• Create an InkSparkle effect that matches the Material 3 ripple on Android 12. Similar to InkRipple, but uses the new custom shader API.
• Uses a generated SPIR-V Fragment Shader from a GLSL source.
• Uses a generated FragmentShaderManager to make uniform updates and compilation more legible.
• Recreated from [Material] Create an InkSparkle that matches the Material 3 ripple effect #96598
• Major step towards closing Introduce new Android 12 style ink ripple #82850 (Fixes Introduce new Android 12 style ink ripple #82850)

Android Samples

Tests

• There are 3 paint check tests for the InkSparkle splashFactory.

1. ElevatedButton (bounded)
2. InkWell (bounded)
3. InkResponse (unbounded)

• There are 18 golden tests to verify the consistency of the sparkle.
  • These tests use a deterministic version of the splashFactory, which is identical to the default splashFactory, except that it does not use Random to seed the turbulence effect.
  • 3 button click positions are tested: top left, center, bottom right.
  • 6 frames are captured for each animation.

Note on performance

Currently, the shader needs to be compiled at run time before the first InkSparkle can be painted. This takes 3-4 milliseconds on a Pixel 6 Pro and 30-35 milliseconds on a 2014 Moto E. The Moto E runs InkRipple at about 5 fps and the InkSparkle at about 5 fps. Even in the worst case, the async shader compilation is negligible, but it could be moved to MaterialApp or Theme creation instead.

Up next

• Introduce new Android 12 style ink ripple #82850
• [proposal] InkRipple and InkSplash implementations warrant improvements #73163
• Fix press and hold on InkSparkle #98669
• [Material] Refactor private methods from InkSparkle into reusable methods for other InkFeatures and InkRipple #98670
• [Material] Check if pixel density should be fed into InkSparkle to match Android 12 #98671
• [Material] Compress the spir-v byte code for InkSparkle #99779
• Change InkSparkle SPIR-V byte code from static const to a file to prepare for Impeller #99783

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.