Unable to get exact circle shape when using card view

Question

I'm using card view for floating action button in android material design. I'm using following code for get the circle

<android.support.v7.widget.CardView
    android:id="@+id/fab"
    android:layout_width="38dp"
    android:layout_height="38dp"
    android:layout_marginBottom="10dp"
    android:layout_marginRight="10dp"
    card_view:background="@color/blue"
    card_view:cardCornerRadius="19dp"
    card_view:cardPreventCornerOverlap = "false"
    card_view:cardElevation="6dp" >
</android.support.v7.widget.CardView>

I have set corner radius as half of width. but still I can't get the circle shape.

Answer 1

To achieve a circular shape using Card view you can set the shape property, android:shape="ring".
app:cardCornerRadius should be set to half the width or height of the child view

<android.support.v7.widget.CardView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:innerRadius="0dp"
        android:shape="ring"
        app:cardCornerRadius="75dp">

        <ImageView
            android:layout_width="150dp"
            android:layout_height="150dp"
            android:layout_gravity="center"
            android:background="@drawable/image" />
     </android.support.v7.widget.CardView>