Files
odfstudio/slideshow
Miklos Vajna 916848d877 tdf#149971 avmedia: implement video crop support in the gsteamer backend
If a media shape had cropping defined, we already took that into account
when presenting a preview for it, but not during video playback.

The reason for this is that the preview may be set by a file importer
(e.g. PPTX) explicitly, in which case the preview is a bitmap we get
without any video processing.

As a start, implement video crop for the gstreamer backend (used on
Linux), and also pass in the media item (containing crop and other
properties) both during the edit view (MediaWindowImpl) and presenting
(ViewMediaShape). We pass in the whole media item, so in case later
other filters (e.g. black-and-white) are wanted, we have all that info
in the backends already.

Other backends (avmediaMacAVF and avmediawin) are untouched so far.
svx/qa/unit/data/video-snapshot.pptx is modified to have a yellow border
when cropping is unimplemented, which is now not visible with the
gtreamer backend, matching PowerPoint behavior. PPTX export was working
out of the box already.

Change-Id: If26b7a4391bcffe9cbddd9933e1bab69be52924e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/138867
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins
2022-08-26 11:48:41 +02:00
..
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2022-03-01 08:21:00 +01:00
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Impress Slideshow Engine

3D Transitions

The 3D transitions are slideshow transition engine using OpenGL and are located in slideshow/source/engine/OGLTrans/. They were initially written by GSOC student Shane.M.Mathews. Radek has later polished the code a bit, added few new 3D transitions, added infrastructure for vertex and fragment shaders. Wrote few transitions with fragment shader too.

Physics Animation Effects

Physics animation effects are simulated by external 2d physics engine library Box2D. They don't directly call Box2D functions but instead use the wrapper in:

  • slideshow/source/inc/box2dtools.hxx
  • slideshow/source/engine/box2dtools.cxx

The wrapper has two corresponding classes to manage the Box2D world and Box2D bodies.

When a physics animation starts, a Box2DWorld is initiated and populated with every shape that is part of the foreground (which are shapes that do not belong to the master slide and not a background shape).

After creation until the end of the slide (not the whole slideshow) the Box2D World isn't destroyed and reused. But the bodies that represent the shapes in the slide get destroyed when there's a point in time that there's no physics animation in progress. And recreated when another physics animation starts.

If there are multiple physics animations in parallel only one of them takes the role of stepping through the simulation.

If there are other animation effects that go in parallel which change the shape position, rotation, or visibility - they also report the change to Box2DWorld. These updates are collected in a queue in Box2DWorld and processed before stepping through the simulation. To achieve convincing results these updates are performed by setting the Box2D body's linear velocity or angular velocity instead of setting directly it's position or rotation.