Android implements custom gesture and gesture recognition functions

1. Complete the Activity of custom gestures first

1.1 You need to declare permissions because you need to store gesture files:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> // Read SD Card authority 
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> // Write SD Card authority 

1.2 Simply write a layout file, which uses GestureOverlayView, equivalent to a drawing component. There is an important attribute gestureStrokeType. When the value is single, it means that only one stroke is drawn. If you want to draw multiple strokes, the value should be set to multiple:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
 android:orientation="vertical"
 tools:context=".addgesture.Main3Activity">
 <Button
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:onClick="recognition"
  android:text=" Recognize gestures " />
 <TextView
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:gravity="center"
  android:text=" Please draw a gesture " />
 <android.gesture.GestureOverlayView
  android:id="@+id/activity_main3_gov"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:gestureStrokeType="multiple" // Multi-stroke rendering 
  ></android.gesture.GestureOverlayView>
</LinearLayout>

1.3 The style of AlertDialog is customized here;

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">
 <LinearLayout
  android:layout_width="match_parent"
  android:layout_height="wrap_content">
  <TextView
   android:layout_width="wrap_content"
   android:layout_height="match_parent"
   android:gravity="center"
   android:text=" Please enter a gesture name " />
  <EditText  // Enter a name for the gesture 
   android:id="@+id/save_dialog_et"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />
 </LinearLayout>
 <ImageView  // Show the drawn gestures 
  android:id="@+id/save_dialog_iv"
  android:layout_width="match_parent"
  android:layout_height="match_parent" />
</LinearLayout>

1.4 Code section:

package com.example.mygesture.addgesture;
import android.Manifest;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
import com.example.mygesture.R;
import com.example.mygesture.recognitiongesture.Main4Activity;
public class Main3Activity extends AppCompatActivity {
 GestureOverlayView gov;   // Defining Drawing Components 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main3);
  if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
   ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);  
  }    // Higher versions need to apply for permissions dynamically 
  init();
 }
 private void init() {
  gov = findViewById(R.id.activity_main3_gov);
//  gov.setGestureColor(Color.RED);  // Set the color of drawing 
  gov.setGestureStrokeWidth(4);  // Set the width of the brush 
  gov.addOnGesturePerformedListener(new GestureOverlayView.OnGesturePerformedListener() { // Set drawing completion monitoring 
   @Override
   public void onGesturePerformed(GestureOverlayView overlay, final Gesture gesture) {
    View saveDialog = getLayoutInflater().inflate(R.layout.save_dialog, null); // Get AlertDialog Layout style of 
    final EditText editText = saveDialog.findViewById(R.id.save_dialog_et);
    ImageView imageView = saveDialog.findViewById(R.id.save_dialog_iv);
    Bitmap bitmap = gesture.toBitmap(128, 128, 10, 0xFFFF0000);  // Convert gestures to bitmaps 
    imageView.setImageBitmap(bitmap);   // Use ImageView Load gesture pictures 
    new AlertDialog.Builder(Main3Activity.this).setView(saveDialog).setPositiveButton(" Determine ", new DialogInterface.OnClickListener() {
     @Override
     public void onClick(DialogInterface dialog, int which) {
      GestureLibrary gestureLibrary = GestureLibraries.fromFile("/mnt/sdcard/mygesture");// Using gesture library to obtain the address of storing gesture files 
      gestureLibrary.addGesture(editText.getText().toString(), gesture);  // Add gesture names and gestures to the gesture library 
      gestureLibrary.save();    // Save Gesture Library 
      Toast.makeText(Main3Activity.this, " Save successfully ", Toast.LENGTH_SHORT).show();
     }
    }).setNegativeButton(" Cancel ", null)
      .show();
   }
  });
 }
 public void recognition(View view) {
  Intent intent = new Intent(this, Main4Activity.class);
  startActivity(intent);
 }
}

2. Next, complete the Activity for recognizing gestures:

Write-first layout file like 2.1 1

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
 android:orientation="vertical"
 tools:context=".recognitiongesture.Main4Activity">

 <TextView
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:gravity="center"
  android:text=" Please draw the gesture to be recognized " />

 <android.gesture.GestureOverlayView
  android:id="@+id/activity_main4_gov"
  android:layout_width="match_parent"
  android:layout_height="match_parent"></android.gesture.GestureOverlayView>
</LinearLayout>

2.2 Code writing

package com.example.mygesture.recognitiongesture;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.gesture.Prediction;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import com.example.mygesture.R;
import java.util.ArrayList;
import java.util.logging.Level;
public class Main4Activity extends AppCompatActivity {
 GestureOverlayView gov;
 GestureLibrary gestureLibrary;  // Defining a Gesture Library 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main4);
  init();
 }
 private void init() {
  gestureLibrary = GestureLibraries.fromFile("/mnt/sdcard/mygesture"); // Getting a Gesture File 
  if (gestureLibrary.load()) {   // Judge whether the gesture file exists and load it 
   Toast.makeText(this, " Gesture file loaded successfully ", Toast.LENGTH_SHORT).show();
  } else {
   Toast.makeText(this, " Gesture file failed to load ", Toast.LENGTH_SHORT).show();
  }
  gov = findViewById(R.id.activity_main4_gov);
  gov.addOnGesturePerformedListener(new GestureOverlayView.OnGesturePerformedListener() {
   @Override
   public void onGesturePerformed(GestureOverlayView overlay, Gesture gesture) {
    ArrayList<Prediction> predictions = gestureLibrary.recognize(gesture); // Match all gestures in the gesture library 
    ArrayList<String> result = new ArrayList<>();  // Match result array 
    for (Prediction pred : predictions) {
     if (pred.score > 2) {    // Matches all gestures in the gesture library and sets the similarity >2 Save the matching results array 
      result.add(" Similarity: " + pred.score);
     }
    }
    if (result.size() > 0) {  // The adapter is used here as the AlertDialog To display the similarity of all gestures 
     ArrayAdapter<Object> arrayAdapter = new ArrayAdapter<Object>(Main4Activity.this, android.R.layout.simple_dropdown_item_1line, result.toArray());
     new AlertDialog.Builder(Main4Activity.this).setAdapter(arrayAdapter, null).setPositiveButton(" Determine ", null).show();
    } else {
     Toast.makeText(Main4Activity.this, " No matching gesture was found ", Toast.LENGTH_SHORT).show();
    }
   }
  });
 }
}

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