I’ve been using Kivy for a couple days and am currently working on an application that requires embedding a Matplotlib plot within it. With help from online resources, I’ve managed to embed a plot within my kivy app, but I’m having trouble with the NavigationToolbar.

Problem Details:

## Imports
## ...

class MyApp(App):
    
    def build(self):
        box = BoxLayout(orientation='vertical')
        box.add_widget(Label(text='My App', size_hint_y=.1))

        plt.plot([1, 3, 2, 4])

        canvas = FigureCanvasKivyAgg(plt.gcf())
        toolbar = NavigationToolbar2Kivy(canvas)

        box.add_widget(canvas)
        box.add_widget(toolbar.actionbar)
        
        return box

MyApp().run()

The code above yields the following output:

As you can see, only a black rectangle is visible in place of the NavigationToolbar. I can’t see any of the buttons (i.e, tools – “Pan”, “Zoom”, “Home”, etc.).

What I Tried:

I did think that maybe the colour of the buttons was the same as the background colour of the NavigationToolbar, so I tried changing background colour like so:

toolbar.actionbar.background_image = ''
toolbar.actionbar.background_color = (1, 1, 1, .5)

box.add_widget(toolbar.actionbar)

But that just resulted in a grey coloured rectangle instead. I still can’t see any of the NavigationToolbar’s buttons to interact with the plot.

EDIT:

There is a question similar to this here, but the solution provided does not seem to work in my case.

The answer to the post suggested that the NavigationToolbar only works on a parent layout, which I have tried like shown below:

class MyApp(App):

    def build(self):
        box = BoxLayout(orientation='vertical')
        child_box = BoxLayout(orientation='vertical')
        box.add_widget(child_box)  ## parent layout: box, child layout: child_box
        
        child_box.add_widget(Label(text='My App', size_hint_y=.1))

        plt.plot([1, 3, 2, 4])

        canvas = FigureCanvasKivyAgg(plt.gcf())
        toolbar = NavigationToolbar2Kivy(canvas)
        
        ## toolbar.actionbar.background_image = ''
        ## toolbar.actionbar.background_color = (1, 1, 1, .5)

        child_box.add_widget(canvas)
        box.add_widget(toolbar.actionbar)

        return box

MyApp().run()

But this yields the same result as the one shown in my output image (with the rectangular area being grey in colour if I uncomment the commented lines).