.. _user_interfaces-embedding_in_tk_canvas:

user_interfaces example code: embedding_in_tk_canvas.py
=======================================================

[`source code <embedding_in_tk_canvas.py>`_]

::

    # -*- noplot -*-
    
    import matplotlib as mpl
    import numpy as np
    import sys
    if sys.version_info[0] < 3:
        import Tkinter as tk
    else:
        import tkinter as tk
    import matplotlib.backends.tkagg as tkagg
    from matplotlib.backends.backend_agg import FigureCanvasAgg
    
    
    def draw_figure(canvas, figure, loc=(0, 0)):
        """ Draw a matplotlib figure onto a Tk canvas
    
        loc: location of top-left corner of figure on canvas in pixels.
    
        Inspired by matplotlib source: lib/matplotlib/backends/backend_tkagg.py
        """
        figure_canvas_agg = FigureCanvasAgg(figure)
        figure_canvas_agg.draw()
        figure_x, figure_y, figure_w, figure_h = figure.bbox.bounds
        figure_w, figure_h = int(figure_w), int(figure_h)
        photo = tk.PhotoImage(master=canvas, width=figure_w, height=figure_h)
    
        # Position: convert from top-left anchor to center anchor
        canvas.create_image(loc[0] + figure_w/2, loc[1] + figure_h/2, image=photo)
    
        # Unfortunately, there's no accessor for the pointer to the native renderer
        tkagg.blit(photo, figure_canvas_agg.get_renderer()._renderer, colormode=2)
    
        # Return a handle which contains a reference to the photo object
        # which must be kept live or else the picture disappears
        return photo
    
    # Create a canvas
    w, h = 300, 200
    window = tk.Tk()
    window.title("A figure in a canvas")
    canvas = tk.Canvas(window, width=w, height=h)
    canvas.pack()
    
    # Generate some example data
    X = np.linspace(0, 2.0*3.14, 50)
    Y = np.sin(X)
    
    # Create the figure we desire to add to an existing canvas
    fig = mpl.figure.Figure(figsize=(2, 1))
    ax = fig.add_axes([0, 0, 1, 1])
    ax.plot(X, Y)
    
    # Keep this handle alive, or else figure will disappear
    fig_x, fig_y = 100, 100
    fig_photo = draw_figure(canvas, fig, loc=(fig_x, fig_y))
    fig_w, fig_h = fig_photo.width(), fig_photo.height()
    
    # Add more elements to the canvas, potentially on top of the figure
    canvas.create_line(200, 50, fig_x + fig_w / 2, fig_y + fig_h / 2)
    canvas.create_text(200, 50, text="Zero-crossing", anchor="s")
    
    # Let Tk take over
    tk.mainloop()
    

Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)