Files
odfstudio/slideshow
Miklos Vajna d0176d65de tdf#149969 slideshow: handle loop from the animation of a media shape
Impress supported video looping on media shapes, while PowerPoint
supports this as part of the animation tree for the slide. To be more
specific, it seems in case there is play command, then it looks up if
there is a media node of the timing tree that has the current shape as
its target, and checks if the looping is enabled for this shape in this
media node.

The PPTX import already creates an (audio) node for the media shape and
we have UNO API to set/get a RepatCount attribute on this.

Rather than tweaking the PPTX import to create a different doc model,
just extend the rendering so in case the shape doesn't enable looping we
can also notice that an animation requested looping.

The PPTX export doesn't write a media node for videos at the moment, so
that still needs work.

Change-Id: Ifc6600be760a954230243fd8151736656958a429
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/139253
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins
2022-09-02 12:30:49 +02:00
..
2022-03-01 08:21:00 +01:00
…
…

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.