一个用于轮播的ViewPagerIndicator-白红宇

####效果图：

####用法：

viewPager = (ViewPager) getView().findViewById(R.id.viewPager);viewPager.setAdapter(new BannerAdapter());indicator = (ViewPagerIndicator) getView().findViewById(R.id.indicator);indicator.attachViewPager(viewPager);复制代码

轮播间隔可在xml中设置（interval_time属性）也可在jav代码中设置: indicator.setIntervalTime(4000);

####代码：

public class ViewPagerIndicator extends View implements ViewPager.OnPageChangeListener, View.OnTouchListener {        private final String TAG = getClass().getSimpleName();        /**         * 绑定的ViewPager         */        private ViewPager mViewPager;        /**         * 每一页的间隔时间         */        private int intervalTime;        /**         * 圆点个数         */        private int mSize;        /**         * 圆点半径（控件高度的一半）         */        private int mDotRadius;        /**         * 两个圆水平距离         */        private int mHorizontalSpacing;        /**         * 两个圆心水平距离         */        private int mDistanceOfDot;        /**         * pager 滑动偏移量         */        private float positionOffset;        /**         * 当前pager         */        private int position;        private Paint mPaint;        /**         * 圆点基础色         */        private int mBaseColor;        /**         * 当前圆点颜色         */        private int mCurrentColor;        /**         * 是否需要轮播         */        private boolean mNeedLoop;        /**         * 和一个ViewPager 绑定         */        public void attachViewPager(ViewPager mViewPager) {            if (mViewPager == null) return;            this.mViewPager = mViewPager;            mViewPager.addOnPageChangeListener(this);            mSize = mViewPager.getAdapter().getCount();            if (mSize > 1) {                invalidate();                if (mNeedLoop) {                    mViewPager.setOnTouchListener(this);                    needSwitchPage = true;                    postDelayed(nextPage, intervalTime);                }            }        }        /**         * 设置每次轮播间隔         */        public void setIntervalTime(int intervalTime) {            this.intervalTime = intervalTime;        }        public ViewPagerIndicator(Context context) {            super(context);            init(null);        }        public ViewPagerIndicator(Context context, AttributeSet attrs) {            super(context, attrs);            init(attrs);        }        public ViewPagerIndicator(Context context, AttributeSet attrs, int defStyleAttr) {            super(context, attrs, defStyleAttr);            init(attrs);        }        private void init(AttributeSet attrs) {            TypedArray ta = getContext().obtainStyledAttributes(attrs, R.styleable.ViewPagerIndicator);            intervalTime = ta.getInt(R.styleable.ViewPagerIndicator_interval_time, 2000);            mBaseColor = ta.getColor(R.styleable.ViewPagerIndicator_base_color, Color.parseColor("#90D3C1B3"));            mCurrentColor = ta.getColor(R.styleable.ViewPagerIndicator_selected_color, Color.WHITE);            mNeedLoop = ta.getBoolean(R.styleable.ViewPagerIndicator_need_loop, true);            ta.recycle();            mPaint = new Paint();            mPaint.setAntiAlias(true);            nextPage = new NextPageRunnable();        }        @Override        protected void onDraw(Canvas canvas) {            super.onDraw(canvas);            if (mSize <= 1) return;            //画基础圆点            int firstDotLeft = ((getWidth() - mSize * 2 * mDotRadius - mHorizontalSpacing * (mSize - 1)) / 2);            int startX = firstDotLeft;            mPaint.setColor(mBaseColor);            for (int i = 0; i < mSize; i++) {                canvas.drawCircle(startX + mDotRadius, getHeight() / 2, mDotRadius, mPaint);                startX += mDistanceOfDot;            }            //画选中的圆点            mPaint.setColor(mCurrentColor);            canvas.drawCircle(firstDotLeft + mDotRadius + (int) (mDistanceOfDot * positionOffset) + position                    * mDistanceOfDot, getHeight() / 2, mDotRadius, mPaint);            Log.d(TAG, "onDraw");        }        @Override        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            this.positionOffset = positionOffset;            this.position = position;            invalidate();        }        @Override        public void onPageSelected(int position) {            Log.d(TAG, "onPageScrolled " + position);        }        @Override        public void onPageScrollStateChanged(int state) {        }        private NextPageRunnable nextPage;        private boolean needSwitchPage;        @Override        public boolean onTouch(View v, MotionEvent event) {            removeCallbacks(nextPage);            switch (event.getAction()) {                case MotionEvent.ACTION_DOWN://接收触摸事件时停止轮播                    needSwitchPage = false;                    break;                case MotionEvent.ACTION_CANCEL:                case MotionEvent.ACTION_UP://手指松开时继续轮播                    needSwitchPage = true;                    postDelayed(nextPage, intervalTime);                    break;            }            return false;        }        /**         * 下一页         */        private class NextPageRunnable implements Runnable {            @Override            public void run() {                if (!needSwitchPage || getVisibility() != VISIBLE || mViewPager == null || !mNeedLoop)                    return;                int currentItem = mViewPager.getCurrentItem();                if (currentItem < mViewPager.getAdapter().getCount() - 1) {                    currentItem++;                } else {                    currentItem = 0;                }                mViewPager.setCurrentItem(currentItem);// 切换到下一个页面                removeCallbacks(nextPage);                postDelayed(nextPage, intervalTime);            }        }        @Override        protected void onVisibilityChanged(@NonNull View changedView, int visibility) {            super.onVisibilityChanged(changedView, visibility);            if (!mNeedLoop) return;            if (visibility == VISIBLE) {                needSwitchPage = true;                postDelayed(nextPage, intervalTime);            } else {                needSwitchPage = false;                removeCallbacks(nextPage);            }            Log.d(TAG, "onVisibilityChanged visibility:" + visibility);        }        @Override        protected void onDetachedFromWindow() {            super.onDetachedFromWindow();            needSwitchPage = false;            removeCallbacks(nextPage);        }        /**         * 初始化圆点尺寸 水平间隔         */        @Override        protected void onSizeChanged(int w, int h, int oldw, int oldh) {            super.onSizeChanged(w, h, oldw, oldh);            mDotRadius = h / 2;            mHorizontalSpacing = (int) (mDotRadius * 1.5f);            mDistanceOfDot = mDotRadius * 2 + mHorizontalSpacing;        }    }复制代码

几个自定义属性：