office-gobmx/emfio/README.md

# WMF/EMF/EMF+ Reader

## Introduction
The **emfio** module is used to read **WMF** (Windows Metafile), **EMF**
(Enhanced Metafiles) and also **EMF+** (enhanced EMF) files [1], which are
binary formats for vector images from Microsoft. These files can contain vector
graphics, bitmap components and text.

This folder contains `emfio/source/reader` which is used for reading the
WMF/EMF/EMF+ files, either directly, or inside a document. For embedding Windows
Metafiles inside a document, one can use "Insert -> Picture -> From File" to put
such a file into the document. It is possible to export the Windows Metafile
by using right click and choose "save".

Most of the records of WMF/EMF formats come from the Windows Graphics Device.
For Interface (GDI) API and EMF+ they come from the newer Windows GDI+.

More information about rendering Windows Metafiles can be found in the
[Visual Class Library (VCL)](../vcl) and also in the
[GDIMetaFile](../vcl/README.GDIMetaFile) documentation.

An example demo that renders a metafile using `vcl` be seen by invoking:

    ./bin/run mtfdemo odk/examples/basic/forms_and_controls/burger.wmf

This opens the burger.wmf file from the ODK examples.

It is also possible to dump metaactions created as the intermediary format
before rendering the metafile using:

    ./bin/run mtfdemo -d odk/examples/basic/forms_and_controls/burger.wmf

If the command is successful, this message will be shown, and metadump.xml will
be put in the current folder:

"Dumped metaactions as metadump.xml"

The demo code structure is described in [GDIMetaFile](../vcl/README.GDIMetaFile)
documentation.

[1] [Windows Meta File](https://en.wikipedia.org/wiki/Windows\_Metafile),
Wikipedia

## EMF+ Specifics
Handling EMF+ is to some extent different from handling WMF/EMF. More
information can be found in the [VCL](../vcl)
documentation.

## How does it work?
`emfio` module takes a byte array and turns it into a `drawinglayer` primitive container. The rendering is done via `drawinglayer` primitives. For more information, you should refer to [VCL](../vcl) documentation.

The drawinglayer primitives created to draw the emf/wmf files can be dumped as
xml for debugging purposes. For more information, please refer to the
[drawinglayer](../drawyinglayer) documentation.

## Limitations
Not all the WMF/EMF/EMF+ records are supported by this module. Unsupported
records are marked as "not implemented", and a warning message will printed
if they are actually read within a file. You can file a bug report for
implementing these records.

Currently, these records are not implemented for WMF (specified in
`wmfreader.cxx`):

```
W_META_SETRELABS W_META_SETPOLYFILLMODE W_META_SETSTRETCHBLTMODE
W_META_SETTEXTCHAREXTRA W_META_SETTEXTJUSTIFICATION W_META_FLOODFILL
W_META_FILLREGION W_META_FRAMEREGION W_META_INVERTREGION
W_META_PAINTREGION W_META_DRAWTEXT W_META_SETMAPPERFLAGS
W_META_SETDIBTODEV W_META_REALIZEPALETTE W_META_ANIMATEPALETTE
W_META_SETPALENTRIES W_META_RESIZEPALETTE W_META_EXTFLOODFILL
W_META_RESETDC W_META_STARTDOC W_META_STARTPAGE W_META_ENDPAGE
W_META_ABORTDOC W_META_ENDDOC
```

And these records are not implemented for EMF/EMF+ (specified in `emfreader.cxx`):

```
EMR_MASKBLT EMR_PLGBLT EMR_SETDIBITSTODEVICE EMR_FRAMERGN
EMR_INVERTRGN EMR_FLATTENPATH EMR_WIDENPATH EMR_POLYDRAW
EMR_SETPALETTEENTRIES EMR_RESIZEPALETTE
EMR_EXTFLOODFILL EMR_ANGLEARC EMR_SETCOLORADJUSTMENT EMR_POLYDRAW16
EMR_CREATECOLORSPACE EMR_SETCOLORSPACE EMR_DELETECOLORSPACE
EMR_GLSRECORD EMR_GLSBOUNDEDRECORD EMR_PIXELFORMAT EMR_DRAWESCAPE
EMR_EXTESCAPE EMR_STARTDOC EMR_SMALLTEXTOUT EMR_FORCEUFIMAPPING
EMR_NAMEDESCAPE EMR_COLORCORRECTPALETTE EMR_SETICMPROFILEA
EMR_SETICMPROFILEW EMR_TRANSPARENTBLT EMR_TRANSPARENTDIB
EMR_GRADIENTFILL EMR_SETLINKEDUFIS EMR_SETMAPPERFLAGS EMR_SETICMMODE
EMR_CREATEMONOBRUSH EMR_SETBRUSHORGEX EMR_SETMETARGN EMR_SETMITERLIMIT
EMR_EXCLUDECLIPRECT EMR_REALIZEPALETTE EMR_SELECTPALETTE
EMR_CREATEPALETTE EMR_ALPHADIBBLEND EMR_SETTEXTJUSTIFICATION
```

Due to the difference on the fonts available on various platforms, the outcome
of text rendering can be different on Linux, Windows, macOS and elsewhere.

## Known Bugs
Known remaining bugs for this module is gathered here:

* [Bug 103859 \[META\] EMF/WMF (Enhanced/Windows Metafile) bugs and
enhancements](https://bugs.documentfoundation.org/show\_bug.cgi?id=103859)

## Dependencies
The direct dependency for **emfio** is [**drawinglayer**](../drawinglayer). The
complete list of dependencies including the indirect dependencies is as below:
```
basegfx drawinglayer cppu cppuhelper sal comphelper tl salhelper vcl svt utl
```

## Tools
Several tools are available for inspecting WMF/EMF/EMF+ files, which are binary
formats. Some of them are:

* [mso-dumper](https://git.libreoffice.org/mso-dumper/): Reads and dumps various
  binary formats from Microsoft including WMF/EMF/EMF+. The output is in a
  custom XML format. emf-dump.py and wmf-dump.py are usable.
* [RE-lab (Formerly OLEToy)](https://github.com/renyxa/re-lab): Reads, dumps and
modifies several binary formats from Microsoft including WMF/EMF/EMF+, and also
other companies.
* [EMF+ diagnostics reporting tool](https://github.com/chrissherlock/emfplus-decoder)
* [limerest](https://gitlab.com/re-lab-project/limerest): A new gui tool based
on OLEToy for working with various binary formats

## Related Software
* [libemf](http://libemf.sourceforge.net/)
* [libwmf](https://github.com/caolanm/libwmf)

## References
Documentation for WMF/EMF/EMF+ formats are available on Microsoft website:

* [\[MS-WMF\]: Windows Metafile Format](https://docs.microsoft.com/en-us/openspecs/windows\_protocols/ms-wmf/4813e7fd-52d0-4f42-965f-228c8b7488d2)
* [\[MS-EMF\]: Enhanced Metafile Format](https://docs.microsoft.com/en-us/openspecs/windows\_protocols/ms-emf/91c257d7-c39d-4a36-9b1f-63e3f73d30ca)
* [\[MS-EMFPLUS\]: Enhanced Metafile Format Plus Extensions](https://docs.microsoft.com/en-us/openspecs/windows\_protocols/ms-emfplus/5f92c789-64f2-46b5-9ed4-15a9bb0946c6)