textview（跑马灯效果）文字长短不限循环播放

textview显示跑马灯效果，使用的是继承的方法onDraw不停地绘制 
优点： 
1.文字长短不限哦 
2.不用非得获取焦点哦　　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <feng.f7_27.activity.CustomTextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:background="#aaffee"/>
        
    </LinearLayout>
    
</LinearLayout>

package feng.f7_27.activity;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.view.Display;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.TextView;

public class CustomTextView extends TextView implements OnClickListener{
    public final static String TAG = CustomTextView.class.getSimpleName();

    private float textLength = 0f;//�ı�����
    private float viewWidth = 0f;
    private float step = 0f;//���ֵĺ����
    private float y = 0f;//���ֵ������
    private float temp_view_plus_text_length = 0.0f;//���ڼ������ʱ����
    private float temp_view_plus_two_text_length = 0.0f;//���ڼ������ʱ����
    public boolean isStarting = false;//�Ƿ�ʼ����
    private Paint paint = null;//��ͼ��ʽ
    private String text = "";//�ı�����


    public CustomTextView(Context context) {
    super(context);
    initView();
    }

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

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

    /** *//**
    * ��ʼ���ؼ�
    */
    private void initView()
    {
    setOnClickListener(this);
    }

    /** *//**
    * �ı���ʼ����ÿ�θ���ı����ݻ����ı�Ч���֮����Ҫ���³�ʼ��һ��
    */
    public void init(WindowManager windowManager)
    {
    paint = getPaint();
    text = getText().toString();
    textLength = paint.measureText(text);
    viewWidth = getWidth();
    if(viewWidth == 0)
    {
    if(windowManager != null)
    {
    Display display = windowManager.getDefaultDisplay();
    viewWidth = display.getWidth();
    }
    }
    step = textLength;
    temp_view_plus_text_length = viewWidth + textLength;
    temp_view_plus_two_text_length = viewWidth + textLength * 2;
    y = getTextSize() + getPaddingTop()+15;
    }
    @Override
    public Parcelable onSaveInstanceState()
    {
    Parcelable superState = super.onSaveInstanceState();
    SavedState ss = new SavedState(superState);

    ss.step = step;
    ss.isStarting = isStarting;

    return ss;

    }                        
    @Override
    public void onRestoreInstanceState(Parcelable state)
    {
    if (!(state instanceof SavedState)) {
    super.onRestoreInstanceState(state);
    return;
    }
    SavedState ss = (SavedState)state;
    super.onRestoreInstanceState(ss.getSuperState());

    step = ss.step;
    isStarting = ss.isStarting;

    }

    public static class SavedState extends BaseSavedState {
    public boolean isStarting = false;
    public float step = 0.0f;
    SavedState(Parcelable superState) {
    super(superState);
    }

    @Override
    public void writeToParcel(Parcel out, int flags) {
    super.writeToParcel(out, flags);
    out.writeBooleanArray(new boolean[]{isStarting});
    out.writeFloat(step);
    }


    public static final Parcelable.Creator<SavedState> CREATOR
    = new Parcelable.Creator<SavedState>() {

    public SavedState[] newArray(int size) {
    return new SavedState[size];
    }

    @Override
    public SavedState createFromParcel(Parcel in) {
    return new SavedState(in);
    }
    };

    private SavedState(Parcel in) {
    super(in);
    boolean[] b = null;
    in.readBooleanArray(b);
    if(b != null && b.length > 0)
    isStarting = b[0];
    step = in.readFloat();
    }
    }

    /** *//**
    * ��ʼ����
    */
    public void startScroll()
    {
    isStarting = true;
    invalidate();
    }

    /** *//**
    * ֹͣ����
    */
    public void stopScroll()
    {
    isStarting = false;
    invalidate();
    }


    @Override
    public void onDraw(Canvas canvas) {
    canvas.drawText(text, temp_view_plus_text_length - step, y, paint);
    if(!isStarting)
    {
    return;
    }
    step += 0.5;
    if(step > temp_view_plus_two_text_length)
    step = textLength;
    invalidate();

    }

    @Override
    public void onClick(View v) {
    if(isStarting)
    stopScroll();
    else
    startScroll();

    }

}

tv.setText("aaaaaavvv");
        tv.init(getWindowManager());
        tv.startScroll();