17

我试图在我的项目中模仿 Google Plus 应用程序，因为它现在似乎是参考。

滚动时的列表视图效果非常好，我想做类似的事情。

我已经开始使用 LayoutAnimationController http://android-er.blogspot.be/2009/10/listview-and-listactivity-layout.html

LayoutAnimationController controller 
   = AnimationUtils.loadLayoutAnimation(
     this, R.anim.list_layout_controller);
  getListView().setLayoutAnimation(controller);

这似乎很糟糕，因为并非所有元素都是动画的：

所以我最终使用了适配器的 getView 并使用了这个：

        AnimationSet set = new AnimationSet(true);

        Animation animation = new AlphaAnimation(0.0f, 1.0f);
        animation.setDuration(800);
        set.addAnimation(animation);

        animation = new TranslateAnimation(
            Animation.RELATIVE_TO_SELF, 0.0f,Animation.RELATIVE_TO_SELF, 0.0f,
            Animation.RELATIVE_TO_SELF, 1.0f,Animation.RELATIVE_TO_SELF, 0.0f
        );
        animation.setDuration(600);
        set.addAnimation(animation);

        row.startAnimation(set);

结果太棒了，我真的很高兴！

不幸的是，它仅在我从列表的顶部滚动到底部时才有效！

我想让它在另一边滚动时工作，我需要稍微改变一下 TranslateAnimation。

所以我的问题是，有没有办法检测我在适配器中是向上还是向下滚动？

4

11 回答 11

23

为OnScrollListener您的ListView. 创建一个标志，指示用户是向上还是向下滚动。通过检查当前的第一个可见项位置是否大于或小于先前的第一个可见项位置，为标志设置适当的值。把那张支票放进去onScrollStateChanged()。

示例代码：

private int mLastFirstVisibleItem;
private boolean mIsScrollingUp;

public void onScrollStateChanged(AbsListView view, int scrollState) {
    final ListView lw = getListView();

    if (view.getId() == lw.getId()) {
        final int currentFirstVisibleItem = lw.getFirstVisiblePosition();

        if (currentFirstVisibleItem > mLastFirstVisibleItem) {
            mIsScrollingUp = false;
        } else if (currentFirstVisibleItem < mLastFirstVisibleItem) {
            mIsScrollingUp = true;
        }

        mLastFirstVisibleItem = currentFirstVisibleItem;
    } 
}

检查mIsScrollingUp中是真还是假getView()，并相应地分配动画。

于 2012-08-24T18:58:22.227 回答
19

我最终这样做了：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    Log.i("",position+" - "+lastposition);

    if (position >= lastposition)
        animation = new TranslateAnimation(Animation.RELATIVE_TO_SELF,
                0.0f, Animation.RELATIVE_TO_SELF, 0.0f,
                Animation.RELATIVE_TO_SELF, 1.0f,
                Animation.RELATIVE_TO_SELF, 0.0f);
    else
        animation = new TranslateAnimation(Animation.RELATIVE_TO_SELF,
                0.0f, Animation.RELATIVE_TO_SELF, 0.0f,
                Animation.RELATIVE_TO_SELF, -1.0f,
                Animation.RELATIVE_TO_SELF, 0.0f);

    animation.setDuration(600);
    set.addAnimation(animation);

    row.startAnimation(set);

    lastposition = position;

}
于 2012-08-24T19:21:04.137 回答
5

更复杂的解决方案（在列表视图中处理长项目高度）

  1. 创建自定义列表视图

    public class ScrollDetectingListView extends ListView {
    public ScrollDetectingListView(Context context) {
        super(context);
    }

    public ScrollDetectingListView(Context context, AttributeSet attrs) {
        super(context,attrs);
    } 

    public ScrollDetectingListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    //we need this protected method for scroll detection
    public int getVerticalScrollOffset() {
        return computeVerticalScrollOffset();
    }
}

  2. 覆盖 onScroll

        listView.setOnScrollListener(new AbsListView.OnScrollListener() {

    private int mInitialScroll = 0;

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {

    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        int scrolledOffset = listView.getVerticalScrollOffset();
        if (scrolledOffset!=mInitialScroll) {
            //if scroll position changed
            boolean scrollUp = (scrolledOffset - mInitialScroll) < 0;
            mInitialScroll = scrolledOffset;
        }
    }
    });
于 2014-08-29T08:45:04.167 回答
5

接受的答案并没有真正“检测”向上或向下滚动。如果当前可见项目真的很大，它将不起作用。使用onTouchListener是要走的路。

这是我使用的代码片段：

listView.setOnTouchListener(new View.OnTouchListener() {
    float initialY, finalY;
    boolean isScrollingUp;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        int action = MotionEventCompat.getActionMasked(event);

        switch(action) {
            case (MotionEvent.ACTION_DOWN):
                initialY = event.getY();
            case (MotionEvent.ACTION_UP):
                finalY = event.getY();

                if (initialY < finalY) {
                    Log.d(TAG, "Scrolling up");
                    isScrollingUp = true;
                } else if (initialY > finalY) {
                    Log.d(TAG, "Scrolling down");
                    isScrollingUp = false;
                }
            default:
        }

        if (isScrollingUp) {
            // do animation for scrolling up
        } else {
            // do animation for scrolling down
        }

        return false; // has to be false, or it will freeze the listView
    }
});
于 2015-05-23T16:20:54.090 回答
4

试试这个 。我希望它对你有帮助。来自@Gal Rom 答案的逻辑。

lv.setOnScrollListener(new OnScrollListener() {
        private int mLastFirstVisibleItem;

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            if(mLastFirstVisibleItem<firstVisibleItem)
            {
                Log.i("SCROLLING DOWN","TRUE");
            }
            if(mLastFirstVisibleItem>firstVisibleItem)
            {
                Log.i("SCROLLING UP","TRUE");
            }
            mLastFirstVisibleItem=firstVisibleItem;

        }
    });
于 2015-03-17T05:12:44.397 回答
4

这是我遇到的最简单和最简单的方法。它就像一个魅力。

view.addOnScrollListener(new View.OnScrollListener() {
                @Override
                public void onScrolled(@NonNull View view, int dx, int dy) {
                    if (dy > 0) {
                        //Scrolling down
                    } else if (dy < 0) {
                        //Scrolling up
                    }
                }
            });
于 2020-03-21T11:14:47.917 回答
2

这是我的方法：它可以让您更直接地反馈您滚动了多少： OnScroll，您只需获得列表中第一项的 Top 位置。立即获得实际的滚动位置信息非常可靠。

listView.getChildAt(0).getTop()
于 2013-05-06T18:25:42.807 回答
0

我使用了这个更简单的解决方案：

public class ScrollDetectingListView extends ListView

...

setOnScrollListener( new OnScrollListener() 
{

    private int mInitialScroll = 0;

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) 
    {
        int scrolledOffset = computeVerticalScrollOffset();

        boolean scrollUp = scrolledOffset > mInitialScroll;
        mInitialScroll = scrolledOffset;
    }


    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {


    }

}
于 2014-05-31T13:21:42.690 回答
0 
list.setOnScrollListener(new OnScrollListener() {
        int last_item;
        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {
            if(last_item<firstVisibleItem+visibleItemCount-1){
                System.out.println("List is scrolling upwards");
            }
            else if(last_item>firstVisibleItem+visibleItemCount-1){
                System.out.println("List is scrolling downwards");
            }
             last_item = firstVisibleItem+visibleItemCount-1;
        }
    });

根据最后一个可见项目的位置，我决定 Listview 是向上还是向下。

于 2015-04-14T12:21:14.350 回答
0

不依赖于视图/等位置的通用解决方案。只需检查垂直滚动偏移量并将其与之前的滚动偏移量进行比较。如果新值大于旧值，则用户向下滚动，反之亦然。

// [START check vertical scroll direction]
int oldScrollOffset = 0;

listView.setOnScrollChangeListener(new View.OnScrollChangeListener() {
        @Override
        public void onScrollChange(View view, int i, int i1, int i2, int i3) {

            Boolean scrollDirectionDown;

            int newScrollOffset = listView.computeVerticalScrollOffset();

            if (newScrollOffset > oldScrollOffset) {
                scrollDirectionDown = true;
            } else {
                scrollDirectionDown = false;
            }

            oldScrollOffset = newScrollOffset;

            if (scrollDirectionDown) {
                // Update accordingly for scrolling down
                Log.d(TAG, "scrolling down");
            } else {
                // Update accordingly for scrolling up
                Log.d(TAG, "scrolling up");
            }

    });
// [END check vertical scroll direction]
于 2019-02-08T02:56:06.493 回答
0 
view.setOnTouchListener(new View.OnTouchListener() {

        private long startClickTime;
        float y0 = 0;
        float y1 = 0;
        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {

            if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
                y0 = motionEvent.getY();
                startClickTime = System.currentTimeMillis();

            } else if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
                if (System.currentTimeMillis() - startClickTime < ViewConfiguration.getTapTimeout()) {

                    // Touch was a simple tap. Do whatever.

                } else {
                    y1 = motionEvent.getY();
                    // Touch was a not a simple tap.
                    if (y1 - y0 > 50) {
                        // this is down
                    } else if (y1 - y0 < 50) {
                        Log.d("daniY", "-");
                        // this is up
                    }
                }

            }

            return true;
        }

    });

这对我有用，这将有助于检测我认为的所有视图的滚动方向。

于 2020-11-19T23:29:36.613 回答