/**
 * 描述:自動翻頁ViewPager
 * 作者：FrankChoo
 */
public class AutoSlideViewPager extends FrameLayout {
    private ViewPager mViewPager;
    private AutoSlideViewPagerAdapter mAdapter;
    private List<ImageView> mImageViewList = new ArrayList<>();//放圖片的list
    private List<ImageView> mDotViewList = new
 
 ArrayList<>();//放圓點的View的list

    private boolean mIsAutoPlay = true;//是否開啟自動輪播
    private int mAutoSlideTime = 5000;//自動翻頁時間(單位mm)
    private int mDotSize = 50;//小圓點的大小, 預設是50
    private int mImageCount = 0;//圖片的數量
    private int mCurrentItem  = 0;//ViewPager的當前頁
    private Context mContext;
    private Timer mTiemr = new
 
 Timer();//定時任務
    private TimerTask mTimerTask = new TimerTask() {
        @Override
        public void run() {
            post(new Runnable() {//post到主執行緒處理頁面切換
                @Override
                public void run() {
                    if (mIsAutoPlay) {//判斷當前狀態是否允許自動滑動
                        mCurrentItem = (mCurrentItem + 1
 
) % mImageCount;
                        mViewPager.setCurrentItem(mCurrentItem);
                    }
                }
            });
        }
    };
    private OnImageClickListener mListener;//圖片點選監聽器介面

    public AutoSlideViewPager(Context context) {
        this(context, null);
        mContext = context;
    }
    public AutoSlideViewPager(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
        mContext = context;
    }
    public AutoSlideViewPager(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mContext = context;
    }

    /**
     * 設定小圓點的大小
     */
    public void setDotSize(int size) {
        mDotSize = size;
    }

    /**
     * 設定自動滑動時間間隔
     */
    public void setAutoSlideTime(int time) {
        mAutoSlideTime = time;
    }

    /**
     * 新增要迴圈的圖片
     */
    public void setImageUriList(List<?> imageUriList){
        mImageCount = imageUriList.size();
        for ( int i = 0; i < mImageCount ; i++) {
            addImageToList(i, imageUriList.get(i));
        }
    }

    /**
     * 設定圖片點選監聽器
     */
    public void setOnImageClickListener(OnImageClickListener listener) {
        mListener = listener;
    }
    public interface OnImageClickListener {
        void onClick(int position);//介面的抽象方法根據需要自行修改
    }

    @Override
    protected void onAttachedToWindow() {
        refreshUI();
        super.onAttachedToWindow();
    }

    /**重新整理當前自定義View*/
    private void refreshUI() {
        removeAllViews();
        //新增ViewPager到該ViewGroup
        mViewPager = new ViewPager(mContext);
        mViewPager.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
        mViewPager.setFocusable(true);
        mAdapter = new AutoSlideViewPagerAdapter(mImageViewList);
        mViewPager.setAdapter(mAdapter);
        mViewPager.addOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }

            @Override
            public void onPageSelected(int position) {
                mCurrentItem = position;
                for(int i = 0; i < mImageCount; i++){
                    if(i == position){
                        mDotViewList.get(i).setImageResource(R.drawable.ic_dot_selected);
                    }else {
                        mDotViewList.get(i).setImageResource(R.drawable.ic_dot_unselected);
                    }
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {
                Log.e("AutoSlideViewPager", "正在滑動");
                switch (state) {
                    //手指拖拽ViewPager時的狀態
                    case 1: {
                        mIsAutoPlay = false;//當手指拖拽ViewPager時進位制自動翻頁
                        break;
                    }
                    //介面切換中
                    case 2: {
                        mIsAutoPlay = true;
                        break;
                    }

                    //滑動結束
                    case 0: {
                        mIsAutoPlay = true;
                        break;
                    }
                }
            }

        });
        addView(mViewPager);

        //新增小圓點到該ViewGroup
        for ( int i =0; i < mImageCount ; i++) {
            addView(mDotViewList.get(i));
        }

        //開啟定時任務
        mTiemr.schedule(mTimerTask, mAutoSlideTime, mAutoSlideTime);
    }

    /**新增ImageView到該ViewGroup*/
    private void addImageToList(final int position, Object uri) {
        //將ImageView新增到List
        ImageView imageView =  new ImageView(mContext);
        imageView.setScaleType(ScaleType.FIT_XY);
        imageView.setImageResource(R.mipmap.image_default);//圖片佔位符
        Glide.with(mContext).load(uri).into(imageView);
        imageView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                mListener.onClick(position);
            }
        });
        mImageViewList.add(imageView);

        //將小圓點新增進List
        ImageView dotView = new ImageView(mContext);
        dotView.setLayoutParams(new ViewGroup.LayoutParams(mDotSize, mDotSize));
        dotView.setImageResource( position == 0 ? (R.drawable.ic_dot_selected) : (R.drawable.ic_dot_unselected));
        mDotViewList.add(dotView);
    }

    /**
     * ViewPager介面卡
     * 非靜態內部類會持有對外部類的引用, 可能會造成記憶體洩漏, 所以最好加上static
     */
    private static class AutoSlideViewPagerAdapter extends PagerAdapter {

        private List<ImageView> children = new ArrayList<>();

        AutoSlideViewPagerAdapter(List<ImageView> children) {
            this.children = children;
        }

        /**獲取子級佈局的數量*/
        @Override
        public int getCount() {
            return children.size();
        }

        /**判斷某個View物件是否為當前被新增到ViewPager容器中的物件*/
        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

        /**例項化ViewPager容器中指定的position位置需要顯示的View物件*/
        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            View view = children.get(position);
            container.addView(view);
            return view;
        }

        /**在ViewPager中移除指定的positon位置的view物件*/
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            View view = children.get(position);
            container.removeView(view);
        }
    }


    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        Log.e("AutoSlideViewPager", "onLayout");
        super.onLayout(changed, left, top, right, bottom);
        int childCount = getChildCount();
        if (childCount != 0) {
            for (int i = 0; i < getChildCount(); i++) {
                View childView = getChildAt(i);
                if (childView instanceof ImageView) {
                    int spacing = mDotSize;
                    int width = mDotSize;
                    int start;
                    if (mImageCount % 2 == 1) {//小白點的數量為奇數時的起點
                        start =  (right - left) / 2 - width/2 - (mImageCount/2) * 2 * spacing;
                    } else {//小白點的數量為偶數時的起點
                        start = (right - left)/2 - width/2 - (mImageCount -1) * spacing;
                    }
                    int mLeft =  start + (i-1) * (2*spacing);
                    int mTop = bottom - (bottom - top)/10;
                    int mRight = mLeft + mDotSize;
                    int mBottom = mTop + mDotSize;
                    childView.layout(mLeft, mTop, mRight, mBottom);

                } else {
                    childView.layout(0, 0, right, bottom);
                }
            }
        }
    }

    /**終止mTiemr定時任務, 防止記憶體洩漏*/
    @Override
    protected void onDetachedFromWindow() {
        mTimerTask.cancel();
        mTiemr.cancel();
        mTiemr = null;
        mTimerTask = null;
        super.onDetachedFromWindow();
    }

}