Input System¶

The input system provides a unified interface for handling keyboard, mouse, and gamepad input.

InputManager¶

class InputManager:
    def __init__(self):
        """Initialize the input manager."""

Methods¶

update()¶

def update(self) -> None

Update input state for the current frame. Should be called once per frame.

is_key_pressed()¶

def is_key_pressed(self, key: int) -> bool

Check if a key is currently being held down.

is_key_just_pressed()¶

def is_key_just_pressed(self, key: int) -> bool

Check if a key was just pressed this frame.

is_key_just_released()¶

def is_key_just_released(self, key: int) -> bool

Check if a key was just released this frame.

get_mouse_position()¶

def get_mouse_position(self) -> Tuple[int, int]

Get the current mouse position as (x, y).

is_mouse_button_pressed()¶

def is_mouse_button_pressed(self, button: int) -> bool

Check if a mouse button is currently being held down.

is_mouse_button_just_pressed()¶

def is_mouse_button_just_pressed(self, button: int) -> bool

Check if a mouse button was just pressed this frame.

is_mouse_button_just_released()¶

def is_mouse_button_just_released(self, button: int) -> bool

Check if a mouse button was just released this frame.

Key Constants¶

Common keyboard key constants:

from pygame import K_a, K_b, K_c  # Letters
from pygame import K_0, K_1, K_2  # Numbers
from pygame import K_LEFT, K_RIGHT, K_UP, K_DOWN  # Arrows
from pygame import K_SPACE, K_RETURN, K_ESCAPE  # Special keys

Mouse Button Constants¶

Mouse button constants:

from pygame import BUTTON_LEFT, BUTTON_MIDDLE, BUTTON_RIGHT

Example Usage¶

Basic Input Handling¶

from src.core.input import InputManager
from pygame import K_SPACE, K_LEFT, K_RIGHT, BUTTON_LEFT

# Create input manager
input_manager = InputManager()

def update():
    # Update input state
    input_manager.update()

    # Check keyboard input
    if input_manager.is_key_pressed(K_LEFT):
        move_left()
    elif input_manager.is_key_pressed(K_RIGHT):
        move_right()

    # Check for jump (only on initial press)
    if input_manager.is_key_just_pressed(K_SPACE):
        jump()

    # Get mouse position
    mouse_x, mouse_y = input_manager.get_mouse_position()

    # Check mouse input
    if input_manager.is_mouse_button_just_pressed(BUTTON_LEFT):
        shoot(mouse_x, mouse_y)

Advanced Input Handling¶

# Checking key combinations
if (input_manager.is_key_pressed(K_LCTRL) and
    input_manager.is_key_just_pressed(K_s)):
    save_game()

# Double click detection
if (input_manager.is_mouse_button_just_pressed(BUTTON_LEFT) and
    time.time() - last_click_time < DOUBLE_CLICK_TIME):
    handle_double_click()

# Mouse movement
prev_x, prev_y = last_mouse_pos
curr_x, curr_y = input_manager.get_mouse_position()
mouse_delta_x = curr_x - prev_x
mouse_delta_y = curr_y - prev_y

Best Practices¶

Input State Management:
Call update() once per frame
Use is_key_just_pressed() for one-time actions
Use is_key_pressed() for continuous actions
Input Mapping:
Define input constants at the start
Consider creating an input configuration system
Support key rebinding
Mouse Input:
Handle both relative and absolute positions
Consider screen scaling when using positions
Implement proper double-click detection
Performance:
Cache input states when needed
Avoid checking input multiple times per frame
Use efficient key combination detection

Common Issues¶

Input Lag¶

Missing update() calls
Processing input multiple times
Heavy processing in input handlers

Missed Input¶

Not using is_key_just_pressed()
Incorrect frame timing
Input buffer overflow

Key Combinations¶

Order dependency issues
Race conditions
Missing key release events

Mouse Position¶

Incorrect coordinate space
Screen scaling issues
Resolution independence problems