Improved rendering

[kunitoki]

This pull request introduces a major architectural improvement to the rendering model for SDLComponentNative, moving each window's rendering to its own dedicated render thread. This change decouples rendering from the message thread, improving responsiveness and allowing multiple windows to render in parallel without serializing on vsync waits. The update also introduces a clear separation between native UI attachment (which must happen on the message thread) and GPU resource management (which now happens on the render thread), and makes several thread-safety and performance improvements throughout the rendering pipeline.

The most important changes are:

Render Thread Architecture:

• SDLComponentNative now renders each window on its own dedicated render thread. The component-tree walk and animation/logic run under a MessageManagerLock, while GL command submission and buffer swap happen unlocked, allowing multiple windows to render in parallel and keeping the message thread responsive. [1] [2]

Native UI and GPU Resource Management Separation:

• Added a new attachToWindow method to GraphicsContext (and implemented it for Metal) to attach rendering surfaces to native UI on the message thread. GPU resource resizing is now handled separately on the render thread via onSizeChanged, ensuring thread safety and correct resource management. [1] [2] [3] [4]

Render Loop and Synchronization Improvements:

• Refactored the render loop in SDLComponentNative to use a dedicated thread (or timer on Emscripten), with explicit signaling for repaint requests and fine-grained sleep for frame timing. The rendering logic is now encapsulated in a new renderFrame method, and thread-safe atomic access is used for render flags. [1] [2] [3] [4] [5]

Repaint and Resource Handling Fixes:

• Improved repaint area management with proper locking, and ensured that resizing and resource attachment are handled on the correct threads. Also, fixed the logic for getting content size and buffer swapping for OpenGL contexts. [1] [2] [3] [4] [5] [6] [7] [8] [9]

Platform and Build Configuration Updates:

• Updated the logic for renderDrivenByTimer to ensure correct behavior on Emscripten and other platforms, and removed unused AsyncUpdater inheritance. [1] [2]

[codecov]

Codecov Report

❌ Patch coverage is 52.21239% with 54 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.97%. Comparing base (8bb6b67) to head (60fd5cc).

Files with missing lines	Patch %	Lines
modules/yup_gui/component/yup_Component.cpp	42.42%	38 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuBuffer.cpp	40.00%	12 Missing ⚠️
modules/yup_core/threads/yup_WaitableTimer.cpp	93.33%	1 Missing ⚠️
modules/yup_gui/component/yup_ComponentNative.h	0.00%	1 Missing ⚠️
modules/yup_rhi/context/yup_GpuDevice.h	50.00%	1 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuComputePipeline.cpp	85.71%	1 Missing ⚠️

❌ Your patch check has failed because the patch coverage (52.21%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #173      +/-   ##
==========================================
- Coverage   80.98%   80.97%   -0.01%     
==========================================
  Files         786      787       +1     
  Lines       82265    82333      +68     
==========================================
+ Hits        66620    66670      +50     
- Misses      15645    15663      +18     

Files with missing lines	Coverage Δ
modules/yup_core/yup_core.cpp	100.00% <ø> (ø)
modules/yup_graphics/context/yup_GraphicsContext.h	75.00% <100.00%> (+8.33%)	⬆️
modules/yup_rhi/context/yup_GpuDevice.cpp	85.56% <100.00%> (ø)
modules/yup_rhi/rhi/yup_GpuBuffer.h	50.00% <ø> (ø)
modules/yup_core/threads/yup_WaitableTimer.cpp	93.33% <93.33%> (ø)
modules/yup_gui/component/yup_ComponentNative.h	33.33% <0.00%> (-16.67%)	⬇️
modules/yup_rhi/context/yup_GpuDevice.h	50.00% <50.00%> (-7.15%)	⬇️
modules/yup_rhi/rhi/yup_GpuComputePipeline.cpp	44.18% <85.71%> (+2.93%)	⬆️
modules/yup_rhi/rhi/yup_GpuBuffer.cpp	68.88% <40.00%> (-17.32%)	⬇️
modules/yup_gui/component/yup_Component.cpp	76.02% <42.42%> (-0.76%)	⬇️

... and 6 files with indirect coverage changes

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