android怎样写一个循环文字滚动的TextView

效果图:

在layout中这样来声明:

<com.kaixin001.view.ScrollText android:id="@+id/news_statustxt" 
        android:layout_width="wrap_content"
      android:layout_height="wrap_content" 
      android:paddingLeft="10dp"
      android:paddingRight="10dp"
      android:layout_gravity="center_vertical"
      android:textColor="#000000"
      android:textSize="16sp"
      android:hint="@string/news_state_hint"
      android:inputType="text"/>

activity这样来调用:

private void initStatus(){
      ivState = (ImageView) findViewById(R.id.news_statusinput);
      //必须使text长度比控件的宽度大
      String s = "dsafsdfsdf(#开心)fsgfdg(#闭嘴)fdgdfgdfgdfgdfgdfgfdgfdgfdgfdgdfg";
      newsModel.setStatus(s);
      String strModel = newsModel.getStatus();
        setStateText(strModel);

   }

   private void setStateText(String strModel){
      if(!TextUtils.isEmpty(strModel)){
         tvState.setStateList(newsModel.getStateList());
         tvState.setText(strModel);
            tvState.init(getWindowManager(), handler);
            tvState.startScroll();
            tvState.start();
        }
   }
   <pre name="code" class="java"> <span style="white-space:pre">  </span> public void setStatus(String status){
      this.status = status;
      if(!TextUtils.isEmpty(status)){
         stateList = ParseNewsInfoUtil.parseStr(status);
      }
   <span style="white-space:pre">   </span>}

private Handler handler = new Handler() {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case ScrollText.TEXT_TIMER:if(tvState != null){tvState.scrollText();}break;default:break;}}};

import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.FontMetrics;
import android.graphics.Paint.Style;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.WindowManager;
import android.widget.TextView;
import com.kaixin001.item.LinkInfo;
import com.kaixin001.model.StateFaceModel;

public class ScrollText extends TextView {

  public static final int TEXT_TIMER = 100;
  private float textLength = 0f;// 文本长度
  private float viewWidth = 0f;
  private float step = 0f;// 文字的横坐标
  private float y = 0f;// 文字的纵坐标
  private float temp_view_plus_text_length = 0.0f;// 用于计算的暂时变量
  private float temp_view_plus_two_text_length = 0.0f;// 用于计算的暂时变量
  private boolean isStarting = false;// 是否開始滚动
  private int left = 0;
  private int right = 0;
  private Paint paint = null;// 画图样式
  private String text = "";// 文本内容
  private Bitmap txtBmp;
  private Canvas txtCanvas;
  private FontMetrics fontMetrics;
  private Timer timer = new Timer();
  private ArrayList<LinkInfo> stateList;

  Handler handler;

  TimerTask task = new TimerTask() {
    public void run() {
      if (handler != null && isStarting) {
        Message msg = Message.obtain();
        msg.what = TEXT_TIMER;
        handler.sendMessage(msg);
      }
    }
  };

  public ScrollText(Context context) {
    super(context);
  }

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

  public ScrollText(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
  }

  /** */
  /**
   * 文本初始化，每次更改文本内容或者文本效果等之后都须要又一次初始化一下
   */
  public void init(WindowManager windowManager, Handler handler) {
    try {
      this.handler = handler;
      paint = new Paint();
      paint.setAntiAlias(true);
      paint.setStyle(Style.STROKE);
      paint.setTextSize(getTextSize());
      paint.setColor(getCurrentTextColor());
      text = getText().toString();
      textLength = 0;
      // textLength = paint.measureText(text);
      int len = stateList.size();
      for (int i = 0; i < len; i++) {
        LinkInfo info = stateList.get(i);
        if (info.isFace()) {// 表情符排版
          Bitmap faceBmp = StateFaceModel.getInstance()
              .getSmallFaceIcon(info.getContent());
          int xLen = faceBmp.getWidth();
          textLength += xLen + 4;
          continue;
        }
        String strContent = info.getContent();
        float xLen = paint.measureText(strContent);
        textLength += xLen;
      }
      left = this.getPaddingLeft();
      right = this.getPaddingRight();
      step = textLength;
      fontMetrics = paint.getFontMetrics();

      y = getPaddingTop();// getTextSize() + getPaddingTop();
      txtBmp = null;
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }

  public void scrollText() {
    if (!isStarting) {
      return;
    }
    invalidate();
    if (viewWidth < textLength) {
      step += 0.5;
      if (step > temp_view_plus_two_text_length) {
        step = textLength;
      }
    }
  }

  public void setStateList(ArrayList<LinkInfo> stateList) {
    this.stateList = stateList;
  }

  private void setTxtBmp() {
    if (txtBmp == null && fontMetrics != null) {
      y = -paint.ascent();// fontMetrics.bottom -
                // fontMetrics.ascent;//(this.getHeight() -
                // (int)fontMetrics.ascent)/2;
      viewWidth = getWidth() - left - right;
      temp_view_plus_text_length = viewWidth + textLength;
      temp_view_plus_two_text_length = viewWidth + textLength * 2;
      txtCanvas = new Canvas();

      int width = (int) viewWidth;
      float height = getHeight();
      txtBmp = Bitmap.createBitmap(width, (int) height, Config.ARGB_8888);
      txtCanvas.setBitmap(txtBmp);

    }
  }

  /** */
  /**
   * 開始滚动
   */
  public void startScroll() {
    isStarting = true;
  }

  /** */
  /**
   * 停止滚动
   */
  public void stopScroll() {
    isStarting = false;
    // invalidate();
  }

  public void start() {
    timer.schedule(task, 10, 20);
  }

  public void stop() {
    timer.cancel();
  }

  @Override
  public void onDraw(Canvas canvas) {
    try {
      setTxtBmp();
      if (txtBmp == null) {
        return;
      }
      Paint txtPaint = new Paint();
      txtPaint.setColor(Color.WHITE);
      txtPaint.setStyle(Style.FILL);
      txtCanvas.drawRect(0, 0, txtBmp.getWidth(), txtBmp.getHeight(),
          txtPaint);
      txtPaint.setAntiAlias(true);
      txtPaint.setStyle(Style.STROKE);
      txtPaint.setTextSize(getTextSize());
      txtPaint.setColor(getCurrentTextColor());
      float x = 0;
      // step为text的宽度
      if (viewWidth < textLength) {
        x = temp_view_plus_text_length - step;
      }
      int len = stateList.size();
      float curLen = x;
      for (int i = 0; i < len; i++) {
        LinkInfo info = stateList.get(i);
        if (info.isFace()) {// 表情符排版
          Bitmap faceBmp = StateFaceModel.getInstance()
              .getSmallFaceIcon(info.getContent());
          int xLen = faceBmp.getWidth();
          txtCanvas.drawBitmap(faceBmp, curLen + 2, 0, txtPaint);
          curLen += xLen + 4;
          continue;
        }
        String strContent = info.getContent();
        strContent = strContent.replaceAll("\n", " ");
        float xLen = txtPaint.measureText(strContent);
        //由于x的值一直降低，所以文字能够滚动
        txtCanvas.drawText(strContent, curLen, y, txtPaint); //<span style="font-family: Arial, Helvetica, sans-serif;">txtCanvas早drawtext.txtBmp上也自然也带有这些text</span>

        curLen += xLen;
      }
      canvas.drawBitmap(txtBmp, left, 0, paint);
    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }

  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    txtBmp = null;
    setTxtBmp();
  }
}