Complete Guide to Implementing DrawerLayout Over ActionBar/Toolbar and Under Status Bar

Core Implementation Principles

Implementing DrawerLayout to overlay ActionBar/Toolbar and extend under the status bar requires the coordinated work of three key components: First, use Toolbar to replace the traditional ActionBar, embedding it into the view hierarchy; Second, configure the fitsSystemWindows property of DrawerLayout to allow its layout to extend into the system bar area; Finally, disable the system's default status bar coloring through theme settings, allowing DrawerLayout to draw in that area.

Layout Structure Design

Proper layout structure is the foundation for achieving the desired effect. Below is a standard layout example:

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/my_drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar
            android:id="@+id/my_awesome_toolbar"
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            android:minHeight="?attr/actionBarSize"
            android:background="?attr/colorPrimary" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="304dp"
        android:layout_height="match_parent"
        android:layout_gravity="left|start"
        android:fitsSystemWindows="true">

    </LinearLayout>

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

In this layout, DrawerLayout serves as the root container with its fitsSystemWindows property set to true, which is key to extending into the status bar area. Toolbar is part of the content view, ensuring the drawer can display in front of the action bar.

Programming Implementation

Corresponding programming configuration is required in Activity or Fragment:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Toolbar toolbar = findViewById(R.id.my_awesome_toolbar);
    setSupportActionBar(toolbar);

    DrawerLayout drawerLayout = findViewById(R.id.my_drawer_layout);
    drawerLayout.setStatusBarBackgroundColor(getResources().getColor(R.color.your_chosen_color));
}

This code first sets the Toolbar as the application's action bar, then obtains the DrawerLayout instance and sets the status bar background color. Note that the setStatusBarBackgroundColor method only takes effect on Lollipop and above, or when using translucent status bar on KitKat.

Theme Configuration

To ensure DrawerLayout correctly displays behind the status bar, corresponding theme configuration needs to be created in the values-v21 directory:

<style name="Theme.MyApp" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowDrawsSystemBarBackgrounds">true</item>
    <item name="android:statusBarColor">@android:color/transparent</item>
    <item name="android:windowTranslucentStatus">true</item>
</style>

These property configurations ensure that system bar backgrounds are drawn by the application, status bar color is set to transparent, and translucent status bar effect is enabled.

Fragment Implementation Solution

When using Fragment as drawer content, the fitsSystemWindows property needs to be set in the onCreateView method:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View mDrawerListView = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
    mDrawerListView.setFitsSystemWindows(true);
    return mDrawerListView;
}

This approach ensures that the Fragment's root view can properly handle the insets of system windows.

Compatibility Considerations

Although the Android Design Support Library provides a more simplified implementation, the method introduced in this article offers better compatibility and controllability. For applications requiring precise control over visual effects, this implementation based on core support libraries is more appropriate. Developers can choose the suitable implementation method based on specific requirements.