PYGLET – On Context Lost Event

In this article we will see how we can trigger on context lost event in PYGLET module in python. Pyglet is easy to use but powerful library for developing visually rich GUI applications like games, multimedia etc. A window is a “heavyweight” object occupying operating system resources. Windows may appear as floating regions or can be set to fill an entire screen (fullscreen). When the context is lost no more GL methods can be called until it is recreated. This is a rare event, triggered perhaps by the user switching to an incompatible video mode. When it occurs, an application will need to reload all objects (display lists, texture objects, shaders) as well as restore the GL state.
We can create a window with the help of command given below 

pyglet.window.Window(width, height, title)

Below is the syntax of the window on context lost event, this method get called when this event is triggered 

@window.event       
def on_context_lost():
    print("Please wait, reloading")

Below is the implementation 

Python3

# importing pyglet module
import pyglet
import pyglet.window.key

# width of window
width = 500

# height of window
height = 500

# caption i.e title of the window
title = "Geeksforgeeks"

# creating a window
window = pyglet.window.Window(width, height, title)

# text
text = "GeeksforGeeks"

# creating a label with font = times roman
# font size = 36
# aligning it to the center
label = pyglet.text.Label(text,
                          font_name ='Times New Roman',
                          font_size = 36,
                          x = window.width//2, y = window.height//2,
                          anchor_x ='center', anchor_y ='center')

# on draw event
@window.event
def on_draw():

    # clearing the window
    window.clear()

    # drawing the label on the window
    label.draw()

# key press event
@window.event
def on_key_press(symbol, modifier):

    print("nn")
    # key "C" get press
    if symbol == pyglet.window.key.C:

        # close the window
        window.close()


@window.event
# window close event
def on_context_lost():

    # printing message
    print("Please wait, reloading")



# image for icon
img = image = pyglet.resource.image("logo.png")

# setting image as icon
window.set_icon(img)

# start running the application
pyglet.app.run()

Output :