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Dialog boxes are a convenient way to prompt the user for a small amount of input, e.g. to display a message, ask a question, or anything else that does not require extensive effort on the user's part.
GTK+ treats a dialog as a window split vertically. The top section is a
GtkVBox, and is where widgets such as a GtkLabel or a GtkEntry should
be packed. The bottom area is known as the
action_area
. This is generally used for
packing buttons into the dialog which may perform functions such as
cancel, ok, or apply. The two areas are separated by a GtkHSeparator.
GtkDialog boxes are created with a call to gtk_dialog_new()
or
gtk_dialog_new_with_buttons()
. gtk_dialog_new_with_buttons()
is recommended; it
allows you to set the dialog title, some convenient flags, and add simple
buttons.
If 'dialog' is a newly created dialog, the two primary areas of the window
can be accessed through gtk_dialog_get_content_area()
and
gtk_dialog_get_action_area()
, as can be seen from the example, below.
A 'modal' dialog (that is, one which freezes the rest of the application from
user input), can be created by calling gtk_window_set_modal()
on the dialog. Use
the GTK_WINDOW()
macro to cast the widget returned from gtk_dialog_new()
into a
GtkWindow. When using gtk_dialog_new_with_buttons()
you can also pass the
GTK_DIALOG_MODAL flag to make a dialog modal.
If you add buttons to GtkDialog using gtk_dialog_new_with_buttons()
,
gtk_dialog_add_button()
, gtk_dialog_add_buttons()
, or
gtk_dialog_add_action_widget()
, clicking the button will emit a signal called
"response" with a response ID that you specified. GTK+ will never assign a
meaning to positive response IDs; these are entirely user-defined. But for
convenience, you can use the response IDs in the GtkResponseType enumeration
(these all have values less than zero). If a dialog receives a delete event,
the "response" signal will be emitted with a response ID of GTK_RESPONSE_DELETE_EVENT.
If you want to block waiting for a dialog to return before returning control
flow to your code, you can call gtk_dialog_run()
. This function enters a
recursive main loop and waits for the user to respond to the dialog, returning the
response ID corresponding to the button the user clicked.
For the simple dialog in the following example, in reality you'd probably use GtkMessageDialog to save yourself some effort. But you'd need to create the dialog contents manually if you had more than a simple message in the dialog.
Example 4. Simple GtkDialog usage.
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/* Function to open a dialog box displaying the message provided. */ void quick_message (gchar *message) { GtkWidget *dialog, *label, *content_area; /* Create the widgets */ dialog = gtk_dialog_new_with_buttons ("Message", main_application_window, GTK_DIALOG_DESTROY_WITH_PARENT, GTK_STOCK_OK, GTK_RESPONSE_NONE, NULL); content_area = gtk_dialog_get_content_area (GTK_DIALOG (dialog)); label = gtk_label_new (message); /* Ensure that the dialog box is destroyed when the user responds. */ g_signal_connect_swapped (dialog, "response", G_CALLBACK (gtk_widget_destroy), dialog); /* Add the label, and show everything we've added to the dialog. */ gtk_container_add (GTK_CONTAINER (content_area), label); gtk_widget_show_all (dialog); } |
The GtkDialog implementation of the GtkBuildable interface exposes the
vbox
and action_area
as internal children with the names "vbox" and
"action_area".
GtkDialog supports a custom <action-widgets> element, which
can contain multiple <action-widget> elements. The "response"
attribute specifies a numeric response, and the content of the element
is the id of widget (which should be a child of the dialogs action_area
).
Example 5. A GtkDialog UI definition fragment.
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<object class="GtkDialog" id="dialog1"> <child internal-child="vbox">" <object class="GtkVBox" id="vbox"> <child internal-child="action_area"> <object class="GtkHButtonBox" id="button_box"> <child> <object class="GtkButton" id="button_cancel"/> </child> <child> <object class="GtkButton" id="button_ok"/> </child> </object> </child> </object> </child> <action-widgets> <action-widget response="3">button_ok</action-widget> <action-widget response="-5">button_cancel</action-widget> </action-widgets> </object> |