CustomBottoBar

package notebook.shbehk.notebook;

import android.content.Context;
import android.graphics.*;
import android.support.design.widget.BottomNavigationView;
import android.util.AttributeSet;

public class CurvedBottomNavigationView extends BottomNavigationView {
    private Path mPath;
    private Paint mPaint;

    /** the CURVE_CIRCLE_RADIUS represent the radius of the fab button */    private final int CURVE_CIRCLE_RADIUS = 256 / 2;
    // the coordinates of the first curve
    private Point mFirstCurveStartPoint = new Point();
    private Point mFirstCurveEndPoint = new Point();
    private Point mFirstCurveControlPoint1 = new Point();
    private Point mFirstCurveControlPoint2 = new Point();

    //the coordinates of the second curve
    @SuppressWarnings("FieldCanBeLocal")
    private Point mSecondCurveStartPoint = new Point();
    private Point mSecondCurveEndPoint = new Point();
    private Point mSecondCurveControlPoint1 = new Point();
    private Point mSecondCurveControlPoint2 = new Point();
    private int mNavigationBarWidth;
    private int mNavigationBarHeight;

    public CurvedBottomNavigationView(Context context) {
        super(context);
        init();
    }

    public CurvedBottomNavigationView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public CurvedBottomNavigationView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mPath = new Path();
        mPaint = new Paint();
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setColor(Color.WHITE);
        setBackgroundColor(Color.TRANSPARENT);
    }

    @Override    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

    }

    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        // get width and height of navigation bar
        // Navigation bar bounds (width & height)
         mNavigationBarWidth = getWidth();
         mNavigationBarHeight = getHeight();
        // the coordinates (x,y) of the start point before curve
        mFirstCurveStartPoint.set((mNavigationBarWidth / 2) - (CURVE_CIRCLE_RADIUS * 2) - (CURVE_CIRCLE_RADIUS / 3), 0);
        // the coordinates (x,y) of the end point after curve
        mFirstCurveEndPoint.set(mNavigationBarWidth / 2, CURVE_CIRCLE_RADIUS + (CURVE_CIRCLE_RADIUS / 4));
        // same thing for the second curve
        mSecondCurveStartPoint = mFirstCurveEndPoint;
        mSecondCurveEndPoint.set((mNavigationBarWidth / 2) + (CURVE_CIRCLE_RADIUS * 2) + (CURVE_CIRCLE_RADIUS / 3), 0);

        // the coordinates (x,y)  of the 1st control point on a cubic curve
        mFirstCurveControlPoint1.set(mFirstCurveStartPoint.x + CURVE_CIRCLE_RADIUS + (CURVE_CIRCLE_RADIUS / 4), mFirstCurveStartPoint.y);
        // the coordinates (x,y)  of the 2nd control point on a cubic curve
        mFirstCurveControlPoint2.set(mFirstCurveEndPoint.x - (CURVE_CIRCLE_RADIUS * 2) + CURVE_CIRCLE_RADIUS, mFirstCurveEndPoint.y);

        mSecondCurveControlPoint1.set(mSecondCurveStartPoint.x + (CURVE_CIRCLE_RADIUS * 2) - CURVE_CIRCLE_RADIUS, mSecondCurveStartPoint.y);
        mSecondCurveControlPoint2.set(mSecondCurveEndPoint.x - (CURVE_CIRCLE_RADIUS + (CURVE_CIRCLE_RADIUS / 4)), mSecondCurveEndPoint.y);

        mPath.reset();
        mPath.moveTo(0, 0);
        mPath.lineTo(mFirstCurveStartPoint.x, mFirstCurveStartPoint.y);

        mPath.cubicTo(mFirstCurveControlPoint1.x, mFirstCurveControlPoint1.y,
                mFirstCurveControlPoint2.x, mFirstCurveControlPoint2.y,
                mFirstCurveEndPoint.x, mFirstCurveEndPoint.y);

        mPath.cubicTo(mSecondCurveControlPoint1.x, mSecondCurveControlPoint1.y,
                mSecondCurveControlPoint2.x, mSecondCurveControlPoint2.y,
                mSecondCurveEndPoint.x, mSecondCurveEndPoint.y);

        mPath.lineTo(mNavigationBarWidth, 0);
        mPath.lineTo(mNavigationBarWidth, mNavigationBarHeight);
        mPath.lineTo(0, mNavigationBarHeight);
        mPath.close();
    }

    @Override    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawPath(mPath, mPaint);

    }
}

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import com.example.saidi.custombottobar.R;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CurvedBottomNavigationView curvedBottomNavigationView = findViewById(R.id.customBottomBar);
        curvedBottomNavigationView.inflateMenu(R.menu.bottom_menu);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorAccent"
        tools:context=".view.MainActivity">

    <com.example.saidi.custombottobar.view.CurvedBottomNavigationView
            android:id="@+id/customBottomBar"
            android:layout_width="match_parent"
            android:layout_height="72dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"/>

</android.support.constraint.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>

<menu xmlns:android="http://schemas.android.com/apk/res/android"

      xmlns:app="http://schemas.android.com/apk/res-auto">

    <item

            android:id="@+id/action_favorites"

            android:enabled="true"

            android:icon="@android:drawable/alert_dark_frame"

            android:title="Page1"

            app:showAsAction="ifRoom"/>

    <item

            android:id="@+id/action_schedules"

            android:enabled="true"

            android:title="Page2"

            app:showAsAction="ifRoom"/>

    <item

            android:id="@+id/action_music"

            android:enabled="true"

            android:icon="@android:drawable/alert_dark_frame"

            android:title="Page3"

            app:showAsAction="ifRoom"/>

</menu>