependency libraries (libpng)
• /!\ API break, must pass an additionnal argument to emf2svg function:

--- a/goodies/old.c
+++ b/goodies/new.c
@@ -22,6 +22,8 @@ int main(int argc, char *argv[]){
     char * emf_content = mmap(0, emf_size, PROT_READ, MAP_PRIVATE, fd, 0);
     /* svg output string */
     char *svg_out = NULL;
+    /* svg output length */
+    size_t svg_out_len;
 
     /*************************** options settings **************************/
 
@@ -44,7 +46,7 @@ int main(int argc, char *argv[]){
 
     /***************************** conversion ******************************/
 
-    int ret = emf2svg(emf_content, emf_size, &svg_out, options);
+    int ret = emf2svg(emf_content, emf_size, &svg_out, &svg_out_len, options);
 
     /***********************************************************************/

• general cleanup of the project (remove external files not needed)

0.5.1:

• fix build on OS X

0.5.0:

• add alpha layer handling in bitmap blobs conversion
• add brush patterns

0.4.0:

• fix text orientation
• fix origin handling in special case

0.3.0:

• completly rework how the origin is calculated, it now takes correctly into account both viewport and window orgs

0.2.0:

• code reorganization
• add support for ANGLEARC, EMRSTRETCHBLT, EMRBITBLT and more
• add handling of bitmap, RLE4 and RLE8 image blobs
• add some rough handling of clipping forms
• fix text rendering to not collapse spaces

0.1.0:

• first version

Development

General source code organisation:

• ./src/lib/emf2svg.c: API entry point.
• ./src/lib/emf2svg_rec_*: EMF record handlers
• ./src/lib/emf2svg_print.c: EMF record printer (debugging).
• ./src/lib/pmf2svg.c: EMF+ record handler.
• ./src/lib/pmf2svg_print.c: EMF+ record printer (debugging).
• ./src/conv/emf2svg.cpp: Command line tool.
• ./deps: external dependencies.

Useful links:

• MS-EMF: EMF specifications.
• MS-EMF+: EMF+ specifications.
• MS-WMF: WMF specifications.
• GDI: GDI specification (clearer than EMF in explaining how it works).
• SVG: SVG specifications.

Testing

• Stats on the number of emf records covered:

$ ./tests/resources/coverage.sh

• Fuzzing on the library:

Using American Fuzzy Lop:

# remove big files from test pool
$ mkdir ./tmp
$ find tests/resources/emf -size +1M -name "*.emf" -exec mv {} ./tmp \; 

# compile with afl compiler
$ cmake -DCMAKE_CXX_COMPILER=afl-clang++ -DCMAKE_C_COMPILER=afl-clang .
$ make

# run afl (see man for more advanced usage)
$ afl-fuzz -i tests/resources/emf -o out/ -t 10000 -- ./emf2svg-conv -i '@@' -o out/ 

# restore the files
mv ./tmp/* tests/resources/emf

• Check correctness and memory leaks (xmllint and valgrind needed):

# options: -n to disable valgrind tests, -v for verbose output 
# see -h for complete list of options
$ ./tests/resources/check_correctness.sh #[-n] [-v]

# generated svg:
$ ls tests/out/test-*
tests/out/test-000.emf.svg  tests/out/test-051.emf.svg
[...]

The emf files used for these checks are located in ./tests/resources/emf/.

Useful Commands

To build, run on emf test files and visualize (with geeqie):

$ cmake .&& \
    make &&\
    "./tests/resources/check_correctness.sh" -n &&\
    geeqie "tests/out"

To check against corrupted emf:

$ cmake -DDEBUG=ON . &&\
    make &&\
    "./tests/resources/check_correctness.sh" -sxN \
    -e "./tests/resources/emf-corrupted/"

To print records index in svg as comments:

$ cmake -DINDEX=ON . && make

To reformat/reindent the code (clang-format):

$ ./goodies/format

Contributing

Contribution are welcomed. Nothing special here, it's the usual "fork; commit(s); pull request". Only one thing however, run ./goodies/format (clang-format) before the pull request.