ea5641baee
Previously, all of the README files have been renamed to README.md and now, the contents of these files were changed to use Markdown format. Other than format inconsistency, some README.md files lacked information about modules, or were out of date. By using LibreOffice / OpenOffice wiki and other documentation websites, these files were updated. Now every README.md file has a title, and some description. The top-level README.md file is changed to add links to the modules. The result of processing the Markdown format README.md files can be seen at: https://docs.libreoffice.org/ Change-Id: Ic3b0c3c064a2498d6a435253b041df010cd7797a Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113424 Tested-by: Jenkins Reviewed-by: Michael Stahl <michael.stahl@allotropia.de> Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>
53 lines
1.9 KiB
Markdown
53 lines
1.9 KiB
Markdown
# UNO-based Graphics Backend
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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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`css::rendering`, with `css::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 Works
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Look at Cairo `canvas` and situation when it is used
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(mostly slideshow).
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## TODO
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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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