Refactoring the WindowGTK classes as part 1 of the larger MEP27 refac…

…tor, splitting up previous PRs into smaller easier to review chunks.

lib/matplotlib/backend_bases.py

@@ -1686,7 +1686,59 @@ def save_args_and_handle_sigint(*args):
             old_sigint_handler(*handler_args)
 
 
-class FigureCanvasBase:
+class ExpandableBase(object):
+    """
+    Base class for GUI elements that can expand to fill the area given to them
+    by the encapsulating container (e.g. the main window).
+    At the moment this class does not do anything apart from mark such classes,
+    but this may well change at a later date, PRs welcome.
+    """
+    pass
+
+class FlowBase(object):
+    """
+    Base mixin class for all GUI elements that can flow, aka laid out in
+    different directions.
+    The MPL window class deals with the manipulation of this mixin, so users
+    don't actually need to interact with this class.
+    Classes the implement this class must override the _update_flow method.
+    """
+    flow_types = ['horizontal', 'vertical']
+
+    def __init__(self, flow='horizontal', flow_locked=False, **kwargs):
+        super(FlowBase, self).__init__(**kwargs)
+        self.flow_locked = flow_locked
+        self.flow = flow
+
+    @property
+    def flow(self):
+        """
+        The direction of flow, one of the strings in `flow_type`.
+        """
+        return FlowBase.flow_types[self._flow]
+
+    @flow.setter
+    def flow(self, flow):
+        if self.flow_locked:
+            return
+
+        try:
+            self._flow = FlowBase.flow_types.index(flow)
+        except ValueError:
+            raise ValueError('Flow (%s), not in list  %s' % (flow, FlowBase.flow_types))
+
+        self._update_flow()
+
+    def _update_flow(self):
+        """
+        Classes that extend FlowBase must override this method.
+        You can use the internal property self._flow whereby
+        flow_types[self._flow] gives the current flow.
+        """
+        raise NotImplementedError
+
+
+class FigureCanvasBase(ExpandableBase):
     """
     The canvas the figure renders into.
 
@@ -2581,6 +2633,120 @@ class NonGuiException(Exception):
     pass
 
 
+class WindowEvent(object):
+    def __init__(self, name, window):
+        self.name = name
+        self.window = window
+
+
+class WindowBase(cbook.EventEmitter):
+    """The base class to show a window on screen.
+
+    Parameters
+    ----------
+    title : str
+        The title of the window.
+    """
+
+    def __init__(self, title, **kwargs):
+        super(WindowBase, self).__init__(**kwargs)
+
+    def show(self):
+        """
+        For GUI backends, show the figure window and redraw.
+        For non-GUI backends, raise an exception to be caught
+        by :meth:`~matplotlib.figure.Figure.show`, for an
+        optional warning.
+        """
+        raise NonGuiException()
+
+    def destroy(self):
+        """Destroys the window"""
+        pass
+
+    def set_fullscreen(self, fullscreen):
+        """Whether to show the window fullscreen or not, GUI only.
+
+        Parameters
+        ----------
+        fullscreen : bool
+            True for yes, False for no.
+        """
+        pass
+
+    def set_default_size(self, width, height):
+        """Sets the default size of the window, defaults to a simple resize.
+
+        Parameters
+        ----------
+        width : int
+            The default width (in pixels) of the window.
+        height : int
+            The default height (in pixels) of the window.
+        """
+        self.resize(width, height)
+
+    def resize(self, width, height):
+        """"For gui backends, resizes the window.
+
+        Parameters
+        ----------
+        width : int
+            The new width (in pixels) for the window.
+        height : int
+            The new height (in pixels) for the window.
+        """
+        pass
+
+    def get_window_title(self):
+        """
+        Get the title text of the window containing the figure.
+        Return None for non-GUI backends (e.g., a PS backend).
+
+        Returns
+        -------
+        str : The window's title.
+        """
+        return 'image'
+
+    def set_window_title(self, title):
+        """
+        Set the title text of the window containing the figure.  Note that
+        this has no effect for non-GUI backends (e.g., a PS backend).
+
+        Parameters
+        ----------
+        title : str
+            The title of the window.
+        """
+        pass
+
+    def add_element(self, element, place):
+        """ Adds a gui widget to the window.
+        This has no effect for non-GUI backends and properties only apply
+        to those backends that support them, or have a suitable workaround.
+
+        Parameters
+        ----------
+        element : A gui element.
+            The element to add to the window
+        place : string
+            The location to place the element, either compass points north,
+            east, south, west, or center.
+        """
+        pass
+
+    def destroy_event(self, *args):
+        """Fires this event when the window wants to destroy itself.
+
+        Note this method should hook up to the backend's internal window's
+        close event.
+        """
+        s = 'window_destroy_event'
+        event = WindowEvent(s, self)
+        self._callbacks.process(s, event)
+
+
 class FigureManagerBase:
     """
     A backend-independent abstraction of a figure container and controller.

lib/matplotlib/backends/_backend_gtk.py

@@ -10,7 +10,7 @@
 from matplotlib._pylab_helpers import Gcf
 from matplotlib.backend_bases import (
     _Backend, FigureCanvasBase, FigureManagerBase, NavigationToolbar2,
-    TimerBase)
+    TimerBase, WindowBase, ExpandableBase)
 from matplotlib.backend_tools import Cursors
 
 import gi
@@ -118,6 +118,109 @@ class _FigureCanvasGTK(FigureCanvasBase):
     _timer_cls = TimerGTK
 
 
+_flow = [Gtk.Orientation.HORIZONTAL, Gtk.Orientation.VERTICAL]
+
+
+class _WindowGTK(WindowBase, Gtk.Window):
+    # Must be implemented in GTK3/GTK4 backends:
+    # * _add_element - to add an widget to a container
+    # * _setup_signals
+    # * _get_self - a method to ensure that we have been fully initialised
+
+    def __init__(self, title, **kwargs):
+        super().__init__(title=title, **kwargs)
+
+        self.set_window_title(title)
+
+        self._layout = {}
+        self._setup_box('_outer', Gtk.Orientation.VERTICAL, False, None)
+        self._setup_box('north', Gtk.Orientation.VERTICAL, False, '_outer')
+        self._setup_box('_middle', Gtk.Orientation.HORIZONTAL, True, '_outer')
+        self._setup_box('south', Gtk.Orientation.VERTICAL, False, '_outer')
+
+        self._setup_box('west', Gtk.Orientation.HORIZONTAL, False, '_middle')
+        self._setup_box('center', Gtk.Orientation.VERTICAL, True, '_middle')
+        self._setup_box('east', Gtk.Orientation.HORIZONTAL, False, '_middle')
+
+        self.set_child(self._layout['_outer'])
+
+        self._setup_signals()
+
+    def _setup_box(self, name, orientation, grow, parent):
+        self._layout[name] = Gtk.Box(orientation=orientation)
+        if parent:
+            self._add_element(self._layout[parent], self._layout[name], True, grow)
+        self._layout[name].show()
+
+    def add_element(self, element, place):
+        element.show()
+
+        # Get the flow of the element (the opposite of the container)
+        flow_index = not _flow.index(self._layout[place].get_orientation())
+        flow = _flow[flow_index]
+        separator = Gtk.Separator(orientation=flow)
+        separator.show()
+
+        try:
+            element.flow = element.flow_types[flow_index]
+        except AttributeError:
+            pass
+
+        # Determine if this element should fill all the space given to it
+        expand = isinstance(element, ExpandableBase)
+
+        if place in ['north', 'west', 'center']:
+            to_start = True
+        elif place in ['south', 'east']:
+            to_start = False
+        else:
+            raise KeyError('Unknown value for place, %s' % place)
+
+        self._add_element(self._layout[place], element, to_start, expand)
+        self._add_element(self._layout[place], separator, to_start, False)
+
+        h = 0
+        for e in [element, separator]:
+            min_size, nat_size = e.get_preferred_size()
+            h += nat_size.height
+
+        return h
+
+    def set_default_size(self, width, height):
+        Gtk.Window.set_default_size(self, width, height)
+
+    def show(self):
+        # show the window
+        Gtk.Window.show(self)
+        if mpl.rcParams["figure.raise_window"]:
+            if self._get_self():
+                self.present()
+            else:
+                # If this is called by a callback early during init,
+                # self.window (a GtkWindow) may not have an associated
+                # low-level GdkWindow (on GTK3) or GdkSurface (on GTK4) yet,
+                # and present() would crash.
+                _api.warn_external("Cannot raise window yet to be setup")
+
+    def destroy(self):
+        Gtk.Window.destroy(self)
+
+    def set_fullscreen(self, fullscreen):
+        if fullscreen:
+            self.fullscreen()
+        else:
+            self.unfullscreen()
+
+    def get_window_title(self):
+        return self.get_title()
+
+    def set_window_title(self, title):
+        self.set_title(title)
+
+    def resize(self, width, height):
+        Gtk.Window.resize(self, width, height)
+
+
 class _FigureManagerGTK(FigureManagerBase):
     """
     Attributes
@@ -135,51 +238,22 @@ class _FigureManagerGTK(FigureManagerBase):
     """
 
     def __init__(self, canvas, num):
-        self._gtk_ver = gtk_ver = Gtk.get_major_version()
-
         app = _create_application()
-        self.window = Gtk.Window()
+        self.window = self._window_class('Matplotlib Figure Manager')
         app.add_window(self.window)
         super().__init__(canvas, num)
 
-        if gtk_ver == 3:
-            self.window.set_wmclass("matplotlib", "Matplotlib")
-            icon_ext = "png" if sys.platform == "win32" else "svg"
-            self.window.set_icon_from_file(
-                str(cbook._get_data_path(f"images/matplotlib.{icon_ext}")))
-
-        self.vbox = Gtk.Box()
-        self.vbox.set_property("orientation", Gtk.Orientation.VERTICAL)
-
-        if gtk_ver == 3:
-            self.window.add(self.vbox)
-            self.vbox.show()
-            self.canvas.show()
-            self.vbox.pack_start(self.canvas, True, True, 0)
-        elif gtk_ver == 4:
-            self.window.set_child(self.vbox)
-            self.vbox.prepend(self.canvas)
-
-        # calculate size for window
+        self.window.add_element(self.canvas, 'center')
         w, h = self.canvas.get_width_height()
 
-        if self.toolbar is not None:
-            if gtk_ver == 3:
-                self.toolbar.show()
-                self.vbox.pack_end(self.toolbar, False, False, 0)
-            elif gtk_ver == 4:
-                sw = Gtk.ScrolledWindow(vscrollbar_policy=Gtk.PolicyType.NEVER)
-                sw.set_child(self.toolbar)
-                self.vbox.append(sw)
-            min_size, nat_size = self.toolbar.get_preferred_size()
-            h += nat_size.height
+        if self.toolbar:
+            h += self.window.add_element(self.toolbar, 'south')  # put in ScrolledWindow in GTK4?
 
         self.window.set_default_size(w, h)
 
         self._destroying = False
-        self.window.connect("destroy", lambda *args: Gcf.destroy(self))
-        self.window.connect({3: "delete_event", 4: "close-request"}[gtk_ver],
-                            lambda *args: Gcf.destroy(self))
+        self.window.mpl_connect('window_destroy_event', lambda *args: Gcf.destroy(self))
+
         if mpl.is_interactive():
             self.window.show()
             self.canvas.draw_idle()
@@ -220,24 +294,9 @@ def show(self):
         # show the figure window
         self.window.show()
         self.canvas.draw()
-        if mpl.rcParams["figure.raise_window"]:
-            meth_name = {3: "get_window", 4: "get_surface"}[self._gtk_ver]
-            if getattr(self.window, meth_name)():
-                self.window.present()
-            else:
-                # If this is called by a callback early during init,
-                # self.window (a GtkWindow) may not have an associated
-                # low-level GdkWindow (on GTK3) or GdkSurface (on GTK4) yet,
-                # and present() would crash.
-                _api.warn_external("Cannot raise window yet to be setup")
 
     def full_screen_toggle(self):
-        is_fullscreen = {
-            3: lambda w: (w.get_window().get_state()
-                          & Gdk.WindowState.FULLSCREEN),
-            4: lambda w: w.is_fullscreen(),
-        }[self._gtk_ver]
-        if is_fullscreen(self.window):
+        if self.window.is_fullscreen():
             self.window.unfullscreen()
         else:
             self.window.fullscreen()
@@ -255,7 +314,7 @@ def resize(self, width, height):
             min_size, nat_size = self.toolbar.get_preferred_size()
             height += nat_size.height
         canvas_size = self.canvas.get_allocation()
-        if self._gtk_ver >= 4 or canvas_size.width == canvas_size.height == 1:
+        if canvas_size.width == canvas_size.height == 1:
             # A canvas size of (1, 1) cannot exist in most cases, because
             # window decorations would prevent such a small window. This call
             # must be before the window has been mapped and widgets have been