CollapsingToolbarLayout and FloatingActionButton

Question

我有一个 CollapsingToolbarLayout，里面有两个 FloatingActionButtons。这些 FABs 仅在 Toolbar 展开时可见。当它折叠时，它们就会被隐藏起来。我希望它们在 Toolbar 折叠时也可见。我该怎么办？

非常感谢您的建议...

    <?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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"
    android:fitsSystemWindows="true"
    tools:context=".CalendarEventInsUpdActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/app_bar_height"
        android:fitsSystemWindows="true"
        android:theme="@style/AppTheme.AppBarOverlay">

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

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="parallax"
                app:popupTheme="@style/AppTheme.PopupOverlay"/>

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

    <include layout="@layout/content_calendar_event"/>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_menu_save"
        app:backgroundTint="@android:color/holo_green_light"
        app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|center"/>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/btnCancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_menu_revert"
        app:backgroundTint="@android:color/holo_red_light"
        app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|end"/>

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

- Jodynek

Answer 1

你需要在FAB上添加一个行为。

可以尝试类似以下的操作：

public class ScrollingFABBehavior extends CoordinatorLayout.Behavior<FloatingActionButton> {
    private int toolbarHeight;

    public ScrollingFABBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.toolbarHeight = Utils.getToolbarHeight(context);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton fab, View dependency) {
        return dependency instanceof AppBarLayout;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, FloatingActionButton fab, View dependency) {
        //do nothing with the fab or write your logic for the FAB
        return true;
    }
}

然后使用XML FAB标签添加行为。

app:layout_behavior="com.example.ScrollingFABBehavior" />

- royB

---

我选择@royB的答案，因为他的解决方案可以让我在Java代码中影响FAB的行为。 - Jodynek

Answer 2

你必须将 Fabs 作为 cordinatorLayout 的直接子元素，并使用布局行为：

<android.support.design.widget.FloatingActionButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

- bryan c

---

使用类似我的 Layout_behaviors。 - bryan c

Answer 3

试试这个 XML。

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

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

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



            <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>

    <include layout="@layout/content_calendar_event"/>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_menu_save"
        app:backgroundTint="@android:color/holo_green_light"
        app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|center"/>

        <android.support.design.widget.FloatingActionButton
        android:id="@+id/btnCancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_menu_revert"
        app:backgroundTint="@android:color/holo_red_light"
        app:layout_anchor="@id/app_bar"
        app:layout_anchorGravity="bottom|end"/>


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

- Muhammad Waleed