Android 实现页面中自定义悬浮窗页面 磁吸四周工具类

以下是一个基于 Android 的自定义悬浮窗页面磁吸四周工具类的示例代码。

首先，我们需要定义一个 FloatingView 类，它继承自 FrameLayout，并实现了 View.OnTouchListener 接口。这个类表示悬浮窗页面，可以包含任意的子 View。

public class FloatingView extends FrameLayout implements View.OnTouchListener {

    private int mLastX;
    private int mLastY;
    private int mStartX;
    private int mStartY;
    private int mScreenWidth;
    private int mScreenHeight;

    public FloatingView(Context context) {
        this(context, null);
    }

    public FloatingView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public FloatingView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        setOnTouchListener(this);
        mScreenWidth = getResources().getDisplayMetrics().widthPixels;
        mScreenHeight = getResources().getDisplayMetrics().heightPixels;
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mStartX = (int) event.getRawX();
                mStartY = (int) event.getRawY();
                mLastX = mStartX;
                mLastY = mStartY;
                break;
            case MotionEvent.ACTION_MOVE:
                int dx = (int) (event.getRawX() - mLastX);
                int dy = (int) (event.getRawY() - mLastY);
                int x = getX() + dx;
                int y = getY() + dy;
                if (x < 0) {
                    x = 0;
                }
                if (x > mScreenWidth - getWidth()) {
                    x = mScreenWidth - getWidth();
                }
                if (y < 0) {
                    y = 0;
                }
                if (y > mScreenHeight - getHeight()) {
                    y = mScreenHeight - getHeight();
                }
                setX(x);
                setY(y);
                mLastX = (int) event.getRawX();
                mLastY = (int) event.getRawY();
                break;
            case MotionEvent.ACTION_UP:
                if (Math.abs(event.getRawX() - mStartX) < 5 && Math.abs(event.getRawY() - mStartY) < 5) {
                    performClick();
                }
                break;
        }
        return true;
    }
}

接下来，我们编写一个辅助类，用于将悬浮窗页面磁吸到屏幕的四周。该类需要维护一个 FloatingView 对象，以及一些悬浮窗的位置信息。

public class FloatingViewHelper {

    private static final int MARGIN = 10;

    private FloatingView mFloatingView;
    private int mScreenWidth;
    private int mScreenHeight;
    private int mLeft;
    private int mTop;
    private int mRight;
    private int mBottom;

    public FloatingViewHelper(Context context, FloatingView floatingView) {
        mFloatingView = floatingView;
        mScreenWidth = context.getResources().getDisplayMetrics().widthPixels;
        mScreenHeight = context.getResources().getDisplayMetrics().heightPixels;
    }

    public void attachToWindow() {
        WindowManager.LayoutParams params = new WindowManager.LayoutParams();
        params.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
        params.format = PixelFormat.RGBA_8888;
        params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
        params.gravity = Gravity.TOP | Gravity.LEFT;
        params.width = WindowManager.LayoutParams.WRAP_CONTENT;
        params.height = WindowManager.LayoutParams.WRAP_CONTENT;
        mFloatingView.setLayoutParams(params);
        mFloatingView.setOnTouchListener(mFloatingView);
        WindowManager wm = (WindowManager) mFloatingView.getContext().getSystemService(Context.WINDOW_SERVICE);
        wm.addView(mFloatingView, params);
    }

    public void detachFromWindow() {
        WindowManager wm = (WindowManager) mFloatingView.getContext().getSystemService(Context.WINDOW_SERVICE);
        wm.removeView(mFloatingView);
    }

    public void snapToEdge() {
        int centerX = (mLeft + mRight) / 2;
        int centerY = (mTop + mBottom) / 2;
        if (centerX < mScreenWidth / 2) {
            mFloatingView.setX(0 + MARGIN);
            mLeft = 0;
            mRight = mLeft + mFloatingView.getWidth();
        } else {
            mFloatingView.setX(mScreenWidth - mFloatingView.getWidth() - MARGIN);
            mRight = mScreenWidth;
            mLeft = mRight - mFloatingView.getWidth();
        }
        if (centerY < mScreenHeight / 2) {
            mFloatingView.setY(0 + MARGIN);
            mTop = 0;
            mBottom = mTop + mFloatingView.getHeight();
        } else {
            mFloatingView.setY(mScreenHeight - mFloatingView.getHeight() - MARGIN);
            mBottom = mScreenHeight;
            mTop = mBottom - mFloatingView.getHeight();
        }
    }

    public void updatePosition() {
        mLeft = (int) mFloatingView.getX();
        mTop = (int) mFloatingView.getY();
        mRight = mLeft + mFloatingView.getWidth();
        mBottom = mTop + mFloatingView.getHeight();
    }
}

最后，我们可以在 Activity 中使用这个辅助类来实现悬浮窗的磁吸效果。

public class MainActivity extends AppCompatActivity {

    private FloatingView mFloatingView;
    private FloatingViewHelper mFloatingViewHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mFloatingView = new FloatingView(this);
        mFloatingView.setBackgroundColor(Color.YELLOW);

        mFloatingViewHelper = new FloatingViewHelper(this, mFloatingView);
        mFloatingViewHelper.attachToWindow();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mFloatingViewHelper.detachFromWindow();
    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if (hasFocus) {
            mFloatingViewHelper.snapToEdge();
            mFloatingViewHelper.updatePosition();
        }
    }
}

这里，我们在 onCreate 方法中创建了一个 FloatingView 对象，并将其添加到 Activity 的界面中。然后，我们创建了一个 FloatingViewHelper 对象，将其附加到 FloatingView 上，并将其添加到 WindowManager 中显示。在 onDestroy 方法中，我们从 WindowManager 中移除了 FloatingView。

在 onWindowFocusChanged 方法中，我们在 Activity 获取焦点时调用了 snapToEdge 方法，将 FloatingView 磁吸到屏幕的四周。我们还调用了 updatePosition 方法，更新了悬浮窗的位置信息。这样，我们就实现了一个简单的悬浮窗页面磁吸四周工具类。