ListView 下拉回弹效果（类似知乎日报首页效果）

来源：互联网发布：pollution 的数据编辑：程序博客网时间：2024/05/11 15:05

项目中需要做一个类似效果，就在StickyListHeaders的基础上写了一部分代码

效果图解释：

下拉，header中ViewPager中的图片变大，松开手，会有个回弹效果。

上代码：

public class HeaderListView extends StickyListHeadersListView {

    private Scroller scroller;    private int len = 50;    private boolean scrollerType = false;    private ViewPager viewPager;    float startY;    int bottom;    public HeaderListView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        scroller = new Scroller(context);    }    public HeaderListView(Context context, AttributeSet attrs) {        super(context, attrs);        scroller = new Scroller(context);    }    public HeaderListView(Context context) {        super(context);        scroller = new Scroller(context);    }    @Override    public void addHeaderView(View v, Object data, boolean isSelectable) {        viewPager = (ViewPager) v.findViewById(R.id.header);        super.addHeaderView(v, data, isSelectable);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        float currentY = ev.getY();        Log.e("currentY", currentY + "");        Log.e("viewPager.getBottom()", viewPager.getBottom() + "");        switch (ev.getAction()) {        case MotionEvent.ACTION_DOWN:            startY = currentY;            bottom = viewPager.getBottom();            break;        case MotionEvent.ACTION_MOVE:            if (startY > bottom && viewPager.isShown() && viewPager.getTop() >= 0) {                int y = (int) (bottom + (currentY - startY) / 2.5f);                Log.e("ACTION_MOVE", "y =" + y);                if (y < viewPager.getBottom() + len && y >= bottom) {                    viewPager.setLayoutParams(new RelativeLayout.LayoutParams(new RelativeLayout.LayoutParams(viewPager                            .getWidth(), y)));                }                scrollerType = false;            }            break;        case MotionEvent.ACTION_UP:            scrollerType = true;            Log.e("ACTION_UP", "" + (bottom - viewPager.getBottom()));            scroller.startScroll(viewPager.getLeft(), viewPager.getBottom(), 0 - viewPager.getLeft(), bottom                    - viewPager.getBottom(), 200);            invalidate();            break;        }        return super.dispatchTouchEvent(ev);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        return super.onInterceptTouchEvent(ev);    }    @Override    public void computeScroll() {        if (scroller.computeScrollOffset()) {            int x = scroller.getCurrX();            int y = scroller.getCurrY();            viewPager.layout(0, 0, x + viewPager.getWidth(), y);            if (!scroller.isFinished() && scrollerType && y > bottom) {                viewPager.setLayoutParams(new RelativeLayout.LayoutParams(viewPager.getWidth(), y));            }            invalidate();        }    }}

Header中的ViewPager左右滑动和listView上下滑动有冲突，解决办法，自定义ViewPager，重写她的dispatchTouchEvent(MotionEvent ev)

public class CustomView extends RelativeLayout {    public CustomView(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        getParent().requestDisallowInterceptTouchEvent(true);        return super.dispatchTouchEvent(ev);    }}

明白思路，自己写个下拉刷新什么的应该就不是很难了。

demo：点我下载

参考：android 中文 api （64） —— Scroller