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