This patch does the following:
- Updates `flutter_tester` to set up an Impeller rendering context and surface if `--enable-impeller` is set to true, using the Vulkan backend with Swiftshader.
- Updates `run_tests.py` to run all tests except the smoke test (that one really has no rendering impact whatsoever) with and without `--enable-impeller`.
- Updates a few tests to work that were trivial:
- A couple tests needed updated goldens for very minor rendering differences. Filed https://github.com/flutter/flutter/issues/135684 to track using Skia gold for this instead.
- Disabled SKP screenshotting if Impeller is enabled, and updated the test checking that to verify an error is thrown if an SKP is requested.
- The Dart GPU based test now asserts that the gpu context is available if Impeller is enabled, and does not deadlock if run in a single threaded mode.
- We were missing some trace events around `Canvas::SaveLayer` for Impeller as compared to Skia.
- A couple other tests had strict checks about exception messages that are slightly different between Skia and Impeller.
- I've filed bugs for other tests that may require a little more work, and skipped them for now. For FragmentProgram on Vulkan I reused an existing bug.
This is part of my attempt to address https://github.com/flutter/flutter/issues/135693, although @chinmaygarde and I had slightly different ideas about how to do this.
The goals here are:
- Run the Dart unit tests we already have with Impeller enabled.
- Enable running more of the framework tests (including gold tests) with Impeller enabled.
- Run all of these tests via public `dart:ui` API rather than mucking around in C++ internals in the engine.
Resolves https://github.com/flutter/flutter/issues/132516.
Add `impeller::HostBuffer` wrapper to Flutter GPU.
* Allows for lazy batch uploads of sparse host data to the GPU.
* Handles platform alignment requirements.
* API returns buffer view handles that will be fed to commands.
Move the GpuContext to its new home. I added a `flutter_tester` test that just verifies an exception is gracefully thrown when Impeller isn't available.
In a later patch, I'll land a way to eagerly supply the Impeller context on the cpp side to enable testing through the playground (as mentioned in https://github.com/flutter/flutter/issues/127712).
