Panel Applet Library Reference Manual

### Mark McLoughlin

`<mark@skynet.ie>`

Copyright © 2001, 2003 Sun Microsystems, Inc.

Abstract

This manual documents the interfaces of the panel applet library for GNOME 2.x and a short guide to porting applets from the GNOME 1.x interfaces.

Table of Contents

Writing Applets
  Hello World Applet
  Bonobo Activation .server Files For Applets
  Defining a Popup Context Menu
  Detecting Changes in the Panel.
  Session/Preference Saving.
  Multiple Applets
Porting Applets from the GNOME 1.x interfaces
  Applet ActivationThe first thing to change when porting to the new API is the header. Include panel-applet.h instead of applet-widget.h.Next you need to change how the applet is activated. Browsing through old applet's code, its obvious that this was done in various ways in the past. The best advice is to hunt out the calls to applet_widget_init, applet_widget_new and applet_widget_add. applet_widget_new and applet_widget_add are now effectively merged into one call panel_applet_new, to which the top-level widget of the applet should be passed. applet_widget_init is not neccessary anymore. So the new code should look something like this #include <panel-applet.h> static BonoboObject * blah_applet_new () { PanelApplet *applet; /* * The old code setting up the applet widgetry * goes here. So effectively delete calls to * applet_widget_init and applet_widget_new * and the replace applet_widget_add with a call * to panel_applet_new. */ applet = panel_applet_new (label); return BONOBO_OBJECT (panel_applet_get_control (applet)); } static BonoboObject * blah_applet_factory (BonoboGenericFactory *this, const gchar *iid, gpointer data) { BonoboObject *applet = NULL; if (!strcmp (iid, "OAFIID:BlahApplet")) applet = blah_applet_new (); return applet; } PANEL_APPLET_BONOBO_FACTORY ("OAFIID:BlahApplet_Factory", "Blah", "0", blah_applet_factory, NULL) You should use PANEL_APPLET_BONOBO_FACTORY or PANEL_APPLET_BONOBO_SHLIB_FACTORY depending on whether you want the applet to be out of process or in process.Activation filesThe next thing to do may be to port from a .gnorba file to a bonobo-activation .server file. You no longer need a .desktop file for applets. A .gnorba looks something like this : [blah] type=exe repo_id=IDL:GNOME/Applet:1.0 description=Blah location_info=blah-de-blah Your .server file should look like this : <oaf_info> <oaf_server iid="OAFIID:BlahApplet" type="exe" location="blah-de-blah-2"> <oaf_attribute name="repo_ids" type="stringv"> <item value="IDL:Bonobo/GenericFactory:1.0""/> <item value="IDL:Bonobo/Unknown:1.0"/> </oaf_attribute> <oaf_attribute name="name" type="string" value="Blah Factory"/> <oaf_attribute name="description" type="string" value="Blah De Blah"/> </oaf_server> <oaf_server iid="OAFIID:BlahApplet" type="factory" location="OAFIID:BlahApplet_Factory"> <oaf_attribute name="repo_ids" type="stringv"> <item value="IDL:GNOME/PanelAppletShell:1.0"/> <item value="IDL:Bonobo/Control:1.0"/> <item value="IDL:Bonobo/Unknown:1.0"/> </oaf_attribute> <oaf_attribute name="name" type="string" value="Blah Applet"/> <oaf_attribute name="description" type="string" value="Blah De Blah"/> <oaf_attribute name="panel:icon" type="string" value="blah-de-blah.png"/> </oaf_server> </oaf_info> A lot of this should be copied and pasted. The most important bit is "panel:icon" which specfies the icon that should be displayed in the "Add to Panel" dialog.Context MenuMost applets also place extra menu items into it context menu. It might be a good idea to port this next. In GNOME 1.x this was done using the applet_widget_register_stock_callback API call. In GNOME 2.x 3 things must be doneAn xml desription of the popup menu must be written.A description of the verbs must be prepared. This is basically a list of callbacks to be call when a certain menu item is clicked in the popup.The menu is registered using a call to panel_applet_setup_menu.The xml description should look something like this : static const char fish_menu_xml [] = "<popup name=\"button3\">\n" " <menuitem name=\"Properties Item\" verb=\"BlahProperties\" _label=\"Properties ...\"\n" " pixtype=\"stock\" pixname=\"gtk-properties\"/>\n" " <menuitem name=\"Help Item\" verb=\"BlahHelp\" _label=\"Help\"\n" " pixtype=\"stock\" pixname=\"gtk-help\"/>\n" " <menuitem name=\"About Item\" verb=\"BlahAbout\" _label=\"About ...\"\n" " pixtype=\"stock\" pixname=\"gnome-stock-about\"/>\n" "</popup>\n"; This could also be in a seperate .xml file and loaded with panel_applet_setup_menu_from_file. The description of the verbs should look something like : static const BonoboUIVerb fish_menu_verbs [] = { BONOBO_UI_VERB ("BlahProperties", display_properties_dialog), BONOBO_UI_VERB ("BlahHelp", display_help_dialog), BONOBO_UI_VERB ("BlahAbout", display_about_dialog), BONOBO_UI_VERB_END }; This is just a list of callbacks invoked when the menu items are clicked. There are other macros you may use other than BONOBO_UI_VERB - see bonobo-ui-component.h.To actually register the menu you just do something like : panel_applet_setup_menu (PANEL_APPLET (blah->applet), blah_menu_xml, blah_menu_verbs, blah); The last argument is the user_data argument passed back to the callbacks.
The Panel Applet Library
  PanelApplet - The PanelApplet object.
  Panel Applet GConf Utilities - Utility methods for manipulating per-applet GConf preferences.

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