Improve CameraView Performance

[zhitaop]

Description of Change

Root cause

Multiple calls to CameraProvider.RefreshAvailableCameras() are scattered throughout the camera initialization code (i.e. in CameraManager and CameraViewHandler.), affecting performance. Ideally, the refresh should only occur once during initialization.

In Addition, developers may also call RefreshAvailableCameras() in the application code (e.g. in a ViewModel for the CameraView) at the same time when the camera view is initializing. This results in duplicate concurrent executions.

For example, when opening the CameraView page in the sample app, a breakpoint set in CameraProvider.RefreshAvailableCameras() is hit up to four times from the following call stacks:

• CameraViewViewModel.RefreshCameras()
• CameraManager.PlatformConnectCamera()
• CameraManager.PlatformStartCameraPreview()
• CameraViewHandler.ConnectHandler

This PR includes the following changes

• Remove redundant RefreshAvailableCameras() calls in CameraManager and CameraViewHandler. Only call the function once in CameraManager.Shared.ConnectCamera() to ensure camera list is populated before connecting the camera.
• Introduce private PlatformRefreshAvailableCameras and refreshAvailableCamerasTask in CameraProvider to prevent duplicate concurrent refreshes. If multiple refreshes are invoked around the same time (e.g., from the ViewModel and the internal camera initialization), subsequent calls simply await the existing task.
• Some small changes in the sample app CameraViewPage. Removed unused code and add isInitialized guard to prevent refresh when navigated back from the photo page to the camera view page.

Linked Issues

• Fixes [BUG] CameraView App crashes when switching camera on Windows #2559

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard

Additional information

This PR has been tested on Windows. Number of invocation of the refresh logic is reduced to one, without altering existing behaviour.

[Copilot]

Pull Request Overview

This PR optimizes camera initialization performance by eliminating redundant calls to RefreshAvailableCameras() and implementing concurrent refresh protection. The optimization reduces multiple simultaneous camera refresh operations from up to four calls down to a single execution during initialization.

• Consolidates camera refresh logic to occur only once during initialization in CameraManager.ConnectCamera()
• Implements task-based deduplication in CameraProvider to prevent concurrent refresh operations
• Removes redundant refresh calls from CameraViewHandler and platform-specific CameraManager implementations

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
CameraView.shared.cs	Simplifies error handling logic in GetAvailableCameras() method
CameraProvider.*.cs	Changes RefreshAvailableCameras() from public to private platform implementation and adds shared task deduplication
CameraViewHandler.shared.cs	Removes redundant camera refresh call from ConnectHandler()
CameraManager.*.cs	Removes redundant refresh calls from platform implementations and consolidates initialization logic
CameraViewPage.xaml*	Adds initialization guard to prevent unnecessary refresh operations in sample app

[zhitaop]

@TheCodeTraveler @bijington

As suggested in #2907, I've created this PR to improve the performance for refresh during camera initialization. Can you please take a look, thanks!

[zhitaop]

@ne0rrmatrix Thanks for the review, I've updated the code accordingly.

[Copilot]

Pull Request Overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

[zhitaop]

@ne0rrmatrix @TheCodeTraveler Would love to get reviews/feedback on this PR and hopefully get it merged soon, to avoid further merge conflicts, thanks!

[Copilot]

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[Copilot]

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[TheCodeTraveler]

Thanks @zhitaop!

I added a few tweaks to improve performance and avoid race conditions:

• Added SemaphoreSlim to CameraProvider to avoid multi-threading race conditions from writing to refreshAvailableCamerasTask and reading from refreshAvailableCamerasTask simultaneously
• Made CameraManager a sealed class to improve performance and simplified its Dispose pattern
• Made CameraProvider a sealed class and implement Disposable to improve performance and memory management
• Call CameraManager.Disconnect in CameraViewHandler.DisconnectHandler()
• Call CameraProvider.Dispose in CameraViewHandler.Dispose

[Copilot]

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[zhitaop]

@TheCodeTraveler Thanks for the improvements to the PR, those are definitely very necessary and useful enhancements!

However, I've identified 2 regressions that would throw uncaught exceptions and cause the app to crash during my testing of the sample app. As these regressions are very likely to be hit by the developers while using the camera view, I've opened a new PR to address them. Could you please have a look?