Floating widget like facebook chat

1. giới thiệu

• Floating widget là view được vẽ trên các ứng dụng khác, vì thế ứng dụng cần permission android.permission.SYSTEM_ALERT_WINDOW. Ta sẽ dùng background service để thêm floating widget vào hierarchy của màn hình hiện tại, vì thế floating widget sẽ luôn ở trên các ứng dụng khác.
• Để có thể drag floating widget ta sẽ override phương thức onTouchListener để lắng nghe sự kiện drag

2. Tạo Project

• thêm permission vào file Manifest.xml

Manifest.xml
...
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
...

• Tạo layout layout_floating_widget.xml cho floating view. Layout này sẽ chứa 2 main layout.

Collapsed view: floating view sẽ hiển thị dưới dạng một button tròn khi chạy, sau khi người dùng click vào sẽ hiển thị dưới dạng expanded view

Expanded View:

view này sẽ chứa button play music, next, previous và open application

layout_floating_widget.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_awidth="wrap_content"
    android:layout_height="wrap_content">
 
     
    <RelativeLayout
        android:id="@+id/root_container"
        android:layout_awidth="wrap_content"
        android:layout_height="wrap_content"
        tools:ignore="UselessParent">
 
         
        <RelativeLayout
            android:id="@+id/collapse_view"
            android:layout_awidth="wrap_content"
            android:visibility="visible"
            android:layout_height="wrap_content"
            android:orientation="vertical">
 
             
            <ImageView
                android:id="@+id/collapsed_iv"
                android:layout_awidth="60dp"
                android:layout_height="60dp"
                android:layout_marginTop="8dp"
                android:src="@drawable/ic_android_circle"
                tools:ignore="ContentDescription"/>
 
             
            <ImageView
                android:id="@+id/close_btn"
                android:layout_awidth="20dp"
                android:layout_height="20dp"
                android:layout_marginLeft="40dp"
                android:src="@drawable/ic_close"
                tools:ignore="ContentDescription"/>
        </RelativeLayout>
 
         
        <LinearLayout
            android:id="@+id/expanded_container"
            android:layout_awidth="wrap_content"
            android:layout_height="wrap_content"
            android:background="#F8BBD0"
            android:visibility="gone"
            android:orientation="horizontal"
            android:padding="8dp">
 
             
            <ImageView
                android:layout_awidth="80dp"
                android:layout_height="80dp"
                android:src="@drawable/music_player"
                tools:ignore="ContentDescription"/>
 
             
            <ImageView
                android:id="@+id/prev_btn"
                android:layout_awidth="30dp"
                android:layout_height="30dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="20dp"
                android:src="@mipmap/ic_previous"
                tools:ignore="ContentDescription"/>
 
             
            <ImageView
                android:id="@+id/play_btn"
                android:layout_awidth="50dp"
                android:layout_height="50dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:src="@mipmap/ic_play"
                tools:ignore="ContentDescription"/>
 
             
            <ImageView
                android:id="@+id/next_btn"
                android:layout_awidth="30dp"
                android:layout_height="30dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:src="@mipmap/ic_play_next"
                tools:ignore="ContentDescription"/>
 
            <RelativeLayout
                android:layout_awidth="wrap_content"
                android:layout_height="match_parent"
                android:orientation="vertical">
 
                <ImageView
                    android:id="@+id/close_button"
                    android:layout_awidth="20dp"
                    android:layout_height="20dp"
                    android:src="@drawable/ic_close"/>
 
                <ImageView
                    android:id="@+id/open_button"
                    android:layout_awidth="20dp"
                    android:layout_height="20dp"
                    android:layout_alignParentBottom="true"
                    android:src="@drawable/ic_open"/>
            </RelativeLayout>
        </LinearLayout>
    </RelativeLayout>
</FrameLayout>

2.1 Thêm floating widget và xử lý drag

chúng ta sẽ tạo service FloatingViewService.java. Bất cứ khi nào ta muốn hiển thị floating view ta sẽ start service.

FloatingViewService.java
public class FloatingViewService extends Service {
   private WindowManager mWindowManager;
   private View mFloatingView;
 
   public FloatingViewService() {
   }
 
   @Override
   public IBinder onBind(Intent intent) {
       return null;
   }
 
   @Override
   public void onCreate() {
       super.onCreate();
       //Inflate the floating view layout we created
       mFloatingView = LayoutInflater.from(this).inflate(R.layout.layout_floating_widget, null);
 
       //Add the view to the window.
       final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
               WindowManager.LayoutParams.WRAP_CONTENT,
               WindowManager.LayoutParams.WRAP_CONTENT,
               WindowManager.LayoutParams.TYPE_PHONE,
               WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
               PixelFormat.TRANSLUCENT);
 
       //Specify the view position
       params.gravity = Gravity.TOP | Gravity.LEFT;        //Initially view will be added to top-left corner
       params.x = 0;
       params.y = 100;
 
       //Add the view to the window
       mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
       mWindowManager.addView(mFloatingView, params);
 
       //….
       //….
   }
 
 
   @Override
   public void onDestroy() {
       super.onDestroy();
       if (mFloatingView != null) mWindowManager.removeView(mFloatingView);
   }
}

Tiếp theo ta sẽ xử lý các function play, pause, open, close application

FloatingViewService.java
//The root element of the collapsed view layout
final View collapsedView = mFloatingView.findViewById(R.id.collapse_view);
//The root element of the expanded view layout
final View expandedView = mFloatingView.findViewById(R.id.expanded_container);
 
 
//Set the close button
ImageView closeButtonCollapsed = (ImageView) mFloatingView.findViewById(R.id.close_btn);
closeButtonCollapsed.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
       //close the service and remove the from from the window
       stopSelf();
   }
});
 
 
//Set the view while floating view is expanded.
//Set the play button.
ImageView playButton = (ImageView) mFloatingView.findViewById(R.id.play_btn);
playButton.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
       Toast.makeText(FloatingViewService.this, "Playing the song.", Toast.LENGTH_LONG).show();
   }
});
 
 
//Set the next button.
ImageView nextButton = (ImageView) mFloatingView.findViewById(R.id.next_btn);
nextButton.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
       Toast.makeText(FloatingViewService.this, "Playing next song.", Toast.LENGTH_LONG).show();
   }
});
 
 
//Set the pause button.
ImageView prevButton = (ImageView) mFloatingView.findViewById(R.id.prev_btn);
prevButton.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
       Toast.makeText(FloatingViewService.this, "Playing previous song.", Toast.LENGTH_LONG).show();
   }
});
 
 
//Set the close button
ImageView closeButton = (ImageView) mFloatingView.findViewById(R.id.close_button);
closeButton.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
       collapsedView.setVisibility(View.VISIBLE);
       expandedView.setVisibility(View.GONE);
   }
});
 
 
//Open the application on thi button click
ImageView openButton = (ImageView) mFloatingView.findViewById(R.id.open_button);
openButton.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
       //Open the application  click.
       Intent intent = new Intent(FloatingViewService.this, MainActivity.class);
       intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
       startActivity(intent);
 
 
       //close the service and remove view from the view hierarchy
       stopSelf();
   }
});

Tiếp theo ta sẽ xử lý phần drag event

FloatingViewService.java
//Drag and move floating view using user's touch action.
mFloatingView.findViewById(R.id.root_container).setOnTouchListener(new View.OnTouchListener() {
   private int initialX;
   private int initialY;
   private float initialTouchX;
   private float initialTouchY;
 
 
   @Override
   public boolean onTouch(View v, MotionEvent event) {
       switch (event.getAction()) {
           case MotionEvent.ACTION_DOWN:
 
 
               //remember the initial position.
               initialX = params.x;
               initialY = params.y;
 
 
               //get the touch location
               initialTouchX = event.getRawX();
               initialTouchY = event.getRawY();
               return true;
           case MotionEvent.ACTION_MOVE:
               //Calculate the X and Y coordinates of the view.
               params.x = initialX + (int) (event.getRawX() - initialTouchX);
               params.y = initialY + (int) (event.getRawY() - initialTouchY);
 
 
               //Update the layout with new X & Y coordinate
               mWindowManager.updateViewLayout(mFloatingView, params);
               return true;
       }
       return false;
   }
});

2.2 Xử lý collapsing/expanding

FloatingViewService.java
case MotionEvent.ACTION_UP:
   int Xdiff = (int) (event.getRawX() - initialTouchX);
   int Ydiff = (int) (event.getRawY() - initialTouchY);
 
 
   //The check for Xdiff <10 && YDiff< 10 because sometime elements moves a little while clicking.
   //So that is click event.
   if (Xdiff < 10 && Ydiff < 10) {
       if (isViewCollapsed()) {
           //When user clicks on the image view of the collapsed layout,
           //visibility of the collapsed layout will be changed to "View.GONE"
           //and expanded view will become visible.
           collapsedView.setVisibility(View.GONE);
           expandedView.setVisibility(View.VISIBLE);
       }
   }
   return true;

2.3 Xử lý permission

với android version <= API22 permission sẽ được thêm trong manifest.xml, tuy nhiên với android version > api22 ta cần phải check permission trên khi runtime nếu permission chưa có ta cần yêu cầu người dùng cho phép permission bằng việc dùng intent action Settings.ACTION_MANAGE_OVERLAY_PERMISSION

import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;
 
 
public class MainActivity extends AppCompatActivity {
   private static final int CODE_DRAW_OVER_OTHER_APP_PERMISSION = 2084;
 
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
 
       //Check if the application has draw over other apps permission or not?
       //This permission is by default available for API<23. But for API > 23
       //you have to ask for the permission in runtime.
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !Settings.canDrawOverlays(this)) {
 
 
           //If the draw over permission is not available open the settings screen
           //to grant the permission.
           Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
                   Uri.parse("package:" + getPackageName()));
           startActivityForResult(intent, CODE_DRAW_OVER_OTHER_APP_PERMISSION);
       } else {
           initializeView();
       }
   }
 
   /**
    * Set and initialize the view elements.
    */
   private void initializeView() {
       findViewById(R.id.notify_me).setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View view) {
               startService(new Intent(MainActivity.this, FloatingViewService.class));
               finish();
           }
       });
   }
 
   @Override
   protected void onActivityResult(int requestCode, int resultCode, Intent data) {
       if (requestCode == CODE_DRAW_OVER_OTHER_APP_PERMISSION) {
           //Check if the permission is granted or not.
           if (resultCode == RESULT_OK) {
               initializeView();
           } else { //Permission is not available
               Toast.makeText(this,
                       "Draw over other app permission not available. Closing the application",
                       Toast.LENGTH_SHORT).show();
 
               finish();
           }
       } else {
           super.onActivityResult(requestCode, resultCode, data);
       }
   }
}

source code