Closes mozilla-mobile#7893: Prevent crash in QrFragment on devices without camera

Author: csadilek

components/feature/qr/src/main/java/mozilla/components/feature/qr/QrFragment.kt

@@ -41,6 +41,7 @@ import android.view.Surface
 import android.view.TextureView
 import android.view.View
 import android.view.ViewGroup
+import android.widget.TextView
 import androidx.annotation.StringRes
 import androidx.core.content.ContextCompat.getColor
 import androidx.fragment.app.Fragment
@@ -52,6 +53,7 @@ import com.google.zxing.common.HybridBinarizer
 import mozilla.components.feature.qr.views.AutoFitTextureView
 import mozilla.components.feature.qr.views.CustomViewFinder
 import mozilla.components.support.base.log.logger.Logger
+import mozilla.components.support.ktx.android.content.hasCamera
 import java.io.Serializable
 import java.util.ArrayList
 import java.util.Arrays
@@ -80,7 +82,7 @@ class QrFragment : Fragment() {
     private val surfaceTextureListener = object : TextureView.SurfaceTextureListener {
 
         override fun onSurfaceTextureAvailable(texture: SurfaceTexture, width: Int, height: Int) {
-            openCamera(width, height)
+            tryOpenCamera(width, height)
         }
 
         override fun onSurfaceTextureSizeChanged(texture: SurfaceTexture, width: Int, height: Int) {
@@ -97,6 +99,8 @@ class QrFragment : Fragment() {
 
     internal lateinit var textureView: AutoFitTextureView
     internal lateinit var customViewFinder: CustomViewFinder
+    internal lateinit var cameraErrorView: TextView
+
     @StringRes
     private var scanMessage: Int? = null
     internal var cameraId: String? = null
@@ -209,6 +213,8 @@ class QrFragment : Fragment() {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         textureView = view.findViewById<View>(R.id.texture) as AutoFitTextureView
         customViewFinder = view.findViewById<View>(R.id.view_finder) as CustomViewFinder
+        cameraErrorView = view.findViewById<View>(R.id.camera_error) as TextView
+
         scanMessage?.let {
             CustomViewFinder.setMessage(it)
         }
@@ -223,7 +229,7 @@ class QrFragment : Fragment() {
         // a camera and start preview from here (otherwise, we wait until the surface is ready in
         // the SurfaceTextureListener).
         if (textureView.isAvailable) {
-            openCamera(textureView.width, textureView.height)
+            tryOpenCamera(textureView.width, textureView.height)
         } else {
             textureView.surfaceTextureListener = surfaceTextureListener
         }
@@ -324,6 +330,30 @@ class QrFragment : Fragment() {
         this.previewSize = Size(length, length)
     }
 
+    /**
+     * Tries to open the camera and displays an error message in case
+     * there's no camera available or we fail to open it. Applications
+     * should ideally check for camera availability, but we use this
+     * as a fallback in case they don't.
+     */
+    @Suppress("TooGenericExceptionCaught")
+    internal fun tryOpenCamera(width: Int, height: Int, skipCheck: Boolean = false) {
+        try {
+            if (context?.hasCamera() == true || skipCheck) {
+                openCamera(width, height)
+            } else {
+                showNoCameraAvailableError()
+            }
+        } catch (e: Exception) {
+            showNoCameraAvailableError()
+        }
+    }
+
+    private fun showNoCameraAvailableError() {
+        cameraErrorView.visibility = View.VISIBLE
+        customViewFinder.visibility = View.GONE
+    }
+
     /**
      * Opens the camera specified by [QrFragment.cameraId].
      */

components/feature/qr/src/main/res/layout/fragment_layout.xml

@@ -11,6 +11,15 @@
     android:focusable="true"
     tools:ignore="Overdraw">
 
+    <TextView
+        android:id="@+id/camera_error"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_centerInParent="true"
+        android:text="@string/mozac_feature_qr_scanner_no_camera"
+        android:textColor="@android:color/white"
+        android:visibility="gone" />
+
     <mozilla.components.feature.qr.views.AutoFitTextureView
         android:id="@+id/texture"
         android:layout_width="match_parent"
@@ -22,4 +31,5 @@
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_centerInParent="true" />
+
 </RelativeLayout>

components/feature/qr/src/main/res/values/strings.xml

@@ -7,4 +7,7 @@
     <!-- Content description (not visible, for screen readers etc.): Description of an image view. -->
     <string name="mozac_feature_qr_scanner">QR scanner</string>
 
+    <!-- Text shown if no camera is available on the device and the QR scanner cannot be displayed. -->
+    <string name="mozac_feature_qr_scanner_no_camera">No camera available on device</string>
+
 </resources>

components/feature/qr/src/test/java/mozilla/components/feature/qr/QrFragmentTest.kt

@@ -11,6 +11,7 @@ import android.hardware.camera2.CameraManager
 import android.media.Image
 import android.util.Size
 import android.view.View
+import android.widget.TextView
 import androidx.fragment.app.FragmentActivity
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.zxing.BarcodeFormat
@@ -32,6 +33,7 @@ import org.junit.Assert.assertSame
 import org.junit.Assert.fail
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.ArgumentMatchers.anyBoolean
 import org.mockito.ArgumentMatchers.anyInt
 import org.mockito.ArgumentMatchers.anyString
 import org.mockito.Mockito.`when`
@@ -68,14 +70,16 @@ class QrFragmentTest {
         whenever(qrFragment.setUpCameraOutputs(anyInt(), anyInt())).then { }
 
         qrFragment.textureView = mock()
+        qrFragment.cameraErrorView = mock()
+        qrFragment.customViewFinder = mock()
         qrFragment.onResume()
-        verify(qrFragment, never()).openCamera(anyInt(), anyInt())
+        verify(qrFragment, never()).tryOpenCamera(anyInt(), anyInt(), anyBoolean())
 
         whenever(qrFragment.textureView.isAvailable).thenReturn(true)
         qrFragment.cameraId = "mockCamera"
         qrFragment.onResume()
         verify(qrFragment, times(2)).startBackgroundThread()
-        verify(qrFragment).openCamera(anyInt(), anyInt())
+        verify(qrFragment).tryOpenCamera(anyInt(), anyInt(), anyBoolean())
     }
 
     @Test
@@ -84,9 +88,11 @@ class QrFragmentTest {
         val view: View = mock()
         val textureView: AutoFitTextureView = mock()
         val viewFinder: CustomViewFinder = mock()
+        val cameraErrorView: TextView = mock()
 
         whenever(view.findViewById<AutoFitTextureView>(R.id.texture)).thenReturn(textureView)
         whenever(view.findViewById<CustomViewFinder>(R.id.view_finder)).thenReturn(viewFinder)
+        whenever(view.findViewById<TextView>(R.id.camera_error)).thenReturn(cameraErrorView)
 
         qrFragment.onViewCreated(view, mock())
         assertEquals(QrFragment.STATE_FIND_QRCODE, QrFragment.qrState)
@@ -369,4 +375,52 @@ class QrFragmentTest {
         assertEquals(768, qrFragment.previewSize?.width)
         assertEquals(768, qrFragment.previewSize?.height)
     }
+
+    @Test
+    fun `tryOpenCamera displays error message if no camera is available`() {
+        val qrFragment = spy(QrFragment.newInstance(mock()))
+
+        qrFragment.textureView = mock()
+        qrFragment.cameraErrorView = mock()
+        qrFragment.customViewFinder = mock()
+
+        qrFragment.tryOpenCamera(0, 0)
+        verify(qrFragment.cameraErrorView).visibility = View.VISIBLE
+        verify(qrFragment.customViewFinder).visibility = View.GONE
+    }
+
+    @Test
+    fun `tryOpenCamera opens camera if available`() {
+        val qrFragment = spy(QrFragment.newInstance(mock()))
+
+        qrFragment.textureView = mock()
+        qrFragment.cameraErrorView = mock()
+        qrFragment.customViewFinder = mock()
+
+        qrFragment.tryOpenCamera(0, 0, skipCheck = true)
+        verify(qrFragment).openCamera(0, 0)
+    }
+
+    @Test
+    fun `tryOpenCamera displays error message if camera throws exception`() {
+        val qrFragment = spy(QrFragment.newInstance(mock()))
+        whenever(qrFragment.setUpCameraOutputs(anyInt(), anyInt())).then { }
+
+        qrFragment.textureView = mock()
+        qrFragment.cameraErrorView = mock()
+        qrFragment.customViewFinder = mock()
+
+        val cameraManager: CameraManager = mock()
+        whenever(cameraManager.openCamera(anyString(), any<CameraDevice.StateCallback>(), any()))
+            .thenThrow(IllegalStateException("no camera"))
+
+        val activity: FragmentActivity = mock()
+        whenever(activity.getSystemService(Context.CAMERA_SERVICE)).thenReturn(cameraManager)
+        whenever(qrFragment.activity).thenReturn(activity)
+        qrFragment.cameraId = "mockCamera"
+
+        qrFragment.tryOpenCamera(0, 0, skipCheck = true)
+        verify(qrFragment.cameraErrorView).visibility = View.VISIBLE
+        verify(qrFragment.customViewFinder).visibility = View.GONE
+    }
 }