car-ui-lib/src/com/android/car/ui/baselayout/ClickBlockingView.java

/*
 * Copyright (C) 2020 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.car.ui.baselayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;

/**
 * A view that doesn't allow any touches to pass through it to views below.
 *
 * <p>Used in baselayouts to prevent clicking through the toolbar.
 */
public class ClickBlockingView extends View {

    private boolean mEatingTouch = false;
    private boolean mEatingHover = false;

    public ClickBlockingView(Context context) {
        super(context);
    }

    public ClickBlockingView(Context context,
            @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public ClickBlockingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public ClickBlockingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr,
            int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        // Copied from androidx.appcompat.widget.Toolbar

        // We always eat touch events, but should still respect the touch event dispatch
        // contract. If the normal View implementation doesn't want the events, we'll just silently
        // eat the rest of the gesture without reporting the events to the default implementation
        // since that's what it expects.

        final int action = ev.getActionMasked();
        if (action == MotionEvent.ACTION_DOWN) {
            mEatingTouch = false;
        }

        if (!mEatingTouch) {
            final boolean handled = super.onTouchEvent(ev);
            if (action == MotionEvent.ACTION_DOWN && !handled) {
                mEatingTouch = true;
            }
        }

        if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
            mEatingTouch = false;
        }

        return true;
    }

    @Override
    public boolean onHoverEvent(MotionEvent ev) {
        // Copied from androidx.appcompat.widget.Toolbar

        // Same deal as onTouchEvent() above. Eat all hover events, but still
        // respect the touch event dispatch contract.

        final int action = ev.getActionMasked();
        if (action == MotionEvent.ACTION_HOVER_ENTER) {
            mEatingHover = false;
        }

        if (!mEatingHover) {
            final boolean handled = super.onHoverEvent(ev);
            if (action == MotionEvent.ACTION_HOVER_ENTER && !handled) {
                mEatingHover = true;
            }
        }

        if (action == MotionEvent.ACTION_HOVER_EXIT || action == MotionEvent.ACTION_CANCEL) {
            mEatingHover = false;
        }

        return true;
    }
}