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Added actor function to check if on screen #370

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b6363f5
Added actor function to check if on screen
Mambouna Sep 13, 2025
126d0f0
Fixed flake8 problems
Mambouna Sep 26, 2025
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14 changes: 14 additions & 0 deletions doc/builtins.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -660,6 +660,20 @@ of transparency:
through a ghost.


On screen or not
''''''''''''''''

There is a simple function to check whether an Actor is visible on the screen:

.. method:: Actor.is_onscreen()

Returns ``True`` if the Actor is currently inside the screen bounds and
``False`` if not.

This can be useful if you have many game objects flying around the screen that
should disappear as soon as they are out of sight.


The Keyboard
------------

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5 changes: 5 additions & 0 deletions src/pgzero/actor.py
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Expand Up @@ -361,5 +361,10 @@ def distance_to(self, target):
dy = ty - myy
return sqrt(dx * dx + dy * dy)

def is_onscreen(self):
"""Returns whether the Actor is within the screen bounds or not."""
return not (self.right < 0 or self.left > game.screen.get_width() or
self.bottom < 0 or self.top > game.screen.get_height())

def unload_image(self):
loaders.images.unload(self._image_name)
23 changes: 23 additions & 0 deletions test/test_actor.py
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import unittest
from unittest.mock import patch

import pygame

Expand Down Expand Up @@ -146,3 +147,25 @@ def test_dir_correct(self):
a = Actor("alien")
for attribute in dir(a):
a.__getattr__(attribute)

# Since the tests don't create the proper screen, it must be mocked for
# these test functions.
@patch("pgzero.actor.game.screen.get_height")
@patch("pgzero.actor.game.screen.get_width")
@patch("pgzero.actor.game.screen")
def test_onscreen(self, mock_screen, mock_get_width, mock_get_height):
"""We can check if the Actor is in the screen bounds."""
mock_get_width.return_value = 200
mock_get_height.return_value = 100
a = Actor("alien", (10, 10))
self.assertTrue(a.is_onscreen())

@patch("pgzero.actor.game.screen.get_height")
@patch("pgzero.actor.game.screen.get_width")
@patch("pgzero.actor.game.screen")
def test_not_onscreen(self, mock_screen, mock_get_width, mock_get_height):
"""We can check if the Actor is not within the screen bounds."""
a = Actor("alien", (10, 1000))
mock_get_width.return_value = 200
mock_get_height.return_value = 100
self.assertFalse(a.is_onscreen())