Integrate Android PDF Library using Flutter

This guide will help you integrate a free trial of the PDFTron SDK into your Android applications using Flutter. Your free trial includes unlimited trial usage and support from solution engineers.

Get the Flutter source code

• Latest stable version of Flutter
• Latest stable version of Android Studio
• Have Android NDK (Native Development Kit) installed
• Have npm or yarn setup

For simplicity, the following guide is based on a boilerplate Flutter app and uses Git Diff syntax to represent lines that have been added to or removed from the app. Please follow these Flutter get started guides to install, set up an editor, and create a Flutter Project if you are a first time Flutter developer

1. Initialize the project by running the command:

   flutter create myapp

2. Add the following dependency to your Flutter project in myapp/pubspec.yaml:

   • If you want to use our null safe package from pub.dev:

     dependencies:
        flutter:
           sdk: flutter
     +   pdftron_flutter:

• If you want to use our null safe package from GitHub:

  dependencies:
     flutter:
        sdk: flutter
  +   pdftron_flutter:
  +     git:
  +       url: git://github.com/PDFTron/pdftron-flutter.git

3. Navigate to your myapp folder:

   cd myapp

   and run the following command to get the required packages:

   flutter packages get

4. Now add the following items in your myapp/android/app/build.gradle file:

   defaultConfig {
       applicationId "com.example.myapp"
   -    minSdkVersion flutter.minSdkVersion
   +    minSdkVersion 21
   +    multiDexEnabled true
   +    manifestPlaceholders += [pdftronLicenseKey:PDFTRON_LICENSE_KEY]
       targetSdkVersion flutter.targetSdkVersion
       versionCode flutterVersionCode.toInteger()
       versionName flutterVersionName
   }

5. In your myapp/android/app/src/main/AndroidManifest.xml file, add the following lines:

   <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.myapp">
   
      <!-- Required to read and write documents from device storage -->
   +  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
      <!-- Required if you want to record audio annotations -->
   +  <uses-permission android:name="android.permission.RECORD_AUDIO" />
   
      <!-- Enable usesCleartextTraffic in application attributes if you are working with HTTP files. If you are only working with HTTPS files, this is not required.-->
      <application
         ...
   +	  android:largeHeap="true"
   +	  android:usesCleartextTraffic="true">
   
        <!-- Add license key in meta-data tag here. This should be inside the application tag. -->
   +    <meta-data
   +      android:name="pdftron_license_key"
   +      android:value="${pdftronLicenseKey}"/>
   
        <activity
            android:name=".MainActivity"
            android:exported="true"
            ...
            android:windowSoftInputMode="adjustResize">
   
            <!-- Specifies an Android theme to apply to this Activity as soon as the Android process has started. This theme is visible to the user while the Flutter UI initializes. After that, this theme continues to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below. This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
   </manifest>

6. In your android/gradle.properties file, add the following line:

   # Add the PDFTRON_LICENSE_KEY variable here. 
   # For trial purposes leave it blank.
   # For production add a valid commercial license key.
   PDFTRON_LICENSE_KEY=

7. If you are using the DocumentView widget, change the parent class of your MainActivity file (either Kotlin or Java) to FlutterFragmentActivity.

   import androidx.annotation.NonNull
   import io.flutter.embedding.android.FlutterFragmentActivity
   import io.flutter.embedding.engine.FlutterEngine
   import io.flutter.plugins.GeneratedPluginRegistrant
   
   class MainActivity : FlutterFragmentActivity() {
       override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
           GeneratedPluginRegistrant.registerWith(flutterEngine);
       }
   }

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