滚动型内滚动的ListView改善 [英] ListView inside ScrollView scroll improvement

问题描述

我可以看到有关里面的ListView滚动型问题的一些问题。我知道，我们不应该做这样的嵌套，只是因为这两个组件都有自己的滚动和谷歌是这么说的（我读过，这是没用的东西）。但是，在我当前的项目，我需要这样的行为：如果列表视图可以滚动 - 它正在滚动，如果不是（顶部或ListView底部边框） - 滚动视图的滚动。
所以，我写了这样code：

I can see some questions about "ListView inside ScrollView" issue. And I know, that we shouldn't do such nesting, just because both components have their own scrolling and Google said so(I've read that it is useless thing). But in my current project I need such behavior: if listview can scroll - it is scrolling, if not(top or bottom border of listview) - scrollview is scrolling. So, I've wrote such code:

public static void smartScroll(final ScrollView scroll, final ListView list){
        scroll.requestDisallowInterceptTouchEvent(true);
        list.setOnTouchListener(new OnTouchListener() {
            private boolean isListTop = false, isListBottom = false;
            private float delta = 0, oldY = 0;
            @Override
            public boolean onTouch(View v, MotionEvent event) {             
                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    oldY = event.getY();
                    break;
                case MotionEvent.ACTION_UP:
                    delta = 0;
                    break;
                case MotionEvent.ACTION_MOVE:
                    delta = event.getY() - oldY;
                    oldY = event.getY();

                    isListTop = false;
                    isListBottom = false;

                    View first = list.getChildAt(0);
                    View last = list.getChildAt(list.getChildCount()-1);                
                    if(first != null && list.getFirstVisiblePosition() == 0 && first.getTop() == 0 && delta > 0.0f){
                        isListTop = true;
                    }
                    if(last != null && list.getLastVisiblePosition() == list.getCount()-1 && last.getBottom() <= list.getHeight() && delta < 0.0f){
                        isListBottom = true;
                    }

                    if( (isListTop && delta > 0.0f) || (isListBottom && delta < 0.0f) ){
                        scroll.post(new Runnable() {
                            public void run() {
                                scroll.smoothScrollBy(0, -(int)delta);
                            }
                        });
                    }

                    break;
                default: break;
                }                   
                scroll.requestDisallowInterceptTouchEvent(true);
                return false;
            }
        });
    }

和它的作品，至少在目标API 8.但也有一些滚动毛刺（不自然的跳跃）。我认为，在scroll.smoothScrollBy原因（0， - （INT）三角洲）;有任何人的想法，如何提高滚动视图滚动:)？它通常被称为（在移动）和岗位，也许这是什么原因？

And it works, at least on target API 8. But there are some scroll glitches(unnatural jumps). I think, the cause in scroll.smoothScrollBy(0, -(int)delta); Have anybody thoughts, how to improve scrollview scrolling :)? It is called often(on move) and on post, maybe that is the cause?

推荐答案

我面临同样的问题。我已经改进了这一code和现在的作品正确的，我认为。

I have faced same problem. I've improved this code and now it works correct i think.

    public static void smartScroll(final ScrollView scroll, final ListView list){
    list.setOnTouchListener(new View.OnTouchListener() {
        private boolean isListTop = false, isListBottom = false;
        private float delta = 0, oldY = 0;
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    scroll.requestDisallowInterceptTouchEvent(true);
                    list.requestDisallowInterceptTouchEvent(false);
                    oldY = event.getY();
                    break;
                case MotionEvent.ACTION_UP:
                    delta = 0;
                    break;
                case MotionEvent.ACTION_MOVE:
                    delta = event.getY() - oldY;
                    oldY = event.getY();

                    isListTop = false;
                    isListBottom = false;

                    View first = list.getChildAt(0);
                    View last = list.getChildAt(list.getChildCount()-1);
                    if(first != null && list.getFirstVisiblePosition() == 0 && first.getTop() == 0 && delta > 0.0f){
                        isListTop = true;
                    }
                    if(last != null && list.getLastVisiblePosition() == list.getCount()-1 && last.getBottom() <= list.getHeight() && delta < 0.0f){
                        isListBottom = true;
                    }

                    if( (isListTop && delta > 0.0f) || (isListBottom && delta < 0.0f) ){
                        scroll.requestDisallowInterceptTouchEvent(false);
                        list.requestDisallowInterceptTouchEvent(true);
                    }
                    break;
                default: break;
            }
            return false;
        }
    });
}

当我们触摸列表视图 - 我们使它的滚动和禁用父滚动：

When we touch listview - we enable its scroll and disable parent scroll:

                    scroll.requestDisallowInterceptTouchEvent(true);
                    list.requestDisallowInterceptTouchEvent(false);

如果我们达到了列表的边界 - 我们禁止其滚动和启用父滚动：

And if we reaching the border of the list - we disable its scroll and enable parent scroll :

                    scroll.requestDisallowInterceptTouchEvent(false);
                    list.requestDisallowInterceptTouchEvent(true);

它滚动pretty smoothy我。希望这有助于。

It scrolls pretty smoothy for me. Hope this helps.

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