android滚动通知的效果

最新推荐文章于 2025-09-19 00:15:00 发布

原创最新推荐文章于 2025-09-19 00:15:00 发布 · 1.7k 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#android

android 专栏收录该内容

14 篇文章

订阅专栏

本文介绍了一个简单的自定义Android滚动文本视图控件，该控件能够在界面上逐条滚动显示多条文本消息，适用于资源消耗较小的应用场景。

这是很久以前写的控件，最近离职比较空闲，重新整理一下，发出来供大家批判．．．
这种效果在淘宝android客户端上也能看到，首页就有,就是有多条广告逐条滚动显示，不过我这个只是文字，没有附加图片，如果需要图片，这个例子完全不能用，因为这个例子的优点就是只有一个Textview,消耗小．

public class NotifyTextView extends TextView  {

    public NotifyTextView(Context context) {
        this(context, null, 0);
    }

    public NotifyTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public NotifyTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        scrollHandler = new ScrollHandler();

        textPaint = getPaint();
        textPaint.setAntiAlias(true);
        initTextHeight();
        initPaddingValue();
        initScrollAnim();
    }

    public void setDataList(List<ScrollNotify> dataList) {
        this.dataList = dataList;
        if (dataList != null && dataList.size() > 0) {
            this.dataList.add(dataList.get(0));
        }
        postInvalidate();
        sendScrollMessage(SCROLL_INTERNAL);
    }

    public void pauseScrollView(){
        isScrolling = false;
        if(scrollHandler != null)
            scrollHandler.removeMessages(SCROLL_WHAT);
    }

    public void restartScrollView(){
        if(!isScrolling){
            sendScrollMessage(SCROLL_INTERNAL);
        }
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (w != oldw || h != oldh) {
            height = h;
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (dataList == null || dataList.size() == 0) {
            super.onDraw(canvas);
        } else {
            int i = 0;
            for (ScrollNotify notify : dataList) {
                canvas.drawText(notify.text, paddingLeft,  (i + 0.5f) * height + textHeight / 2 - bottomY, textPaint);
                i++;
            }
        }
    }

    private void sendScrollMessage(long delayTimeInMills) {
        isScrolling = true;
        scrollHandler.removeMessages(SCROLL_WHAT);
        scrollHandler.sendEmptyMessageDelayed(SCROLL_WHAT, delayTimeInMills);
    }

    private void initScrollAnim() {
        if(valueAnimator == null){
            valueAnimator = ValueAnimator.ofFloat(0.0f,1.0f);
            valueAnimator.setDuration(SCROLL_TIME);
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    float franction = (float) animation.getAnimatedValue();
                    int scrollY=currentScrollY+(int)(franction*height);
                    scrollTo(0,scrollY);
                }
            });
        }
    }

    private void initTextHeight() {
        Paint.FontMetrics fm = textPaint.getFontMetrics();
        textHeight = (int) (fm.descent - fm.ascent);
        bottomY = (int) fm.descent;
    }

    private void initPaddingValue() {
        int marginLeft = 0;
        if (getLayoutParams() != null && getLayoutParams() instanceof ViewGroup.MarginLayoutParams) {
            ViewGroup.MarginLayoutParams params = (ViewGroup.MarginLayoutParams) getLayoutParams();
            marginLeft = params.leftMargin;
        }
        paddingLeft = getPaddingLeft() + marginLeft;
    }

    private class ScrollHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case SCROLL_WHAT:
                    scrollOnce();
                    sendScrollMessage(SCROLL_INTERNAL);
                default:
                    break;
            }
        }

        private void scrollOnce() {
            int scollerY = NotifyTextView.this.getScrollY();
            if (dataList != null && scollerY >= height * (dataList.size() - 1)) {
                scrollTo(0, 0);
            }
            currentScrollY = getScrollY();
            if(valueAnimator != null){
                valueAnimator.start();
            }
        }
    }


    public static class ScrollNotify {
        public String text;
        public OnClickListener onClickListener;
    }

    private ScrollHandler scrollHandler;
    private int height;
    private boolean isScrolling = false;

    private ValueAnimator valueAnimator;
    private int currentScrollY;

    private List<ScrollNotify> dataList;
    private TextPaint textPaint;
    private int bottomY;
    private int textHeight;
    private int paddingLeft;


    private static final int SCROLL_WHAT = 11;
    private static final int SCROLL_INTERNAL = 2000;
    private static final int SCROLL_TIME = 600;

使用很简单：

  NotifyTextView　scrollText = (NotifyTextView) findViewById(R.id.scrollText);
        List<NotifyTextView.ScrollNotify> datas = new ArrayList<NotifyTextView.ScrollNotify>();
        for(int i=0;i<10;i++){
            NotifyTextView.ScrollNotify data = new NotifyTextView.ScrollNotify();
            data.text = "供简体中文和另外_"+i;
            datas.add(data);
        }
        scrollText.setDataList(datas);