Android实现歌词滚动效果

public class VerticalScrollTextView extends TextView { private Paint mPaint; private float mX; private Paint mPathPaint;  public int index = 0; private List<Sentence> list; public float mTouchHistoryY; private int mY;  private float middleY;// private static final int DY = 40; // public VerticalScrollTextView(Context context) { super(context); init(); } public VerticalScrollTextView(Context context, AttributeSet attr) { super(context, attr); init(); } public VerticalScrollTextView(Context context, AttributeSet attr, int i) { super(context, attr, i); init(); } private void init() { setFocusable(true); if(list==null){  list=new ArrayList<Sentence>();  Sentence sen=new Sentence(0," ");  list.add(0, sen); }  //  mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setTextSize(24); mPaint.setColor(Color.BLACK); mPaint.setAlpha(80); mPaint.setTypeface(Typeface.SERIF); //  mPathPaint = new Paint(); mPathPaint.setAntiAlias(true); mPathPaint.setColor(Color.RED); mPathPaint.setTextSize(24); 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.LEFT); if (index == -1)  return; p2.setTextAlign(Paint.Align.LEFT); //  canvas.drawText(list.get(index).getName(), mX, middleY, p2); float tempY = middleY; //  for (int i = index - 1; i >= 0; i--) {    tempY = tempY - DY;  if (tempY < 0) {  break;  }  canvas.drawText(list.get(i).getName(), mX, tempY, p);   } tempY = middleY; // for (int i = index + 1; i < list.size(); i++) {  //   tempY = tempY + DY;  if (tempY > mY) {  break;  }  canvas.drawText(list.get(i).getName(), mX, tempY, p);   } } protected void onSizeChanged(int w, int h, int ow, int oh) { super.onSizeChanged(w, h, ow, oh); mX = w * 0.3f;  mY = h; middleY = h * 0.5f; } public long updateIndex(int index) {  if (index == -1)  return -1; this.index=index;  return index; } public List<Sentence> getList() { return list; } public void setList(List<Sentence> list) { this.list = list; } public void updateUI(){ new Thread(new updateThread()).start(); } class updateThread implements Runnable { long time = 300;  int i=0; public void run() {  while (true) {  long sleeptime = updateIndex(i);  time += sleeptime;  mHandler.post(mUpdateResults);  if (sleeptime == -1)   return;  try {   Thread.sleep(time);   i++;   if(i==getList().size())   {    i=0;    time = 300;   }  } catch (InterruptedException e) {      e.printStackTrace();  }  } } } Handler mHandler = new Handler(); Runnable mUpdateResults = new Runnable() { public void run() {  invalidate(); //  } };}

public class Sentence { private String name; private int index; public Sentence(int index,String name){ this.name=name; this.index=index; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getIndex() { return index; } public void setIndex(int index) { this.index = index; }}

<com.mypackager.ui.VerticalScrollTextView  android:id="@+id/scoll_textView"  android:layout_width="500dp"  android:layout_height="500dp"  android:text="@string/company_intrduce_text"  android:visibility="gone"  ></com.mypackager.VerticalScrollTextView>

List lst=new ArrayList<Sentence>();  for(int i=0;i<8;i++){  if(i%2==0){   Sentence sen=new Sentence(i,i+1+"NanJINGXIXI");   lst.add(i, sen);  }else{   Sentence sen=new Sentence(i,i+1+"Hello world!");   lst.add(i, sen);  }  }   play_textView.setList(lst);  play_textView.updateUI();