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Creating a System Overlay (Always on Top over all Apps) in Android
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="de.mobilej.overlay"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="14" />
<application android:label="SystemOverlay" >
<activity
android:name="de.mobilej.overlay.Main"
android:exported="true" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:name="de.mobilej.overlay.OverlayShowingService"
android:exported="false" />
</application>
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
</manifest>
package de.mobilej.overlay;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class Main extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent svc = new Intent(this, OverlayShowingService.class);
startService(svc);
finish();
}
}
package de.mobilej.overlay;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;
import android.widget.Button;
import android.widget.Toast;
public class OverlayShowingService extends Service implements OnTouchListener, OnClickListener {
private View topLeftView;
private Button overlayedButton;
private float offsetX;
private float offsetY;
private int originalXPos;
private int originalYPos;
private boolean moving;
private WindowManager wm;
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
overlayedButton = new Button(this);
overlayedButton.setText("Overlay button");
overlayedButton.setOnTouchListener(this);
overlayedButton.setAlpha(0.0f);
overlayedButton.setBackgroundColor(0x55fe4444);
overlayedButton.setOnClickListener(this);
WindowManager.LayoutParams params = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.TYPE_SYSTEM_ALERT, WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL, PixelFormat.TRANSLUCENT);
params.gravity = Gravity.LEFT | Gravity.TOP;
params.x = 0;
params.y = 0;
wm.addView(overlayedButton, params);
topLeftView = new View(this);
WindowManager.LayoutParams topLeftParams = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.TYPE_SYSTEM_ALERT, WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL, PixelFormat.TRANSLUCENT);
topLeftParams.gravity = Gravity.LEFT | Gravity.TOP;
topLeftParams.x = 0;
topLeftParams.y = 0;
topLeftParams.width = 0;
topLeftParams.height = 0;
wm.addView(topLeftView, topLeftParams);
}
@Override
public void onDestroy() {
super.onDestroy();
if (overlayedButton != null) {
wm.removeView(overlayedButton);
wm.removeView(topLeftView);
overlayedButton = null;
topLeftView = null;
}
}
@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
float x = event.getRawX();
float y = event.getRawY();
moving = false;
int[] location = new int[2];
overlayedButton.getLocationOnScreen(location);
originalXPos = location[0];
originalYPos = location[1];
offsetX = originalXPos - x;
offsetY = originalYPos - y;
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
int[] topLeftLocationOnScreen = new int[2];
topLeftView.getLocationOnScreen(topLeftLocationOnScreen);
System.out.println("topLeftY="+topLeftLocationOnScreen[1]);
System.out.println("originalY="+originalYPos);
float x = event.getRawX();
float y = event.getRawY();
WindowManager.LayoutParams params = (LayoutParams) overlayedButton.getLayoutParams();
int newX = (int) (offsetX + x);
int newY = (int) (offsetY + y);
if (Math.abs(newX - originalXPos) < 1 && Math.abs(newY - originalYPos) < 1 && !moving) {
return false;
}
params.x = newX - (topLeftLocationOnScreen[0]);
params.y = newY - (topLeftLocationOnScreen[1]);
wm.updateViewLayout(overlayedButton, params);
moving = true;
} else if (event.getAction() == MotionEvent.ACTION_UP) {
if (moving) {
return true;
}
}
return false;
}
@Override
public void onClick(View v) {
Toast.makeText(this, "Overlay button click event", Toast.LENGTH_SHORT).show();
}
}
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