# pygui.py: Immediate–mode GUI library.
# This file contains no direct Pygame calls—it relies entirely on functions supplied by the backend.
# The backend must supply: Rect, get_mouse_pos, get_mouse_pressed,
# and event type constants: MOUSEBUTTONDOWN, MOUSEBUTTONUP, MOUSEMOTION.
class Window:
TITLE_HEIGHT = 30
PADDING = 5
SPACING = 5
def __init__(self, title, x, y, width=None, height=None):
self.title = title
self.x = x
self.y = y
self.width = width if width is not None else 200
# Start with a minimal height if none is provided.
self.height = height if height is not None else (self.TITLE_HEIGHT + self.PADDING)
self.cursor_y = self.y + self.TITLE_HEIGHT + self.PADDING
self.dragging = False
self.drag_offset = (0, 0)
@property
def rect(self):
return Window.backend.Rect(self.x, self.y, self.width, self.height)
@property
def title_rect(self):
return Window.backend.Rect(self.x, self.y, self.width, self.TITLE_HEIGHT)
def handle_event(self, ev):
# ev is a dictionary with keys: type, button, pos.
if ev.get('type') == 'MOUSEBUTTONDOWN':
if ev.get('button') == 1 and self.title_rect.collidepoint(ev.get('pos')):
self.dragging = True
self.drag_offset = (ev.get('pos')[0] - self.x, ev.get('pos')[1] - self.y)
elif ev.get('type') == 'MOUSEBUTTONUP':
if ev.get('button') == 1:
self.dragging = False
elif ev.get('type') == 'MOUSEMOTION':
if self.dragging:
self.x = ev.get('pos')[0] - self.drag_offset[0]
self.y = ev.get('pos')[1] - self.drag_offset[1]
self.cursor_y = self.y + self.TITLE_HEIGHT + self.PADDING
def begin(self, render):
render.draw_rect((50, 50, 50), self.rect.rect)
render.draw_rect((70, 70, 70), self.title_rect.rect)
render.draw_text(self.title, (self.x + self.PADDING, self.y + 5))
self.cursor_y = self.y + self.TITLE_HEIGHT + self.PADDING
def layout(self):
return (self.x + self.PADDING, self.cursor_y)
def next(self, widget_height):
self.cursor_y += widget_height + self.SPACING
class PyGUI:
# These are assigned via set_backend.
backend = None
renderer = None
current_window = None
windows = []
active_slider = None # Stores (window_id, label, offset)
prev_mouse = False # For one–click widget toggling
@staticmethod
def set_backend(backend, renderer):
"""
backend: an object that provides Rect, get_mouse_pos, get_mouse_pressed,
and event type constants: MOUSEBUTTONDOWN, MOUSEBUTTONUP, MOUSEMOTION.
renderer: an instance of the backend’s Render class.
"""
PyGUI.backend = backend
PyGUI.renderer = renderer
Window.backend = backend
@staticmethod
def Begin(title, x, y, width=None, height=None):
win = Window(title, x, y, width, height)
PyGUI.current_window = win
PyGUI.windows.append(win)
win.begin(PyGUI.renderer)
@staticmethod
def End():
if PyGUI.current_window:
win = PyGUI.current_window
# Auto–resize window height to enclose all widgets.
win.height = win.cursor_y - win.y + win.PADDING
PyGUI.current_window = None
@staticmethod
def Label(text):
if not PyGUI.current_window:
return
win = PyGUI.current_window
pos = win.layout()
PyGUI.renderer.draw_text(text, pos)
win.next(20)
@staticmethod
def Button(text):
if not PyGUI.current_window:
return False
win = PyGUI.current_window
btn_rect = PyGUI.backend.Rect(win.x + win.PADDING, win.cursor_y, win.width - 2 * win.PADDING, 25)
PyGUI.renderer.draw_rect((100, 100, 100), btn_rect.rect)
PyGUI.renderer.draw_text(text, (btn_rect.x + 5, btn_rect.y + 5))
clicked = False
mouse_pos = PyGUI.backend.get_mouse_pos()
if btn_rect.collidepoint(mouse_pos):
PyGUI.renderer.draw_rect((150, 150, 150), btn_rect.rect, border=2)
if PyGUI.backend.get_mouse_pressed()[0]:
clicked = True
win.next(25)
return clicked
@staticmethod
def Slider(label, value, min_val, max_val):
if not PyGUI.current_window:
return value
win = PyGUI.current_window
pos = win.layout()
text = f"{label}: {value:.2f}"
PyGUI.renderer.draw_text(text, pos)
win.next(20)
slider_width = win.width - 2 * win.PADDING
slider_rect = PyGUI.backend.Rect(win.x + win.PADDING, win.cursor_y, slider_width, 10)
PyGUI.renderer.draw_rect((100, 100, 100), slider_rect.rect)
norm = (value - min_val) / (max_val - min_val)
knob_x = win.x + win.PADDING + norm * slider_width
knob_rect = PyGUI.backend.Rect(knob_x - 5, win.cursor_y - 5, 10, 20)
PyGUI.renderer.draw_rect((200, 200, 200), knob_rect.rect)
slider_id = (id(win), label)
mp = PyGUI.backend.get_mouse_pos()
mp_pressed = PyGUI.backend.get_mouse_pressed()[0]
# Start slider drag if none active and mouse is pressed inside slider_rect.
if PyGUI.active_slider is None and slider_rect.collidepoint(mp) and mp_pressed:
offset = mp[0] - knob_x
PyGUI.active_slider = (slider_id, offset)
if PyGUI.active_slider is not None and PyGUI.active_slider[0] == slider_id:
offset = PyGUI.active_slider[1]
rel = mp[0] - (win.x + win.PADDING) - offset
norm = max(0, min(rel / slider_width, 1))
value = min_val + norm * (max_val - min_val)
if not mp_pressed:
PyGUI.active_slider = None
win.next(20)
return value
@staticmethod
def Checkbox(label, value):
if not PyGUI.current_window:
return value
win = PyGUI.current_window
pos = win.layout()
box_rect = PyGUI.backend.Rect(win.x + win.PADDING, win.cursor_y, 20, 20)
PyGUI.renderer.draw_rect((100, 100, 100), box_rect.rect, border=2)
if value:
PyGUI.renderer.draw_rect((200, 200, 200), box_rect.rect)
PyGUI.renderer.draw_text(label, (box_rect.x + box_rect.width + 5, win.cursor_y))
new_value = value
mp = PyGUI.backend.get_mouse_pos()
mp_pressed = PyGUI.backend.get_mouse_pressed()[0]
# Toggle only on the transition (mouse pressed now but not in the previous frame).
if box_rect.collidepoint(mp) and mp_pressed and not PyGUI.prev_mouse:
new_value = not value
win.next(20)
return new_value
@staticmethod
def handle_event(event):
# Convert a backend event (e.g. a Pygame event) into a generic dictionary.
generic = {}
if event.type == PyGUI.backend.MOUSEBUTTONDOWN:
generic['type'] = 'MOUSEBUTTONDOWN'
generic['button'] = event.button
generic['pos'] = event.pos
elif event.type == PyGUI.backend.MOUSEBUTTONUP:
generic['type'] = 'MOUSEBUTTONUP'
generic['button'] = event.button
generic['pos'] = event.pos
elif event.type == PyGUI.backend.MOUSEMOTION:
generic['type'] = 'MOUSEMOTION'
generic['pos'] = event.pos
for win in PyGUI.windows:
win.handle_event(generic)
@staticmethod
def update():
# Call at end of frame to record the current mouse state (for one–click toggling).
PyGUI.prev_mouse = PyGUI.backend.get_mouse_pressed()[0]