"""
A Hello World GUI.

The purpose of this App is to test that Kivy is installed correctly.

Author: Walker M. White (wmw2)
Date:   August 25, 2017 (Python 3 Version)
"""

# Import a bunch of Kivy stuff
import kivy
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.label import Label
from kivy.graphics.vertex_instructions import Rectangle
from kivy.graphics.context_instructions import Color
from kivy.config import Config
Config.set('graphics', 'multisamples', '0')

from kivy.metrics import dp


class Panel(FloatLayout):
    """
    A drawing canvas to display the label.
    
    This is a simple Kivy panel that contains Hello World.
    """
    
    def __init__(self,**kw):
        """
        Constructor: Makes a new Panel for drawing shapes
        
        Precondition: **kw are Kivy key-word arguments
        """
        # Pass Kivy arguments to super class.
        super(Panel,self).__init__(**kw)
        
        # Need kivy.metrics to handle retina Macs properly
        rsize = [0,0]
        rsize[0] = self.size[0]*dp(1)
        rsize[1] = self.size[0]*dp(1)
        
        # Make the background solid white
        color = Color(1.0,1.0,1.0,1.0)
        self.canvas.add(color)
        rect = Rectangle(pos=self.pos, size=rsize)
        self.canvas.add(rect)
        
        # Add the label
        label = Label(text="Hello World!")
        label.color = [0.0,0.0,0.0,1.0]
        label.size_hint = (1,1)
        label.font_size = 48*dp(1) # Again, retina Macs
        label.bold = True
        self.add_widget(label)


class HelloApp(App):
    """
    The primary application object.
    
    
    We create and run this instance to get the panel.
    """
    
    def build(self):
        """
        Builds and application with a single internal panel
        """
        Config.set('graphics', 'width', '450')
        Config.set('graphics', 'height', '250')
        return Panel(size=(450,250))


# Application Code
if __name__ == '__main__':
    HelloApp().run()