package com.example.floatingbutton;
 
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.*;
import android.graphics.PixelFormat;
import android.net.Uri;
import android.os.Build;
import android.os.IBinder;
import android.provider.Settings;
import android.view.*;
import android.widget.ImageView;
import android.widget.Toast;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import androidx.core.app.NotificationCompat;
 
/**
 * MainActivity：用于申請權限并啟動/停止 FloatingService
 */
public class MainActivity extends AppCompatActivity {
 
    private static final int REQ_OVERLAY = 1000;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
		// 啟動懸浮按鈕
        findViewById(R.id.btn_start).setOnClickListener(v -> {
            if (Settings.canDrawOverlays(this)) {
                startService(new Intent(this, FloatingService.class));
                finish(); // 可選：關閉 Activity，懸浮按鈕仍會顯示
            } else {
                // 請求懸浮窗權限
                Intent intent = new Intent(
                  Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
                  Uri.parse("package:" + getPackageName()));
                startActivityForResult(intent, REQ_OVERLAY);
            }
        });
 
		// 停止懸浮按鈕
        findViewById(R.id.btn_stop).setOnClickListener(v -> {
            stopService(new Intent(this, FloatingService.class));
        });
    }
 
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQ_OVERLAY) {
            if (Settings.canDrawOverlays(this)) {
                startService(new Intent(this, FloatingService.class));
            } else {
                Toast.makeText(this, "未授予懸浮窗權限", Toast.LENGTH_SHORT).show();
            }
        }
    }
}
 
/**
 * FloatingService：前臺 Service，添加可拖拽懸浮按鈕
 */
public class FloatingService extends Service {
 
    private WindowManager windowManager;
    private View floatView;
    private WindowManager.LayoutParams params;
 
    @Override
    public void onCreate() {
        super.onCreate();
        // 1. 創(chuàng)建前臺通知
        String channelId = createNotificationChannel();
        Notification notification = new NotificationCompat.Builder(this, channelId)
            .setContentTitle("Floating Button")
            .setContentText("懸浮按鈕已啟動")
            .setSmallIcon(R.drawable.ic_floating)
            .setOngoing(true)
            .build();
        startForeground(1, notification);
 
        // 2. 初始化 WindowManager 與 LayoutParams
        windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
        params = new WindowManager.LayoutParams();
        params.width  = WindowManager.LayoutParams.WRAP_CONTENT;
        params.height = WindowManager.LayoutParams.WRAP_CONTENT;
        params.format = PixelFormat.TRANSLUCENT;
        params.flags  = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                      | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
        // 不同 SDK 對懸浮類型的支持
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            params.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
        } else {
            params.type = WindowManager.LayoutParams.TYPE_PHONE;
        }
        // 默認初始位置
        params.gravity = Gravity.TOP | Gravity.START;
        params.x = 100;
        params.y = 300;
 
        // 3. 載入自定義布局
        floatView = LayoutInflater.from(this)
                      .inflate(R.layout.floating_view, null);
        ImageView iv = floatView.findViewById(R.id.iv_float);
        iv.setOnTouchListener(new FloatingOnTouchListener());
 
        // 4. 添加到窗口
        windowManager.addView(floatView, params);
    }
 
    // 前臺通知 Channel
    private String createNotificationChannel() {
        String channelId = "floating_service";
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel chan = new NotificationChannel(
                channelId, "懸浮按鈕服務",
                NotificationManager.IMPORTANCE_NONE);
            ((NotificationManager)getSystemService(NOTIFICATION_SERVICE))
                .createNotificationChannel(chan);
        }
        return channelId;
    }
 
    @Override
    public void onDestroy() {
        super.onDestroy();
        if (floatView != null) {
            windowManager.removeView(floatView);
            floatView = null;
        }
    }
 
    @Nullable @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
 
    /**
     * 觸摸監(jiān)聽：支持拖拽與點擊
     */
    private class FloatingOnTouchListener implements View.OnTouchListener {
        private int initialX, initialY;
        private float initialTouchX, initialTouchY;
        private long touchStartTime;
 
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    // 記錄按下時數(shù)據(jù)
                    initialX = params.x;
                    initialY = params.y;
                    initialTouchX = event.getRawX();
                    initialTouchY = event.getRawY();
                    touchStartTime = System.currentTimeMillis();
                    return true;
                case MotionEvent.ACTION_MOVE:
                    // 更新懸浮位置
                    params.x = initialX + (int)(event.getRawX() - initialTouchX);
                    params.y = initialY + (int)(event.getRawY() - initialTouchY);
                    windowManager.updateViewLayout(floatView, params);
                    return true;
                case MotionEvent.ACTION_UP:
                    long clickDuration = System.currentTimeMillis() - touchStartTime;
                    // 如果按下和抬起位置變化不大且時間短，則視為點擊
                    if (clickDuration < 200 
                        && Math.hypot(event.getRawX() - initialTouchX,
                                      event.getRawY() - initialTouchY) < 10) {
                        Toast.makeText(FloatingService.this,
                            "懸浮按鈕被點擊！", Toast.LENGTH_SHORT).show();
                        // 這里可啟動 Activity 或其他操作
                    }
                    return true;
            }
            return false;
        }
    }
}

<!-- ===================================================================
     AndroidManifest.xml — 入口、權限與 Service 聲明
=================================================================== -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.floatingbutton">
    <!-- 懸浮窗權限 -->
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
    <application ...>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- 聲明 Service -->
        <service android:name=".FloatingService"
                 android:exported="false"/>
    </application>
</manifest>

<!-- ===================================================================
     activity_main.xml — 包含啟動/停止按鈕
=================================================================== -->
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout_root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    android:padding="24dp">
 
    <Button
        android:id="@+id/btn_start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="啟動懸浮按鈕"/>
 
    <Button
        android:id="@+id/btn_stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="停止懸浮按鈕"
        android:layout_marginTop="16dp"/>
</LinearLayout>

<!-- ===================================================================
     floating_view.xml — 懸浮按鈕布局
=================================================================== -->
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="48dp"
    android:layout_height="48dp">
 
    <ImageView
        android:id="@+id/iv_float"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/ic_float"
        android:background="@drawable/float_bg"
        android:padding="8dp"/>
</FrameLayout>

<!-- ===================================================================
     float_bg.xml — 按鈕背景（圓形 + 陰影）
=================================================================== -->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="#FFFFFF"/>
    <size android:width="48dp" android:height="48dp"/>
    <corners android:radius="24dp"/>
    <padding android:all="4dp"/>
    <stroke android:width="1dp" android:color="#CCCCCC"/>
    <!-- 陰影需在代碼中或 ShadowLayer 中設置 -->
</shape>