Event fixes

Addresses issues brought up here:

- Custom properties not updating when expected.
- Events not firing on first frame.

One important aspect of all of this:
- Custom properties on events update with LinearAnimation.apply.
- Events on timelines and state machines accrue/report during StateMachine/LinearAnimation.advance

These could happen when the state machine would transition to a layer with an animation. The first frame would apply with mix 0 meaning all non-mixable properties wouldn't be applied per https://github.com/rive-app/rive/pull/5960/files.

I took a slightly different approach. Now apply will always try to apply values. If mix is 0, non mixing properties will apply. I think semantically this makes more sense too. If you don't want to apply, don't apply. Apply with mix 0 is effectively a no-op as we had it before, so it was just a perf suck.

So I re-worked the various call sites for apply to not call it when attempting to mix in an effectively mixed-out animation. This has one caveat for blend states. Because the blend state advances all the animations in sync, .advance must still be called when mix is 0, so events will still report but custom property keyframes in mixed out animations will not update. I think that's reasonable, but may not be immediately apparent. We can opt to not report events when the mix is 0 by introducing a "reportEvents" boolean to advance, or add an option to the blend state for whether or not they should report.

236d788ea Event fixes (#5997)

Co-authored-by: Alex Gibson <agibson.uk@gmail.com>
Co-authored-by: Luigi Rosso <luigi-rosso@users.noreply.github.com>
7 files changed
tree: 16bc4b515a528e4838701da47e5db622fbae9284
  1. .github/
  2. .vscode/
  3. build/
  4. decoders/
  5. dependencies/
  6. dev/
  7. include/
  8. rivinfo/
  9. skia/
  10. src/
  11. tess/
  12. test/
  13. utils/
  14. vello/
  15. viewer/
  16. .dockerignore
  17. .gitignore
  18. .lua-format
  19. .rive_head
  20. build.sh
  21. Dockerfile
  22. Doxyfile
  24. README.md

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Rive C++ is a runtime library for Rive, a real-time interactive design and animation tool.

The C++ runtime for Rive provides these runtime features:

  • Loading Artboards and their contents from .riv files.
  • Querying LinearAnimations and StateMachines from Artboards.
  • Making changes to Artboard hierarchy (fundamentally same guts used by LinearAnimations and StateMachines) and effienclty solving those changes via Artboard::advance.
  • Abstract Renderer for submitting high level vector path commands with retained path objects to optimize and minimize path re-computation (ultimately up to the concrete rendering implementation).
  • Example concrete renderer written in C++ with Skia. Skia renderer code is in skia/renderer/src/skia_renderer.cpp.

Build System

We use premake5. The Rive dev team primarily works on MacOS. There is some work done by the community to also support Windows and Linux. PRs welcomed for specific platforms you wish to support! We encourage you to use premake as it's highly extensible and configurable for a variety of platforms.


In the rive-cpp directory, run build.sh to debug build and build.sh release for a release build.

If you've put the premake5 executable in the rive-cpp/build folder, you can run it with PATH=.:$PATH ./build.sh

Rive makes use of clang vector builtins, which are, as of 2022, still a work in progress. Please use clang and ensure you have the latest version.

Building skia projects

cd skia/dependencies
./make_skia.sh      // this will invoke get_skia.sh

To build viewer (plus you'll needed CMake installed)



Uses the Catch2 testing framework.

cd dev

In the dev directory, run test.sh to compile and execute the tests.

(if you've installed premake5 in rive-cpp/build, you can run it with PATH=../../build:$PATH ./test.sh)

The tests live in rive/test. To add new tests, create a new xxx_test.cpp file here. The test harness will automatically pick up the new file.

There's a VSCode command provided to run tests from the Tasks: Run Task command palette.

Code Formatting

rive-cpp uses clang-format, you can install it with brew on MacOS: brew install clang-format.

Memory Checks

Note that if you‘re on MacOS you’ll want to install valgrind, which is somewhat complicated these days. This is the easiest solution (please PR a better one when it becomes available).

brew tap LouisBrunner/valgrind
brew install --HEAD LouisBrunner/valgrind/valgrind

You can now run the all the tests through valgrind by running test.sh memory.

Disassembly Explorer

If you want to examine the generated assembly code per cpp file, install Disassembly Explorer in VSCode.

A disassemble task is provided to compile and preview the generated assembly. You can reach it via the Tasks: Run Task command palette or you can bind it to a shortcut by editing your VSCode keybindings.json:

        "key": "cmd+d",
        "command": "workbench.action.tasks.runTask",
        "args": "disassemble"