How to make a tkinter canvas polygon transparent?
My solution is inspired by this answer on a similar question but for rectangles, not polygons.
Unfortunately, Tkinter doesn't support RGBA, so it's impossible just to pass fill args fill="#ff000055". Instead, we can create an image which contains the rectangle and has RGBA channel using PIL.
Here is an example:
from tkinter import *from PIL import Image, ImageDraw, ImageTkdef create_polygon(*args, **kwargs): if "alpha" in kwargs: if "fill" in kwargs: # Get and process the input data fill = root.winfo_rgb(kwargs.pop("fill"))\ + (int(kwargs.pop("alpha") * 255),) outline = kwargs.pop("outline") if "outline" in kwargs else None # We need to find a rectangle the polygon is inscribed in # (max(args[::2]), max(args[1::2])) are x and y of the bottom right point of this rectangle # and they also are the width and height of it respectively (the image will be inserted into # (0, 0) coords for simplicity) image = Image.new("RGBA", (max(args[::2]), max(args[1::2]))) ImageDraw.Draw(image).polygon(args, fill=fill, outline=outline) images.append(ImageTk.PhotoImage(image)) # prevent the Image from being garbage-collected return canvas.create_image(0, 0, image=images[-1], anchor="nw") # insert the Image to the 0, 0 coords raise ValueError("fill color must be specified!") return canvas.create_polygon(*args, **kwargs)images = [] # to hold the newly created image(s) root = Tk()canvas = Canvas(width=260, height=310)canvas.pack()create_polygon(10, 10, 10, 20, 200, 300, 250, 150, 10, 10, fill="blue", alpha=0.5)create_polygon(150, 100, 200, 120, 240, 180, 210, 200, 150, 150, 100, 200, fill="blue", alpha=0.2)root.mainloop()
If anyone is looking for Tkinter's transparency and outline options, I found them here:
These lines of code will produce a transparent polygon with an outline.
root = tk.Tk()root.state('zoomed')canvas = tk.Canvas(root)canvas.pack(fill = "both", expand = True)#points = polygon_pointscanvas.create_polygon(points, outline='red', fill='', width = 10)