Question

When I draw a rectangle at global scope:

c = Canvas(width=IMAGE_WIDTH, height=IMAGE_HEIGHT, bg='black') 
c.create_rectangle([100, 100, 110, 110], fill='white')
c.pack()
root = Tk() 

and follow this by drawing multiple rectangles in a loop

class gDrawer :
    def __init__(self) :
        self.rect_array = []
        self.x = 0
        self.y = 0

    def incr_counter(self,c,event=None): 
        one_pixel_loc = [self.x, self.y, self.x+5, self.y+5]
        self.rect_array.append(c.create_rectangle(one_pixel_loc, fill='white'))
        self.x += 1

gd = gDrawer()

for xx in range(100) :
    print xx
    gd.incr_counter(c)

root.mainloop()

The single drawn rectangle stays on the canvas while the loop drawn rectangle moves rather than creating a trail of rectangles. I’d like to draw a trail of rectangles and not a moving one, so what is going on here?

Answer 1

The default color for the outline of a rectangle is black. This makes it seem like the other rectangles aren’t being drawn when their outline is just overlapping.

Try changing:

self.rect_array.append(c.create_rectangle(one_pixel_loc, fill='white'))

to this:

self.rect_array.append(c.create_rectangle(one_pixel_loc, fill='white', outline='white')

Not sure if this is exactly what you’re looking for, hope it helps.