android实现歌词自动滚动效果

package ru.org.piaozhiye.lyric; 
import java.io.File; 
import java.util.List; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Path; 
import android.graphics.Typeface; 
import android.util.AttributeSet; 
import android.widget.TextView; 
/** 
 * @author root 
 * 
 */ 
public class LyricView extends TextView { 
 private Paint mPaint; 
 private float mX; 
 private static Lyric mLyric; 
 private Paint mPathPaint; 
 public String test = "test"; 
 public int index = 0; 
 private List<Sentence> list; 
 public float mTouchHistoryY; 
 private int mY; 
 private long currentDunringTime; // 当前行歌词持续的时间，用该时间来sleep 
 private float middleY;// y轴中间 
 private static final int DY = 50; // 每一行的间隔 
 public LyricView(Context context) { 
 super(context); 
 init(); 
 } 
 public LyricView(Context context, AttributeSet attr) { 
 super(context, attr); 
 init(); 
 } 
 public LyricView(Context context, AttributeSet attr, int i) { 
 super(context, attr, i); 
 init(); 
 } 
 private void init() { 
 setFocusable(true); 
 PlayListItem pli = new PlayListItem("Because Of You", 
 "/sdcard/MP3/Because Of You.mp3", 0L, true); 
 mLyric = new Lyric(new File("/sdcard/MP3/Because Of You.lrc"), pli); 
 list = mLyric.list; 
 // 非高亮部分 
 mPaint = new Paint(); 
 mPaint.setAntiAlias(true); 
 mPaint.setTextSize(22); 
 mPaint.setColor(Color.WHITE); 
 mPaint.setTypeface(Typeface.SERIF); 
 // 高亮部分 当前歌词 
 mPathPaint = new Paint(); 
 mPathPaint.setAntiAlias(true); 
 mPathPaint.setColor(Color.RED); 
 mPathPaint.setTextSize(22); 
 mPathPaint.setTypeface(Typeface.SANS_SERIF); 
 } 
 protected void onDraw(Canvas canvas) { 
 super.onDraw(canvas); 
 canvas.drawColor(0xEFeffff); 
 Paint p = mPaint; 
 Paint p2 = mPathPaint; 
 p.setTextAlign(Paint.Align.CENTER); 
 if (index == -1) 
 return; 
 p2.setTextAlign(Paint.Align.CENTER); 
 // 先画当前行，之后再画他的前面和后面，这样就保持当前行在中间的位置 
 canvas.drawText(list.get(index).getContent(), mX, middleY, p2); 
 float tempY = middleY; 
 // 画出本句之前的句子 
 for (int i = index - 1; i >= 0; i--) { 
 // Sentence sen = list.get(i); 
 // 向上推移 
 tempY = tempY - DY; 
 if (tempY < 0) { 
 break; 
 } 
 canvas.drawText(list.get(i).getContent(), mX, tempY, p); 
 // canvas.translate(0, DY); 
 } 
 tempY = middleY; 
 // 画出本句之后的句子 
 for (int i = index + 1; i < list.size(); i++) { 
 // 往下推移 
 tempY = tempY + DY; 
 if (tempY > mY) { 
 break; 
 } 
 canvas.drawText(list.get(i).getContent(), mX, tempY, p); 
 // canvas.translate(0, DY); 
 } 
 } 
 protected void onSizeChanged(int w, int h, int ow, int oh) { 
 super.onSizeChanged(w, h, ow, oh); 
 mX = w * 0.5f; // remember the center of the screen 
 mY = h; 
 middleY = h * 0.5f; 
 } 
 // 
 /** 
 * @param time 
 * 当前歌词的时间轴 
 * 
 * @return currentDunringTime 歌词只需的时间 
 */ 
 public long updateIndex(long time) { 
 // 歌词序号 
 index = mLyric.getNowSentenceIndex(time); 
 if (index == -1) 
 return -1; 
 Sentence sen = list.get(index); 
 // 返回歌词持续的时间，在这段时间内sleep 
 return currentDunringTime = sen.getDuring(); 
 } 
} 

package ru.org.piaozhiye; 
import java.io.IOException; 
import ru.org.piaozhiye.lyric.LyricView; 
import android.app.Activity; 
import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.os.Handler; 
public class LyricDemo extends Activity { 
 private MediaPlayer mp; 
 private LyricView lyricView; 
 private String path = "/sdcard/MP3/Because Of You.mp3"; 
 /** Called when the activity is first created. */ 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.main); 
 lyricView = (LyricView) findViewById(R.id.audio_lrc); 
 mp = new MediaPlayer(); 
 mp.reset(); 
 try { 
 mp.setDataSource(path); 
 mp.prepare(); 
 } catch (IllegalArgumentException e) { 
 // TODO Auto-generated catch block 
 e.printStackTrace(); 
 } catch (IllegalStateException e) { 
 // TODO Auto-generated catch block 
 e.printStackTrace(); 
 } catch (IOException e) { 
 // TODO Auto-generated catch block 
 e.printStackTrace(); 
 } 
 mp.start(); 
 new Thread(new UIUpdateThread()).start(); 
 } 
 class UIUpdateThread implements Runnable { 
 long time = 100; // 开始 的时间，不能为零，否则前面几句歌词没有显示出来 
 public void run() { 
 while (mp.isPlaying()) { 
 long sleeptime = lyricView.updateIndex(time); 
 time += sleeptime; 
 mHandler.post(mUpdateResults); 
 if (sleeptime == -1) 
  return; 
 try { 
  Thread.sleep(sleeptime); 
 } catch (InterruptedException e) { 
  // TODO Auto-generated catch block 
  e.printStackTrace(); 
 } 
 } 
 } 
 } 
 Handler mHandler = new Handler(); 
 Runnable mUpdateResults = new Runnable() { 
 public void run() { 
 lyricView.invalidate(); // 更新视图 
 } 
 }; 
}