Demo metal texture rendering within flutter app.
Note: the GIF is janky, but that's due to the GIF being a GIF
Flutter renders widgets, one of which is a Texture widget. It sends a message to
the Swift host, which creates a CVPixelBuffer linked to a metal MTLTexture.
It then starts a render-loop, linked to the display refresh rate with CVDisplayLink
and renders a quad with a mock increasing tick uniform.
The idea is to benchmark and spike using flutter for widget rendering while having visuals rendered using a different strategy.
Some parts were based on https://github.com/mogol/opengl_texture_widget_example
Not a proper measurement, just quick glancing at the activity monitor.
Flutter version: 2.8.0-3.1.pre
Performance seems fine, but CPU usage is relatively high.
Rendering Texture(textureId: id) linked to the display's frame-rate causes
CPU usage to hover at around 16% on my computer to tick the render loop.
For reference, an empty view app uses 2% CPU idle.
Most of the time is spent in Flutter's internal rendering code.
Wrapping its tree on a RepaintBoundary seems to improve this by 2-4%.
One improvement would be to stop the render loop when an app goes into the background.
Rendering 5 textures at the same time pushes CPU up to around 30%. It might be possible to say each texture after the first is causing a ~4% CPU usage increase.
I'd imagine some CPU usage is caused by the Swift render loop I wrote & could be optimised a bit more.
