How to make Toolbar transparent on scroll?

Question

Android

Good afternoon, at the moment the activity layout looks like this:

<FrameLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:background="?attr/colorPrimary"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/fragmentContainer"/>

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@android:color/transparent">
    </android.support.v7.widget.Toolbar>
    
</FrameLayout >

And everything seems to be fine, the toolbar turns out to be transparent, but the fragment is inserted in full screen and a transparent toolbar is superimposed on it. I want the fragment to be inserted as usual, under the toolbar, and when scrolling up, the toolbar becomes transparent.
What I want is implemented in QuickPic.
I tried to make paddings for the size of the toolbar, but in this case the toolbar gets a fixed color and it doesn't become transparent when scrolling. How to be?