pycanvas example

pycanvas_example.py

#!/usr/bin/env python3

import pycanvas

# We need this global constant to get the mouse position
WINDOW = pycanvas.get_window()


@pycanvas.init
async def init(canvas: pycanvas.Canvas):
    """
    Canvas initialization function.
    It is only called once, before `loop`.
    
    This is similar to p5's `setup`, except that the `pycanvas.init()`
    decorator already creates the canvas for us.
    """

    # Equivalent to canvas.set_size(width=1920, height=1080, unit="px")
    # but `set_size` does not have fine-granulated unit picking
    canvas.set_width(1920, "px")
    canvas.set_height(1080, "px")

    # Defaults to white which could be fine for this example
    # but this allows to show how to set the canvas background
    canvas.set_background(pycanvas.UniformFill(255, 198, 127))  # pale orange (#FFC67F)


@pycanvas.loop(refresh=True, exit_key="\x1b")
async def loop(canvas: pycanvas.Canvas, pen: pycanvas.Pen):  # pen = canvas.pen
    """
    Canvas draw function.
    It is called indefinitely, after `init`.

    It stops if `Ctrl+C` is pressed, or if the `exit_key` is detected in the stdin.
    
    Resembles p5's `draw`, with the same difference than `init`.

    `pen` argument is a shortcut for `canvas.pen`.
    """

    # Resetting the canvas so we only see the current mouse pos
    canvas.reset()
  
    # The pen does not write anything yet
    pen.lift()

    # Originally `mouse_x` and `mouse_y` were descriptors but the cost of getting
    # the mouse position is too big on most platforms to fit in so there are methods now
    pen.move(WINDOW.mouse_x(), WINDOW.mouse_y())
    
    # Sets the pen to black ; UniformFill() because it could be a gradient or image
    pen.set_color(pycanvas.UniformFill(0, 0, 0))
    # By default, the size is 10 which is a bit too small
    pen.set_size(30)

    # The pen writes a small dot where the mouse is
    pen.put_down()