CollapsingToolbarLayout无法识别滚动显示

Question

我创建了一个简单的CollapsingToolbarLayout,它就像一个魅力.我的问题是,如果我尝试在nestedscrollview上使用一个滚动滚动,它会在我释放手指时停止.正常滚动就像它应该的那样工作.

我的活动代码未更改=>自动生成的空活动.(我刚刚点击了在android studio中创建新的空活动并编辑了XML).

我在这里看到,imageview本身的滚动手势是错误的,但不是,滚动本身是错误的:看到这里.

我尝试通过java代码激活"平滑滚动".似乎如果我滚动得足够远以至于不再可见图像视图,则可以识别出手势.

TLDR:只要图像视图可见,为什么抛弃手势不起作用？我的XML代码如下所示:

    <android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/profile_app_bar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        android:fitsSystemWindows="true">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/profile_collapsing_toolbar_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginStart="48dp"
            app:expandedTitleMarginEnd="64dp"
            android:fitsSystemWindows="true">

            <ImageView
                android:id="@+id/image"
                android:layout_width="match_parent"
                android:layout_height="420dp"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                android:src="@drawable/headerbg"
                android:maxHeight="192dp"

                app:layout_collapseMode="parallax"/>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_collapseMode="pin" />

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        app:layout_anchor="@id/profile_app_bar_layout"
        app:layout_anchorGravity="bottom|right|end"
        android:layout_height="@dimen/fab_size_normal"
        android:layout_width="@dimen/fab_size_normal"
        app:elevation="2dp"
        app:pressedTranslationZ="12dp"
        android:layout_marginRight="8dp"
        android:layout_marginEnd="8dp"/>

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/profile_content_scroll"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:layout_gravity="fill_vertical"
        android:minHeight="192dp"
        android:overScrollMode="ifContentScrolls"
        >

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/LoremIpsum"/>

        </RelativeLayout>

    </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>

Answer 1

我在使用ImageView内部和NestedScrollView的CollapsingToolbarLayout时遇到了完全相同的问题.手指松开后,滚动停止.

但是,我注意到一些奇怪的事情.如果您使用OnClickListener(例如Button)从视图开始滚动手指,则滚动滚动效果非常好.

因此,我用一个奇怪的解决方案修复它.在NestedScrollView的直接子节点上设置OnClickListener(不执行任何操作).然后它完美地运作!

<android.support.v4.widget.NestedScrollView 
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   app:layout_behavior="@string/appbar_scrolling_view_behavior">

  <LinearLayout
      android:id="@+id/content_container"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="vertical">

    <!-- Page Content -->

  </LinearLayout>

</android.support.v4.widget.NestedScrollView>

给直接子(LinearLayout)一个id并在Activity中设置OnClickListener

ViewGroup mContentContainer = (ViewGroup) findViewById(R.id.content_container);    
mContentContainer.setOnClickListener(this);

@Override
public void onClick(View view) {
    int viewId = view.getId();
}

笔记:

使用Support Design Library 25.0.1进行测试

CollapsingToolbarLayout with scrollFlags ="scroll | enterAlwaysCollapsed"

Answer 2

我知道这个问题是在一年前提出来的,但这个问题似乎仍未在支持/设计库中得到解决.您可以解决此问题,以便它在优先级队列中进一步向上移动.

也就是说,我尝试了大部分已发布的解决方案,包括patrick-iv的解决方案,但没有成功.我能够开始工作的唯一方法是模仿fling并在检测到某些条件时以编程方式调用它onPreNestedScroll().在我调试的几个小时内,我注意到它onNestedFling()从未被调用过向上(向下滚动),似乎过早地被消耗掉了.我不能100%肯定地说这将适用于100%的实现,但它适用于我的用途,所以我最终解决了这个问题,即使它非常hacky并且绝对不是我想要做的.

public class NestedScrollViewBehavior extends AppBarLayout.Behavior {

    // Lower value means fling action is more easily triggered
    static final int MIN_DY_DELTA = 4;
    // Lower values mean less velocity, higher means higher velocity
    static final int FLING_FACTOR = 20;

    int mTotalDy;
    int mPreviousDy;
    WeakReference<AppBarLayout> mPreScrollChildRef;

    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child,
                                  View target, int dx, int dy, int[] consumed) {
        super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed);
        // Reset the total fling delta distance if the user starts scrolling back up
        if(dy < 0) {
            mTotalDy = 0;
        }
        // Only track move distance if the movement is positive (since the bug is only present
        // in upward flings), equal to the consumed value and the move distance is greater
        // than the minimum difference value
        if(dy > 0 && consumed[1] == dy && MIN_DY_DELTA < Math.abs(mPreviousDy - dy)) {
            mPreScrollChildRef = new WeakReference<>(child);
            mTotalDy += dy * FLING_FACTOR;
        }
        mPreviousDy = dy;
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout parent, AppBarLayout child,
                                       View directTargetChild, View target, int nestedScrollAxes) {
        // Stop any previous fling animations that may be running
        onNestedFling(parent, child, target, 0, 0, false);
        return super.onStartNestedScroll(parent, child, directTargetChild, target, nestedScrollAxes);
    }

    @Override
    public void onStopNestedScroll(CoordinatorLayout parent, AppBarLayout abl, View target) {
        if(mTotalDy > 0 && mPreScrollChildRef != null && mPreScrollChildRef.get() != null) {
            // Programmatically trigger fling if all conditions are met
            onNestedFling(parent, mPreScrollChildRef.get(), target, 0, mTotalDy, false);
            mTotalDy = 0;
            mPreviousDy = 0;
            mPreScrollChildRef = null;
        }
        super.onStopNestedScroll(parent, abl, target);
    }
}

并将其应用于AppBar

AppBarLayout scrollView = (AppBarLayout)findViewById(R.id.appbar);
CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams)scrollView.getLayoutParams();
params.setBehavior(new NestedScrollViewBehavior());

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