Android文字长度未超过屏幕宽度也可以滚动的TextView 跑马灯

Android自带的跑马灯效果文字长度没有超过屏幕的话不会滚动，但是我们这边产品需求是文字长度没有超过屏幕长度也需要滚动，我看了一个人的博客上实现了Android跑马灯的效果从他博客上获得了灵感，自己改动了一下。其实很简单就是利用handler循环发送消息，不断的调用invalidate（）方法drawText从而达到文字滚动的效果。关键地方是当文字整个移出屏幕时我们需要吧x坐标置为屏幕宽度，这样文字才能循环滚动。

public class MarqueeTextView extends TextView {
    /** 是否停止滚动 */
    private boolean mStopMarquee;
    private String mText;
    private float mCoordinateX;
    private float mTextWidth;
    private float windowWith;

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


    public void setText(String text) {
        this.mText = text;
        mTextWidth = getPaint().measureText(mText);
        DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
        windowWith = displayMetrics.widthPixels;
        if (mHandler.hasMessages(0))
            mHandler.removeMessages(0);
        mHandler.sendEmptyMessageDelayed(0, 2000);
    }


    @SuppressLint("NewApi")
    @Override
    protected void onAttachedToWindow() {
        mStopMarquee = false;
        if (!(mText == null || mText.isEmpty()))
            mHandler.sendEmptyMessageDelayed(0, 2000);
        super.onAttachedToWindow();
    }


    @Override
    protected void onDetachedFromWindow() {
        mStopMarquee = true;
        if (mHandler.hasMessages(0))
            mHandler.removeMessages(0);
        super.onDetachedFromWindow();
    }


    @SuppressLint("NewApi")
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (!(mText == null || mText.isEmpty()))
            canvas.drawText(mText, mCoordinateX, 30, getPaint());
    }


    @SuppressLint("HandlerLeak")
    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case 0:
                    if(mCoordinateX < 0 && Math.abs(mCoordinateX) > mTextWidth){
                        mCoordinateX = windowWith;
                    }else{
                        mCoordinateX -= 1;
                    }
                    invalidate();
                    sendEmptyMessageDelayed(0,30);
                    break;
            }
        }
    };
}