[meld] meld.ui: Add a prototype encoding selector

[Kai Willadsen <kaiw src gnome org>]

commit 78089f8d1cbd8b75fed9b082488ed66466f0a656
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Oct 27 06:56:52 2017 +1000

    meld.ui: Add a prototype encoding selector
    
    Currently this is UI-only, and doesn't actually change any document
    encoding stuff.

 data/ui/encoding-selector.ui |   83 +++++++++++++++++++++++++++++++++++++++
 meld/ui/bufferselectors.py   |   38 ++++++++++++++++++
 meld/ui/listselector.py      |   88 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 209 insertions(+), 0 deletions(-)
---
diff --git a/data/ui/encoding-selector.ui b/data/ui/encoding-selector.ui
new file mode 100644
index 0000000..151744a
--- /dev/null
+++ b/data/ui/encoding-selector.ui
@@ -0,0 +1,83 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.8 -->
+  <object class="GtkListStore" id="liststore">
+    <columns>
+      <!-- column-name name -->
+      <column type="gchararray"/>
+      <!-- column-name encoding -->
+      <column type="GtkSourceEncoding"/>
+    </columns>
+  </object>
+  <object class="GtkTreeModelFilter" id="treemodelfilter">
+    <property name="child_model">liststore</property>
+  </object>
+  <template class="EncodingSelector" parent="GtkGrid">
+    <property name="width_request">300</property>
+    <property name="height_request">400</property>
+    <property name="visible">True</property>
+    <property name="can_focus">False</property>
+    <property name="has_focus">False</property>
+    <property name="is_focus">False</property>
+    <property name="row_spacing">3</property>
+    <property name="border_width">6</property>
+    <child>
+      <object class="GtkSearchEntry" id="entry">
+        <property name="visible">True</property>
+        <property name="can_focus">True</property>
+        <property name="has_focus">True</property>
+        <property name="is_focus">False</property>
+        <property name="activates_default">True</property>
+        <property name="placeholder_text" translatable="yes">Search text encoding...</property>
+      </object>
+      <packing>
+        <property name="left_attach">0</property>
+        <property name="top_attach">0</property>
+        <property name="width">1</property>
+        <property name="height">1</property>
+      </packing>
+    </child>
+    <child>
+      <object class="GtkScrolledWindow" id="scrolledwindow1">
+        <property name="visible">True</property>
+        <property name="can_focus">True</property>
+        <property name="has_focus">False</property>
+        <property name="is_focus">False</property>
+        <property name="hexpand">True</property>
+        <property name="vexpand">True</property>
+        <property name="shadow_type">in</property>
+        <child>
+          <object class="GtkTreeView" id="treeview">
+            <property name="visible">True</property>
+            <property name="can_focus">True</property>
+            <property name="has_focus">False</property>
+            <property name="is_focus">False</property>
+            <property name="model">treemodelfilter</property>
+            <property name="headers_visible">False</property>
+            <property name="headers_clickable">False</property>
+            <property name="enable_search">False</property>
+            <child internal-child="selection">
+              <object class="GtkTreeSelection" id="treeview_selection"/>
+            </child>
+            <child>
+              <object class="GtkTreeViewColumn" id="treeviewcolumn">
+                <child>
+                  <object class="GtkCellRendererText" id="cellrenderertext"/>
+                  <attributes>
+                    <attribute name="text">0</attribute>
+                  </attributes>
+                </child>
+              </object>
+            </child>
+          </object>
+        </child>
+      </object>
+      <packing>
+        <property name="left_attach">0</property>
+        <property name="top_attach">1</property>
+        <property name="width">1</property>
+        <property name="height">1</property>
+      </packing>
+    </child>
+  </template>
+</interface>
diff --git a/meld/ui/bufferselectors.py b/meld/ui/bufferselectors.py
new file mode 100644
index 0000000..d01cece
--- /dev/null
+++ b/meld/ui/bufferselectors.py
@@ -0,0 +1,38 @@
+
+from gi.repository import GLib
+from gi.repository import GObject
+from gi.repository import Gtk
+from gi.repository import GtkSource
+
+from meld.conf import _, ui_file
+from meld.ui.listselector import FilteredListSelector
+
+
+class EncodingSelector(FilteredListSelector, Gtk.Grid):
+    # The subclassing here is weird; the Selector must directly
+    # subclass Gtk.Grid, or the template building explodes.
+
+    __gtype_name__ = 'EncodingSelector'
+
+    __gsignals__ = {
+        'encoding-selected': (
+            GObject.SignalFlags.RUN_FIRST | GObject.SignalFlags.ACTION,
+            None, (GtkSource.Encoding,)),
+    }
+
+    # These exist solely to make subclassing easier.
+    value_accessor = 'get_charset'
+    change_signal_name = 'encoding-selected'
+
+    def populate_model(self):
+        for enc in GtkSource.Encoding.get_all():
+            self.liststore.append((self.get_value_label(enc), enc))
+
+    def get_value_label(self, enc):
+        return _('{name} ({charset})').format(
+            name=enc.get_name(), charset=enc.get_charset())
+
+
+template = open(ui_file('encoding-selector.ui'), 'rb').read()
+template_bytes = GLib.Bytes.new(template)
+EncodingSelector.set_template(template_bytes)
diff --git a/meld/ui/listselector.py b/meld/ui/listselector.py
new file mode 100644
index 0000000..99d2d72
--- /dev/null
+++ b/meld/ui/listselector.py
@@ -0,0 +1,88 @@
+
+from gi.repository import Gtk
+
+
+class TemplateHackMixin(object):
+
+    def get_template_child(self, widget_type, name):
+        # Taken from an in-progress patch on bgo#701843
+
+        def get_template_child(widget, widget_type, name):
+            # Explicitly use gtk_buildable_get_name() because it is masked by
+            # gtk_widget_get_name() in GI.
+            if isinstance(widget, widget_type) and \
+                    isinstance(widget, Gtk.Buildable) and \
+                    Gtk.Buildable.get_name(widget) == name:
+                return widget
+
+            if isinstance(widget, Gtk.Container):
+                for child in widget.get_children():
+                    result = get_template_child(child, widget_type, name)
+                    if result is not None:
+                        return result
+
+        return get_template_child(self, widget_type, name)
+
+
+class FilteredListSelector(TemplateHackMixin):
+
+    __gtype_name__ = 'FilteredListSelector'
+
+    NAME_COLUMN, VALUE_COLUMN = 0, 1
+
+    def __init__(self):
+        Gtk.Grid.__init__(self)
+        self.init_template()
+
+        self.entry = self.get_template_child(Gtk.SearchEntry, 'entry')
+        self.treeview = self.get_template_child(Gtk.TreeView, 'treeview')
+        self.treeview_selection = self.treeview.get_selection()
+        # FIXME: Should be able to access as a template child, but can't.
+        self.listfilter = self.treeview.get_model()
+        self.liststore = self.listfilter.get_model()
+
+        self.populate_model()
+        self.filter_string = ''
+        self.entry.connect('changed', self.on_entry_changed)
+        self.listfilter.set_visible_func(self.name_filter)
+
+        self.entry.connect('activate', self.on_activate)
+        self.treeview.connect('row-activated', self.on_activate)
+
+    def populate_model(self):
+        raise NotImplementedError
+
+    def select_value(self, value):
+        if not value:
+            return
+
+        new_value_getter = getattr(value, self.value_accessor)
+        for row in self.liststore:
+            row_value = row[self.VALUE_COLUMN]
+            if not row_value:
+                continue
+            old_value_getter = getattr(row_value, self.value_accessor)
+            if old_value_getter() != new_value_getter():
+                continue
+            self.treeview_selection.select_path(row.path)
+            self.treeview.scroll_to_cell(row.path, None, True, 0.5, 0)
+
+    def name_filter(self, model, it, *args):
+        if not self.filter_string:
+            return True
+        name = model.get_value(it, self.NAME_COLUMN).lower()
+        return self.filter_string.lower() in name
+
+    def on_entry_changed(self, entry):
+        self.filter_string = entry.get_text()
+        self.listfilter.refilter()
+        first = self.listfilter.get_iter_first()
+        if first:
+            self.treeview_selection.select_iter(first)
+
+    def on_activate(self, *args):
+        model, it = self.treeview_selection.get_selected()
+        if not it:
+            return
+        value = model.get_value(it, self.VALUE_COLUMN)
+        self.emit(self.change_signal_name, value)