Apps Including buttons making my canvas drawing like hexagon shape in Android ?

[Zaheer Ahmed]

I'm creating a canvas drawing app in Android that has lots of buttons in xml file. The problems is when I draw a circle with all those buttons included in the file it's never a smooth circle it's full of corners like hexagon shape but when I exclude buttons may be leaving in one or two, it draws a perfect smooth circle. I have tried to split the file into three so I've included them using but still same result.

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".MainActivity">

<!--First Draw -->
<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:openDrawer="start">

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

        <ImageButton
            android:id="@+id/nav_one"
            android:layout_width="30dp"
            android:layout_height="60dp"
            android:layout_marginTop="100dp"
            android:layout_marginBottom="100dp"
            android:background="@drawable/ic_tab_res_bkg"/>
        <ImageButton
            android:id="@+id/nav_two"
            android:layout_width="30dp"
            android:layout_height="60dp"
            android:layout_marginTop="200dp"
            android:background="@drawable/ic_tab_tools_bkg"/>
    </LinearLayout>

    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

   <!-- The navigation drawer -->

   <ListView android:id="@+id/resource_bank"
        android:layout_width="350dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:choiceMode="singleChoice"
        android:divider="@android:color/background_light"
        android:dividerHeight="0dp"
        android:background="#f4f1f1"
        />
    <ListView android:id="@+id/tools"
        android:layout_width="350dp"
        android:layout_height="match_parent"
        android:layout_gravity="end"
        android:choiceMode="singleChoice"
        android:divider="@android:color/background_light"
        android:dividerHeight="0dp"
        android:background="#dedada"/>

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

<RelativeLayout
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center" >

    <xxxxx.xxxxxx.xxxx.xxxxxx.DrawView
        android:id="@+id/canvas_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <FrameLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/canvas_view">

        <!-- Pen icons -->

    <include  layout="@layout/activity_pen_color" android:id="@+id/pen_color" />
    <include layout="@layout/activity_pen_style"  android:id="@+id/pen_style" />

        <!--  Navigation bar icons  -->

        <ImageView
            android:id="@+id/icon_bar"
            android:layout_width="match_parent"
            android:layout_height="70dp"
            android:layout_gravity="bottom"
            android:background="@drawable/icon_bar_bkg"
            />
        <Button
            android:id="@+id/ic_select"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginLeft="150dp"
            android:layout_marginTop="60dp"
            android:elevation="1dp"
            android:background="@drawable/ic_select_bkg"/>
        <TextView
            android:id="@+id/text_select"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="150dp"
            android:layout_marginTop="90dp"
            android:text="Select"
            android:textColor="@color/colorAccent"
            />
        <Button
            android:id="@+id/ic_pens"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginLeft="200dp"
            android:layout_marginTop="60dp"
            android:elevation="1dp"
            android:background="@drawable/ic_pen_bkg"/>
        <TextView
            android:id="@+id/text_pens"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="200dp"
            android:layout_marginTop="90dp"
            android:text="Pen"
            android:textColor="@color/colorAccent"
            />
    </FrameLayout>
  </RelativeLayout>