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Android selfie App review
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‎content/learning-paths/smartphones-and-mobile/build-android-selfie-app-using-mediapipe-multimodality/3-camera-permission.md‎

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---
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title: Handle camera permissions
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weight: 3
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### FIXED, DO NOT MODIFY
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layout: learningpathall
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---
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## Run the app on your device
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1. Connect your Android device to your computer via a USB data cable. If this is your first time running and debugging Android apps, follow [this guide](https://developer.android.com/studio/run/device#setting-up) and double check this checklist:
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1. You have enabled USB debugging on your Android device following [this doc](https://developer.android.com/studio/debug/dev-options#Enable-debugging).
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2. You have confirmed by tapping "OK" on your Android device when an "Allow USB debugging" dialog pops up, and checked "Always allow from this computer".
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![Allow USB debugging dialog](https://ftc-docs.firstinspires.org/en/latest/_images/AllowUSBDebugging.jpg)
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2. Make sure your device model name and SDK version correctly show up on the top right toolbar. Click the "Run" button to build and run the app.
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3. After a while, you should see a success notification in Android Studio and the app showing up on your Android device.
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4. However, the app shows only a black screen while printing error messages in your [Logcat](https://developer.android.com/tools/logcat) which looks like this:
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```
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2024-11-20 11:15:00.398 18782-18818 Camera2CameraImpl com.example.holisticselfiedemo E Camera reopening attempted for 10000ms without success.
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2024-11-20 11:30:13.560 667-707 BufferQueueProducer pid-667 E [SurfaceView - com.example.holisticselfiedemo/com.example.holisticselfiedemo.MainActivity#0](id:29b00000283,api:4,p:2657,c:667) queueBuffer: BufferQueue has been abandoned
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2024-11-20 11:36:13.100 20487-20499 isticselfiedem com.example.holisticselfiedemo E Failed to read message from agent control socket! Retrying: Bad file descriptor
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2024-11-20 11:43:03.408 2709-3807 PackageManager pid-2709 E Permission android.permission.CAMERA isn't requested by package com.example.holisticselfiedemo
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```
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5. Do not worry. This is expected behavior because you haven't correctly configured this app's [permissions](https://developer.android.com/guide/topics/permissions/overview) yet. Android OS restricts this app's access to camera features due to privacy reasons.
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## Request camera permission at runtime
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1. Navigate to `manifest.xml` in your `app` subproject's `src/main` path. Declare camera hardware and permission by inserting the following lines into the `<manifest>` element. Make sure it's declared outside and above `<application>` element.
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```xml
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<uses-feature
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android:name="android.hardware.camera"
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android:required="true" />
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<uses-permission android:name="android.permission.CAMERA" />
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```
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2. Navigate to `strings.xml` in your `app` subproject's `src/main/res/values` path. Insert the following lines of text resources, which will be used later.
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```xml
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<string name="permission_request_camera_message">Camera permission is required to recognize face and hands</string>
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<string name="permission_request_camera_rationale">To grant Camera permission to this app, please go to system settings</string>
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```
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3. Navigate to `MainActivity.kt` and add the following permission related values to companion object:
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```kotlin
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// Permissions
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private val PERMISSIONS_REQUIRED = arrayOf(Manifest.permission.CAMERA)
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private const val REQUEST_CODE_CAMERA_PERMISSION = 233
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```
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4. Add a new method named `hasPermissions()` to check on runtime whether camera permission has been granted:
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```kotlin
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private fun hasPermissions(context: Context) = PERMISSIONS_REQUIRED.all {
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ContextCompat.checkSelfPermission(context, it) == PackageManager.PERMISSION_GRANTED
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}
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```
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5. Add a condition check in `onCreate()` wrapping `setupCamera()` method, to request camera permission on runtime.
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```kotlin
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if (!hasPermissions(baseContext)) {
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requestPermissions(
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arrayOf(Manifest.permission.CAMERA),
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REQUEST_CODE_CAMERA_PERMISSION
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)
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} else {
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setupCamera()
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}
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```
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6. Override `onRequestPermissionsResult` method to handle permission request results:
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```kotlin
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override fun onRequestPermissionsResult(
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requestCode: Int,
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permissions: Array<out String>,
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grantResults: IntArray
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) {
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when (requestCode) {
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REQUEST_CODE_CAMERA_PERMISSION -> {
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if (PackageManager.PERMISSION_GRANTED == grantResults.getOrNull(0)) {
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setupCamera()
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} else {
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val messageResId =
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if (shouldShowRequestPermissionRationale(Manifest.permission.CAMERA))
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R.string.permission_request_camera_rationale
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else
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R.string.permission_request_camera_message
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Toast.makeText(baseContext, getString(messageResId), Toast.LENGTH_LONG).show()
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}
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}
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else -> super.onRequestPermissionsResult(requestCode, permissions, grantResults)
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}
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}
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```
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## Verify camera permission
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1. Rebuild and run the app. Now you should see a dialog pop up requesting camera permissions!
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2. Tap `Allow` or `While using the app` (depending on your Android OS versions). Then you should see your own face in the camera preview. Good job!
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{{% notice Tip %}}
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Sometimes you might need to restart the app to observe the permission change take effect.
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{{% /notice %}}
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In the next section, you will learn how to integrate MediaPipe vision solutions.

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