[camera_avfoundation] Abstract UIKit dependencies for macOS support (Part 2)

[Mairramer]

Part 2 of the ongoing effort to add macOS support to the camera_avfoundation plugin.

Part of flutter/flutter#41708

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[Mairramer]

/gemini review

[gemini-code-assist]

Code Review

This pull request refactors the camera_avfoundation package to conditionally compile iOS-specific device orientation APIs (UIDevice, UIDeviceOrientation) using #if os(iOS) blocks, and transitions the internal representation of device orientation to PlatformDeviceOrientation. Feedback suggests optimizing the non-iOS fallback logic for setting exposure and focus points of interest in DefaultCamera.swift by using optional chaining instead of repeatedly instantiating PlatformPoint.

[Mairramer]

/gemini review

[gemini-code-assist]

Code Review

This pull request refactors the camera AVFoundation implementation to support non-iOS platforms by wrapping iOS-specific device orientation and UIDevice dependencies in #if os(iOS) conditional compilation blocks, and migrating orientation properties to use the platform-agnostic PlatformDeviceOrientation type. The review feedback identifies potential issues in DefaultCamera.swift where try? is used with lockForConfiguration() during exposure and focus point updates, which could lead to silent failures or crashes, and suggests handling these errors using do-catch blocks.

[gemini-code-assist]

Using try? with lockForConfiguration() can lead to silent failures and potential runtime crashes. If the lock cannot be acquired, try? returns nil and execution continues, attempting to set exposurePointOfInterest without holding the lock, and then calling unlockForConfiguration() which will fail or crash. Instead, we should properly handle the error by propagating it via the completion handler and only unlocking if the lock was successfully acquired.

    do {
      try captureDevice.lockForConfiguration()
    } catch {
      completion(.failure(error))
      return
    }
    #if os(iOS)
      let orientation = UIDevice.current.orientation
      // A nil point resets to the center.
      let exposurePoint = cgPoint(
        for: point ?? PlatformPoint(x: 0.5, y: 0.5), withOrientation: orientation)
      captureDevice.exposurePointOfInterest = exposurePoint
    #else
      captureDevice.exposurePointOfInterest = CGPoint(
        x: point?.x ?? 0.5,
        y: point?.y ?? 0.5)
    #endif
    captureDevice.unlockForConfiguration()

[Mairramer]

The code already exists; it was simply wrapped.

[gemini-code-assist]

Using try? with lockForConfiguration() can lead to silent failures and potential runtime crashes. If the lock cannot be acquired, try? returns nil and execution continues, attempting to set focusPointOfInterest without holding the lock, and then calling unlockForConfiguration() which will fail or crash. Instead, we should properly handle the error by propagating it via the completion handler and only unlocking if the lock was successfully acquired.

Suggested change

	#if os(iOS)
	let orientation = deviceOrientationProvider.orientation
	try? captureDevice.lockForConfiguration()
	// A nil point resets to the center.
	captureDevice.focusPointOfInterest =
	cgPoint(
	for: point ?? PlatformPoint(x: 0.5, y: 0.5),
	withOrientation: orientation)
	#else
	try? captureDevice.lockForConfiguration()
	captureDevice.focusPointOfInterest = CGPoint(
	x: point?.x ?? 0.5,
	y: point?.y ?? 0.5)
	#endif
	captureDevice.unlockForConfiguration()
	do {
	try captureDevice.lockForConfiguration()
	} catch {
	completion(.failure(error))
	return
	}
	#if os(iOS)
	let orientation = deviceOrientationProvider.orientation
	// A nil point resets to the center.
	captureDevice.focusPointOfInterest =
	cgPoint(
	for: point ?? PlatformPoint(x: 0.5, y: 0.5),
	withOrientation: orientation)
	#else
	captureDevice.focusPointOfInterest = CGPoint(
	x: point?.x ?? 0.5,
	y: point?.y ?? 0.5)
	#endif
	captureDevice.unlockForConfiguration()

[Mairramer]

The code already exists; it was simply wrapped.