协调器布局，工具栏顶部空白背景

Question

I am trying to implement a CoordinatorLayout in which I need a shrinking card view. I plan to have different layouts for expanded and shrunk state of this card view later on. I have successfully implemented empty card view but I am getting a weird background in top margin of this card view.

Its difficult to explain in words so here are the pictures

Here is how my XML looks like for this activity

<?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">

<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:layout_margin="16dp">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:elevation="4dp"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        app:toolbarId="@+id/toolbar">

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

            <!--<android.support.v7.widget.CardView-->
                <!--android:layout_width="match_parent"-->
                <!--android:layout_height="match_parent"-->
                <!--android:background="@color/colorAccent"-->
                <!--android:layout_margin="8dp"/>-->
        </android.support.v7.widget.Toolbar>

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

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

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/fab_margin"
    app:layout_anchor="@id/app_bar"
    app:layout_anchorGravity="bottom|end"
    app:srcCompat="@android:drawable/ic_dialog_email"/>

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

I want this toolbar to float like a card view. Let me know if more details are needed from my end.

You can find full source code on Github Here .

Answer 1

You are setting layout_margin to your AppBarLayout which sets margin for this view vertically as well as horizontally (simply for top, bottom, right and left).

If you want to set margin from a specific side then you have to set margins manually by layout_marginLeft , layout_marginRight , layout_marginBottom and layout_marginTop .

So simply, if you want to remove top margin. Then simply set margins manually as,

<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:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginBottom="16dp">

       <!-- your components here -->

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

Answer 2

• I ended up adding the same amount padding to the CoordinatorLayout

  android:paddingTop="16dp"

• change android:layout_margin="16" in your AppBarLayout to

   android:layout_marginLeft="16dp" android:layout_marginRight="16dp" android:layout_marginBottom="16dp" 

I have tested it and it works