Force background of matplotlib figure to be transparent

Question

I'm trying to include a matplotlib figure in a Python Gtk3 application I'm writing. I'd like to set the background colour of the figure to be transparent, so that the figure just shows up against the natural grey background of the application, but nothing I've tried so far seems to be working.

Here's an MWE:

from gi.repository import Gtk
import matplotlib.pyplot as plt
import matplotlib.lines as mlines
import numpy as np
from matplotlib.backends.backend_gtk3agg import FigureCanvasGTK3Agg as FigureCanvas

class MyWindow(Gtk.Window):
    def __init__(self):
        Gtk.Window.__init__(self)
        fig, ax = plt.subplots()
        #fig.patch.set_alpha(0.0)
        x,y = np.array([[0, 1], [0, 0]])
        line = mlines.Line2D(x, y, c='#729fcf')
        ax.add_line(line)
        plt.axis('equal')
        plt.axis('off')

        fig.tight_layout()

        sw = Gtk.ScrolledWindow()
        sw.set_border_width(50)
        canvas = FigureCanvas(fig)
        sw.add_with_viewport(canvas)

        layout = Gtk.Grid()
        layout.add(sw)

        self.add(layout)

win = MyWindow()
win.connect("delete-event", Gtk.main_quit)
win.show_all()
Gtk.main()

If the fig.patch.set_alpha(0.0) line is uncommented, the colour of the background just changes to white, rather than grey. All suggestions greatly appreciated!

are you sure that the background of an empty `Gtk.Window` isn't white by default on your platform? this seems to be the case for me (Unity desktop). — ali_m, Oct 10 '13 at 16:48
No, I checked and it seems to be grey. I managed to get around the problem using the `get_style` method of the parent window to get the background colour and then set it as the facecolour of the axes. It's not a great solution, but it works. — Donagh, Oct 14 '13 at 11:52

SpinUp __ A Davis · Answer 1 · 2013-10-17T04:32:24.677

3

It seems to me that it's the axes background that needs to be hidden. You might try using ax.patch.set_facecolor('None') or ax.patch.set_visible(False).

Alternatively, have you tried setting both the figure and axes patches off? This may be accomplished by:

for item in [fig, ax]:
    item.patch.set_visible(False)

edited Oct 17 '13 at 04:32

answered Oct 09 '13 at 07:07

SpinUp __ A Davis

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Neither work for me, unfortunately. Can you confirm that it's definitely working on your machine? – Donagh Oct 09 '13 at 13:32
Both ways remove the color of the axes patch here, at least on a regular figure. I can't test your MWE, for lack of available modules related to the GTK backend. – SpinUp __ A Davis Oct 16 '13 at 07:53
Hmmm...on my system, both set the background colour to white. I posted my solution below. It's not universal, but it works for me. – Donagh Oct 17 '13 at 21:57
1

I can write by using `figure.patch.set_visible(False)` does the trick – dvdvck Sep 11 '14 at 05:25
I had to use both `ax.patch.set_visible(False)` and `figure.patch.set_visible(False)` to get transparent background. – HiFile.app - best file manager Oct 02 '16 at 19:25

score 2 · Answer 2 · answered Oct 17 '13 at 21:55

I solved it this way. It's not ideal, but it works.

from gi.repository import Gtk
import matplotlib.pyplot as plt
import matplotlib.lines as mlines
import numpy as np
from matplotlib.backends.backend_gtk3agg import FigureCanvasGTK3Agg as FigureCanvas
from matplotlib.colors import ColorConverter

class MyWindow(Gtk.Window):
    def __init__(self):
        Gtk.Window.__init__(self)
        fig, ax = plt.subplots()
        #fig.patch.set_alpha(0.0)
        x,y = np.array([[0, 1], [0, 0]])
        line = mlines.Line2D(x, y, c='#729fcf')
        ax.add_line(line)
        plt.axis('equal')
        plt.axis('off')

        fig.tight_layout()

        win = Gtk.Window()
        style = win.get_style_context()
        bg_colour = style.get_background_color(
        Gtk.StateType.NORMAL).to_color().to_floats()
        cc = ColorConverter()
        cc.to_rgba(bg_colour)

        fig.patch.set_facecolor(bg_colour)

        sw = Gtk.ScrolledWindow()
        sw.set_border_width(50)
        canvas = FigureCanvas(fig)
        sw.add_with_viewport(canvas)

        layout = Gtk.Grid()
        layout.add(sw)

        self.add(layout)

win = MyWindow()
win.connect("delete-event", Gtk.main_quit)
win.show_all()
Gtk.main()

This is the only solution that worked for me with matplotlib 3.4.1. — Roberto Leinardi, Apr 02 '21 at 10:15

score 0 · Answer 3 · answered Mar 28 '18 at 12:20

0

A combination of

fig.patch.set_visible(False)
self.setStyleSheet("background-color:transparent;")

works for me (self is a subclass of Canvas). Any of these two alone do not work.

answered Mar 28 '18 at 12:20

klmn

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Force background of matplotlib figure to be transparent

3 Answers3

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