如何在另一个tk小部件中使用matplotlib在matplotlib之外的mathtext渲染？

Question

I know that matplotlib can render math expressions readily with, for instance,

txt=Text(x,y,r'$\frac{1}{2}')

which would make the fraction 1 over 2 at x,y. However, instead of placing the text at x,y I would like to use the rendered string in a separate tk application (like an Entry or Combobox). How can I obtain the rendered string from matplotlib's mathtext and put it into my tk widget? Of course I would welcome other options that would render the latex strings into my tk widget without matplotlib, but it seems like matplotlib has already done most of the work.

Answer 1

I couldn't really find that information in documentation, or net in general, but I was able to find solution by reading mathtext source code. That example is saving image to a file.

from matplotlib.mathtext import math_to_image
math_to_image("$\\alpha$", "alpha.png", dpi=1000, format='png')

You can always use ByteIO and use that buffer as a replace for image file, keeping data in memory. Or you can render directly from numpy array that is returned by data.as_array() in following code example (this code also uses cmap to control color of printed math expression).

from matplotlib.mathtext import MathTextParser
from matplotlib.image import imsave
parser =  MathTextParser('bitmap')
data, someint = parser.parse("$\\alpha$", dpi=1000)
imsave("alpha.png",data.as_array(),cmap='gray')

UPDATE

Here is complete TkInter example based on Hello World! example from Tkinter documentation, as requested. This one uses PIL library.

import tkinter as tk
from matplotlib.mathtext import math_to_image
from io import BytesIO
from PIL import ImageTk, Image

class Application(tk.Frame):
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.pack()
        self.createWidgets()



    def createWidgets(self):

        #Creating buffer for storing image in memory
        buffer = BytesIO()

        #Writing png image with our rendered greek alpha to buffer
        math_to_image('$\\alpha$', buffer, dpi=1000, format='png')

        #Remoting bufeer to 0, so that we can read from it
        buffer.seek(0)

        # Creating Pillow image object from it
        pimage= Image.open(buffer)

        #Creating PhotoImage object from Pillow image object
        image = ImageTk.PhotoImage(pimage)

        #Creating label with our image
        self.label = tk.Label(self,image=image)

        #Storing reference to our image object so it's not garbage collected,
        # as TkInter doesn't store references by itself
        self.label.img = image

        self.label.pack(side="bottom")
        self.QUIT = tk.Button(self, text="QUIT", fg="red",
                                            command=root.destroy)
        self.QUIT.pack(side="top")

root = tk.Tk()
app = Application(master=root)
app.mainloop()