Documentation/Maemo 5 Developer Guide/Porting Software/Porting MaemoPad

2010-11-15T20:13:24Z

221.194.132.212: 52

This is a practical example of porting a [[Open development/Maemo roadmap/Diablo|Diablo]] (Maemo 4.1) application to [[Open development/Maemo roadmap/Fremantle|Fremantle]] (Maemo 5). The example application, MaemoPad, is a simple Notepad-like editor.

[[Image:maemopad.png|frame|center|alt=Screenshot of MaemoPad|MaemoPad main window]]

== Porting MaemoPad from Diablo to Fremantle ==

Porting from Diablo to Fremantle involved mostly changes in GTK+- and Hildon-specific parts of the code, because newer versions of these libraries are now in use, and because of the new Fremantle GUI guidelines. This subsection will first explain how to install MaemoPad, and then proceeds to describing the main changes in the code. The reader is recommended to familiarize with chapters [[Documentation/Maemo 5 Developer Guide/Application Development|Application Development]] and [[Documentation/Maemo 5 Developer Guide/Human Interface Guidelines|Human Interface Guidelines]] before this one. For reference, see GTK+ and Hildon APIs from [http://maemo.org/development/sdks/maemo_5_api_documentation/ Maemo Fremantle APIs].

=== Installing MaemoPad ===

MaemoPad can be installed and tested in the Scratchbox environment.

* If not already activated, activate the X86 target, go to the testing directory, and download the source package of maemopad application.

<pre>
[sbox-FREMANTLE_ARMEL] > sb-conf select FREMANTLE_X86
[sbox-FREMANTLE_X86 ~] > mkdir maemopad
[sbox-FREMANTLE_X86 ~/maemopad] > cd maemopad
[sbox-FREMANTLE_X86 ~/maemopad] > apt-get source maemopad
...apt output...
</pre>

* Check that you have the correct files.

<pre>
[sbox-FREMANTLE_X86: ~/maemopad] > ls -l
total 352
drwxrwxr-x 6 maemo maemo 4096 Jul 28 14:09 maemopad-2.5
-rw-rw-r-- 1 maemo maemo 465 Jul 6 16:02 maemopad_2.5.dsc
-rw-rw-r-- 1 maemo maemo 346129 Jul 6 16:02 maemopad_2.5.tar.gz
</pre>

* Go to the <code>maemopad-2.5</code> source directory, and build the maemopad package with <code>dpkg-buildpackage</code> command as shown here:

<pre>
[sbox-FREMANTLE_X86: ~/maemopad] > cd maemopad-2.5
[sbox-FREMANTLE_X86: ~/maemopad/maemopad-2.5] > dpkg-buildpackage -rfakeroot
dpkg-buildpackage: source package is maemopad
dpkg-buildpackage: source version is 2.5
dpkg-buildpackage: source changed by Soumya Bijjal <soumya.3.bijjal@nokia.com>
dpkg-buildpackage: host architecture i386
dpkg-buildpackage: source version without epoch 2.3
.... etc ....
</pre>

* Install the newly compiled <code>maemopad_2.5_i386.deb</code> file inside the Scratchbox environment:

<pre>
[sbox-FREMANTLE_X86: ~/maemopad] > dpkg -i maemopad_2.5_i386.deb
... output from dpkg ...
</pre>

* Make sure you have the SDK UI running in Xephyr.
* You can now run MaemoPad by selecting it from the menu.

The MaemoPad source code resides in folder <code>maemopad-2.5/src:</code>

<pre>
[sbox-FREMANTLE_X86: ~/maemopad] ls maemopad-2.5/src
total 280
-rw-rw-r-- 1 maemo maemo 25491 Jul 28 15:45 Makefile
-rw-rw-r-- 1 maemo maemo 491 Jul 28 14:09 Makefile.am
-rw-rw-r-- 1 maemo maemo 23238 Jul 28 14:09 Makefile.in
-rwxrwxr-x 1 maemo maemo 83433 Jul 28 15:45 maemopad
-rw-rw-r-- 1 maemo maemo 82928 Jul 28 15:45 maemopad-maemopad-window.o
-rw-rw-r-- 1 maemo maemo 18564 Jul 28 15:45 maemopad-main.o
-rw-rw-r-- 1 maemo maemo 20400 Jul 28 14:09 maemopad-window.c
-rw-rw-r-- 1 maemo maemo 2391 Jul 28 14:09 maemopad-window.h
-rw-rw-r-- 1 maemo maemo 2193 Jul 28 14:09 main.c
</pre>

For comparison, the Diablo version of MaemoPad can also be examined:

<pre>
[sbox-FREMANTLE_X86: ~/maemopad] > svn export https://vcs.maemo.org/svn/\
maemoexamples/tags/maemo_4.1/maemopad diablo_maemopad
[sbox-FREMANTLE_X86: ~/src] ls -lR diablo_maemopad/src
diablo_maemopad/src/:
total 16
-rw-rw-r-- 1 maemo maemo 537 May 15 2008 Makefile.am
-rw-rw-r-- 1 maemo maemo 557 May 15 2008 appdata.h
-rw-rw-r-- 1 maemo maemo 2789 Dec 3 2008 main.c
drwxrwxr-x 2 maemo maemo 4096 Aug 20 11:53 ui

diablo_maemopad/src/ui:
total 36
-rw-rw-r-- 1 maemo maemo 12163 Dec 3 2008 callbacks.c
-rw-rw-r-- 1 maemo maemo 1682 Oct 29 2008 callbacks.h
-rw-rw-r-- 1 maemo maemo 14982 Dec 3 2008 interface.c
-rw-rw-r-- 1 maemo maemo 2695 Dec 3 2008 interface.h
</pre>

=== Code reorganization ===

If one takes a look at MaemoPad source code for Diablo and Fremantle, there are many bug fixes, and there have been major refractorizations. These are, however, not necessary for porting and are not discussed here in detail. The main change is reorganizing the files, which is already apparent from the <code>ls</code> lists above:

* <code>src/ui</code> subfolder has been dropped
* <code>src/ui/callbacks.c</code> and <code>src/ui/interface</code> have been combined into <code>src/maemopad-window.c</code>, similarly for header files
* <code>appdata.h</code> is included in <code>main.c</code>
* In <code>src/Makefile.am</code>, <code>maemopad_SOURCES = <list of source files></code> has been updated correspondingly.

=== Device-specific changes ===

The previous device, N810, had a separate full-screen and ESC keys that were dropped from the new device. In MaemoPad, pressing the full-screen key was replaced by Ctrl-F. This required the following addition:

maemopad-window.c
<source lang="c">
#include <gdk/gdkkeysyms.h>
</source>

to include GDK definition for key "f", <code>GDK_f</code> to replace the earlier <code>HILDON_HARDKEY_FULLSCREEN</code>. Callback for Esc was completely removed. The full-screen action itself was principally unchanged. The key event function was modified correspondingly:

Diablo callbacks.c
<source lang="c">
gboolean key_press(GtkWidget * widget, GdkEventKey * event,
gpointer data)
{
...
if (event->keyval == HILDON_HARDKEY_FULLSCREEN && !keypressed){
keypressed = TRUE;
...
if (event->keyval == HILDON_HARDKEY_ESC && !keypressed){
keypressed = TRUE;
...
</source>

Fremantle maemopad-window.c

<source lang="c">
static gboolean maemopad_window_on_key_press(GtkWidget *widget, GdkEventKey *event,
gpointer data)
{
...
if (event->keyval == GDK_f && (event->state & GDK_CONTROL_MASK) && !self- >key_pressed) {
self->key_pressed = TRUE;
...
</source>

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=== GUI design changes ===

Because of new UI guidelines, a toolbar that was at the bottom of the MaemoPadwindow in Diablo was dropped. This meant removing the function <code>create_toolbar</code> and its declaration from <code>interface.c</code>. Also the call for the function was dropped from the same file. Likewise, related declarations were dropped:

Diablo interface.h

<source lang="c">
/* Toolbar */
GtkWidget* toolbar;
GtkWidget* iconw;
GtkToolItem* new_tb;
GtkToolItem* open_tb;
...
GtkToolItem* fullscreen_tb;
</source>

Also the menu system was changed. In Diablo, a <code>GtkMenu</code> was used, but it was replaced with a <code>HildonAppMenu</code> in Fremantle, as shown in Figure:

[[Image:maemopad_menu.png|frame|center|alt=Screenshot of MaemoPad menu|MaemoPad menu]]

Function <code>create_menu()</code> is responsible for creating the menus in both versions:

Diablo interface.c

<source lang="c">
static void create_menu( AppUIData *main )
{
/* Create needed handles */
GtkMenu *main_menu;
GtkWidget *file_menu, *edit_menu, *sendvia_menu;
GtkWidget *separator = NULL;
GtkWidget *close = NULL;
/* Create main menu and new menus for submenus in our drop down menu */
main_menu = GTK_MENU( gtk_menu_new () );
file_menu = gtk_menu_new ();
edit_menu = gtk_menu_new ();
sendvia_menu = gtk_menu_new ();
/* Create the menu items */
main->file_item = gtk_menu_item_new_with_label ( _("File") );
main->new_item = gtk_menu_item_new_with_label ( _("New") );
main->open_item = gtk_menu_item_new_with_label ( _("Open") );
...
/* Add menu items to right menus */
gtk_menu_append( main_menu, main->file_item );
gtk_menu_append( file_menu, main->new_item );
gtk_menu_append( file_menu, main->open_item );
...
gtk_menu_append( main_menu, close );
/* Add submenus to the right items */
gtk_menu_item_set_submenu( GTK_MENU_ITEM (main->file_item), file_menu );
gtk_menu_item_set_submenu( GTK_MENU_ITEM (main->edit_item), edit_menu );
gtk_menu_item_set_submenu( GTK_MENU_ITEM (main->sendvia_item), sendvia_menu );
/* Attach the callback functions to the activate signal */
g_signal_connect( G_OBJECT( main->new_item ), "activate",
G_CALLBACK ( callback_file_new), main );
g_signal_connect( G_OBJECT( main->open_item ), "activate",
G_CALLBACK ( callback_file_open), main );
...
g_signal_connect( G_OBJECT( close ), "activate", gtk_main_quit, NULL );
/* Add menu to HildonWindow */
hildon_window_set_menu(main->data->window, main_menu);
/* We need to show menu items */
gtk_widget_show_all( GTK_WIDGET( main_menu ) );
}
</source>

Fremantle maemopad-window.c

<source lang="c">
static GtkWidget* add_menu_item (GtkWidget *main_menu, const gchar* title,
GCallback clicked_callback, gpointer user_data)
{
HildonAppMenu *app_menu = HILDON_APP_MENU (main_menu);
/* Create a button, add it, and return it: */
GtkWidget *button = hildon_button_new_with_text (HILDON_SIZE_AUTO,
HILDON_BUTTON_ARRANGEMENT_VERTICAL, title, NULL);
gtk_widget_show (button);
g_signal_connect_after (button, "clicked",
G_CALLBACK (clicked_callback), user_data);
hildon_app_menu_append (app_menu, GTK_BUTTON (button));
return button;
}
/* Create the menu items needed: */
static void create_menu (MaemopadWindow *self)
{
/* Create needed handles */
GtkWidget *main_menu = hildon_app_menu_new ();
/* Create the menu items */
self->new_item = add_menu_item (main_menu, _("New"),
G_CALLBACK (&maemopad_window_on_menu_file_new), self);
self->open_item = add_menu_item (main_menu, _("Open"),
G_CALLBACK (&maemopad_window_on_menu_file_open), self);
...
self->close_item = add_menu_item (main_menu, _("Close"),
G_CALLBACK (&maemopad_window_on_menu_close), self);
/* Add menu to HildonWindow */
hildon_window_set_app_menu (
HILDON_WINDOW (self),
HILDON_APP_MENU (main_menu));
/* We need to show menu items */
gtk_widget_show_all (GTK_WIDGET (main_menu));
}
</source>

As a result to changes in the .c file, the following menu widget declarations used in Diablo became unnecessary:

Diablo interface.h

<source lang="c">
GtkWidget *file_item;
GtkWidget *edit_item;
GtkWidget *sendvia_item;
</source>

Menu callbacks were also changed. There were some changes in the callbacks themselves as a result of code reorganizations, but the main change from the menu viewpoint was that the 1st arguments of the callbacks were changed from <code>GtkAction</code> to <code>GtkButton</code>, like in the following example:

Diablo callbacks.c

<source lang="c">
void callback_file_new(GtkAction * action, gpointer data)
</source>

Fremantle maemopad-window.c

<source lang="c">
static void maemopad_window_on_menu_file_new (GtkButton *button, gpointer data)
</source>

=== Other updates in GTK+ and Hildon ===

<ul>
<li>
Rich text support was changed with the new GTK+, as described in [http://live.gnome.org/Maemo/Gtk210Migration Maemo-GTK+ 2.6 to 2.10 Migration].This required editing two lines:

Part of function <code>create_textarea()</code> in Diablo interface.c

<source lang="c">
/* Enable Rich Text Support */
gtk_text_buffer_set_can_paste_rich_text ( main->buffer, TRUE );
gtk_text_buffer_set_rich_text_format ( main->buffer, "RTF" );
</source>

Part of function <code>create_textarea()</code> in Fremantle maemopad-window.c

<source lang="c">
/* Enable Rich Text Support */
gtk_text_buffer_register_serialize_tagset (self->buffer, "RTF");
gtk_text_buffer_register_deserialize_tagset (self->buffer, "RTF");
</source>
</li>

<li>
<code>HildonFontSelectionDialog</code> was deprecated and replaced with a <code>GtkFontButton</code>. In Diablo, the font callback was a callback to a regular <code>GtkAction</code>:

callback.c

<source lang="c">
void callback_font( GtkAction * action, gpointer data )
{
...
new_font = interface_font_chooser( mainview );
/* if we got a new font from chooser -> change font */
if( new_font != NULL ) {
mainview->font_desc = new_font;
gtk_widget_modify_font ( mainview->textview, mainview->font_desc );
}
}
</source>

Function <code>callback_font</code> got the font from an auxiliary function <code>interface_font_chooser()</code> and then modified the font in the text view. The auxiliary function <code>interface_font_chooser()</code> in turn opened a <code>HildonFontSelectionDialog</code> that returned the font parameters:

callback.c

<source lang="c">
/* Font chooser */
PangoFontDescription* interface_font_chooser( AppUIData * main )
{
...
font = pango_font_description_new();
/* create dialog */
dialog = HILDON_FONT_SELECTION_DIALOG ( hildon_font_selection_dialog_new( NULL, NULL ) );
gtk_widget_show_all (GTK_WIDGET(dialog));
if (gtk_dialog_run (GTK_DIALOG (dialog)) == GTK_RESPONSE_OK)
{
g_object_get(G_OBJECT(dialog),
"family", &family,
"size", &size,
"bold", &bold,
"italic", &italic,
NULL);
pango_font_description_set_family(font, family);
pango_font_description_set_size(font, size * PANGO_SCALE);
if (bold) {
pango_font_description_set_weight(font, PANGO_WEIGHT_BOLD);
} else {
pango_font_description_set_weight(font, PANGO_WEIGHT_NORMAL);
}
if (italic) {
pango_font_description_set_style(font, PANGO_STYLE_ITALIC);
} else {
pango_font_description_set_style(font, PANGO_STYLE_NORMAL);
}
}
gtk_widget_destroy(GTK_WIDGET(dialog));
return font;
}
</source>

Instead of the deprecated <code>HildonFontSelectionDialog</code>, Fremantle uses a <code>GtkFontButton</code> directly in the font button callback:

maemopad-window.c

<source lang="c">
/* font */
static void maemopad_window_on_font_set (GtkFontButton *button, gpointer data)
{
...
font_name = gtk_font_button_get_font_name (button);
if (!font_name)
return;
new_font = pango_font_description_from_string (font_name);
/* Change the font used in the GtkTextView */
if (new_font) {
if (self->font_desc)
pango_font_description_free (self->font_desc);
self->font_desc = new_font;
gtk_widget_modify_font (self->textview, self->font_desc);
}
}
</source>

This <code>GtkFontButton</code> was initialized in function <code>create_menu()</code> (see above) in <code>maemopad-window.c</code> so that it would respond to the <code>"font-set"</code> signal and call the callback above:

<source lang="c">
self->font_item = gtk_font_button_new ();
gtk_widget_show (self->font_item);
g_signal_connect_after (self->font_item, "font-set",
G_CALLBACK (maemopad_window_on_font_set), self);
hildon_app_menu_append (HILDON_APP_MENU (main_menu), GTK_BUTTON (self->font_item));
</source>
</li>

<li>
Instead of <code>GtkTextView</code>, a [http://maemo.org/api_refs/5.0/5.0-final/hildon/HildonTextView.html HildonTextView] is now used:

Diablo callback.c

<source lang="c">
/* Create the text area */
void create_textarea( AppUIData *main )
{
/* Text view */
main->textview = gtk_text_view_new ();
...
/* Get handle */
main->buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (main->textview));
...
}
</source>

Fremantle maemopad-window.c

<source lang="c">
static void create_textarea (MaemopadWindow *self)
{
/* Text view */
self->textview = hildon_text_view_new ();
....
/* Get handle */
self->buffer = hildon_text_view_get_buffer (GTK_TEXT_VIEW (self->textview));
}
</source>
</li>

<li>
All Hildon applications should now initialize hildon before using it. In maemopad this is done by calling <code>hildon_gtk_init()</code> which also calls <code>gtk_init()</code> so the original call can be removed:

Diablo main.c

<source lang="c">
/* Init the gtk - must be called before any hildon stuff */
gtk_init( &argc, &argv );
</source>

Fremantle main.c

<source lang="c">
/* Inititialize GTK+ and hildon: */
hildon_gtk_init( &argc, &argv );
</source>

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[[Category:Documentation]]
[[Category:Fremantle]]

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