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Fix Apple camera preview orientation #310

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Merged
jfversluis merged 1 commit into from
Jun 17, 2026
Merged

Fix Apple camera preview orientation #310

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190 changes: 182 additions & 8 deletions ZXing.Net.MAUI/Apple/CameraManager.ios.maccatalyst.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ public NativePlatformCameraPreviewView CreateNativeView()
public void Connect()
{
UpdateCamera(startIfStopped: true);
view?.StartObservingOrientationChanges();

if (videoDataOutput == null)
{
Expand Down Expand Up @@ -315,6 +316,8 @@ public Task<IReadOnlyList<CameraInfo>> GetAvailableCameras()

public void Disconnect()
{
view?.StopObservingOrientationChanges();

if (captureSession != null)
{
if (captureSession.Running)
Expand Down Expand Up @@ -439,6 +442,7 @@ public void AutoFocus()

public void Dispose()
{
view?.StopObservingOrientationChanges();
}

static AVCaptureDeviceType[] CaptureDevices()
Expand Down Expand Up @@ -485,30 +489,200 @@ public PreviewView(AVCaptureVideoPreviewLayer layer) : base()
}

public readonly AVCaptureVideoPreviewLayer PreviewLayer;
NSObject orientationObserver;
UIInterfaceOrientation? lastInterfaceOrientation;

public void StartObservingOrientationChanges()
{
if (orientationObserver != null)
return;

UIDevice.CurrentDevice.BeginGeneratingDeviceOrientationNotifications();
orientationObserver = NSNotificationCenter.DefaultCenter.AddObserver(
UIDevice.OrientationDidChangeNotification,
_ => RequestLayoutUpdate());

RequestLayoutUpdate();
}

public void StopObservingOrientationChanges()
{
if (orientationObserver == null)
return;

NSNotificationCenter.DefaultCenter.RemoveObserver(orientationObserver);
orientationObserver.Dispose();
orientationObserver = null;
UIDevice.CurrentDevice.EndGeneratingDeviceOrientationNotifications();
}

public override void LayoutSubviews()
{
base.LayoutSubviews();
CATransform3D transform = CATransform3D.MakeRotation(0, 0, 0, 1.0f);
switch (UIDevice.CurrentDevice.Orientation)
var interfaceOrientation = GetInterfaceOrientation();
var transform = CATransform3D.MakeRotation(0, 0, 0, 1.0f);
switch (interfaceOrientation)
{
case UIDeviceOrientation.Portrait:
case UIInterfaceOrientation.Portrait:
transform = CATransform3D.MakeRotation(0, 0, 0, 1.0f);
break;
case UIDeviceOrientation.PortraitUpsideDown:
case UIInterfaceOrientation.PortraitUpsideDown:
transform = CATransform3D.MakeRotation((nfloat)Math.PI, 0, 0, 1.0f);
break;
case UIDeviceOrientation.LandscapeLeft:
transform = CATransform3D.MakeRotation((nfloat)(-Math.PI / 2), 0, 0, 1.0f);
case UIInterfaceOrientation.LandscapeLeft:
transform = CATransform3D.MakeRotation((nfloat)(Math.PI / 2), 0, 0, 1.0f);
break;
case UIDeviceOrientation.LandscapeRight:
transform = CATransform3D.MakeRotation((nfloat)Math.PI / 2, 0, 0, 1.0f);
case UIInterfaceOrientation.LandscapeRight:
transform = CATransform3D.MakeRotation((nfloat)(-Math.PI / 2), 0, 0, 1.0f);
break;
}

PreviewLayer.Transform = transform;
PreviewLayer.Frame = Layer.Bounds;
}

protected override void Dispose(bool disposing)
{
if (disposing)
StopObservingOrientationChanges();

base.Dispose(disposing);
}

void RequestLayoutUpdate()
{
if (NSThread.IsMain)
{
UpdateLayout();
return;
}

BeginInvokeOnMainThread(UpdateLayout);
}

void UpdateLayout()
{
SetNeedsLayout();
if (Window != null)
LayoutIfNeeded();
}

UIInterfaceOrientation GetInterfaceOrientation()
{
var interfaceOrientation = GetSceneInterfaceOrientation()
?? GetDeviceInterfaceOrientation()
?? lastInterfaceOrientation
?? UIInterfaceOrientation.Portrait;

lastInterfaceOrientation = interfaceOrientation;
return interfaceOrientation;
}

UIInterfaceOrientation? GetSceneInterfaceOrientation()
{
if (!SupportsWindowScenes())
return null;

#pragma warning disable CA1416
var currentWindowScene = Window?.WindowScene;
if (currentWindowScene != null)
{
var currentOrientation = GetWindowSceneInterfaceOrientation(currentWindowScene);
if (IsKnownOrientation(currentOrientation))
return currentOrientation;
}

foreach (var scene in GetConnectedWindowScenes())
{
var sceneOrientation = GetWindowSceneInterfaceOrientation(scene);
if (IsForegroundScene(scene) && HasKeyWindow(scene) && IsKnownOrientation(sceneOrientation))
return sceneOrientation;
}

foreach (var scene in GetConnectedWindowScenes())
{
var sceneOrientation = GetWindowSceneInterfaceOrientation(scene);
if (IsForegroundScene(scene) && IsKnownOrientation(sceneOrientation))
return sceneOrientation;
}
#pragma warning restore CA1416

return null;
}

static IEnumerable<UIWindowScene> GetConnectedWindowScenes()
{
var application = UIApplication.SharedApplication;
if (application?.ConnectedScenes == null)
yield break;

foreach (var scene in application.ConnectedScenes)
{
if (scene is UIWindowScene windowScene)
yield return windowScene;
}
}

static UIInterfaceOrientation? GetDeviceInterfaceOrientation()
{
switch (UIDevice.CurrentDevice.Orientation)
{
case UIDeviceOrientation.Portrait:
return UIInterfaceOrientation.Portrait;
case UIDeviceOrientation.PortraitUpsideDown:
return UIInterfaceOrientation.PortraitUpsideDown;
case UIDeviceOrientation.LandscapeLeft:
return UIInterfaceOrientation.LandscapeRight;
case UIDeviceOrientation.LandscapeRight:
return UIInterfaceOrientation.LandscapeLeft;
default:
return null;
}
}

static UIInterfaceOrientation GetWindowSceneInterfaceOrientation(UIWindowScene scene)
{
#if IOS
if (OperatingSystem.IsIOSVersionAtLeast(26))
return scene.EffectiveGeometry.InterfaceOrientation;
#elif MACCATALYST
if (OperatingSystem.IsMacCatalystVersionAtLeast(26))
return scene.EffectiveGeometry.InterfaceOrientation;
#endif

#pragma warning disable CA1422
return scene.InterfaceOrientation;
#pragma warning restore CA1422
}

static bool HasKeyWindow(UIWindowScene scene)
{
foreach (var window in scene.Windows)
{
if (window.IsKeyWindow)
return true;
}

return false;
}

static bool IsForegroundScene(UIWindowScene scene)
=> scene.ActivationState == UISceneActivationState.ForegroundActive
|| scene.ActivationState == UISceneActivationState.ForegroundInactive;

static bool IsKnownOrientation(UIInterfaceOrientation orientation)
=> orientation != UIInterfaceOrientation.Unknown;

static bool SupportsWindowScenes()
{
#if IOS
return OperatingSystem.IsIOSVersionAtLeast(13);
#elif MACCATALYST
return OperatingSystem.IsMacCatalystVersionAtLeast(13);
#else
return false;
#endif
}
}
}
#endif
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