android 可以控制速度的跑马灯

1.自定义textview

public class ScrollTextView extends TextView {

    // scrolling feature
    private Scroller mSlr;

    // milliseconds for a round of scrolling
    private int mRndDuration = 100000;

    // the X offset when paused
    private int mXPaused = 0;

    // whether it's being paused
    private boolean mPaused = true;

    /*
    * constructor
    */
    public ScrollTextView(Context context) {
        this(context, null);
        // customize the TextView
        setSingleLine();
        setEllipsize(null);
        setVisibility(INVISIBLE);
    }

    /*
    * constructor
    */
    public ScrollTextView(Context context, AttributeSet attrs) {
        this(context, attrs, android.R.attr.textViewStyle);
        // customize the TextView
        setSingleLine();
        setEllipsize(null);
        setVisibility(INVISIBLE);
    }

    /*
    * constructor
    */
    public ScrollTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // customize the TextView
        setSingleLine();
        setEllipsize(null);
        setVisibility(INVISIBLE);
    }

    /**
     * begin to scroll the text from the original position
     */
    public void startScroll() {
        // begin from the very right side
        mXPaused = -1 * getWidth();
        // assume it's paused
        mPaused = true;
        resumeScroll();
    }

    /**
     * resume the scroll from the pausing point
     */
    public void resumeScroll() {

        if (!mPaused)
            return;

        // Do not know why it would not scroll sometimes
        // if setHorizontallyScrolling is called in constructor.
        setHorizontallyScrolling(true);

        // use LinearInterpolator for steady scrolling
        mSlr = new Scroller(this.getContext(), new LinearInterpolator());
        setScroller(mSlr);

        int scrollingLen = calculateScrollingLen();
        int distance = scrollingLen - (getWidth() + mXPaused);
        int duration = (new Double(mRndDuration * distance * 1.00000
                / scrollingLen)).intValue();

        setVisibility(VISIBLE);
        mSlr.startScroll(mXPaused, 0, distance, 0, duration);
        invalidate();
        mPaused = false;
    }

    /**
     * calculate the scrolling length of the text in pixel
     *
     * @return the scrolling length in pixels
     */
    private int calculateScrollingLen() {
        TextPaint tp = getPaint();
        Rect rect = new Rect();
        String strTxt = getText().toString();
        tp.getTextBounds(strTxt, 0, strTxt.length(), rect);
        int scrollingLen = rect.width() + getWidth();
        rect = null;
        return scrollingLen;
    }

    /**
     * pause scrolling the text
     */
    public void pauseScroll() {
        if (null == mSlr)
            return;

        if (mPaused)
            return;

        mPaused = true;

        // abortAnimation sets the current X to be the final X,
        // and sets isFinished to be true
        // so current position shall be saved
        mXPaused = mSlr.getCurrX();

        mSlr.abortAnimation();
    }

    @Override
     /*
     * override the computeScroll to restart scrolling when finished so as that
     * the text is scrolled forever
     */
    public void computeScroll() {
        super.computeScroll();

        if (null == mSlr) return;

        if (mSlr.isFinished() && (!mPaused)) {
            this.startScroll();
        }
    }

    public int getRndDuration() {
        return mRndDuration;
    }

    public void setRndDuration(int duration) {
        this.mRndDuration = duration;
    }

    public boolean isPaused() {
        return mPaused;
    }
}

2.布局文件

activity_main11

xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

            android:id="@+id/start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="start"
        android:text="走起" />

            android:id="@+id/stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="stop"
        android:text="停止" />

            android:id="@+id/startfor0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="startFor0"
        android:text="从头开始" />

            android:id="@+id/test"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="#339320"
        android:singleLine="true"
        android:textColor="#000000"
        android:textSize="20dp" >
    

3.mainActivity

public class MainActivity11 extends Activity implements View.OnClickListener {
    private ScrollTextView test;
    private Button start,stop,startfor0;
    private List data;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main11);
        test = (ScrollTextView) this.findViewById(R.id.test);
        start = (Button) findViewById(R.id.start);
        stop = (Button) findViewById(R.id.stop);
        startfor0 = (Button) findViewById(R.id.startfor0);
        start.setOnClickListener(this);
        stop.setOnClickListener(this);
        startfor0.setOnClickListener(this);
        data = new ArrayList<>();
        data.add("跑马灯1");
        data.add("跑马灯2");
        data.add("跑马灯3");
        setAlwaysMarqueeTextViewData();
    }

    /**
     * 设置最新咨询三条数据
     */
    private void setAlwaysMarqueeTextViewData(){
        if(data!=null){//从集合里获取数据来显示在跑马灯上
            test.setText(data.get(0)+";    "+data.get(1)+";    "+data.get(2));
            test.startScroll();
        }

    }
    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.start:
                //开始
                test.startScroll();
                break;
            case R.id.stop:
                //停止
                test.pauseScroll();
                break;
            case R.id.startfor0:
                //从头开始
                test.resumeScroll();
                break;
        }
    }
}