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New chapter about how to migrate from gnome-ui/bonobo-ui/etc. to

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2003-12-08  Federico Mena Quintero  <federico@ximian.com>

	* gtk/migrating-GtkAction.sgml: New chapter about how to migrate
	from gnome-ui/bonobo-ui/etc. to GtkAction.

	* gtk/gtk-docs.sgml: Integrated the above.

	* gtk/Makefile.am (content_files): Added migrating-GtkAction.sgml.
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9
docs/reference/ChangeLog
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@ -1,3 +1,12 @@
2003-12-08 Federico Mena Quintero <federico@ximian.com>
* gtk/migrating-GtkAction.sgml: New chapter about how to migrate
from gnome-ui/bonobo-ui/etc. to GtkAction.
* gtk/gtk-docs.sgml: Integrated the above.
* gtk/Makefile.am (content_files): Added migrating-GtkAction.sgml.
Sun Nov 23 20:59:57 2003 Matthias Clasen <maclas@gmx.de>
* gtk/tree_widget.sgml: Add a missing comma.

1
docs/reference/gtk/Makefile.am
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@ -85,6 +85,7 @@ content_files = \
changes-2.0.sgml \
compiling.sgml \
framebuffer.sgml \
migrating-GtkAction.sgml \
migrating-GtkFileChooser.sgml \
objects_grouped.sgml \
question_index.sgml \

2
docs/reference/gtk/gtk-docs.sgml
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@ -180,6 +180,7 @@
<!ENTITY gtk-Changes-1-2 SYSTEM "changes-1.2.sgml">
<!ENTITY gtk-Changes-2-0 SYSTEM "changes-2.0.sgml">
<!ENTITY gtk-migrating-GtkFileChooser SYSTEM "migrating-GtkFileChooser.sgml">
<!ENTITY gtk-migrating-GtkAction SYSTEM "migrating-GtkAction.sgml">
<!ENTITY version SYSTEM "version.xml">
<!ENTITY gtk-query-immodules SYSTEM "gtk-query-immodules-2.0.xml">
]>
@ -545,6 +546,7 @@ that is, GUI components such as <link linkend="GtkButton">GtkButton</link> or
</partintro>
&gtk-migrating-GtkFileChooser;
&gtk-migrating-GtkAction;
</part>
<part>

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docs/reference/gtk/migrating-GtkAction.sgml Normal file
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@ -0,0 +1,388 @@
<chapter id="gtk-migrating-GtkAction">
<chapterinfo>
<author>
<firstname>Federico</firstname>
<surname>Mena-Quintero</surname>
<affiliation>
<address>
<email>federico@ximian.com</email>
</address>
</affiliation>
</author>
</chapterinfo>
<title>Migrating from old menu and toolbar systems to GtkAction</title>
<para>
Prior to GTK+ 2.4, there were several APIs in use to create menus
and toolbars. GTK+ itself included #GtkItemFactory, which was
historically used in the GIMP; libgnomeui provided the gnome-ui
set of macros; libbonoboui provided a complex mechanism to do menu
merging across embedded components. GTK+ 2.4 includes a system
for creating menus and toolbars, with merging of items, based
around the #GtkAction mechanism.
</para>
<section id="actions-and-action-groups">
<title>Actions and Action Groups</title>
<para>
A #GtkAction represents an operation that the user can perform
from the menus and toolbars of an application. It is similar to
"verbs" in other menu systems. A #GtkAction has a name, which
is its identifier, and it can have several widgets that
represent it in the user interface. For example, an action for
<symbol>EditCopy</symbol> can have a menu item as well as a
toolbar button associated to it. If there is nothing selected
in the document, the application can simply de-sensitize the
<symbol>EditCopy</symbol> action; this will cause both the menu
item and the toolbar button to be de-sensitized automatically.
Similarly, whenever the user selects the menu item or the
toolbar button associated to the <symbol>EditCopy</symbol>
action, the corresponding #GtkAction object will emit an
"activate" signal.
</para>
<para>
#GtkActionGroup is simply a group of #GtkAction objects. An
application may want to have several groups: one for global
actions such as "new document", "about", and "exit"; then one
group for each open document with actions specific to the
document, such as "cut", "copy", "paste", and "print".
</para>
<para>
Normal actions are simply commands, such as
<symbol>FileSave</symbol> or <symbol>EditCopy</symbol>. Toggle
actions can be active or inactive, such as
<symbol>FormatBold</symbol> or <symbol>ViewShowRulers</symbol>.
Radio actions define a set of items for which one and only one
can be active at a time, for example, {
<symbol>ViewHighQuality</symbol>,
<symbol>ViewNormalQuality</symbol>,
<symbol>ViewLowQuality</symbol> }.
</para>
</section>
<section id="ui-manager">
<title>User Interface Manager Object</title>
<para>
#GtkUIManager is an object that can construct menu and toolbar
widgets from an XML description. These widgets are in turn
associated to corresponding actions and action groups.
</para>
<para>
#GtkUIManager supports merging of menus and toolbars for
applications that have multiple components, each with separate
sets of commands. For example, a word processor that can embed
images may want to have toolbar buttons for Bold and Italic when
the cursor is on a text block, but Crop and Brightness/Contrast
buttons when the cursor is on an image. These actions, which
change depending on the state of the application, can be merged
and de-merged from a #GtkUIManager as appropriate.
</para>
</section>
<section id="migrating-gnomeuiinfo">
<title>Migrating from GnomeUIInfo</title>
<para>
Prior to GTK+ 2.4, some applications used the GnomeUIInfo
mechanism from
<filename>&lt;libgnomeui/gnome-app-helper.h&gt;</filename> to
define their menus and toolbars. With it, a program decleres an
array of <structname>GnomeUIInfo</structname> structures, which
contain information for menu or toolbar items such as their
label, icon, and accelerator key. Then, one calls
<function>gnome_app_fill_menu()</function> or
<function>gnome_app_fill_toolbar()</function>, or one of the
related functions, to create the appropriate widgets based on
these structures.
</para>
<para>
A downside of this API is that the same structures are used to
pass back pointers to the widgets that got created. This means
that the structures cannot simply be kept around if the program
requires multiple instances of the user interface (e.g. several
windows); each new invocation of
<function>gnome_app_fill_menu()</function> would overwrite the
widget fields of the structures.
</para>
<para>
Another disadvantage is that there is no automatic way to
synchronize the state of related controls. If there are toolbar
toogle buttons for "Bold", "Italic", "Underline", and also
corresponding menu items under "Format/Bold", etc., one has to
synchronize their toggled states by hand whenever the user
selects any one of them.
</para>
<para>
Finally, there is no way to do menu and toolbar merging for
applications that require embedded components.
</para>
<para>
To convert an application that uses GnomeUIInfo into the new
GtkAction mechanism, you need to do several things:
</para>
<orderedlist>
<listitem>
<para>
Separate your existing GnomeUIInfo entries into normal
actions, toggle actions, and radio actions, and then create a
separate array of #GtkActionEntry structures for each
group. This will allow you to create the necessary
#GtkActionGroup objects. Note that this does not describe
the actual "shape" that your menus and toolbars will have;
it simply defines the set of commands that will appear in them.
</para>
</listitem>
<listitem>
<para>
Create an XML description of your menus and toolbars for use
with #GtkUIManager. This defines the actual shape of the
menus and toolbars.
</para>
</listitem>
<listitem>
<para>
Port the code that uses gnome-app and gnome-app-helper to
#GtkAction and #GtkUIManager.
</para>
</listitem>
</orderedlist>
<example id="gnomeuiinfo-example">
<title>GnomeUIInfo Example</title>
<para>
The following code shows a declaration of a simple menu bar to
be used with <function>gnome_app_fill_menu()</function> or
similar. The menu hierarchy looks like this:
</para>
<itemizedlist>
<listitem>
<para><guimenu>File</guimenu></para>
<simplelist>
<member><guimenuitem>Open</guimenuitem></member>
<member><guimenuitem>&mdash;</guimenuitem></member>
<member><guimenuitem>Exit</guimenuitem></member>
</simplelist>
</listitem>
<listitem>
<para><guimenu>View</guimenu></para>
<simplelist>
<member><guimenuitem>Zoom In</guimenuitem></member>
<member><guimenuitem>Zoom Out</guimenuitem></member>
<member><guimenuitem>&mdash;</guimenuitem></member>
<member><guimenuitem>[ ] Full Screen</guimenuitem></member>
<member><guimenuitem>&mdash;</guimenuitem></member>
<member><guimenuitem>( ) High Quality</guimenuitem></member>
<member><guimenuitem>( ) Normal Quality</guimenuitem></member>
<member><guimenuitem>( ) Low Quality</guimenuitem></member>
</simplelist>
</listitem>
</itemizedlist>
<programlisting>
static GnomeUIInfo file_menu_items[] = {
{ GNOME_APP_UI_ITEM, "_Open", "Open a file",
open_callback, NULL, NULL, GNOME_APP_PIXMAP_STOCK, GTK_STOCK_OPEN,
'o', GDK_CONTROL_MASK, NULL },
{ GNOME_APP_UI_SEPARATOR },
{ GNOME_APP_UI_ITEM, "E_xit", "Exit the program",
exit_callback, NULL, NULL, GNOME_APP_PIXMAP_STOCK, GTK_STOCK_QUIT,
'q', GDK_CONTROL_MASK, NULL},
{ GNOME_APP_UI_ENDOFINFO }
};
static GnomeUIInfo view_radio_items[] = {
{ GNOME_APP_UI_ITEM, "_High Quality", "Display images in high quality, slow mode",
high_quality_callback, NULL, NULL, GNOME_APP_PIXMAP_NONE, NULL,
0, 0, NULL },
{ GNOME_APP_UI_ITEM, "_Normal Quality", "Display images in normal quality",
normal_quality_callback, NULL, NULL, GNOME_APP_PIXMAP_NONE, NULL,
0, 0, NULL },
{ GNOME_APP_UI_ITEM, "_Low Quality", "Display images in low quality, fast mode",
low_quality_callback, NULL, NULL, GNOME_APP_PIXMAP_NONE, NULL,
0, 0, NULL },
{ GNOME_APP_UI_ENDOFINFO }
};
static GnomeUIInfo view_menu_items[] = {
{ GNOME_APP_UI_ITEM, "Zoom _In", "Zoom into the image",
zoom_in_callback, NULL, NULL, GNOME_APP_PIXMAP_STOCK, GTK_STOCK_ZOOM_IN,
GDK_PLUS, 0, NULL },
{ GNOME_APP_UI_ITEM, "Zoom _Out", "Zoom away from the image",
zoom_out_callback, NULL, NULL, GNOME_APP_PIXMAP_STOCK, GTK_STOCK_ZOOM_OUT,
GDK_MINUS, 0, NULL },
{ GNOME_APP_UI_SEPARATOR },
{ GNOME_APP_UI_TOGGLEITEM, "_Full Screen", "Switch between full screen and windowed mode",
full_screen_callback, NULL, NULL, GNOME_APP_PIXMAP_NONE, NULL,
GDK_F11, 0, NULL },
{ GNOME_APP_UI_SEPARATOR },
{ GNOME_APP_UI_RADIOITEMS, NULL, NULL, view_radio_items },
{ GNOME_APP_UI_ENDOFINFO }
};
static GnomeUIInfo menubar[] = {
{ GNOME_APP_UI_SUBTREE, "_File", NULL, file_menu_items },
{ GNOME_APP_UI_SUBTREE, "_View", NULL, view_menu_items },
{ GNOME_APP_UI_ENDOFINFO }
}
</programlisting>
</example>
<example id="gnomeuiinfo-action-entries">
<title><structname>GtkActionEntry</structname> Structures</title>
<para>
The following code is the set of actions that are present in
the <link linkend="gnomeuiinfo-example">previous
example</link>. Note that the toggle and radio entries are
separate from normal actions. Also, note that #GtkActionEntry
structures take key names in the format of
gdk_accelerator_parse() rather than key values plus modifiers;
you will have to convert these values by hand. For example,
<constant>GDK_F11</constant> with no modifiers is equivalent
to a key name of <literal>"F11"</literal>. Likewise,
<literal>"o"</literal> with
<constant>GDK_CONTROL_MASK</constant> is equivalent to
<literal>"&lt;ontrol&gt;O"</literal>.
</para>
<programlisting>
/* Normal items */
static GtkActionEntry entries[] = {
{ "FileMenu", NULL, "_File" },
{ "ViewMenu", NULL, "_View" },
{ "Open", GTK_STOCK_OPEN, "_Open", "&lt;control&gt;O", "Open a file", open_action_callback },
{ "Exit", GTK_STOCK_OPEN, "E_xit", "&lt;control&gt;Q", "Exit the program", exit_action_callback },
{ "ZoomIn", GTK_STOCK_ZOOM_IN, "Zoom _In", "plus", "Zoom into the image", zoom_in_action_callback },
{ "ZoomOut", GTK_STOCK_ZOOM_OUT, "Zoom _Out", "minus", "Zoom away from the image", zoom_out_action_callback },
};
/* Toggle items */
static GtkToggleActionEntry toggle_entries[] = {
{ "FullScreen", NULL, "_Full Screen", "F11", "Switch between full screen and windowed mode", full_screen_action_callback, FALSE }
};
/* Radio items */
static GtkRadioActionEntry radio_entries[] = {
{ "HighQuality", NULL, "_High Quality", NULL, "Display images in high quality, slow mode", 0 },
{ "NormalQuality", NULL, "_Normal Quality", NULL, "Display images in normal quality", 1 },
{ "LowQuality", NULL, "_Low Quality", NULL, "Display images in low quality, fast mode", 2 }
};
</programlisting>
</example>
<example id="gnomeuiinfo-xml">
<title>XML Description</title>
<para>
After extracting the actions, you will need to create an XML
description of the actual layout of your menus and toolbars
for use with #GtkUIManager. The following code shows a simple
menu bar that corresponds to the <link
linkend="gnomeuiinfo-example">previous example</link>. Note
that the <guimenu>File</guimenu> and <guimenu>View</guimenu>
menus have their names specified in the <link
linkend="gnomeuiinfo-action-entries">action entries</link>,
not in the XML itself. This is because the XML description
only contains <emphasis>identifiers</emphasis> for the items
in the GUI, rather than human-readable names.
</para>
<programlisting>
static const char *ui_description =
"&lt;ui&gt;"
" &lt;menubar name="MainMenu"&gt;"
" &lt;menu action="FileMenu"&gt;"
" &lt;menuitem action="Open"/&gt;"
" &lt;menuitem action="Exit"/&gt;"
" &lt;/menu&gt;"
" &lt;menu action="ViewMenu"&gt;"
" &lt;menuitem action="ZoomIn"/&gt;"
" &lt;menuitem action="ZoomOut"/&gt;"
" &lt;separator/&gt;"
" &lt;menuitem action="FullScreen"/&gt;"
" &lt;separator/&gt;"
" &lt;menuitem action="HighQuality"/&gt;"
" &lt;menuitem action="NormalQuality"/&gt;"
" &lt;menuitem action="LowQuality"/&gt;"
" &lt;/menu&gt;"
" &lt;/menubar&gt;"
"&lt;/ui&gt;";
</programlisting>
</example>
<example id="gnomeuiinfo-code">
<title>Creating the Menu Bar</title>
<para>
In this last example, we will create a #GtkActionGroup based
on the <link linkend="gnomeuiinfo-action-entries">action
entries</link> we created above. We will then create a
#GtkUIManager with the <link linkend="gnomeuiinfo-xml">XML
description</link> of the menu layout. We will also extract
the accelerator group and the widgets from the #GtkUIManager
put them into a window.
</para>
<programlisting>
GtkWidget *window;
GtkWidget *vbox;
GtkWidget *menubar;
GtkActionGroup *action_group;
GtkUIManager *ui_manager;
GtkAccelGroup *accel_group;
GError *error;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
vbox = gtk_vbox_new (FALSE, 0);
gtk_container_add (GTK_CONTAINER (window), vbox);
action_group = gtk_action_group_new ("MenuActions");
gtk_action_group_add_actions (action_group, entries, G_N_ELEMENTS (entries), window);
gtk_action_group_add_toggle_actions (action_group, toggle_entries, G_N_ELEMENTS (toggle_entries), window);
gtk_action_group_add_radio_actions (action_group, radio_entries, G_N_ELEMENTS (radio_entries), 0, radio_action_callback, window);
ui_manager = gtk_ui_manager_new ();
gtk_ui_manager_insert_action_group (ui_manager, action_group, 0);
accel_group = gtk_ui_manager_get_accel_group (ui_manager);
gtk_window_add_accel_group (GTK_WINDOW (window), accel_group);
error = NULL;
if (!gtk_ui_manager_add_ui_from_string (ui_manager, ui_description, -1, &amp;error))
{
g_message ("building menus failed: %s", error-&gt;message);
g_error_free (error);
exit (EXIT_FAILURE);
}
menubar = gtk_ui_manager_get_widget ("/MainMenu");
gtk_box_pack_start (GTK_BOX (vbox), menubar, FALSE, FALSE, 0);
gtk_widget_show_all (window);
</programlisting>
</example>
</section>
</chapter>
<!--
Local variables:
mode: sgml
sgml-parent-document: ("gtk-docs.sgml" "book" "part" "chapter")
End:
-->