ViewPager.java

/*
 * Copyright (c) 2015 PocketHub
 *
 * 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.github.pockethub.android.ui;

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

/**
 * {@link ViewPager} extension with support for horizontally scrolling an
 * embedded {@link WebView}
 */
public class ViewPager extends android.support.v4.view.ViewPager {

    /**
     * @param context
     */
    public ViewPager(final Context context) {
        super(context);
    }

    /**
     * @param context
     * @param attrs
     */
    public ViewPager(final Context context, final AttributeSet attrs) {
        super(context, attrs);
    }

    /**
     * Set current item and return whether the item changed
     * <p>
     * This method does not call {@link #setCurrentItem(int)} unless the item
     * parameter differs from the current item
     *
     * @param item
     * @return true if set, false if same
     */
    public boolean setItem(final int item) {
        final boolean changed = item != getCurrentItem();
        if (changed) {
            setCurrentItem(item, false);
        }
        return changed;
    }

    /**
     * Set current item, invoke the listener if changes, and return whether the
     * item changed
     * <p>
     * This method does not call {@link #setCurrentItem(int)} unless the item
     * parameter differs from the current item
     *
     * @param item
     * @param listener
     * @return true if set, false if same
     */
    public boolean setItem(final int item, final OnPageChangeListener listener) {
        final boolean changed = setItem(item);
        if (changed && listener != null) {
            listener.onPageSelected(item);
        }
        return changed;
    }

    /**
     * Schedule a call to {@link #setItem(int)} to occur on the UI-thread
     *
     * @param item
     * @param listener
     */
    public void scheduleSetItem(final int item,
                                final OnPageChangeListener listener) {
        post(() -> setItem(item, listener));
    }

    /**
     * Schedule a call to {@link #setItem(int)} to occur on the UI-thread
     *
     * @param item
     */
    public void scheduleSetItem(final int item) {
        post(() -> setItem(item));
    }

    @Override
    protected boolean canScroll(final View v, final boolean checkV,
                                final int dx, final int x, final int y) {
        return super.canScroll(v, checkV, dx, x, y);
    }
}