如何在Android中利用TextView实现一个跑马灯效果

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:tools="http://schemas.android.com/tools" 
  android:layout_width="fill_parent" 
  android:layout_height="fill_parent" 
  android:orientation="vertical" > 
 
 
  <Button 
    android:id="@+id/start" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="start" 
    android:text="开始" /> 
 
 
  <Button 
    android:id="@+id/stop" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="stop" 
    android:text="停止" /> 
 
 
  <Button 
    android:id="@+id/startfor0" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="startFromHead" 
    android:text="重置" /> 
 
 
  <com.xuhui.customrolllight.MarqueeText 
    android:id="@+id/test" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:background="#339320" 
    android:ellipsize="marquee" 
    android:singleLine="true" 
    android:text="滚动效果，不管多少字" 
 
    android:ellipsize = "marquee" // 跑马灯效果，字数不超过就不动，超过就滚动 
    android:textColor="#000000" 
    android:textSize="20dp" > 
  </com.xuhui.customrolllight.MarqueeText> 
 
 
</LinearLayout> 

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.util.AttributeSet; 
import android.widget.TextView; 
 
 
public class MarqueeText extends TextView implements Runnable { 
private int currentScrollX; // 当前滚动的位置 
private boolean isStop = false; 
private int textWidth; 
private boolean isMeasure = false; 
 
 
public MarqueeText(Context context) { 
super(context); 
} 
 
 
public MarqueeText(Context context, AttributeSet attrs) { 
super(context, attrs); 
} 
 
 
public MarqueeText(Context context, AttributeSet attrs, int defStyle) { 
super(context, attrs, defStyle); 
} 
 
 
@Override 
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
// TODO Auto-generated method stub 
super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
currentScrollX = this.getWidth(); 
} 
 
 
protected void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
if (!isMeasure) { 
getTextWidth();// 文字宽度只需要获取一次就可以了 
isMeasure = true; 
} 
} 
 
 
private void getTextWidth() { 
Paint paint = this.getPaint(); 
String str = this.getText().toString(); 
textWidth = (int) paint.measureText(str); 
} 
 
 
@Override 
/* 
* public void run() { currentScrollX-=2;//滚动速度.+号表示往左边- 
* scrollTo(currentScrollX,0); if(isStop){ return; } 
* if(getScrollX()<=-(this.getWidth())){ scrollTo(textWidth,0); 
* currentScrollX=textWidth; } postDelayed(this, 5); } 
*/ 
public void run() { 
currentScrollX += 2;// 滚动速度.+号表示往左边- 
scrollTo(currentScrollX, 0); 
if (isStop) { 
return; 
} 
if (getScrollX() >= (textWidth)) { 
currentScrollX = -(this.getWidth());// 当前出现的位置 
} 
postDelayed(this, 1); 
} 
/*（ public void run() { 
 
 
// currentScrollX += 3;// 滚动速度.+号表示往左边- 
// scrollTo(currentScrollX, 0); 
 
 
if (textWidth>this.getWidth()) { 
currentScrollX += 3;// 滚动速度.+号表示往左边- 
scrollTo(currentScrollX, 0); 
} 
if (getScrollX() >= (textWidth)) { 
// scrollTo(this.getWidth(),0); 
currentScrollX = -(this.getWidth());// 当前出现的位置 
} 
postDelayed(this, 5); 
}）这里面实现的是没有省略号的效果。文字没有超出框的长度就不滚，超出就滚*/ 
 
// 开始滚动 
public void startScroll() { 
isStop = false; 
this.removeCallbacks(this); 
post(this); 
} 
 
 
// 停止滚动 
public void stopScroll() { 
isStop = true; 
} 
 
 
// 从头开始滚动 
public void startFromHead() { 
currentScrollX = 0; 
startScroll(); 
} 
} 

import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
 
 
public class MainActivity extends Activity { 
 
 
private MarqueeText test; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
test=(MarqueeText) findViewById(R.id.test); 
 
} 
public void start(View v){ 
test.startScroll(); 
} 
public void stop(View v){ 
test.stopScroll(); 
} 
public void startFromHead(View v){ 
test.startFromHead(); 
} 
}