类似一种选项按钮：SlidingTab

类似一种选项按钮：SlidingTab

之前写过一个seleteTab,由于之前写的匆忙很多代码有点乱，现在更新一下

public class SlidingTab extends LinearLayout implements View.OnClickListener, ValueAnimator.AnimatorUpdateListener {
    private GradientDrawable mIndicatorDrawable = new GradientDrawable();
    private GradientDrawable mRectDrawable = new GradientDrawable();
    private Context context;
    private Paint linePaint;
    private int tabWidth;
    private List tabList = new ArrayList<>();
    private IndicatorPoint indicatorPoint = new IndicatorPoint();
    private int position;
    private boolean isFirst = true;
    private ValueAnimator valueAnimator;

    public SlidingTab(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initView(context, attrs);
    }

    private void initView(Context context, AttributeSet attrs) {
        this.context = context;
        setOrientation(HORIZONTAL);
        setWillNotDraw(false);//重写onDraw方法,需要调用这个方法来清除flag
        setClipChildren(false);
        setClipToPadding(false);
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.selectTabView);
        typedArray.recycle();
        //动画
        valueAnimator = ObjectAnimator.ofObject(new PointEvaluator(), startPoint, endPoint);
        valueAnimator.addUpdateListener(this);
    }
    //填充tab （View的长度在代码中写死了）
    public void setTabList(List tabs) {
        tabList.clear();
        tabList.addAll(tabs);

        for (String tab : tabList) {
            TextView textView = new TextView(context);
            LayoutParams layoutParams = new LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 1.0f);
            textView.setGravity(Gravity.CENTER);
            textView.setText(tab);
            textView.setId(tabList.indexOf(tab));
            textView.setOnClickListener(this);
            addView(textView, tabList.indexOf(tab), layoutParams);
        }

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //话外部的轮廓线
        int width = getWidth();
        int height = getHeight();
        mRectDrawable.setStroke(2, Color.RED);
        mRectDrawable.setCornerRadius(getHeight() / 2);
        mRectDrawable.setBounds(0, 0, width, height);
        mRectDrawable.draw(canvas);

        //初始化指示器
        if (isFirst) {
            indicatorPoint.left = getChildAt(0).getLeft();
            indicatorPoint.right = getChildAt(0).getRight();
            ((TextView) getChildAt(0)).setTextColor(Color.WHITE);
        }
        mIndicatorDrawable.setColor(Color.BLUE);
        mIndicatorDrawable.setCornerRadius(getHeight() / 2 - 2);
        mIndicatorDrawable.setBounds(indicatorPoint.left + 2, 2, indicatorPoint.right - 2, height - 2);
        mIndicatorDrawable.draw(canvas);
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == position) {
            return;
        }
        isFirst = false;

        //没有动画直接运行
     /*   View tabView = getChildAt(v.getId());
        indicatorPoint.left = tabView.getLeft();
        indicatorPoint.right = tabView.getRight();
        position = v.getId();
        invalidate();*/

        //设置动画  期初对象
        View startView = getChildAt(position);
        startPoint.left = startView.getLeft();
        startPoint.right = startView.getRight();
        ((TextView) startView).setTextColor(Color.BLACK);

        View tabView = getChildAt(v.getId());
        endPoint.left = tabView.getLeft();
        endPoint.right = tabView.getRight();
        ((TextView) tabView).setTextColor(Color.WHITE);

        valueAnimator.setObjectValues(startPoint, endPoint);
        valueAnimator.setDuration(260);
        valueAnimator.start();
        position = v.getId();
    }

    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        IndicatorPoint animatedValue = (IndicatorPoint) animation.getAnimatedValue();
        indicatorPoint.left = animatedValue.left;
        indicatorPoint.right = animatedValue.right;
        invalidate();
    }
    //自定义估值器
    class PointEvaluator implements TypeEvaluator {
        @Override
        public IndicatorPoint evaluate(float fraction, IndicatorPoint startValue, IndicatorPoint endValue) {
            float left = startValue.left + fraction * (endValue.left - startValue.left);
            float right = startValue.right + fraction * (endValue.right - startValue.right);
            IndicatorPoint point = new IndicatorPoint();
            point.left = ((int) left);
            point.right = ((int) right);
            return point;
        }
    }

    private IndicatorPoint startPoint = new IndicatorPoint();
    private IndicatorPoint endPoint = new IndicatorPoint();


    //创建动画执行的对象
    private class IndicatorPoint {
        public int left;
        public int right;
    }
}