A paint program¶
Drag the mouse to paint. The wheel changes the brush, the keys r, g and b pick a colour, and c clears the page. A right click drops a dot.
How it works¶
- Callbacks are functions with special names, such as mouse_dragged(). You define them, and funground calls them when something happens.
- f.background("white") is in setup(), so it runs once. draw() never wipes the canvas, and the paint stays.
- mouse_dragged() draws a line from f.pmouse_x, f.pmouse_y (where the mouse was last frame) to f.mouse_x, f.mouse_y (where it is now). That joins the strokes up smoothly.
- mouse_pressed() checks f.mouse_button and draws a dot on a right click. mouse_wheel(delta) changes the brush size, and f.constrain() keeps it between 1 and 40.
- key_pressed() uses f.key to clear or to pick a colour. key_typed() prints the key to the console.
- draw() redraws the strip at the bottom each frame, so the words stay up to date.
Make it yours¶
- Add colours: put "y": "gold" in the dictionary in key_pressed().
- Change the brush limits: 1 and 40 in f.constrain().
- Change the starting colour (colour = "navy") or the starting brush (brush = 8).
- Make the right click drop a bigger dot: change brush * 3 to brush * 6 in mouse_pressed().
- Delete the print line in key_typed() if you do not want the messages in the console.
The code¶
Copy it into a file and run it.
"""A paint program
Drag the mouse to paint. The wheel changes the brush, the keys r, g and b pick a colour, and c
clears the page. A right click drops a dot.
How it works:
- Callbacks are functions with special names, such as mouse_dragged(). You define them, and
funground calls them when something happens.
- f.background("white") is in setup(), so it runs once. draw() never wipes the canvas, and the
paint stays.
- mouse_dragged() draws a line from f.pmouse_x, f.pmouse_y (where the mouse was last frame) to
f.mouse_x, f.mouse_y (where it is now). That joins the strokes up smoothly.
- mouse_pressed() checks f.mouse_button and draws a dot on a right click. mouse_wheel(delta)
changes the brush size, and f.constrain() keeps it between 1 and 40.
- key_pressed() uses f.key to clear or to pick a colour. key_typed() prints the key to the console.
- draw() redraws the strip at the bottom each frame, so the words stay up to date.
Make it yours:
- Add colours: put "y": "gold" in the dictionary in key_pressed().
- Change the brush limits: 1 and 40 in f.constrain().
- Change the starting colour (colour = "navy") or the starting brush (brush = 8).
- Make the right click drop a bigger dot: change brush * 3 to brush * 6 in mouse_pressed().
- Delete the print line in key_typed() if you do not want the messages in the console.
"""
import funground as f
brush = 8
colour = "navy"
def setup():
f.size(640, 400)
f.background("white") # once: the drawing stays on the canvas
def draw():
f.no_stroke()
f.fill("white")
f.rect(0, 360, 640, 40)
f.fill("black")
f.text_size(14)
f.text(f"drag to paint | wheel: brush {brush} | r g b: colour | c: clear | last key: {f.key}", 10, 372)
def mouse_dragged():
f.stroke(colour)
f.stroke_width(brush)
f.line(f.pmouse_x, f.pmouse_y, f.mouse_x, f.mouse_y)
def mouse_pressed():
if f.mouse_button == "right": # right-click drops a dot
f.no_stroke()
f.fill(colour)
f.circle(f.mouse_x, f.mouse_y, brush * 3)
def mouse_wheel(delta):
global brush
brush = int(f.constrain(brush - delta, 1, 40))
def key_pressed():
global colour
if f.key == "c":
f.background("white")
colour = {"r": "tomato", "g": "seagreen", "b": "navy"}.get(f.key, colour)
def key_typed():
print("typed", f.key, f.key_code, f.is_key_pressed)
f.run()