src/com/android/settings/accessibility/TextReadingPreviewPager.java

/*
 * Copyright (C) 2022 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.settings.accessibility;

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

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.viewpager.widget.ViewPager;

/**
 * The view pager is used for displaying screen preview with different size configuration changes.
 */
public class TextReadingPreviewPager extends ViewPager {

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

    @Override
    public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
        return (nestedScrollAxes & View.SCROLL_AXIS_VERTICAL) != 0;
    }

    @Override
    public void onNestedScrollAccepted(View child, View target, int axes) {
        super.onNestedScrollAccepted(child, target, axes);
        // Allow the nested scrollview inside of the view pager to be scrollable.
        getParent().requestDisallowInterceptTouchEvent(true);
    }

    @Override
    public void onNestedScroll(
            View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
        if (dyUnconsumed != 0) {
            // Assume dyUnconsumed != 0 means the target has been scrolled to the end vertically.
            // We could let the parent to consume the rest of the dyUnconsumed
            getParent().requestDisallowInterceptTouchEvent(false);
        }
        super.onNestedScroll(target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
    }
}