CameraX for Kotlin: Complete Guide with Examples

1. What is it and why is it needed

CameraX is a library from Google for developing cameras on Android, written in Kotlin and Java. It provides a simple and consistent API for working with the camera, abstracting away the complexity of low-level Camera2 APIs. CameraX solves many problems developers face: support for different Android versions, working with various device manufacturers, handling the Activity/Fragment lifecycle and screen rotations.

Why is CameraX needed? First, it significantly simplifies development: instead of hundreds of lines of code to set up the camera, preview, and capture images, you write 10-20 lines. Second, it ensures compatibility with devices from Android 5.0 (API 21) and above. Third, CameraX automatically handles complex scenarios such as switching between cameras, changing orientation, and preserving state during screen rotation. Fourth, the library includes built-in Extensions such as HDR, night mode, and portrait mode, which work on most devices without additional configuration.

CameraX is ideal for applications that require quick camera integration: messengers, social networks, QR code scanning apps, video calling apps, and simple cameras. If you need to create a professional application with full control over every frame (e.g., for computer vision or professional video recording), you might consider Camera2, but for 90% of tasks, CameraX is the best choice.

2. Installation

CameraX is installed via the Gradle build system. For a Kotlin project, add dependencies to the build.gradle file (Module: app).

Exact command (Gradle):

dependencies {\n    // Core CameraX\n    def camerax_version = "1.3.1"\n    implementation "androidx.camera:camera-core:${camerax_version}"\n    implementation "androidx.camera:camera-camera2:${camerax_version}"\n    implementation "androidx.camera:camera-lifecycle:${camerax_version}"\n    implementation "androidx.camera:camera-view:${camerax_version}"\n\n    // If extensions are needed (HDR, night mode, etc.)\n    implementation "androidx.camera:camera-extensions:${camerax_version}"\n\n    // For video\n    implementation "androidx.camera:camera-video:${camerax_version}"\n}

Also make sure the Google repository is specified in build.gradle (Project):

allprojects {\n    repositories {\n        google()\n        mavenCentral()\n    }\n}

After adding the dependencies, sync the project (Sync Now).

3. Quick Start — Minimal Working Example

Create a new Activity or Fragment. In the layout (XML), add PreviewView:

<?xml version="1.0" encoding="utf-8"?>\n<androidx.constraintlayout.widget.ConstraintLayout\n    xmlns:android="http://schemas.android.com/apk/res/android"\n    android:layout_width="match_parent"\n    android:layout_height="match_parent">\n\n    <androidx.camera.view.PreviewView\n        android:id="@+id/viewFinder"\n        android:layout_width="match_parent"\n        android:layout_height="match_parent" />\n\n</androidx.constraintlayout.widget.ConstraintLayout>

Now the Activity code in Kotlin:

import android.os.Bundle\nimport androidx.appcompat.app.AppCompatActivity\nimport androidx.camera.core.CameraSelector\nimport androidx.camera.core.Preview\nimport androidx.camera.lifecycle.ProcessCameraProvider\nimport androidx.core.content.ContextCompat\nimport java.util.concurrent.ExecutorService\nimport java.util.concurrent.Executors\n\nclass MainActivity : AppCo