fix: Use proper aspect ratio in Preview View on Android (#2964)

Uses video's aspect ratio if video is enabled, photo's aspect ratio if photo is enabled, and automatic aspect ratio otherwise.

---------

Co-authored-by: Marc Rousavy <me@mrousavy.com>

package/android/src/main/java/com/mrousavy/camera/core/CameraConfiguration.kt

@@ -51,6 +51,22 @@ data class CameraConfiguration(
   data class Audio(val nothing: Unit)
   data class Preview(val surfaceProvider: SurfaceProvider)
 
+  val targetPreviewAspectRatio: Float?
+    get() {
+      val format = format ?: return null
+      val video = video as? Output.Enabled<Video>
+      val photo = photo as? Output.Enabled<Photo>
+      return if (video != null) {
+        // Video capture is enabled, use video aspect ratio
+        format.videoWidth.toFloat() / format.videoHeight.toFloat()
+      } else if (photo != null) {
+        // Photo capture is enabled, use photo aspect ratio
+        format.photoWidth.toFloat() / format.photoHeight.toFloat()
+      } else {
+        null
+      }
+    }
+
   @Suppress("EqualsOrHashCode")
   sealed class Output<T> {
     val isEnabled: Boolean

package/android/src/main/java/com/mrousavy/camera/core/CameraSession+Configuration.kt

@@ -20,13 +20,7 @@ import androidx.camera.lifecycle.ProcessCameraProvider
 import androidx.camera.video.Recorder
 import androidx.camera.video.VideoCapture
 import androidx.lifecycle.Lifecycle
-import com.mrousavy.camera.core.extensions.byId
-import com.mrousavy.camera.core.extensions.forSize
-import com.mrousavy.camera.core.extensions.id
-import com.mrousavy.camera.core.extensions.isSDR
-import com.mrousavy.camera.core.extensions.setTargetFrameRate
-import com.mrousavy.camera.core.extensions.toCameraError
-import com.mrousavy.camera.core.extensions.withExtension
+import com.mrousavy.camera.core.extensions.*
 import com.mrousavy.camera.core.types.CameraDeviceFormat
 import com.mrousavy.camera.core.types.Torch
 import com.mrousavy.camera.core.types.VideoStabilizationMode
@@ -67,6 +61,9 @@ internal fun CameraSession.configureOutputs(configuration: CameraConfiguration)
 
   Log.i(CameraSession.TAG, "Using FPS Range: $fpsRange")
 
+  val photoConfig = configuration.photo as? CameraConfiguration.Output.Enabled<CameraConfiguration.Photo>
+  val videoConfig = configuration.video as? CameraConfiguration.Output.Enabled<CameraConfiguration.Video>
+
   // 1. Preview
   val previewConfig = configuration.preview as? CameraConfiguration.Output.Enabled<CameraConfiguration.Preview>
   if (previewConfig != null) {
@@ -85,6 +82,16 @@ internal fun CameraSession.configureOutputs(configuration: CameraConfiguration)
         }
         preview.setTargetFrameRate(fpsRange)
       }
+
+      val targetPreviewAspectRatio = configuration.targetPreviewAspectRatio
+      if (targetPreviewAspectRatio != null) {
+        Log.i(CameraSession.TAG, "Preview aspect ratio: $targetPreviewAspectRatio")
+        val previewResolutionSelector = ResolutionSelector.Builder()
+          .forAspectRatio(targetPreviewAspectRatio)
+          .setAllowedResolutionMode(ResolutionSelector.PREFER_CAPTURE_RATE_OVER_HIGHER_RESOLUTION)
+          .build()
+        preview.setResolutionSelector(previewResolutionSelector)
+      }
     }.build()
     preview.setSurfaceProvider(previewConfig.config.surfaceProvider)
     previewOutput = preview
@@ -93,7 +100,6 @@ internal fun CameraSession.configureOutputs(configuration: CameraConfiguration)
   }
 
   // 2. Image Capture
-  val photoConfig = configuration.photo as? CameraConfiguration.Output.Enabled<CameraConfiguration.Photo>
   if (photoConfig != null) {
     Log.i(CameraSession.TAG, "Creating Photo output...")
     val photo = ImageCapture.Builder().also { photo ->
@@ -114,7 +120,6 @@ internal fun CameraSession.configureOutputs(configuration: CameraConfiguration)
   }
 
   // 3. Video Capture
-  val videoConfig = configuration.video as? CameraConfiguration.Output.Enabled<CameraConfiguration.Video>
   if (videoConfig != null) {
     Log.i(CameraSession.TAG, "Creating Video output...")
     val currentRecorder = recorderOutput

package/android/src/main/java/com/mrousavy/camera/core/extensions/ResolutionSelector+forAspectRatio.kt

@@ -0,0 +1,20 @@
+package com.mrousavy.camera.core.extensions
+
+import androidx.camera.core.resolutionselector.ResolutionSelector
+import kotlin.math.abs
+
+/**
+ * Gets a [ResolutionSelector] that finds a resolution closest to the given target aspect ratio.
+ */
+fun ResolutionSelector.Builder.forAspectRatio(aspectRatio: Float): ResolutionSelector.Builder {
+  return this.setResolutionFilter { supportedSizes, _ ->
+    return@setResolutionFilter supportedSizes.sortedWith(
+      compareBy(
+        // Compare difference in aspect ratios first,
+        { abs(it.width.toFloat() / it.height - aspectRatio) },
+        // ..and total resolution afterwards.
+        { -(it.width * it.height) }
+      )
+    )
+  }
+}