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Dynamsoft Label Recognizer - Android User Guide

Requirements

  • Operating systems:
    • Supported OS: Android 5 or higher (Android 7 or higher recommended)
    • Supported ABI: armeabi-v7a, arm64-v8a, x86, x86_64
  • Environment: Android Studio 3.4+.

Installation

If you don’t have SDK yet, please download the Dynamsoft Label Recognizer(DLR) SDK from the Dynamsoft website and unzip the package. After decompression, the root directory of the DLR installation package is DynamsoftLabelRecognizer, which is represented by [INSTALLATION FOLDER].

Build Your First Application

The following sample will demonstrate how to take a picture and recognize it.

Note:

  • The following steps are completed in Android Studio 4.2.
  • You can download the similar complete source code from Here.

Create a New Project

  1. Open Android Studio and select New Project… in the File > New > New Project… menu to create a new project.

  2. Choose the correct template for your project. In this sample, we’ll use Empty Activity.

  3. When prompted, choose your app name (DLRAndroidSample) and set the Save location, Language, and Minimum SDK (21)

    Note: With minSdkVersion set to 21, your app is available on more than 94.1% of devices on the Google Play Store (last update: March 2021).

Include the Library

There are two ways to include the Dynamsoft Label Recognizer SDK into your project:

Local Binary Dependency

  1. Copy the file [INSTALLATION FOLDER]\DynamsoftLabelRecognizerAndroid.aar and [INSTALLATION FOLDER]\DynamsoftCoreAndroid.aar to the target directory DLRAndroidSample\app\libs

  2. Open the file DLRAndroidSample\app\build.gradle, and add reference in the dependencies:
     dependencies {
         implementation fileTree(dir: 'libs', include: ['*.aar'])
     }
    
  3. Click Sync Now. After the synchronization completes, the SDK is added to the project.

  4. import the package int the file MainActivity.java
     import com.dynamsoft.dlr.*;
    

Remote Binary Dependency

  1. Open the file DLRAndroidSample\app\build.gradle, and add the remote repository:
     repositories {
         maven {
             url "https://download2.dynamsoft.com/maven/dc/aar"
         }
         maven {
             url "https://download2.dynamsoft.com/maven/dlr/aar"
         }
     }
    
  2. Add reference in the dependencies:
     dependencies {
         implementation 'com.dynamsoft:dynamsoftcore:{version-number}@aar'
         implementation 'com.dynamsoft:dynamsoftlabelrecognizer:{version-number}@aar'
     }
    

    Note:Please replace {version-number} with the correct version number.

  3. Click Sync Now. After the synchronization completes, the SDK is added to the project.

  4. import the package in the file MainActivity.java
     import com.dynamsoft.dlr.*;
    

Initialize the Dynamsoft Label Recognizer

  1. Initialize the license

     LabelRecognizer.initLicense("DLS2eyJvcmdhbml6YXRpb25JRCI6IjIwMDAwMSIsInByb2R1Y3RzIjoyfQ==", new DLRLicenseVerificationListener() {
         @Override
         public void DLRLicenseVerificationCallback(boolean isSuccess, Exception error) {
             if(!isSuccess){
                 error.printStackTrace();
             }
         }
     });
    

    Note:

    • Network connection is required for the license to work.
    • “DLS2***” is a default 7-day trial license used in the sample.
    • If the license has expired, please request a trial license through the customer portal.
  2. Create an instance of Dynamsoft Label Recognizer

     LabelRecognizer dlr = new LabelRecognizer();
    

Recognizing and Output Results

  1. Recognizing text

     DLRResult[] results = dlr.recognizeByFile(imgPath, "");
    

    The variable imgPath represents the temporary storage location of the photos taken, which will be explained later.

  2. Get and output the recognition results

     if (results != null && results.length > 0) {
         String strCurResult = "";
         for (int i = 0; i < results.length; i++) {
                
             // Get result of each text area (also called label).
             DLRResult result = results[i];
             strCurResult += "Result " + i + ":\n";
             for (int j = 0; j < result.lineResults.length; j++) {
    
                 // Get the result of each text line in the label.
                 DLRLineResult lineResult = result.lineResults[j];
                 strCurResult += ">>Line Result " + j + ": " + lineResult.text + "\n";
             }
         }
     }
    

    The recognition results of SDK are organized into a four-tier structure:

    • DLRResult[] corresponds to the results of an image
    • DLRResult corresponds to the result of a TextArea (also called Label)
    • DLRLineResult corresponds to the result of each TextLine in the Label
    • DLRCharacterResult corresponds to the result of each Character in the TextLine

    The structure is shown in the figure below:

    DLR Result Structure

    Figure 1 – DLR Result Structure

Additional Auxiliary Steps

  1. In the Project window, open app > res > layout > activity_main.xml, and add four controls (one ImageView, one TextView and two Buttons). The following code shows the addition code of activity_main.xml.
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical">
    
         <ImageView
             android:id="@+id/imgView"
             android:layout_width="match_parent"
             android:layout_height="520dp"/>
    
         <TextView
             android:id="@+id/txtView"
             android:layout_width="match_parent"
             android:layout_height="100dp"
             android:background="#DEEEF6"
             android:text="Recognition Results" />
    
         <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:orientation="horizontal">
    
             <Button
                 android:id="@+id/btnCapture"
                 android:layout_width="wrap_content"
                 android:layout_height="match_parent"
                 android:layout_weight="1"
                 android:text="Take a Photo" />
    
             <Button
                 android:id="@+id/btnRecognize"
                 android:layout_width="wrap_content"
                 android:layout_height="match_parent"
                 android:layout_weight="1"
                 android:text="Recognize Text" />
         </LinearLayout>
     </LinearLayout>
    
  2. Add four UI variables and event response codes

     // Click to take a photo
     private Button btnCapture;
     // Click to recognize thext
     private Button btnRecognize;
     // Display the photo taken with Camera App
     private ImageView imgView;
     // Display the recognition results
     private TextView txtView;
    
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         btnCapture =(Button)findViewById(R.id.btnCapture);
         btnRecognize =(Button)findViewById(R.id.btnRecognize);
         imgView = (ImageView)findViewById(R.id.imgView);
         txtView = (TextView)findViewById(R.id.txtView);
    
         btnCapture.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 // take a photo with Camera App
                 takePhoto();
             }
         });
    
         btnRecognize.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 // recognize text in the photo
                 recognizeText();
             }
         });
     }
    

    Note: The implementation of the recognizeText function has been explained in Initialize the Dynamsoft Label Recognizer and Recognizing and output results.

  3. Take a photo with the camera app.
     // Uri of the captured photo
     private Uri imgUri;
     // The full path of the captured photo
     private String imgPath;
    
     private void takePhoto() {
         String status= Environment.getExternalStorageState();
         if(status.equals(Environment.MEDIA_MOUNTED)) {
             try {
                 File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
                 imgPath = outputImage.getAbsolutePath();
    
                 if (outputImage.exists()) {
                     outputImage.delete();
                 }
                 outputImage.createNewFile();
    
                 if (Build.VERSION.SDK_INT >= 24) {
                     imgUri = FileProvider.getUriForFile(this, "com.example.dlrandroidsample", outputImage);
                 } else {
                     imgUri = Uri.fromFile(outputImage);
                 }
    
                 Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                 intent.putExtra(MediaStore.EXTRA_OUTPUT, imgUri);
                 startActivityForResult(intent, Image_Capture_Code);
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
     }   
    
  4. Display the photo in the ImageView control
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         super.onActivityResult(requestCode, resultCode, data);
    
         if (requestCode == Image_Capture_Code && resultCode == RESULT_OK) {
             try {
                 Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imgUri));
                 imgView.setImageBitmap(bitmap);
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
     }    
    
  5. Config the FileProvdier in the file AndroidManifest.xml
     <provider
         android:authorities="com.example.dlrandroidsample"
         android:name="androidx.core.content.FileProvider"
         android:exported="false"
         android:grantUriPermissions="true">
         <meta-data
             android:name="android.support.FILE_PROVIDER_PATHS"
             android:resource="@xml/file_paths">
         </meta-data>
     </provider>
    

    Note: Make sure that the authorities string matches the second argument to getUriForFile. In the meta-data section of the provider definition, you can see that the provider expects eligible paths to be configured in a dedicated resource file, res/xml/file_paths.xml. Here is the content required for this particular example:

     <?xml version="1.0" encoding="utf-8"?>
     <paths xmlns:android="http://schemas.android.com/apk/res/android">
         <external-cache-path name="my_images" path="." />
     </paths>
    

You can download the similar complete source code from Here.

Build and Run the Project

  1. Select the device that you want to run your app on from the target device drop-down menu in the toolbar.

  2. Click Run app button, then Android Studio installs your app on your connected device and starts it.

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