br.com.cybereagle.androidwidgets.view.PagerContainer.java Source code

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Here is the source code for br.com.cybereagle.androidwidgets.view.PagerContainer.java

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/*
 * Copyright 2013 Cyber Eagle
 *
 *    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.
 *
 * Copyright (c) 2012 Wireless Designs, LLC
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package br.com.cybereagle.androidwidgets.view;

import android.content.Context;
import android.graphics.Point;
import android.os.Build;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
import br.com.cybereagle.androidwidgets.util.ViewUtils;

/**
 * PagerContainer: A layout that displays a ViewPager with its children that are outside
 * the typical pager bounds.
 *
 * To use this, wrap your ViewPager with it, set the ViewPager's width to be equal the width
 * of its child, set the ViewPager's gravity to center and make this PagerContainer larger
 * than the ViewPager. You should also set the offscreenPageLimit of the ViewPager in a way
 * that it prepares more children that is really show, so that it loads the children before
 * you reach the last children, that gives a poor effect.
 *
 */
public class PagerContainer extends FrameLayout implements ViewPager.OnPageChangeListener {

    protected ViewPager pager;
    boolean needsRedraw = false;

    protected Point center = new Point();
    protected Point initialTouch = new Point();

    public PagerContainer(Context context) {
        super(context);
        init();
    }

    public PagerContainer(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public PagerContainer(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init() {
        //Disable clipping of children so non-selected pages are visible
        setClipChildren(false);

        //Child clipping doesn't work with hardware acceleration in Android 3.x/4.x
        //You need to set this value here if using hardware acceleration in an
        // application targeted at these releases.
        ViewUtils.enableSoftwareLayer(this);
    }

    @Override
    protected void onFinishInflate() {
        try {
            pager = (ViewPager) getChildAt(0);
            pager.setOnPageChangeListener(this);
            //If hardware acceleration is enabled, you should also remove
            // clipping on the pager for its children.
            pager.setClipChildren(false);
        } catch (Exception e) {
            throw new IllegalStateException("The root child of PagerContainer must be a ViewPager");
        }
    }

    public ViewPager getViewPager() {
        return pager;
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        center.x = w / 2;
        center.y = h / 2;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        //We capture any touches not already handled by the ViewPager
        // to implement scrolling from a touch outside the pager bounds.
        switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN:
            initialTouch.x = (int) ev.getX();
            initialTouch.y = (int) ev.getY();
        default:
            ev.offsetLocation(center.x - initialTouch.x, center.y - initialTouch.y);
            break;
        }

        return pager.dispatchTouchEvent(ev);
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        //Force the container to redraw on scrolling.
        //Without this the outer pages render initially and then stay static
        if (needsRedraw)
            invalidate();
    }

    @Override
    public void onPageSelected(int position) {
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        needsRedraw = (state != ViewPager.SCROLL_STATE_IDLE);
    }
}