zenghao.com.study.banner4.BannerController.java Source code

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Here is the source code for zenghao.com.study.banner4.BannerController.java

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/* 
 * Copyright (C) 2017.  BoBoMEe(wbwjx115@gmail.com) 
 * 
 * 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 zenghao.com.study.banner4;

import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.MotionEvent;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;

/** 
 * Created on 2017/1/17.?11:04. 
 * 
 * @author bobomee. 
 */

public class BannerController {

    /** 
     * the message.what for scroll 
     */
    private static final int SCROLL_WHAT = 0;
    private BannerConfig confing;
    private ViewPager mViewPager;
    private Handler mHandler;
    private boolean isAutoScroll = false;
    private boolean isStopByTouch = false;
    private int mTotalCount = 0;
    private PageChangeListener mPageChangeListener;

    public BannerController(Context pContext) {
        this.confing = BannerConfig.sConfig(pContext);
        mHandler = new MyHandler(Looper.myLooper(), this);
    }

    public BannerController(BannerConfig pBannerConfig) {
        this.confing = pBannerConfig;
        mHandler = new MyHandler(Looper.myLooper(), this);
    }

    public BannerController viewPager(ViewPager pViewPager) {
        this.mViewPager = pViewPager;
        setViewPagerScroller();
        return this;
    }

    private void addSimpleOnPageChangeListener(ViewPager.SimpleOnPageChangeListener pSimpleOnPageChangeListener) {
        if (null == mPageChangeListener) {
            mPageChangeListener = new PageChangeListener();
        }
        mPageChangeListener.addListener(pSimpleOnPageChangeListener);
    }

    public BannerController pageChangeListener(ViewPager.SimpleOnPageChangeListener pOnPageChangeListener) {
        addSimpleOnPageChangeListener(pOnPageChangeListener);
        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                mPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }

            @Override
            public void onPageSelected(int position) {
                mPageChangeListener.onPageSelected(position);
            }

            @Override
            public void onPageScrollStateChanged(int state) {
                mPageChangeListener.onPageScrollStateChanged(state);
            }
        });
        return this;
    }

    /** 
     * set ViewPager scroller to change animation duration when sliding 
     */
    private void setViewPagerScroller() {
        try {
            Field scrollerField = ViewPager.class.getDeclaredField("mScroller");
            scrollerField.setAccessible(true);

            FixedSpeedScroller lScroller = confing.getScroller();
            setAuto();

            scrollerField.set(mViewPager, lScroller);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /** 
     * change the speed when swipe 
     */
    public void setSwipe() {
        FixedSpeedScroller lFixedSpeedScroller = confing.getScroller();
        lFixedSpeedScroller.setScrollDurationFactor(confing.getSwipeScrollFactor());
    }

    /** 
     * change the speed when auto scroll 
     */
    public void setAuto() {
        FixedSpeedScroller lFixedSpeedScroller = confing.getScroller();
        lFixedSpeedScroller.setScrollDurationFactor(confing.getAutoScrollFactor());
    }

    /** 
     * start auto scroll, first scroll delay time is {@link BannerConfig#getInterval()} 
     */
    public void startAutoScroll() {
        isAutoScroll = true;
        sendScrollMessage(confing.getInterval());
    }

    /** 
     * start auto scroll 
     * 
     * @param delayTimeInMills first scroll delay time 
     */
    public void startAutoScroll(long delayTimeInMills) {
        isAutoScroll = true;
        sendScrollMessage(delayTimeInMills);
    }

    /** 
     * stop auto scroll 
     */
    private void stopAutoScroll() {
        isAutoScroll = false;
        mHandler.removeMessages(SCROLL_WHAT);
    }

    private void sendScrollMessage(long delayTimeInMills) {
        /** remove messages before, keeps one message is running at most **/
        mHandler.removeMessages(SCROLL_WHAT);
        mHandler.sendEmptyMessageDelayed(SCROLL_WHAT, delayTimeInMills);
    }

    /** 
     * scroll only once 
     */
    private void scrollOnce() {
        PagerAdapter adapter = mViewPager.getAdapter();
        if (adapter == null || (mTotalCount = adapter.getCount()) <= 1)
            return;
        int currentItem = mViewPager.getCurrentItem();
        int nextItem = (confing.getDirection() == BannerConfig.LEFT) ? --currentItem : ++currentItem;
        mViewPager.setCurrentItem(nextItem, true);
        sendScrollMessage(confing.getInterval());
    }

    private static class MyHandler extends Handler {

        private final WeakReference<BannerController> mBannerScrollWeakReference;

        public MyHandler(Looper pLooper, BannerController pBannerScroll) {
            super(pLooper);
            this.mBannerScrollWeakReference = new WeakReference<BannerController>(pBannerScroll);
        }

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            switch (msg.what) {
            case SCROLL_WHAT:
                BannerController lBannerScroll = this.mBannerScrollWeakReference.get();
                if (lBannerScroll != null && lBannerScroll.isAutoScroll) {
                    lBannerScroll.scrollOnce();
                }
                break;
            default:
                break;
            }
        }
    }

    /** 
     * <ul> 
     * if stopScrollWhenTouch is true 
     * <li>if event is down, stop auto scroll.</li> 
     * <li>if event is up, start auto scroll again.</li> 
     * </ul> 
     */
    public void dispatchTouchEvent(MotionEvent ev) {

        PagerAdapter adapter = mViewPager.getAdapter();
        if (null != adapter && adapter.getCount() > 0) {
            int action = MotionEventCompat.getActionMasked(ev);

            if (action == MotionEvent.ACTION_DOWN) {
                if (isAutoScroll && confing.isStopScrollWhenTouch()) {
                    isStopByTouch = true;
                    setSwipe();
                    stopAutoScroll();
                }
            } else if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
                if (isStopByTouch && confing.isStopScrollWhenTouch()) {
                    setAuto();
                    startAutoScroll();
                }
            }
        }
    }

    public void onDetachedFromWindow() {
        stopAutoScroll();
    }

    public BannerConfig getConfing() {
        return confing;
    }

    public boolean isLast() {
        if (mTotalCount == 0)
            return true;
        int lCurrentItem = mViewPager.getCurrentItem();
        return lCurrentItem == mTotalCount - 1;
    }

    public boolean isFirst() {
        if (mTotalCount == 0)
            return true;
        int lCurrentItem = mViewPager.getCurrentItem();
        return lCurrentItem == 0;
    }
}