LibreOffice » libreofficekit
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LibreOfficeKit can be used for accessing LibreOffice functionality through C/C++, without any need to use UNO.
For now it only offers document conversion (in addition to an experimental tiled rendering API).
LOK functionality can be accessed by including
LibreOfficeKit.h[xx] in your
LOK initialisation (
lok_init) requires the inclusion of
your program. If you use the C++
LibreOfficeKit.hxx header, it already includes
LibreOfficeKitInit.h for you.
LibreOfficeKit.hxx is a simple and fully inlined C++ wrapper for the same
functionality as in
An example program can be seen on: https://gitlab.com/ojwb/lloconv
To use LOK Tiled Rendering you will need the following before the LOK includes:
(This must be define before ANY LOK header, i.e. including the Init header.)
Currently only bitmap-buffer rendering is supported, with a 32-bit BGRA colorspace (further alternatives could feasibly be implemented as needed). Scanlines are ordered top-down (whereas LibreOffice will internally default to bottom-up).
On top of the tiled rendering API, a set of new methods have been added to the
lok::Document class to allow basic editing, too. Communication between the LOK
client and LibreOffice is a two-way channel. The client can initiate an action
by calling the above mentioned methods. The most important methods for the
client -> LibreOffice communication are:
initializeForRendering(), expected to be called right after
postKeyEvent(), expected to be called when the user provides input on the (soft-)keyboard.
postMouseEvent(), expected to be called when the user generated a touch or mouse event.
In general, all coordinates are always in absolute twips (20th of a point, or:
1" = 1440 twips). See
LibreOfficeKit.hxx for a full list of
methods and their documentation.
The other way around (LibreOffice -> LOK client) is implemented using a
callback. A LOK client can register a callback using the registerCallback()
method. Whenever editing requires some action on the client side, a callback
event is emitted. The callback types are described using the
LibreOfficeKitCallbackType enumeration in
LibreOfficeKitEnums.h, the callback
function signature itself is provided by the LibreOfficeKitCallback typedef in
LibreOfficeKitTypes.h. The most important callback types:
LOK_CALLBACK_INVALIDATE_TILES: drop all tiles cached on client-side that intersect with the provided rectangle
LOK_CALLBACK_INVALIDATE_VISIBLE_CURSOR: need to set the position and/or the size of the cursor
LOK_CALLBACK_TEXT_SELECTION: need to adjust the selection overlay provided by the client as the set of rectangles describing the selection overlay changed
There are currently two known LOK clients supporting tiled editing:
gtktiledviewer(see below), which allows testing the LOK core implementation on (desktop) Linux
Core has next to no idea what is the LOK client, so for effective development,
it’s recommended that the core part is developed against
once a feature works there, then implement the Android part, with its slower
development iteration (slow uploading to the device, the need to link all
object files into a single
bin/run gtktiledviewer --lo-path=$PWD/instdir/program path/to/test.odt
To receive all incoming events from core use
G_MESSAGES_DEBUG=all bin/run gtktiledviewer --lo-path=$PWD/instdir/program ../test.odt
To debug with
export LO_TRACE='gdb --tui --args'
bin/run, this will run gtktiledviewer in the debugger instead.
Currently consists of only a very basic GTK document viewer widget.
The widget uses
g_info() instead of
SAL_INFO(), use the
environment variable to display those messages.