Merge pull request matplotlib#3546 from alexeicolin/pr--example-ui-em…

…bed-in-tk-canvas

DOC : Example of embedding a figure into an existing Tk canvas

examples/user_interfaces/embedding_in_tk_canvas.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python
+# -*- noplot -*-
+
+import matplotlib as mpl
+import numpy as np
+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)
+
+    # Unfortunatly, 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()