Implement font zooming in the editor

Give controls for zoom in, zoom out, and reset zoom in the menu and via hotkey.
Also add a new placeholder in the view menu to allow positioning the menuitems
properly. Still want to keep the highlighting menu item at the  bottom.

This is implemented by using a builtin libpeas python plugin. Add support for
loading these plugins at startup. They cannot be enabled or disabled through the
UI. They can still be disabled in gsettings but will be automatically reloaded
when xed is restarted.

Closes: https://github.com/linuxmint/xed/issues/45

configure.ac

@@ -173,6 +173,8 @@ else
 	enable_introspection=no
 fi
 
+AM_PATH_PYTHON([3.2.3])
+
 dnl ================================================================
 dnl GSettings related settings
 dnl ================================================================
@@ -236,6 +238,8 @@ plugins/sort/Makefile
 plugins/spell/Makefile
 plugins/spell/org.x.editor.plugins.spell.gschema.xml
 plugins/taglist/Makefile
+plugins/textsize/Makefile
+plugins/textsize/textsize/Makefile
 plugins/time/Makefile
 plugins/time/org.x.editor.plugins.time.gschema.xml
 plugins/trailsave/Makefile

debian/xed.install

@@ -1,8 +1,7 @@
 usr/bin/xed
 usr/lib/*/xed/girepository-1.0/
 usr/lib/xed/xed-bugreport.sh
-usr/lib/*/xed/plugins/*.plugin
+usr/lib/*/xed/plugins/
-usr/lib/*/xed/plugins/*.so
 usr/lib/*/xed/*.so
 usr/share/applications/xed.desktop
 usr/share/dbus-1/

plugins/Makefile.am

@@ -5,6 +5,7 @@ DIST_SUBDIRS =		\
 	sort 			\
 	spell			\
 	taglist			\
+	textsize 		\
 	time			\
 	trailsave
 
@@ -15,6 +16,7 @@ SUBDIRS = 			\
 	sort			\
 	spell			\
 	taglist			\
+	textsize 		\
 	time			\
 	trailsave
 

plugins/textsize/Makefile.am

@@ -0,0 +1,16 @@
+# Textsize Plugin
+SUBDIRS = textsize
+plugindir = $(XED_PLUGINS_LIBS_DIR)
+
+plugin_in_files = textsize.plugin.desktop.in
+%.plugin: %.plugin.desktop.in $(INTLTOOL_MERGE) $(wildcard $(top_srcdir)/po/*po) ; $(INTLTOOL_MERGE) $(top_srcdir)/po $< $@ -d -u -c $(top_builddir)/po/.intltool-merge-cache
+
+plugin_DATA = $(plugin_in_files:.plugin.desktop.in=.plugin)
+
+EXTRA_DIST =            \
+    $(plugin_in_files)
+
+CLEANFILES = $(plugin_DATA)
+DISTCLEANFILES = $(plugin_DATA)
+
+-include $(top_srcdir)/git.mk

plugins/textsize/textsize.plugin.desktop.in

@@ -0,0 +1,11 @@
+[Plugin]
+Loader=python3
+Module=textsize
+IAge=3
+_Name=Text Size
+_Description=Allow controlling the zoom levels of the text
+Icon=gnome-mime-text-x-python
+Authors=Steve Frécinaux <steve@istique.net>;Linux Mint team
+Copyright=Copyright © 2017 by the authors
+Website=https://github.com/linuxmint
+Builtin=true

plugins/textsize/textsize/Makefile.am

@@ -0,0 +1,11 @@
+plugindir = $(XED_PLUGINS_LIBS_DIR)/textsize
+
+plugin_PYTHON =         \
+    __init__.py         \
+    signals.py          \
+    documenthelper.py
+
+CLEANFILES =
+DISTCLEANFILES =
+
+-include $(top_srcdir)/git.mk

plugins/textsize/textsize/__init__.py

@@ -0,0 +1,233 @@
+# -*- coding: utf-8 -*-
+#
+#  __init__.py - Text size plugin
+#
+#  Copyright (C) 2008 - Konstantin Mikhaylov <jtraub.devel@gmail.com>
+#  Copyright (C) 2009 - Wouter Bolsterlee <wbolster@gnome.org>
+#  Copyright (C) 2010 - Ignacio Casal Quinteiro <icq@gnome.org>
+#  Copyright (C) 2010 - Jesse van den Kieboom <jessevdk@gnome.org>
+#  Copyright (C) 2017 - Linux Mint team <https://github.com/linuxmint>
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program 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 General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 51 Franklin Street, Fifth Floor,
+#  Boston, MA 02110-1301, USA.
+
+from gi.repository import GObject, Gio, Gtk, Gdk, Xed
+from .documenthelper import DocumentHelper
+
+MENU_PATH = "/MenuBar/ViewMenu/ViewOps_1"
+
+class TextSizePlugin(GObject.Object, Xed.WindowActivatable):
+    __gtype_name__ = "TextSizePlugin"
+
+    window = GObject.property(type=Xed.Window)
+
+    def __init__(self):
+        GObject.Object.__init__(self)
+
+    def do_activate(self):
+        self._views  = {}
+
+        # Insert menu items
+        self._insert_menu()
+
+        # Insert document helpers
+        for view in self.window.get_views():
+            self.add_document_helper(view)
+
+        self.window.connect('tab-added', self.on_tab_added)
+        self.window.connect('tab-removed', self.on_tab_removed)
+
+        self._accel_group = Gtk.AccelGroup()
+        self.window.add_accel_group(self._accel_group)
+
+        self._proxy_callback_map = {
+            'LargerTextAction': self.on_larger_text_accel,
+            'SmallerTextAction': self.on_smaller_text_accel,
+            'NormalSizeAction': self.on_normal_size_accel
+        }
+
+        self._proxy_mapping = {}
+        self._init_proxy_accels()
+        self._accel_map_handler_id = Gtk.AccelMap.get().connect('changed', self.on_accel_map_changed)
+
+    def _install_proxy(self, action):
+        if not isinstance(action, Gtk.Action):
+            action = self._action_group.get_action(str(action))
+
+        if not action:
+            return
+
+        entry = Gtk.AccelMap.lookup_entry(action.get_accel_path())
+
+        if not entry:
+            return
+
+        mapping = {
+            Gdk.KEY_equal: Gdk.KEY_KP_Equal,
+            Gdk.KEY_KP_Equal: Gdk.KEY_equal,
+            Gdk.KEY_minus: Gdk.KEY_KP_Subtract,
+            Gdk.KEY_KP_Subtract: Gdk.KEY_minus,
+            Gdk.KEY_0: Gdk.KEY_KP_0,
+            Gdk.KEY_KP_0: Gdk.KEY_0
+        }
+
+        if entry[0] in mapping:
+            key = mapping[entry[0]]
+            mod = entry[1]
+
+            callback = self._proxy_callback_map[action.get_name()]
+
+            self._accel_group.connect_group(key, mod, Gtk.ACCEL_LOCKED, callback)
+            self._proxy_mapping[action] = (key, mod)
+
+    def _init_proxy_accels(self):
+        self._install_proxy('LargerTextAction')
+        self._install_proxy('SmallerTextAction')
+        self._install_proxy('NormalSizeAction')
+
+    def do_deactivate(self):
+        # Remove any installed menu items
+        self._remove_menu()
+
+        for view in self.window.get_views():
+            self.remove_document_helper(view)
+
+        self.window.remove_accel_group(self._accel_group)
+
+        Gtk.AccelMap.get().disconnect(self._accel_map_handler_id)
+
+        self._accel_group = None
+        self._action_group = None
+
+    def _insert_menu(self):
+        # Get the GtkUIManager
+        manager = self.window.get_ui_manager()
+
+        # Create a new action group
+        self._action_group = Gtk.ActionGroup("XedTextSizePluginActions")
+        self._action_group.add_actions([("LargerTextAction", None, _("_Larger Text"),
+                                         "<Ctrl>equal", None,
+                                         self.on_larger_text_activate),
+                                         ("SmallerTextAction", None, _("S_maller Text"),
+                                         "<Ctrl>minus", None,
+                                         self.on_smaller_text_activate),
+                                         ("NormalSizeAction", None, _("_Normal size"),
+                                         "<Ctrl>0", None,
+                                         self.on_normal_size_activate)])
+
+        # Insert the action group
+        manager.insert_action_group(self._action_group)
+
+        self._ui_id = manager.new_merge_id();
+
+        manager.add_ui(self._ui_id,
+                       MENU_PATH,
+                       "LargerTextAction",
+                       "LargerTextAction",
+                       Gtk.UIManagerItemType.MENUITEM,
+                       False)
+
+        manager.add_ui(self._ui_id,
+                       MENU_PATH,
+                       "SmallerTextAction",
+                       "SmallerTextAction",
+                       Gtk.UIManagerItemType.MENUITEM,
+                       False)
+
+        manager.add_ui(self._ui_id,
+                       MENU_PATH,
+                       "NormalSizeAction",
+                       "NormalSizeAction",
+                       Gtk.UIManagerItemType.MENUITEM,
+                       False)
+
+    def _remove_menu(self):
+        # Get the GtkUIManager
+        manager = self.window.get_ui_manager()
+
+        # Remove the ui
+        manager.remove_ui(self._ui_id)
+
+        # Remove the action group
+        manager.remove_action_group(self._action_group)
+
+        # Make sure the manager updates
+        manager.ensure_update()
+
+    def do_update_state(self):
+        self._action_group.set_sensitive(self.window.get_active_document() != None)
+
+    def get_helper(self, view):
+        if not hasattr(view, "textsize_document_helper"):
+            return None
+        return view.textsize_document_helper
+
+    def add_document_helper(self, view):
+        if self.get_helper(view) != None:
+            return
+
+        DocumentHelper(view)
+
+    def remove_document_helper(self, view):
+        helper = self.get_helper(view)
+
+        if helper != None:
+            helper.stop()
+
+    def call_helper(self, cb):
+        view = self.window.get_active_view()
+
+        if view:
+            cb(self.get_helper(view))
+
+    # Menu activate handlers
+    def on_larger_text_activate(self, action, user_data=None):
+        self.call_helper(lambda helper: helper.larger_text())
+
+    def on_smaller_text_activate(self, action, user_data=None):
+        self.call_helper(lambda helper: helper.smaller_text())
+
+    def on_normal_size_activate(self, action, user_data=None):
+        self.call_helper(lambda helper: helper.normal_size())
+
+    def on_larger_text_accel(self, group, accel, key, mod):
+        self.call_helper(lambda helper: helper.larger_text())
+
+    def on_smaller_text_accel(self, group, accel, key, mod):
+        self.call_helper(lambda helper: helper.smaller_text())
+
+    def on_normal_size_accel(self, group, accel, key, mod):
+        self.call_helper(lambda helper: helper.normal_size())
+
+    def on_tab_added(self, window, tab):
+        self.add_document_helper(tab.get_view())
+
+    def on_tab_removed(self, window, tab):
+        self.remove_document_helper(tab.get_view())
+
+    def _remap_proxy(self, action):
+        # Remove previous proxy
+
+        if action in self._proxy_mapping:
+            item = self._proxy_mapping[action]
+            self._accel_group.disconnect_key(item[0], item[1])
+
+        self._install_proxy(action)
+
+    def on_accel_map_changed(self, accelmap, path, key, mod):
+        for action in self._action_group.list_actions():
+            if action.get_accel_path() == path:
+                self._remap_proxy(action)
+                return

plugins/textsize/textsize/documenthelper.py

@@ -0,0 +1,189 @@
+# -*- coding: utf-8 -*-
+#
+#  documenthelper.py - Document helper
+#
+#  Copyright (C) 2010 - Jesse van den Kieboom
+#  Copyright (C) 2017 - Linux Mint team
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program 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 General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 51 Franklin Street, Fifth Floor,
+#  Boston, MA 02110-1301, USA.
+
+
+from .signals import Signals
+from gi.repository import Gtk, Gdk, Pango
+
+class DocumentHelper(Signals):
+    def __init__(self, view):
+        Signals.__init__(self)
+
+        self._view = view
+
+        self.connect_signal(self._view, 'scroll-event', self.on_scroll_event)
+        self.connect_signal(self._view, 'button-press-event', self.on_button_press_event)
+
+        self._view.textsize_document_helper = self
+
+        self._default_font = None
+        self._last_font = None
+        self._font_tags = {}
+
+    def stop(self):
+        if self._default_font:
+            self._view.override_font(self._default_font)
+
+        self.remove_font_tags()
+        self.disconnect_signals(self._view)
+
+        self._view.textsize_document_helper = None
+
+    def remove_font_tags(self):
+        buf = self._view.get_buffer()
+        table = buf.get_tag_table()
+
+        # Remove all the font tags
+        for size in self._font_tags:
+            tag = self._font_tags[size]
+            table.remove(tag)
+
+        self._font_tags = {}
+
+    def update_default_font(self):
+        context = self._view.get_style_context()
+        description = context.get_font(context.get_state()).copy()
+
+        if not self._last_font or description.hash() != self._last_font.hash():
+            self._default_font = description
+
+    def get_font_tags(self, start, end):
+        tags = set()
+
+        # Check all the know font tags
+        for size in self._font_tags:
+            tag = self._font_tags[size]
+
+            if start.has_tag(tag):
+                tags.add(tag)
+            else:
+                cp = start.copy()
+
+                if cp.forward_to_tag_toggle(tag) and cp.compare(end) < 0:
+                    tags.add(tag)
+
+        return list(tags)
+
+    def set_font_size(self, amount):
+        self.update_default_font()
+
+        context = self._view.get_style_context()
+        description = context.get_font(context.get_state()).copy()
+
+        buf = self._view.get_buffer()
+        bounds = buf.get_selection_bounds()
+        size = description.get_size() / Pango.SCALE
+
+        if not bounds:
+            description.set_size(max(1, (size + amount)) * Pango.SCALE)
+
+            self._view.override_font(description)
+            self._last_font = description
+        else:
+            start = bounds[0]
+            end = bounds[1]
+
+            tags = self.get_font_tags(start, end)
+
+            if not tags:
+                # Simply use the overall font size as the base
+                newsize = size + amount
+            elif len(tags) == 1:
+                newsize = tags[0].props.font_desc.get_size() / Pango.SCALE + amount
+            else:
+                newsize = 0
+
+                for tag in tags:
+                    newsize += tag.props.font_desc.get_size() / Pango.SCALE
+
+                newsize = round(newsize / len(tags))
+
+            newsize = int(max(1, newsize))
+
+            if not newsize in self._font_tags:
+                newtag = buf.create_tag(None)
+
+                desc = description
+                desc.set_size(newsize * Pango.SCALE)
+
+                newtag.props.font_desc = desc
+                self._font_tags[newsize] = newtag
+            else:
+                newtag = self._font_tags[newsize]
+
+            # Remove all the previous mix of tags
+            for tag in tags:
+                buf.remove_tag(tag, start, end)
+
+            buf.apply_tag(newtag, start, end)
+
+    def larger_text(self):
+        self.set_font_size(1)
+
+    def smaller_text(self):
+        self.set_font_size(-1)
+
+    def normal_size(self):
+        self.update_default_font()
+
+        buf = self._view.get_buffer()
+        bounds = buf.get_selection_bounds()
+
+        if not bounds:
+            self.remove_font_tags()
+
+            self._view.override_font(self._default_font)
+            self._last_font = self._default_font
+        else:
+            tags = self.get_font_tags(bounds[0], bounds[1])
+
+            for tag in tags:
+                buf.remove_tag(tag, bounds[0], bounds[1])
+
+    def on_scroll_event(self, view, event):
+        state = event.state & Gtk.accelerator_get_default_mod_mask()
+
+        if state != Gdk.ModifierType.CONTROL_MASK:
+            return False
+
+        if event.direction == Gdk.ScrollDirection.UP:
+            self.larger_text()
+            return True
+        elif event.direction == Gdk.ScrollDirection.DOWN:
+            self.smaller_text()
+            return True
+        elif event.direction == Gdk.ScrollDirection.SMOOTH:
+            if event.delta_y > 0:
+                self.smaller_text()
+            elif event.delta_y < 0:
+                self.larger_text()
+
+        return False
+
+    def on_button_press_event(self, view, event):
+        state = event.state & Gtk.accelerator_get_default_mod_mask()
+
+        if state == Gdk.ModifierType.CONTROL_MASK and event.button == 2:
+            self.normal_size()
+            return True
+        else:
+            return False

plugins/textsize/textsize/signals.py

@@ -0,0 +1,69 @@
+class Signals(object):
+    def __init__(self):
+        self._signals = {}
+
+    def _connect(self, obj, name, handler, connector):
+        ret = self._signals.setdefault(obj, {})
+
+        hid = connector(name, handler)
+        ret.setdefault(name, []).append(hid)
+
+        return hid
+
+    def connect_signal(self, obj, name, handler):
+        return self._connect(obj, name, handler, obj.connect)
+
+    def connect_signal_after(self, obj, name, handler):
+        return self._connect(obj, name, handler, obj.connect_after)
+
+    def disconnect_signals(self, obj):
+        if obj not in self._signals:
+            return False
+
+        for name in self._signals[obj]:
+            for hid in self._signals[obj][name]:
+                obj.disconnect(hid)
+
+        del self._signals[obj]
+        return True
+
+    def block_signal(self, obj, name):
+        if obj not in self._signals:
+            return False
+
+        if name not in self._signals[obj]:
+            return False
+
+        for hid in self._signals[obj][name]:
+            obj.handler_block(hid)
+
+        return True
+
+    def unblock_signal(self, obj, name):
+        if obj not in self._signals:
+            return False
+
+        if name not in self._signals[obj]:
+            return False
+
+        for hid in self._signals[obj][name]:
+            obj.handler_unblock(hid)
+
+        return True
+
+    def disconnect_signal(self, obj, name):
+        if obj not in self._signals:
+            return False
+
+        if name not in self._signals[obj]:
+            return False
+
+        for hid in self._signals[obj][name]:
+            obj.disconnect(hid)
+
+        del self._signals[obj][name]
+
+        if len(self._signals[obj]) == 0:
+            del self._signals[obj]
+
+        return True

xed/resources/ui/xed-ui.xml

@@ -56,6 +56,9 @@
       <menuitem name="ViewFullscreenMenu" action="ViewFullscreen"/>
       <separator/>
       <menuitem name="ViewWordWrapMenu" action="ViewWordWrap"/>
+      <separator/>
+      <placeholder name="ViewOps_1" />
+      <separator/>
       <menu name="ViewHighlightModeMenu" action="ViewHighlightMode">
         <placeholder name="LanguagesMenuPlaceholder">
         </placeholder>

xed/xed-plugins-engine.c

@@ -58,6 +58,7 @@ xed_plugins_engine_init (XedPluginsEngine *engine)
 {
     gchar *typelib_dir;
     GError *error = NULL;
+    const GList *all_plugins, *l;
 
     xed_debug (DEBUG_PLUGINS);
 
@@ -93,17 +94,6 @@ xed_plugins_engine_init (XedPluginsEngine *engine)
         error = NULL;
     }
 
-    // private_path = g_build_filename (LIBDIR, "girepository-1.0", NULL);
-
-    // if (!g_irepository_require_private (g_irepository_get_default (), private_path, "Xed", "1.0", 0, &error))
-    // {
-    //     g_warning ("Could not load Xed repository: %s", error->message);
-    //     g_error_free (error);
-    //     error = NULL;
-    // }
-
-    // g_free (private_path);
-
     peas_engine_add_search_path (PEAS_ENGINE (engine),
                                  xed_dirs_get_user_plugins_dir (),
                                  xed_dirs_get_user_plugins_dir ());
@@ -117,6 +107,23 @@ xed_plugins_engine_init (XedPluginsEngine *engine)
                      engine,
                      "loaded-plugins",
                      G_SETTINGS_BIND_DEFAULT);
+
+    /* Load our builtin plugins */
+    all_plugins = peas_engine_get_plugin_list (PEAS_ENGINE (engine));
+
+    for (l = all_plugins; l != NULL; l = l->next)
+    {
+        if (peas_plugin_info_is_builtin (l->data))
+        {
+            gboolean loaded;
+
+            loaded = peas_engine_load_plugin (PEAS_ENGINE (engine), l->data);
+            if (!loaded)
+            {
+                g_warning ("Failed to load builtin plugin: %s", peas_plugin_info_get_name (l->data));
+            }
+        }
+    }
 }
 
 static void