Is There a bug in CameraX CameraView because it doesn't work?

Question

I am developing an android app that lets users to record videos. I am using CameraX and CameraView as my options. The code used to work 2 weeks ago, but starting this week, CameraView has been displaying black screen only. Are there any solutions to this or am I doing something wrong?

1) build.gradle(app)

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.example.cameraxprototype4"
        minSdkVersion 28
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8.toString()
    }
}

dependencies {
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.0'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    def camerax_version = "1.0.0-beta06"
    implementation "androidx.camera:camera-core:$camerax_version"
    implementation "androidx.camera:camera-camera2:$camerax_version"
    implementation "androidx.camera:camera-lifecycle:$camerax_version"
    implementation "androidx.camera:camera-view:1.0.0-alpha13"

}

2) manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.cameraxprototype4">

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.RECORD_AUDIO"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

3) camera activity

package com.example.cameraxprototype4

import android.Manifest
import android.content.pm.PackageManager
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Environment
import android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AlertDialog
import androidx.camera.core.VideoCapture
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import kotlinx.android.synthetic.main.activity_main.*
import java.io.File

class MainActivity : AppCompatActivity() {

    val TAG = MainActivity::class.java.simpleName

    var isRecording: Boolean = false

    var CAMERA_PERMISSION = Manifest.permission.CAMERA
    var RECORD_AUDIO_PERMISSION = Manifest.permission.RECORD_AUDIO

    var RC_PERMISSION = 101

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val recordFiles = ContextCompat.getExternalFilesDirs(this, Environment.DIRECTORY_MOVIES)
        val storageDirectory = recordFiles[0]
        val videoRecordingFilePath = "${storageDirectory.absoluteFile}/${System.currentTimeMillis()}_video.mp4"

        preview.setOnClickListener {
            if (isRecording) {
                isRecording = false
                record.text = "Record Video"
                Toast.makeText(this, "Recording Stopped", Toast.LENGTH_SHORT).show()
                preview.stopRecording()
            } else {
                isRecording = true
                record.text = "Stop Recording"
                Toast.makeText(this, "Recording Started", Toast.LENGTH_SHORT).show()
                recordVideo(videoRecordingFilePath)
            }
        }
    }

    private fun startCameraSession() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            preview.bindToLifecycle(this)
        }
    }

    private fun recordVideo(videoRecordingFilePath: String) {
        preview.startRecording(File(videoRecordingFilePath), ContextCompat.getMainExecutor(this), object: VideoCapture.OnVideoSavedCallback {
            override fun onVideoSaved(file: File) {
                Toast.makeText(this@MainActivity, "Recording Saved", Toast.LENGTH_SHORT).show()
                Log.d(TAG, "onVideoSaved $videoRecordingFilePath")
            }

            override fun onError(videoCaptureError: Int, message: String, cause: Throwable?) {
                Toast.makeText(this@MainActivity, "Recording Failed", Toast.LENGTH_SHORT).show()
                Log.e(TAG, "onError $videoCaptureError $message")
            }
        })
    }

    private fun requestPermissions() {
        ActivityCompat.requestPermissions(this, arrayOf(CAMERA_PERMISSION, RECORD_AUDIO_PERMISSION), RC_PERMISSION)
    }

    private fun checkPermissions(): Boolean {
        return ((ActivityCompat.checkSelfPermission(this, CAMERA_PERMISSION)) == PackageManager.PERMISSION_GRANTED
                && (ActivityCompat.checkSelfPermission(this, CAMERA_PERMISSION)) == PackageManager.PERMISSION_GRANTED)
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when(requestCode) {
            RC_PERMISSION -> {
                var allPermissionsGranted = false
                for (result in grantResults) {
                    if (result != PackageManager.PERMISSION_GRANTED) {
                        allPermissionsGranted = false
                        break
                    } else {
                        allPermissionsGranted = true
                    }
                }
                if (allPermissionsGranted) startCameraSession() else permissionsNotGranted()
            }
        }
    }

    private fun permissionsNotGranted() {
        AlertDialog.Builder(this).setTitle("Permissions required")
            .setMessage("These permissions are required to use this app. Please allow Camera and Audio permissions first")
            .setCancelable(false)
            .setPositiveButton("Grant") { dialog, which -> requestPermissions() }
            .show()
    }
}

4) camera XML Layout

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.camera.view.CameraView
        android:id="@+id/preview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:lensFacing="back"
        app:scaleType="fitCenter"
        app:pinchToZoomEnabled="true"
        app:captureMode="video"
        app:flash="off"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"/>

    <Button
        android:id="@+id/record"
        android:layout_width="50dp"
        android:layout_height="50dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginBottom="20dp"/>



</androidx.constraintlayout.widget.ConstraintLayout>

Is this the exact code you're using? Because it doesn't seem like you're calling `startCameraSession()` from the `onCreate()` method, which means your `CameraView` isn't being bound to a lifecycle owner. — Husayn Hakeem, Jul 25 '20 at 03:22
I have tried in another emulators and other devices and it provides the same result — Jeremy, Jul 26 '20 at 00:21
This is a code copied off from the original version. I am calling `startCameraSession()` at `onRequestPermission(...)` function, which should occur before `onCreate()`. Also, I have tried calling `startCameraSession()`, but it still shows black — Jeremy, Jul 26 '20 at 00:23

score 1 · Accepted Answer · answered Jul 28 '20 at 15:39

onRequestPermissionsResult() is not called before onCreate(), it it invoked after you explicitly request a permission from the user and they either grant the permission or not (via the permission dialog).

Once onCreate() is called, you have to explicitly check if all the permissions you need are granted, if they are, you then call preview.bindToLifecycle(this), if 1 or more of the permissions isn't granted, you request them first, then once onRequestPermissionsResult() is invoked, once again you check if the permissions are granted, then react accordingly.

So the logic should look like this:

override fun onCreate(savedInstanceState: Bundle?) {
    // ...
    if (checkPermissions()) {
        preview.bindToLifecycle(this)
    } else {
        requestPermissions()
    }
}

override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
    // ...
    if (requestCode == RC_PERMISSION) {
        if (checkPermissions()) {
            preview.bindToLifecycle(this)
        } else {
            // Handle the scenario where the user doesn't grant all the required permissions
        }
    }
}

Also, in your manifest file, you're declaring 3 permissions (WRITE_EXTERNAL_STORAGE, CAMERA, RECORD_AUDIO), but requestPermissions() is missing the WRITE_EXTERNAL_STORAGE permission, and checkPermissions() only checks the CAMERA permission. Make sure you request and check all the permissions.

oh, I see my problem now. Thank you! – Jeremy Jul 28 '20 at 22:57 — Jeremy, Jul 28 '20 at 22:57

Is There a bug in CameraX CameraView because it doesn't work?

1 Answers1