LibreOffice » canvas
View module in: git
UNO-based graphics backend, lesser impedance to modern graphics APIs than vcl.
canvas framework is the successor of the system GUI and graphics
backend VCL. Basic functionality is available, supplying just as much
features as necessary to provide a VCL-equivalent feature set (except
proper BiDi/CTL support).
canvas framework consists of the following two modules,
cppcanvas. Additionally, a new generic graphics tooling is used (but
not exclusively by the canvas, Armin’s drawinglayer module also make
use of it), which resides in
The UNO API used by the canvas is primarily under
being the central interface.
slideshow engine has replaced the former Impress-embedded
presentation framework with a fully independent UNO component, and it
is based on the canvas. Some features used there are only available
canvas, like double-buffering, and hardware-accelerated
alpha-blending (currently not on all platforms).
canvas is one of backends of canvas component.
canvas is mostly
used for slideshow rendering and also for emf+ rendering. we hoped it
will even be used by drawing layer, but it didn’t happen (yet?) for
API look at
offapi/com/sun/star/rendering/, the implementation is in
canvas backend uses Cairo library for rendering. Main advantage
is support of alpha transparency and in some cases accelerated
The backend itself is quite old and stable, not many changes in that area lately, mostly changes for emf+ rendering, communication with vcl and bugfixes
Look at Cairo
canvas and situation when it is used
There still might be more cases when we can save some roundtrips when exchanging data with vcl.