API: overhaul how active figures are tracked

- switch from list to dict keyed on Figures
- go with pyplot style numbering
- improve the clean up logic to try and not leak refs

Author: tacaswell

Diff for: mpl_gui/__init__.py

@@ -16,7 +16,7 @@
 import functools
 import logging
 import warnings
-from weakref import WeakKeyDictionary
+import weakref
 
 from matplotlib.backend_bases import FigureCanvasBase as _FigureCanvasBase
 
@@ -70,7 +70,7 @@ def show(figs, *, block=None, timeout=0):
         if fig.canvas.manager is not None:
             managers.append(fig.canvas.manager)
         else:
-            managers.append(promote_figure(fig))
+            managers.append(promote_figure(fig, num=None))
 
     if block is None:
         block = not is_interactive()
@@ -117,33 +117,41 @@ def __init__(self, *, block=None, timeout=0, prefix="Figure "):
         # settings stashed to set defaults on show
         self._timeout = timeout
         self._block = block
-        # Settings / state to control the default figure label
-        self._fig_to_number = WeakKeyDictionary()
-        self._prefix = prefix
         # the canonical location for storing the Figures this registry owns.
-        # any additional views must never include a figure not in the list but
+        # any additional views must never include a figure that is not a key but
         # may omit figures
-        self.figures = []
+        self._fig_to_number = dict()
+        # Settings / state to control the default figure label
+        self._prefix = prefix
+
+    @property
+    def figures(self):
+        return tuple(self._fig_to_number)
 
     def _register_fig(self, fig):
         # if the user closes the figure by any other mechanism, drop our
         # reference to it.  This is important for getting a "pyplot" like user
         # experience
-        fig.canvas.mpl_connect(
-            "close_event",
-            lambda e: self.figures.remove(fig) if fig in self.figures else None,
-        )
-        # hold a hard reference to the figure.
-        self.figures.append(fig)
+        def registry_cleanup(fig_wr):
+            fig = fig_wr()
+            if fig is not None:
+                if fig.canvas is not None:
+                    fig.canvas.mpl_disconnect(cid)
+                self.close(fig)
+
+        fig_wr = weakref.ref(fig)
+        cid = fig.canvas.mpl_connect("close_event", lambda e: registry_cleanup(fig_wr))
         # Make sure we give the figure a quasi-unique label.  We will never set
         # the same label twice, but will not over-ride any user label (but
         # empty string) on a Figure so if they provide duplicate labels, change
         # the labels under us, or provide a label that will be shadowed in the
         # future it will be what it is.
-        fignum = max(self._fig_to_number.values(), default=0) + 1
+        fignum = max(self._fig_to_number.values(), default=-1) + 1
         if fig.get_label() == "":
             fig.set_label(f"{self._prefix}{fignum:d}")
         self._fig_to_number[fig] = fignum
+        if is_interactive():
+            promote_figure(fig, num=fignum)
         return fig
 
     @property
@@ -302,8 +310,7 @@ def close(self, val):
             # disconnect canvas from figure
             _FigureCanvasBase(figure=fig)
         assert fig.canvas.manager is None
-        if fig in self.figures:
-            self.figures.remove(fig)
+        self._fig_to_number.pop(fig, None)
 
 
 class FigureContext(FigureRegistry):