Add basic AnchoredWindow.

/*

 * Copyright (C) 2017 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.android.server.autofill;

import static com.android.server.autofill.Helper.DEBUG;

import android.content.Context;

import android.graphics.Rect;

import android.util.Slog;

import android.view.Gravity;

import android.view.MotionEvent;

import android.view.View;

import android.view.ViewGroup;

import android.view.WindowManager;

import android.view.WindowManager.LayoutParams;

import android.widget.FrameLayout;

/**

 * A window above the application that is smartly anchored to a rectangular region.

 */

final class AnchoredWindow {

    private static final String TAG = "AutoFill";

    private final WindowManager mWm;

    private final View mRootView;

    private final View mView;

    private final int mWidth;

    private final int mHeight;

    private boolean mIsShowing = false;

    /**

     * Constructor.

     *

     * @param wm window manager that draws the view on a window

     * @param view singleton view in the window

     * @param width requested width of the view

     * @param height requested height of the view

     */

    AnchoredWindow(WindowManager wm, View view, int width, int height) {

        mWm = wm;

        mRootView = wrapView(view, width, height);

        mView = view;

        mWidth = width;

        mHeight = height;

    }

    /**

     * Shows the window.

     *

     * @param bounds the rectangular region this window should be anchored to

     */

    void show(Rect bounds) {

        LayoutParams params = createBaseLayoutParams();

        params.x = bounds.left;

        params.y = bounds.bottom;

        if (!mIsShowing) {

            if (DEBUG) Slog.d(TAG, "adding view " + mView);

            mWm.addView(mRootView, params);

        } else {

            if (DEBUG) Slog.d(TAG, "updating view " + mView);

            mWm.updateViewLayout(mRootView, params);

        }

        mIsShowing = true;

    }

    /**

     * Hides the window.

     */

    void hide() {

        if (DEBUG) Slog.d(TAG, "removing view " + mView);

        if (mIsShowing) {

            mWm.removeView(mRootView);

        }

        mIsShowing = false;

    }

    /**

     * Wraps a view with a SelfRemovingView and sets its requested width and height.

     */

    private View wrapView(View view, int width, int height) {

        ViewGroup viewGroup = new SelfRemovingView(view.getContext());

        viewGroup.addView(view, new ViewGroup.LayoutParams(width, height));

        return viewGroup;

    }

    private static LayoutParams createBaseLayoutParams() {

        LayoutParams params = new LayoutParams();

        // TODO(b/33197203): LayoutParams.TYPE_AUTOFILL

        params.type = LayoutParams.TYPE_SYSTEM_ALERT;

        params.flags =

                LayoutParams.SOFT_INPUT_STATE_UNCHANGED

                | LayoutParams.FLAG_LAYOUT_IN_SCREEN

                | LayoutParams.FLAG_LAYOUT_NO_LIMITS

                | LayoutParams.FLAG_NOT_FOCUSABLE

                | LayoutParams.FLAG_NOT_TOUCH_MODAL

                | LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH;

        params.gravity = Gravity.TOP | Gravity.LEFT;

        params.width = LayoutParams.WRAP_CONTENT;

        params.height = LayoutParams.WRAP_CONTENT;

        return params;

    }

    /** FrameLayout that listens for touch events removes itself if the touch event is outside. */

    private final class SelfRemovingView extends FrameLayout {

        public SelfRemovingView(Context context) {

            super(context);

        }

        @Override

        public boolean onTouchEvent(MotionEvent event) {

            if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {

                hide();

                return true;

            } else {

                return super.onTouchEvent(event);

            }

        }

    }

}