如何确定Turtle画布上特定坐标处的填充颜色？

Question

我正在尝试创建一个函数，该函数将返回 Turtle 画布上指定坐标处的填充颜色。我使用海龟库中的 find_overlapping 方法来查找画布上的对象，但此方法并不总是返回所需的结果。

这是我当前的方法：

from turtle import *

def get_pixel_color(x, y):
    y = -y
    canvas = getcanvas()
    ids = canvas.find_overlapping(x, y, x, y)
    if ids:
        index = ids[-1]
        color = canvas.itemcget(index, "fill")
        if color:
            return color
    return "white"

但是，即使画布上的指定坐标处有填充，此方法有时也会返回“白色”。如何正确确定 Turtle 画布上特定坐标处的填充颜色？

我的代码示例

from turtle import *

def get_pixel_color(x, y):
    y = -y
    canvas = getcanvas()
    ids = canvas.find_overlapping(x, y, x, y)
    print(ids)
    if ids:
        index = ids[-1]
        color = canvas.itemcget(index, "fill")
        print(canvas.itemcget(index, "fill"))
        if color:
            return color
    return "white"

def frange(start, stop, step):
    while start <= stop:
        yield start
        start += step
        
SIZE = 40
tracer(0)
screensize(14000, 14000)
color('red')
position = pos()
left(90)
color('yellow')
begin_fill() 

for i in range(5):
    fd(9 * SIZE)
    rt(120)

end_fill()

color('red')
up()
setpos(position)
rt(120)
down()
for i in range(5):
    fd(9 * SIZE)
    rt(120)

up()
update()
c = 0

for x in range(-5, 10):
    for y in range(-5, 13):
        real_x, real_y = x * SIZE, y * SIZE
        print(get_pixel_color(real_x, real_y), pencolor())
        if get_pixel_color(real_x, real_y) == 'yellow':
            setpos(real_x, real_y)
            dot(5, 'blue')
            continue
            

done()

如有任何帮助，我们将不胜感激！

Answer 1

我建议使用截图功能来实现此目的：

from turtle import *
from time import sleep
import mss
import mss.tools

# Get the position and size of the turtle canvas window
shape('turtle')
screen=Screen()
screen.setup(width=350, height=300)
screen.setworldcoordinates(-175, -150, 175, 150)

def get_pixel_color(x, y):
    window = screen.getcanvas().winfo_toplevel()
    window_pos = (window.winfo_x(), window.winfo_y())
    canvas_width = window.winfo_width()
    canvas_height = window.winfo_height()
    print(f"{window_pos=}  ( {canvas_width=}, {canvas_height=} )" )
    screen_x = window_pos[0] + canvas_width//2 + x
    screen_y = window_pos[1] + canvas_height//2 - y
    with mss.mss() as sct:
        monitor = { "top": screen_y,    "left": screen_x, "width": 1, "height": 1 }
        img = sct.grab(monitor)
        color = img.pixel(0, 0)
        return '#{:02x}{:02x}{:02x}'.format(color[0], color[1], color[2])

screensize( 300, 300)
SIZE = 150 ; pensize(7)
# tracer(0)
color('red')        ; begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
color('green')  ; begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
color('blue')       ; begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
rt(60)
color('darkred')    ; begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
color('darkgreen'); begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
color('darkblue')       ; begin_fill();fd(SIZE);rt(120);fd(SIZE);rt(120);fd(SIZE);end_fill()
update()

# Sleep for a short time to ensure the canvas is updated
sleep(0.5)
# Check colors at random positions
color('white'); pu()
colorPositions=[ None, (0, -55 ), (0,55), (-75,55), (-75,-55), (75,55), (75,-55)]
for colorNo in range( 1, 6      +1):
    x , y = colorPositions[colorNo]
    color = get_pixel_color(x, y)
    sleep(0.33)
    goto(x,y); stamp(); write(f"   {colorNo}", font=("Arial",12))
    print(f"Color {colorNo} at ({x:3d}, {y:3d}): {color}")

done()

window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 1 at (  0, -55): #8b0000
window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 2 at (  0,  55): #008000
window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 3 at (-75,  55): #00008b
window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 4 at (-75, -55): #0000ff
window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 5 at ( 75,  55): #006400
window_pos=(790, 419)  ( canvas_width=350, canvas_height=300 )
Color 6 at ( 75, -55): #f0f0f0