Retrocompatible python3 implementation of Gtk.Template (Dustin Spicuzza)

src/gi_composites.py

@@ -0,0 +1,266 @@
+#
+# Copyright 2015 Dustin Spicuzza <[email protected]>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
+# USA
+
+from os.path import abspath, join
+
+import inspect
+import warnings
+
+from gi.repository import Gio
+from gi.repository import GLib
+from gi.repository import GObject
+from gi.repository import Gtk
+
+__all__ = ['GtkTemplate']
+
+class GtkTemplateWarning(UserWarning):
+    pass
+
+def _connect_func(builder, obj, signal_name, handler_name,
+                  connect_object, flags, cls):
+    '''Handles GtkBuilder signal connect events'''
+
+    if connect_object is None:
+        extra = ()
+    else:
+        extra = (connect_object,)
+
+    # The handler name refers to an attribute on the template instance,
+    # so ask GtkBuilder for the template instance
+    template_inst = builder.get_object(cls.__gtype_name__)
+
+    if template_inst is None: # This should never happen
+        errmsg = "Internal error: cannot find template instance! obj: %s; " \
+                 "signal: %s; handler: %s; connect_obj: %s; class: %s" % \
+                 (obj, signal_name, handler_name, connect_object, cls)
+        warnings.warn(errmsg, GtkTemplateWarning)
+        return
+
+    handler = getattr(template_inst, handler_name)
+
+    if flags == GObject.ConnectFlags.AFTER:
+        obj.connect_after(signal_name, handler, *extra)
+    else:
+        obj.connect(signal_name, handler, *extra)
+
+    template_inst.__connected_template_signals__.add(handler_name)
+
+
+def _register_template(cls, template_bytes):
+    '''Registers the template for the widget and hooks init_template'''
+
+    # This implementation won't work if there are nested templates, but
+    # we can't do that anyways due to PyGObject limitations so it's ok
+
+    if not hasattr(cls, 'set_template'):
+        raise TypeError("Requires PyGObject 3.13.2 or greater")
+
+    cls.set_template(template_bytes)
+
+    bound_methods = set()
+    bound_widgets = set()
+
+    # Walk the class, find marked callbacks and child attributes
+    for name in dir(cls):
+
+        o = getattr(cls, name, None)
+
+        if inspect.ismethod(o):
+            if hasattr(o, '_gtk_callback'):
+                bound_methods.add(name)
+                # Don't need to call this, as connect_func always gets called
+                #cls.bind_template_callback_full(name, o)
+        elif isinstance(o, _Child):
+            cls.bind_template_child_full(name, True, 0)
+            bound_widgets.add(name)
+
+    # Have to setup a special connect function to connect at template init
+    # because the methods are not bound yet
+    cls.set_connect_func(_connect_func, cls)
+
+    cls.__gtemplate_methods__ = bound_methods
+    cls.__gtemplate_widgets__ = bound_widgets
+
+    base_init_template = cls.init_template
+    cls.init_template = lambda s: _init_template(s, cls, base_init_template)
+
+
+def _init_template(self, cls, base_init_template):
+    '''This would be better as an override for Gtk.Widget'''
+
+    if self.__class__ is not cls:
+        raise TypeError("Inheritance from classes with @GtkTemplate decorators "
+                        "is not allowed at this time")
+
+    connected_signals = set()
+    self.__connected_template_signals__ = connected_signals
+
+    base_init_template(self)
+
+    for name in self.__gtemplate_widgets__:
+        widget = self.get_template_child(cls, name)
+        self.__dict__[name] = widget
+
+        if widget is None:
+            # Bug: if you bind a template child, and one of them was
+            #      not present, then the whole template is broken (and
+            #      it's not currently possible for us to know which
+            #      one is broken either -- but the stderr should show
+            #      something useful with a Gtk-CRITICAL message)
+            raise AttributeError("A missing child widget was set using "
+                                 "GtkTemplate.Child and the entire "
+                                 "template is now broken (widgets: %s)" %
+                                 ', '.join(self.__gtemplate_widgets__))
+
+    for name in self.__gtemplate_methods__.difference(connected_signals):
+        errmsg = ("Signal '%s' was declared with @GtkTemplate.Callback " +
+                  "but was not present in template") % name
+        warnings.warn(errmsg, GtkTemplateWarning)
+
+class _Child(object):
+    '''
+        Assign this to an attribute in your class definition and it will
+        be replaced with a widget defined in the UI file when init_template
+        is called
+    '''
+
+    __slots__ = []
+
+    @staticmethod
+    def widgets(count):
+        '''
+            Allows declaring multiple widgets with less typing::
+
+                button    \
+                label1    \
+                label2    = GtkTemplate.Child.widgets(3)
+        '''
+        return [_Child() for _ in range(count)]
+
+
+class _GtkTemplate(object):
+    '''
+        Use this class decorator to signify that a class is a composite
+        widget which will receive widgets and connect to signals as
+        defined in a UI template. You must call init_template to
+        cause the widgets/signals to be initialized from the template::
+
+            @GtkTemplate(ui='foo.ui')
+            class Foo(Gtk.Box):
+
+                def __init__(self):
+                    super(Foo, self).__init__()
+                    self.init_template()
+
+        The 'ui' parameter can either be a file path or a GResource resource
+        path::
+
+            @GtkTemplate(ui='/org/example/foo.ui')
+            class Foo(Gtk.Box):
+                pass
+
+        To connect a signal to a method on your instance, do::
+
+            @GtkTemplate.Callback
+            def on_thing_happened(self, widget):
+                pass
+
+        To create a child attribute that is retrieved from your template,
+        add this to your class definition::
+
+            @GtkTemplate(ui='foo.ui')
+            class Foo(Gtk.Box):
+
+                widget = GtkTemplate.Child()
+
+
+        Note: This is implemented as a class decorator, but if it were
+        included with PyGI I suspect it might be better to do this
+        in the GObject metaclass (or similar) so that init_template
+        can be called automatically instead of forcing the user to do it.
+
+        .. note:: Due to limitations in PyGObject, you may not inherit from
+                  python objects that use the GtkTemplate decorator.
+    '''
+
+    __ui_path__ = None
+
+    @staticmethod
+    def Callback(f):
+        '''
+            Decorator that designates a method to be attached to a signal from
+            the template
+        '''
+        f._gtk_callback = True
+        return f
+
+
+    Child = _Child
+
+    @staticmethod
+    def set_ui_path(*path):
+        '''
+            If using file paths instead of resources, call this *before*
+            loading anything that uses GtkTemplate, or it will fail to load
+            your template file
+
+            :param path: one or more path elements, will be joined together
+                         to create the final path
+        '''
+        _GtkTemplate.__ui_path__ = abspath(join(*path))
+
+
+    def __init__(self, ui):
+        self.ui = ui
+
+    def __call__(self, cls):
+
+        if not issubclass(cls, Gtk.Widget):
+            raise TypeError("Can only use @GtkTemplate on Widgets")
+
+        # Nested templates don't work
+        if hasattr(cls, '__gtemplate_methods__'):
+            raise TypeError("Cannot nest template classes")
+
+        # Load the template either from a resource path or a file
+        # - Prefer the resource path first
+
+        try:
+            template_bytes = Gio.resources_lookup_data(self.ui, Gio.ResourceLookupFlags.NONE)
+        except GLib.GError:
+            ui = self.ui
+            if isinstance(ui, (list, tuple)):
+                ui = join(ui)
+
+            if _GtkTemplate.__ui_path__ is not None:
+                ui = join(_GtkTemplate.__ui_path__, ui)
+
+            with open(ui, 'rb') as fp:
+                template_bytes = GLib.Bytes.new(fp.read())
+
+        _register_template(cls, template_bytes)
+        return cls
+
+
+# Future shim support if this makes it into PyGI?
+#if hasattr(Gtk, 'GtkTemplate'):
+#    GtkTemplate = lambda c: c
+#else:
+GtkTemplate = _GtkTemplate
+
+

src/image.py

@@ -17,6 +17,7 @@
 
 import cairo, random, math
 from gi.repository import Gtk, Gdk, Gio, GdkPixbuf, Pango, GLib
+from .gi_composites import GtkTemplate
 from .history_manager import DrHistoryManager
 from .selection_manager import DrSelectionManager
 from .properties import DrPropertiesDialog
@@ -38,18 +39,19 @@ def __init__(self, pb_name):
 
 ################################################################################
 
-@Gtk.Template(resource_path='/com/github/maoschanz/drawing/ui/image.ui')
+@GtkTemplate(ui='/com/github/maoschanz/drawing/ui/image.ui')
 class DrImage(Gtk.Box):
 	__gtype_name__ = 'DrImage'
 
-	_drawing_area = Gtk.Template.Child()
-	_h_scrollbar = Gtk.Template.Child()
-	_v_scrollbar = Gtk.Template.Child()
+	_drawing_area = GtkTemplate.Child()
+	_h_scrollbar = GtkTemplate.Child()
+	_v_scrollbar = GtkTemplate.Child()
 
 	SCALE_FACTOR = 1.0 # XXX doesn't work well enough to be anything else
 
 	def __init__(self, window, **kwargs):
 		super().__init__(**kwargs)
+		self.init_template()
 		self.window = window
 
 		self.gfile = None

src/meson.build

@@ -33,6 +33,7 @@ configure_file(
 
 drawing_sources = [
 	'__init__.py',
+	'gi_composites.py',
 	'main.py',
 
 	'window.py',

src/preferences.py

@@ -16,29 +16,31 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from gi.repository import Gtk, Gio, Gdk
+from .gi_composites import GtkTemplate
 from .utilities import utilities_add_unit_to_spinbtn
 
-@Gtk.Template(resource_path='/com/github/maoschanz/drawing/ui/preferences.ui')
+@GtkTemplate(ui='/com/github/maoschanz/drawing/ui/preferences.ui')
 class DrPrefsWindow(Gtk.Window):
 	__gtype_name__ = 'DrPrefsWindow'
 
-	content_area = Gtk.Template.Child()
-	stack = Gtk.Template.Child()
+	content_area = GtkTemplate.Child()
+	stack = GtkTemplate.Child()
 
-	page_images = Gtk.Template.Child()
-	page_tools = Gtk.Template.Child()
-	page_advanced = Gtk.Template.Child()
+	page_images = GtkTemplate.Child()
+	page_tools = GtkTemplate.Child()
+	page_advanced = GtkTemplate.Child()
 
-	adj_width = Gtk.Template.Child()
-	adj_height = Gtk.Template.Child()
-	adj_preview = Gtk.Template.Child()
+	adj_width = GtkTemplate.Child()
+	adj_height = GtkTemplate.Child()
+	adj_preview = GtkTemplate.Child()
 
 	_current_grid = None
 	_grid_attach_cpt = 0
 	_gsettings = Gio.Settings.new('com.github.maoschanz.drawing')
 
 	def __init__(self, is_beta, wants_csd, **kwargs):
 		super().__init__(**kwargs)
+		self.init_template()
 		if wants_csd:
 			header_bar = Gtk.HeaderBar(
 				visible=True, \

src/window.py

@@ -18,6 +18,7 @@
 # Import libs
 import os, traceback
 from gi.repository import Gtk, Gdk, Gio, GdkPixbuf, GLib
+from .gi_composites import GtkTemplate
 
 # Import tools
 from .tool_arc import ToolArc
@@ -76,27 +77,28 @@
 
 ################################################################################
 
-@Gtk.Template(resource_path=UI_PATH+'window.ui')
+@GtkTemplate(ui=UI_PATH+'window.ui')
 class DrWindow(Gtk.ApplicationWindow):
 	__gtype_name__ = 'DrWindow'
 
 	gsettings = Gio.Settings.new('com.github.maoschanz.drawing')
 
 	# Window empty widgets
-	tools_flowbox = Gtk.Template.Child()
-	toolbar_box = Gtk.Template.Child()
-	info_bar = Gtk.Template.Child()
-	info_label = Gtk.Template.Child()
-	info_action = Gtk.Template.Child()
-	notebook = Gtk.Template.Child()
-	bottom_panes_box = Gtk.Template.Child()
-	unfullscreen_btn = Gtk.Template.Child()
-	bottom_meta_box = Gtk.Template.Child()
-	tools_scrollable_box = Gtk.Template.Child()
-	tools_nonscrollable_box = Gtk.Template.Child()
+	tools_flowbox = GtkTemplate.Child()
+	toolbar_box = GtkTemplate.Child()
+	info_bar = GtkTemplate.Child()
+	info_label = GtkTemplate.Child()
+	info_action = GtkTemplate.Child()
+	notebook = GtkTemplate.Child()
+	bottom_panes_box = GtkTemplate.Child()
+	unfullscreen_btn = GtkTemplate.Child()
+	bottom_meta_box = GtkTemplate.Child()
+	tools_scrollable_box = GtkTemplate.Child()
+	tools_nonscrollable_box = GtkTemplate.Child()
 
 	def __init__(self, **kwargs):
 		super().__init__(**kwargs)
+		self.init_template()
 		self.app = kwargs['application']
 
 		self.pointer_to_current_page = None # this ridiculous hack allows to