自定义TextView跑马灯效果

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.TextView;

/**
 * 跑马灯文本框控件
 * 
 */
public class ScrollAlwaysTextView extends TextView {

    public ScrollAlwaysTextView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    public ScrollAlwaysTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
        if (focused)
            super.onFocusChanged(focused, direction, previouslyFocusedRect);
    }

    @Override
    public void onWindowFocusChanged(boolean focused) {
        if (focused)
            super.onWindowFocusChanged(focused);
    }

    @Override
    public boolean isFocused() {
        return true;
    }
}

   <com.example.tes.ScrollAlwaysTextView
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:singleLine="true"
        android:ellipsize="marquee"
        android:text="我是跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯跑马灯"
        android:marqueeRepeatLimit="marquee_forever"
        android:gravity="center"
        android:textStyle="bold" />