renderCache property
Opt-in to a special render mode where the frames of the animation are lazily rendered and kept in a cache. Subsequent runs of the animation will be cheaper to render.
This is useful is the animation is complex and can consume lot of energy from the battery. This will trade an excessive CPU usage for an increase memory usage. The main use-case is a short and small (size on the screen) animation that is played repeatedly.
There are 2 kinds of caches:
- RenderCache.raster: keep the frame rasterized in the cache (as dart:ui.Image). Subsequent runs of the animation are very cheap for both the CPU and GPU but it takes a lot of memory (rendered_width * rendered_height * frame_rate * duration_of_the_animation). This should only be used for very short and very small animations.
- RenderCache.drawingCommands: keep the frame as a list of graphical operations (dart:ui.Picture). Subsequent runs of the animation are cheaper for the CPU but not for the GPU. Memory usage is a lot lower than RenderCache.raster.
The render cache is managed internally and will release the memory once the animation disappear. The cache is shared between all animations. Any change in the configuration of the animation (delegates, frame rate etc...) will clear the cache entry. For RenderCache.raster, any change in the size will invalidate the cache entry. The cache use the final size visible on the screen (with all transforms applied).
In order to not exceed the memory limit of a device, the raster cache is constrained to maximum 50MB. After that, animations are not cached anymore.
Implementation
/// Any change in the configuration of the animation (delegates, frame rate etc...)
/// will clear the cache entry.
/// For RenderCache.raster, any change in the size will invalidate the cache entry. The cache
/// use the final size visible on the screen (with all transforms applied).
///
/// In order to not exceed the memory limit of a device, the raster cache is constrained
/// to maximum 50MB. After that, animations are not cached anymore.
/// {@endtemplate}
final RenderCache? renderCache;