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Legacy Maemo 5 Documentation/Graphical UI Tutorial/Controls

Revision as of 15:17, 19 October 2009

Controls

Hildon provides a set of controls specially designed for touchscreens that allows to build simple and easy-to-use interfaces. This chapter explains how to use these widgets.

Buttons

A Hildon application can use several types of buttons. Hildon provides specialized buttons derived from GtkButton which provide additional commodities specific to the Hildon framework. Using GtkButtons and GtkToggleButtons is also recommended.

Hildon Button

HildonButton is a GtkButton which usually contains two labels, title and value. It can also include an image.

To create a HildonButton, use the following functions:

GtkWidget*  hildon_button_new               (HildonSizeType size,
                                             HildonButtonArrangement arrangement);
GtkWidget*  hildon_button_new_with_text     (HildonSizeType size,
                                             HildonButtonArrangement arrangement,
                                             const gchar *title,
                                             const gchar *value)

Note that in the creation of a HildonButton you must indicate the value for the properties "size" and "arrangement", choosing a Hildon size and a horizontal or vertical arrangement of the labels.

You can set and retrieve both labels by using the following convenience functions:

void        hildon_button_set_title         (HildonButton *button,
                                             const gchar *title);
void        hildon_button_set_value         (HildonButton *button,
                                             const gchar *value);
const gchar* hildon_button_get_title        (HildonButton *button);
const gchar* hildon_button_get_value        (HildonButton *button);

Alternatively, use the following function to set both labels of a HildonButton:

void        hildon_button_set_text          (HildonButton *button,
                                             const gchar *title,
                                             const gchar *value);

To add images to HildonButtons, use the following functions to set and retrieve the current image: hildon_button_set_image() and hildon_button_get_image().

You can also set the position of the image.

void        hildon_button_set_image_position (HildonButton *button,
                                              GtkPositionType position);

Currently supported positions are GTK_POS_LEFT or GTK_POS_RIGHT.

The visual style (color, fonts, etc) of a HildonButton can be changed by using the function hildon_button_set_style(). Use HILDON_BUTTON_STYLE_NORMAL to make it look like a normal HildonButton, or HILDON_BUTTON_STYLE_PICKER to make it look like a HildonPickerButton.

The next simple example shows how to create a HildonButton, set the label text and add an image.

Example 7.1. Example of a Hildon button with a label and an image

GtkWidget *
create_button (void)
{
    GtkWidget *button;
    GtkWidget *image;
    /* Create a hildon button */
    button = hildon_button_new (HILDON_SIZE_AUTO_WIDTH | HILDON_SIZE_FINGER_HEIGHT,
                                HILDON_BUTTON_ARRANGEMENT_VERTICAL);
    /* Set labels value */
    hildon_button_set_text (HILDON_BUTTON (button), "Some title", "Some value");
    /* Set image */
    image = gtk_image_new_from_stock (GTK_STOCK_INFO, GTK_ICON_SIZE_BUTTON);
    hildon_button_set_image (HILDON_BUTTON (button), image);
    hildon_button_set_image_position (HILDON_BUTTON (button), GTK_POS_RIGHT);
    return button;
}

Hildon Check Button

HildonCheckButton is a button that contains a label and a check box. The check box toggles between checked or unchecked.

To create a HildonCheckButton:

 GtkWidget*  hildon_check_button_new         (HildonSizeType size);

Note that, again, you must specify the size of the button.

You can retrieve or set the current state of the button with the following functions, respectively:

gboolean    hildon_check_button_get_active  (HildonCheckButton *button);
void        hildon_check_button_set_active  (HildonCheckButton *button,
                                             gboolean is_active);

The signal "toggled" is emitted when the state of the button changes. A handler can be attached to this signal if a further action is required.

Here is a simple example which creates a check button and a simple callback to handle the signal "toggled".

Example 7.2. Example of a Hildon check button

void
button_toggled (HildonCheckButton *button, gpointer user_data)
{
    gboolean active;
    active = hildon_check_button_get_active (button);
    if (active)
       g_debug ("Button is active");
    else
       g_debug ("Button is not active");
}
GtkWidget *
create_button (void)
{
    GtkWidget *button;
    button = hildon_check_button_new (HILDON_SIZE_AUTO);
    gtk_button_set_label (GTK_BUTTON (button), "Click me");
    g_signal_connect (button, "toggled", G_CALLBACK (button_toggled), NULL);
    return button;
}

Using Gtk Buttons and Toggles

As was said above, apart from Hildon specific buttons, use GtkButton and GtkToggleButton also in the Hildon framework.

GtkButton

If only a label is needed, you do not need to use HildonButtons and a GtkButton can be used instead. You can use it as you would do in a GTK application. The only change is the creation function that you must use:

GtkWidget*  hildon_gtk_button_new           (HildonSizeType size);

This alternative constructor allows you to set a Hildon size for the newly create function.

GtkToggleButton

To create a GtkToggleButton in a Hildon application you should use:

GtkWidget*  hildon_gtk_toggle_button_new    (HildonSizeType size);

GtkRadioButton

To create a GtkRadioButton in a Hildon application, use:

GtkWidget*  hildon_gtk_radio_button_new     (HildonSizeType size,
                                             GSList *group);

The most common use case of this type of buttons in a Hildon application is as filters in a application menu. For more information, see section Touch View Menu.

Text display and handling

Text entry fields are used for entering one or more lines of plain text. Use a HildonEntry for a single-line text input or HildonTextView if you need a multi-line text input.

Hildon Text Entry

The HildonEntry is a GTK+ widget which represents a text entry. It is derived from the GtkEntry widget and provides additional commodities specific to the Hildon framework.

The main additional feature is a placeholder text to display if the entry is empty and not in focus.

Creating a new HildonEntry:

GtkWidget*  hildon_entry_new                (HildonSizeType size);

Note that the creation function needs to specify a size from HildonSizeType.

The placeholder is stored as a property. To set it, use the following convenience function:

void        hildon_entry_set_placeholder    (HildonEntry *entry,
                                             const gchar *text);

Here's a very simple example showing how to create a HindonEntry.

Example 7.3. Example of a Hildon entry

GtkWidget *
create_entry (void)
{
    GtkWidget *entry;
    entry = hildon_entry_new (HILDON_SIZE_AUTO);
    hildon_entry_set_placeholder (HILDON_ENTRY (entry),
	                          "First name");
    return entry;
}

Hildon Text Area

The HildonTextView is a GTK+ widget which represents a text area in Hildon applications. It is derived from the GtkTextView widget and provides additional commodities specific to the Hildon framework.

Create a HildonTextView:

GtkWidget*  hildon_text_view_new            (void);

Like for the HildonTextEntry presented above, you can store a placeholder as well using the function.

void        hildon_text_view_set_placeholder    (HildonEntry *entry,
                                                 const gchar *text);

The text that is being edited with a HildonTextView is represented by a object GtkTextBuffer. The following functions can be used to set and retrieve the buffer associated with a HildonTextView.

void        hildon_text_view_set_buffer         (HildonTextView *text_view,
                                                 GtkTextBuffer *buffer);
GtkTextBuffer* hildon_text_view_get_buffer      (HildonTextView *text_view);

Here is an example that shows how to create a HildonTextView and how to set its placeholder. Also, the buffer is retrieved and a function is set as a handler to the "changed" of the buffer. The handler simply gets the text from the HildonTextView's buffer and prints it.

Example 7.4. Example of a Hildon text view with a placeholder

static void
text_changed                                    (GtkTextBuffer *buffer,
                                                 gpointer      *user_data)
{
    gchar *text;
    GtkTextIter start, end;
    gtk_text_buffer_get_start_iter (buffer, &start);
    gtk_text_buffer_get_end_iter (buffer, &end);
    text = gtk_text_buffer_get_text (buffer, &start, &end, FALSE);
    g_debug (text);
}
GtkWidget *
create_text_view (void)
{
    GtkWidget *text_view;
    text_view = hildon_text_view_new();
    hildon_text_view_set_placeholder (HILDON_TEXT_VIEW (text_view),
                                      "Type some text here");
    buffer = hildon_text_view_get_buffer (textview);
    g_signal_connect (buffer,
                      "changed",
                      G_CALLBACK (text_changed),
                      NULL);
    return text_view;
}

Warning

Although HildonTextView is derived from GtkTextView, gtk_text_view_get_buffer() and gtk_text_view_set_buffer() must never be used to get/set the buffer in this widget, hildon_text_view_get_buffer() and hildon_text_view_set_buffer() must be used instead.

Notification widgets

To cover the main use cases regarding notification of users, Hildon provides banners and notes. Banner widgets display a text information during a certain period of time. Notes are specialized GtkDialogs that need a small amount of input from the user.

Banners

A HildonBanner is useful to display information which does not need any user response. This widget automatically disappears after a certain time period.

To create and show a banner, use the following function:

GtkWidget*  hildon_banner_show_information  (GtkWidget *widget,
                                             const gchar *icon_name,
                                             const gchar *text);
GtkWidget*  hildon_banner_show_informationf (GtkWidget *widget,
                                             const gchar *icon_name,
                                             const gchar *format,
                                             ...);
GtkWidget*  hildon_banner_show_information_with_markup
                                            (GtkWidget *widget,
                                             const gchar *icon_name,
                                             const gchar *markup);

All functions above require a widget as an argument that must be a pointer to the owner widget of the banner. Usually, the owner is the window that represents the currently displayed view.

Function hildon_banner_show_information() shows a banner with the given text.

Function hildon_banner_show_informationf() shows a banner which displays the text given by the printf-like formated string applied to the parameters that the rest of the function's arguments represent.

You can also apply a Pango markup and add some attributes to the displayed text. To do that, either use hildon_banner_show_information_with_markup() to create the banner or setup the markup by calling hildon_banner_set_markup() after the initialization. [@@COMMENT@@ LINK TO PANGO MARKUP]

Warning

Currently, icons are not displayed in banners, so any value that you pass as the icon_name is ignored.

The period of time after the banner automatically disappear is stored in the property "timeout" (in miliseconds). A convenience function to set this property is provided:

void        hildon_banner_set_timeout       (HildonBanner *self,
                                             guint timeout);

Here is a simple example showing how to setup and show an informational banner.

Example 7.5. Setting up an informational banner

    GtkWidget* banner;
    /* Create a banner with a markup */
    banner = hildon_banner_show_information_with_markup (widget,
                                                         NULL,
                                                         "<b>Information banner</b>");
    hildon_banner_set_timeout (HILDON_BANNER (banner), 9000);

Note

Only one timed banner can exist for each window in your application. If you spawn a new banner before the previous one has timed out, the first one is replaced.

Notes

HildonNotes are GtkDialogs designed to request a small amount of input from users. Usually, notes show an information text and buttons to confirm and cancel, for example, according to their type.

Unlike banners, notes always need a user action, that is, notes do not disappear automatically after a period of time.

The HildonNote widget provides functions to create and show different types of notes: information notes, confirmation notes and cancel notes.

GtkWidget*  hildon_note_new_information     (GtkWindow *parent,
                                             const gchar *description);
GtkWidget*  hildon_note_new_confirmation    (GtkWindow *parent,
                                             const gchar *description);
GtkWidget*  hildon_note_new_confirmation_add_buttons
                                            (GtkWindow *parent,
                                             const gchar *description,
                                             ...);
GtkWidget*  hildon_note_new_cancel_with_progress_bar
                                            (GtkWindow *parent,
                                             const gchar *description,
                                             GtkProgressBar *progressbar);

Every function to create notes receives as a parameter the parent window of the newly created note. This is important in order to allow the window manager to handle the windows properly.

Information Notes

Information notes are used to show an information to the users. This note disappears when user taps outside the note's area. Otherwise the note remains visible.

Here is an example of how to show an information note and handle the user's answer.

Example 7.6. Example of a Hildon information note

static void
show_information_note                          (GtkWidget *parent)
{
  GtkWidget *window, *note;
  gint response;
  note = hildon_note_new_information (NULL,
    "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
    "Maecenas tristique dictum est. Aenean rhoncus aliquam mi."
    "In hac habitasse platea dictumst.");
  response = gtk_dialog_run (GTK_DIALOG (note));
  if (response == GTK_RESPONSE_DELETE_EVENT)
    g_debug ("%s: GTK_RESPONSE_DELETE_EVENT", __FUNCTION__);
  gtk_object_destroy (GTK_OBJECT (note));
}

Confirmation Notes

Confirmation notes show an information text that is usually a question and two buttons labelled "Yes" and "No".

To create a confirmation note with the text you specify and two buttons labelled "Yes"/"No", use hildon_note_new_confirmation() as follows:

Example 7.7. Example of a Hildon confirmation note

static void
show_confirmation_note                          (GtkWidget *parent)
{
    GtkWidget *note;
    gint response;
    note = hildon_note_new_confirmation (parent,
                                         "Do you want foo ?");
    response = gtk_dialog_run (GTK_DIALOG (note));
    if (response == GTK_RESPONSE_DELETE_EVENT)
      g_debug ("%s: GTK_RESPONSE_DELETE_EVENT", __FUNCTION__);
    gtk_object_destroy (GTK_OBJECT (note));
}

Alternatively, you can use hildon_note_new_confirmation_add_buttons() to create a confirmation note with custom buttons.

Example 7.8. Example of a Hildon copnfirmation note with custom buttons

static void
show_confirmation_note                          (GtkWidget *parent)
{
    GtkWidget *note;
    gint response;
    note = hildon_note_new_confirmation_add_buttons(parent,
                                                    "Do you want foo?",
                                                    "ACCEPT", GTK_RESPONSE_OK,
                                                    "CANCEL", GTK_RESPONSE_CANCEL,
                                                    "DELETE", GTK_RESPONSE_DELETE_EVENT,
                                                    NULL);
    response = gtk_dialog_run (GTK_DIALOG (note));
    if (response == GTK_RESPONSE_DELETE_EVENT)
      g_debug ("%s: GTK_RESPONSE_DELETE_EVENT", __FUNCTION__);
    gtk_object_destroy (GTK_OBJECT (note));
}

Cancel Notes

A cancel note displays a text, a Cancel button and a progress bar. They are useful to tell users that a long task is in progress. Also, cancel notes allow users to cancel the task in progress.

Next example shows how to create a cancel note with a progress bar. Note that to control the progress bar, additional code is needed.

Example 7.9. Example of a Hildon cancel note with a progress bar

static void
show_information_note                          (GtkWidget *parent)
{
  GtkWidget *note
  GtkProgressBar *progressbar
  gint response;
  progressbar = gtk_progress_bar_new()
  note = hildon_note_new_cancel_with_progress_bar (parent,
                                                  "A large task is happening"
                                                  progressbar);
  response = gtk_dialog_run (GTK_DIALOG (note));
  if (response == GTK_RESPONSE_DELETE_EVENT)
    g_debug ("%s: GTK_RESPONSE_DELETE_EVENT", __FUNCTION__);
  gtk_object_destroy (GTK_OBJECT (note));
}