Partial Rendering refers to a rendering technique where
only a portion of the scene or screen is updated, rather
than redrawing the entire output. It is commonly used as
a performance optimization strategy, focusing on redrawing
only the regions that have changed, often called dirty regions.
This introduces RenderDirtyRegion, which assists
in collecting a compact dirty region from render tasks.
To efficient data-processing, this divide the screen region
with a designated size of partition and handles the partitl rendering
computation with a divide-conquer metholodgy.
Each backend can utilize this class to support efficient partial rendering.
This is implemented using a Line Sweep and Subdivision Merging O(NlogN).
The basic per-frame workflow is as follows:
0. RenderDirtyRegion::init() //set the screen size to properly partition the regions
1. RenderDirtyRegion::prepare() //Call this in Renderer::preRender().
2. RenderDirtyRegion::add() //Add all dirty paints for the frame before rendering.
3. RenderDirtyRegion::commit() //Generate the partial rendering region list before rendering.
4. RenderDirtyRegion::partition() //Get a certian partition
5. RenderDirtyRegion::get() //Retrieve the current dirty region list of a partition and use it when drawing paints.
6. RenderDirtyRegion::clear() //Reset the state.
RenderMethod introduced for 2 utilities for paritial renderings
1. RenderMethod::damage() //add a force dirty region, especially useful for scene effects
2. RenderMethod::partial() //toggle the partial rendering feature
issue: https://github.com/thorvg/thorvg/issues/1747
redefiend properties so that min/max are prioritized,
as they are accessed more frequently than pos/size
during rendering calculations.
also introduced miscellaneous functions to improve usability.
- modify the concept of AABB to apply only to transformed shapes.
- transform points before computing the bounding box min/max
to obtain a more compact shape region.
- trimmming memory by removing the cached matrix, about 36kb
of memory has been reduced per paint instance.
previously, the bounding box calculation was simply
determined by comparing all the points, which led to
incorrect sizing due to Bezier control points.
Now, it accurately computes the curve boundary,
properly addressing this issue.
ThorVG pImpl idiom caused internal data to be scattered
across hierarchical classes. This refactoring consolidates
the data by inheriting pImpl internally, reducing memory
allocation counts and eliminating unnecessary strategy methods.
This corrects the return value to Result::InsufficientCondition
when a custom transform is applied.
Additionally, unnecessary x and y member fields have been removed.
The viewport function defines the rectangular area of the canvas
that will be used for drawing operations.
It is used to clip the rendering output to the boundaries of the rectangle.
Apps can use this function to set the drawing region within the canvas.
When the ThorVG canvas is partially inside the screen area such as during scrolling
it could help enhance rendering performance.
New Experimental API:
- Result Canvas::viewport(int32_t x, int32_t y, int32_t w, int32_t h) noexcept;
Issue: https://github.com/thorvg/thorvg/issues/2274
Get rid of the polymorphism function table,
use the switch directly instead.
We profiled, both binary & performance is better than before.
Tested on a local machine (single thread):
- Lottie: 2ms improved
- Binary: -0.5kb
