From 09e46f321e32331be7f5389d1af15a3027cec1d7 Mon Sep 17 00:00:00 2001
From: Andrea Brighi <andrea.brighi8@studio.unibo.it>
Date: Sun, 14 May 2023 17:15:54 +0200
Subject: [PATCH] feat(app): add PreviewViewComposable to show the camera
 preview stream

---
 .../app/ui/common/PreviewViewComposable.kt    | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 app/src/main/kotlin/com/intelligentbackpack/app/ui/common/PreviewViewComposable.kt

diff --git a/app/src/main/kotlin/com/intelligentbackpack/app/ui/common/PreviewViewComposable.kt b/app/src/main/kotlin/com/intelligentbackpack/app/ui/common/PreviewViewComposable.kt
new file mode 100644
index 00000000..18e5466c
--- /dev/null
+++ b/app/src/main/kotlin/com/intelligentbackpack/app/ui/common/PreviewViewComposable.kt
@@ -0,0 +1,75 @@
+package com.intelligentbackpack.app.ui.common
+
+import android.util.Log
+import androidx.camera.core.CameraSelector
+import androidx.camera.core.ImageAnalysis
+import androidx.camera.core.ImageCapture
+import androidx.camera.core.Preview
+import androidx.camera.lifecycle.ProcessCameraProvider
+import androidx.camera.view.PreviewView
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalLifecycleOwner
+import androidx.compose.ui.viewinterop.AndroidView
+import androidx.core.content.ContextCompat
+import com.intelligentbackpack.app.sensor.BarcodeAnalyser
+import java.util.concurrent.Executors
+
+@androidx.camera.core.ExperimentalGetImage
+@Composable
+fun PreviewViewComposable(modifier: Modifier, barcodeAnalyser: BarcodeAnalyser) {
+    val lifecycleOwner = LocalLifecycleOwner.current
+    var cameraProvider: ProcessCameraProvider? = null
+    DisposableEffect(key1 = cameraProvider) {
+        onDispose {
+            cameraProvider?.unbindAll() // closes the camera
+        }
+    }
+    AndroidView(
+        { context ->
+            val cameraExecutor = Executors.newSingleThreadExecutor()
+            val previewView = PreviewView(context).also {
+                it.scaleType = PreviewView.ScaleType.FILL_CENTER
+            }
+            val cameraProviderFuture = ProcessCameraProvider.getInstance(context)
+            cameraProviderFuture.addListener({
+                cameraProvider = cameraProviderFuture.get()
+
+                val preview = Preview.Builder()
+                    .build()
+                    .also {
+                        it.setSurfaceProvider(previewView.surfaceProvider)
+                    }
+
+                val imageCapture = ImageCapture.Builder().build()
+
+                val imageAnalyzer = ImageAnalysis.Builder()
+                    .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
+                    .build()
+                    .apply {
+                        setAnalyzer(cameraExecutor, barcodeAnalyser)
+                    }
+
+                val cameraSelector = CameraSelector.Builder()
+                    .requireLensFacing(CameraSelector.LENS_FACING_BACK)
+                    .build()
+
+                try {
+                    // Unbind use cases before rebinding
+                    cameraProvider?.unbindAll()
+
+                    // Bind use cases to camera
+                    cameraProvider?.bindToLifecycle(
+                        lifecycleOwner, cameraSelector, preview, imageCapture, imageAnalyzer
+                    )
+
+                } catch (exc: Exception) {
+                    Log.e("DEBUG", "Use case binding failed", exc)
+                }
+            }, ContextCompat.getMainExecutor(context))
+            previewView
+        },
+        modifier = modifier
+    )
+}
\ No newline at end of file