Fix preview size for camera view on Androud (#723) (#731)

- Fix based on sample implementation for Camera2 API from Google
- https://github.com/android/camera-samples/blob/4aac9c7763c285d387194a558416a4458f29e275/CameraXTfLite/utils/src/main/java/com/example/android/camera/utils/CameraSizes.kt#L50-L78

Co-authored-by: Eugen Richter <[email protected]>
Co-authored-by: Gerald Versluis <[email protected]>

Author: 3 people

samples/XCT.Sample/Pages/Views/CameraViewPage.xaml

@@ -24,6 +24,7 @@
                     IsEnabled="False"
                     Maximum="10"
                     Minimum="1"
+                    HorizontalOptions="FillAndExpand"
                     ValueChanged="ZoomSlider_ValueChanged"
                     Value="1" />
             </StackLayout>

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/CameraView/Android/CameraFragment.android.cs

@@ -36,12 +36,19 @@
 using Xamarin.Forms;
 using Xamarin.Forms.Platform.Android;
 using Camera = Android.Hardware.Camera;
+using Math = System.Math;
 using Rect = Android.Graphics.Rect;
+using APoint = Android.Graphics.Point;
 
 namespace Xamarin.CommunityToolkit.UI.Views
 {
 	class CameraFragment : Fragment, TextureView.ISurfaceTextureListener
 	{
+		// Max preview width that is guaranteed by Camera2 API
+		const int MAX_PREVIEW_HEIGHT = 1080;
+		// Max preview height that is guaranteed by Camera2 API
+		const int MAX_PREVIEW_WIDTH = 1920;
+
 		CameraDevice device;
 		CaptureRequest.Builder sessionBuilder;
 		CameraCaptureSession session;
@@ -222,14 +229,42 @@ public async Task RetrieveCameraDevice(bool force = false)
 					}
 					Element.MaxZoom = maxDigitalZoom = (float)characteristics.Get(CameraCharacteristics.ScalerAvailableMaxDigitalZoom);
 					activeRect = (Rect)characteristics.Get(CameraCharacteristics.SensorInfoActiveArraySize);
+					sensorOrientation = (int)characteristics.Get(CameraCharacteristics.SensorOrientation);
+
+					var displaySize = new APoint();
+					Activity.WindowManager.DefaultDisplay.GetSize(displaySize);
+					var rotatedViewWidth = texture.Width;
+					var rotatedViewHeight = texture.Height;
+					var maxPreviewWidth = displaySize.X;
+					var maxPreviewHeight = displaySize.Y;
+
+					if (sensorOrientation == 90 || sensorOrientation == 270)
+					{
+						rotatedViewWidth = texture.Height;
+						rotatedViewHeight = texture.Width;
+						maxPreviewWidth = displaySize.Y;
+						maxPreviewHeight = displaySize.X;
+					}
+
+					if (maxPreviewHeight > MAX_PREVIEW_HEIGHT)
+					{
+						maxPreviewHeight = MAX_PREVIEW_HEIGHT;
+					}
+
+					if (maxPreviewWidth > MAX_PREVIEW_WIDTH)
+					{
+						maxPreviewWidth = MAX_PREVIEW_WIDTH;
+					}
+
 					photoSize = GetMaxSize(map.GetOutputSizes((int)ImageFormatType.Jpeg));
 					videoSize = GetMaxSize(map.GetOutputSizes(Class.FromType(typeof(MediaRecorder))));
 					previewSize = ChooseOptimalSize(
 						map.GetOutputSizes(Class.FromType(typeof(SurfaceTexture))),
-						texture.Width,
-						texture.Height,
+						rotatedViewWidth,
+						rotatedViewHeight,
+						maxPreviewWidth,
+						maxPreviewHeight,
 						cameraTemplate == CameraTemplate.Record ? videoSize : photoSize);
-					sensorOrientation = (int)characteristics.Get(CameraCharacteristics.SensorOrientation);
 					cameraType = (LensFacing)(int)characteristics.Get(CameraCharacteristics.LensFacing);
 
 					if (Resources.Configuration.Orientation == AOrientation.Landscape)
@@ -923,17 +958,25 @@ ASize GetMaxSize(ASize[] imageSizes)
 		}
 
 		// chooses the smallest one whose width and height are at least as large as the respective requested values
-		ASize ChooseOptimalSize(ASize[] choices, int width, int height, ASize aspectRatio)
+		ASize ChooseOptimalSize(ASize[] choices, int width, int height, int maxWidth, int maxHeight, ASize aspectRatio)
 		{
 			var bigEnough = new List<ASize>();
+			var notBigEnough = new List<ASize>();
 			var w = aspectRatio.Width;
 			var h = aspectRatio.Height;
 			foreach (var option in choices)
 			{
-				if (option.Height == option.Width * h / w &&
-						option.Width >= width && option.Height >= height)
+				if (option.Width <= maxWidth && option.Height <= maxHeight &&
+				    option.Height == option.Width * h / w)
 				{
-					bigEnough.Add(option);
+					if (option.Width >= width && option.Height >= height)
+					{
+						bigEnough.Add(option);
+					}
+					else
+					{
+						notBigEnough.Add(option);
+					}
 				}
 			}
 
@@ -943,11 +986,15 @@ ASize ChooseOptimalSize(ASize[] choices, int width, int height, ASize aspectRati
 				var minArea = bigEnough.Min(s => s.Width * s.Height);
 				return bigEnough.First(s => s.Width * s.Height == minArea);
 			}
-			else
+
+			if (notBigEnough.Count > 0)
 			{
-				LogError("Couldn't find any suitable preview size");
-				return choices[0];
+				var maxArea = notBigEnough.Max(s => s.Height * s.Width);
+				return notBigEnough.First(s => s.Height * s.Width == maxArea);
 			}
+
+			LogError("Couldn't find any suitable preview size");
+			return choices[0];
 		}
 		#endregion
 	}