Android 项目必备（四十四）--＞Android 实现悬浮窗

前言

悬浮窗是一种比较常见的需求。例如把视频通话界面缩小成一个悬浮窗，然后用户可以在其他界面上处理事情。

本文将讲解悬浮窗实现步骤、原理、实例代码等

实现原理

1. WindowMananger 接口

Android 的界面绘制，都是通过 WindowMananger 的服务来实现的。那么，既然要实现一个能够在自身应用以外的界面上的悬浮窗，我们就要利用 WindowManager 来实现。

(frameworks/base/core/java/android/view/WindowMananger.java)@SystemService(Context.WINDOW_SERVICE)public interface WindowManager extends ViewManager {...}

WindowManager 实现了 ViewManager 接口，可以通过获取 WINDOW_SERVICE 系统服务得到。而ViewManager 接口有 addView 方法，我们就是通过这个方法将悬浮窗控件加入到屏幕中去。

2. LayoutParam 设置

这里需要着重说明的是 LayoutParam 里的 type 变量。这个变量是用来指定窗口类型的。

if (Build.VERSION.SDK_INT >= Build.VERSioN_CODES.O) {layoutParams.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;} else {    layoutParams.type = WindowManager.LayoutParams.TYPE_PHONE;}

具体实现

实现一个自动轮播图的悬浮窗。

1. 效果图

2. 声明及申请权限

@Requiresapi(api = Build.VERSION_CODES.M)public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        if (requestCode == 1) {            if (!Settings.canDrawOverlays(this)) {                Toast.makeText(this, "授权失败", Toast.LENGTH_SHORT).show();            } else {                Toast.makeText(this, "授权成功", Toast.LENGTH_SHORT).show();                startService(new Intent(MainActivity.this, FloatingImageDisplayService.class));            }        }     }        public void startFloatingImageDisplayService(View view) {        if (FloatingImageDisplayService.isStarted) {            return;        }        if (!Settings.canDrawOverlays(this)) {            Toast.makeText(this, "当前无权限，请授权", Toast.LENGTH_SHORT);            startActivityForResult(new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + getPackageName())), 1);        } else {            startService(new Intent(MainActivity.this, FloatingImageDisplayService.class));        }    }}

3. 构建悬浮窗需要的控件

image_display.xml

4. 将控件添加到WindowManager

@RequiresApi(api = Build.VERSION_CODES.M)public class FloatingImageDisplayService extends Service {    public static boolean isStarted = false;    private WindowManager windowManager;    private WindowManager.LayoutParams layoutParams;    private View displayView;    private int[] images;    private int imageIndex = 0;    private Handler changeImageHandler;    @Override    public void onCreate() {        super.onCreate();        isStarted = true;        windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);        layoutParams = new WindowManager.LayoutParams();        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {            layoutParams.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;        } else {            layoutParams.type = WindowManager.LayoutParams.TYPE_PHONE;        }        layoutParams.fORMat = PixelFormat.RGBA_8888;        layoutParams.gravity = Gravity.LEFT | Gravity.TOP;        layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;        layoutParams.width = 500;        layoutParams.height = 500;        layoutParams.x = 300;        layoutParams.y = 300;        images = new int[] {                R.mipmap.image_01,                R.mipmap.image_02,                R.mipmap.image_03,                R.mipmap.image_04,                R.mipmap.image_05        };        changeImageHandler = new Handler(this.getMainLooper(), changeImageCallback);    }    @Override    public IBinder onBind(Intent intent) {        return null;    }    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        showFloatingWindow();        return super.onStartCommand(intent, flags, startId);    }    private void showFloatingWindow() {        if (Settings.canDrawOverlays(this)) {            LayoutInflater layoutInflater = LayoutInflater.from(this);            displayView = layoutInflater.inflate(R.layout.image_display, null);            displayView.setOnTouchListener(new FloatinGonTouchListener());            ImageView imageView = displayView.findViewById(R.id.image_display_imageview);            imageView.setImageResource(images[imageIndex]);            windowManager.addView(displayView, layoutParams);            changeImageHandler.sendEmptyMessageDelayed(0, 2000);        }    }    private Handler.Callback changeImageCallback = new Handler.Callback() {        @Override        public boolean handleMessage(Message msg) {            if (msg.what == 0) {                imageIndex++;                if (imageIndex >= 5) {                    imageIndex = 0;                }                if (displayView != null) {                    ((ImageView) displayView.findViewById(R.id.image_display_imageview)).setImageResource(images[imageIndex]);                }                changeImageHandler.sendEmptyMessageDelayed(0, 2000);            }            return false;        }    };    private class FloatingOnTouchListener implements View.OnTouchListener {        private int x;        private int y;        @Override        public boolean onTouch(View view, MotionEvent event) {            switch (event.getAction()) {                case MotionEvent.ACTION_DOWN:                    x = (int) event.getRawX();                    y = (int) event.getRawY();                    break;                case MotionEvent.ACTION_MOVE:                    int nowX = (int) event.getRawX();                    int nowY = (int) event.getRawY();                    int movedX = nowX - x;                    int movedY = nowY - y;                    x = nowX;                    y = nowY;                    layoutParams.x = layoutParams.x + movedX;                    layoutParams.y = layoutParams.y + movedY;                    windowManager.updateViewLayout(view, layoutParams);                    break;                default:                    break;            }            return false;        }    }}

来源地址：https://blog.csdn.net/duoduo_11011/article/details/130031272