java - CollapsingToolbarLayout 和 FloatingActionButton

Question

我有 CollapsingToolbarLayout 和两个 FloatingActionButtons。这些 FAB 仅在 Toolbar 展开时可见。折叠时，它们会隐藏起来。如果工具栏也折叠了，我需要它们可见。我该怎么做？

非常感谢您的提示...

    <?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>

Answer 1

您需要添加一个 Behavior到 FAB。

尝试类似的东西:

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" />