[geary/mjog/mail-merge-plugin: 21/28] Plugin.Composer: Support registering composer menu items

[Michael Gratton <mjog src gnome org>]

commit 65509e213b9336c298a1e4eee089682d4b396a88
Author: Michael Gratton <mike vee net>
Date:   Fri Jul 3 18:03:47 2020 +1000

    Plugin.Composer: Support registering composer menu items
    
    Allow plugins to register per-composer actions and add menu items to
    their own section in the composer's menu.

 .../application/application-plugin-manager.vala    | 37 ++++++++++++++++++++++
 src/client/composer/composer-widget.vala           | 10 ++++++
 src/client/plugin/plugin-composer.vala             | 35 ++++++++++++++++++++
 3 files changed, 82 insertions(+)
---
diff --git a/src/client/application/application-plugin-manager.vala 
b/src/client/application/application-plugin-manager.vala
index 82df12e70..5c3cf87ad 100644
--- a/src/client/application/application-plugin-manager.vala
+++ b/src/client/application/application-plugin-manager.vala
@@ -376,12 +376,18 @@ public class Application.PluginManager : GLib.Object {
 
         private Composer.Widget backing;
         private weak ApplicationImpl application;
+        private GLib.SimpleActionGroup? action_group = null;
+        private GLib.Menu? menu_items = null;
+        private string action_group_name;
+
+
 
 
         public ComposerImpl(Composer.Widget backing,
                             ApplicationImpl application) {
             this.backing = backing;
             this.application = application;
+            this.action_group_name = application.plugin.action_group_name + "-cmp";
         }
 
         public void save_to_folder(Plugin.Folder? location) {
@@ -407,6 +413,37 @@ public class Application.PluginManager : GLib.Object {
             this.application.backing.controller.present_composer(this.backing);
         }
 
+        public void register_action(GLib.Action action) {
+            if (this.action_group == null) {
+                this.action_group = new GLib.SimpleActionGroup();
+                this.backing.insert_action_group(
+                    this.action_group_name,
+                    this.action_group
+                );
+            }
+
+            this.action_group.add_action(action);
+        }
+
+        public void deregister_action(GLib.Action action) {
+            this.action_group.remove_action(action.get_name());
+        }
+
+        public void append_menu_item(Plugin.Actionable menu_item) {
+            if (this.menu_items == null) {
+                this.menu_items = new GLib.Menu();
+                this.backing.insert_menu_section(this.menu_items);
+            }
+            this.menu_items.append(
+                menu_item.label,
+                GLib.Action.print_detailed_name(
+                    this.action_group_name + "." + menu_item.action.name,
+                    menu_item.action_target
+                )
+            );
+        }
+
+
     }
 
 
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index 77330ca39..d51df99c4 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -1034,6 +1034,16 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
         }
     }
 
+    /**
+     * Inserts a menu section into the composer's menu.
+     */
+    public void insert_menu_section(GLib.MenuModel section) {
+        var menu = this.more_options_button.menu_model as GLib.Menu;
+        if (menu != null) {
+            menu.insert_section(0, null, section);
+        }
+    }
+
     /** Overrides the draft folder as a destination for saving. */
     internal async void set_save_to_override(Geary.Folder? save_to)
         throws GLib.Error {
diff --git a/src/client/plugin/plugin-composer.vala b/src/client/plugin/plugin-composer.vala
index 9765ef13d..269ed2be5 100644
--- a/src/client/plugin/plugin-composer.vala
+++ b/src/client/plugin/plugin-composer.vala
@@ -80,4 +80,39 @@ public interface Plugin.Composer : Geary.BaseObject {
      */
     public abstract void save_to_folder(Plugin.Folder? location);
 
+    /**
+     * Registers a plugin action with this specific composer.
+     *
+     * Once registered, the action will be available for use in user
+     * interface elements such as {@link Actionable}.
+     *
+     * @see deregister_action
+     */
+    public abstract void register_action(GLib.Action action);
+
+    /**
+     * De-registers a plugin action, removing it from this composer.
+     *
+     * Makes a previously registered no longer available.
+     *
+     * @see register_action
+     */
+    public abstract void deregister_action(GLib.Action action);
+
+    /**
+     * Adds a menu item to the composer's menu.
+     *
+     * The menu item will be added to a section unique to this plugin
+     * on the composer's menu. The item's action must be registered
+     * either with the application via {@link
+     * Application.register_action} if it is a global action, or with
+     * the composer via {@link register_action} if it is
+     * composer-specific for it to be successfully activated.
+     *
+     * @see register_action
+     * @see Application.register_action
+     */
+    public abstract void append_menu_item(Actionable menu_item);
+
+
 }