Android: Make view on top of listview scroll together with the listview

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名媛妹妹
名媛妹妹 2021-02-06 06:13

I have a listview which is obviously scrollable. The listview contains some form questions. Once the user submitts the form we put a stamp-like looking custom view on top of the

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  • 2021-02-06 06:58

    for View of top screen you can add headerview so bind coustom layout as headerlayout of listview..so you have scroll same as listview...

    View headerview = ((LayoutInflater)getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.track_footer_view, null, false);
        listview.addHeaderView(headerview);
    
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  • 2021-02-06 07:01

    I found a solution. Not sure if it is too elegant, but it works so will leave it unless somebody comes up with something better.

    The view which I want to scroll together with the list is a custom view, which has to know about the list view. So I implement a setListView(ListView listView) method on it:

    private int scrollY; //1
    private Map<Integer, Integer> listViewItemHeights = new Hashtable<>();
    public void setListView(final ListView listView) {
        listView.setOnScrollListener(new OnScrollListener() {  //2
            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {} //3
    
            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { //4
                View c = listView.getChildAt(0);
                if (c != null) {
                    int oldScrollY = scrollY;
                    scrollY = -c.getTop();
    
                    listViewItemHeights.put(listView.getFirstVisiblePosition(), c.getHeight());
                    for (int i = 0; i < listView.getFirstVisiblePosition(); ++i) {
                        if (listViewItemHeights.get(i) != null)
                            scrollY += listViewItemHeights.get(i);
                    }
                    scrollBy(0, scrollY - oldScrollY);
                }
            }
        });
    }
    

    Comment No.1: this is a variable letting me keep track of the current scroll position.

    Comment No.2: setting a new on scroll listener to let my custom view know when the list

    Comment No.3: this does not need to be implemented in this case.

    Comment No.4: this is where magic happens. Note in the end I scroll my view by scrollY - oldScrollY, let me start with this bit first. oldScrollY is the kept scroll position, scrollY is the new one. I need to scroll by the difference between them. As for how scrollY is calculated I refer you to my answer here: Android getting exact scroll position in ListView, it is how the scroll position is calculated in list view.

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