How to change menu icon size on toolbar?

Question

This is my menu.xml file:

<?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/men_item_scan"
          android:title="@null"
          android:icon="@mipmap/scan_qr"
        app:showAsAction="always"/>
</menu>

and question is how can i change the size of the icon? the scan_qr.png's size is 224*89 but it's so small when the app is running on my phone.

Answer 1

Finally, i used @ShivaSnape 's method, and it works for me.

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    android:background="@color/colorPrimary">
    <ImageView
        android:id="@+id/img_qrorrfid"
        android:layout_gravity="end"
        android:layout_width="112dp"
        android:layout_height="44dp"
        android:scaleType="centerInside"
        android:src="@mipmap/scan_qr"/>
</android.support.v7.widget.Toolbar>