Android文字长度未超过屏幕宽度也可以滚动的TextView

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;
}
}
};
}