SpinButtonRef

public struct SpinButtonRef : SpinButtonProtocol, GWeakCapturing

A GtkSpinButton is an ideal way to allow the user to set the value of some attribute. Rather than having to directly type a number into a GtkEntry, GtkSpinButton allows the user to click on one of two arrows to increment or decrement the displayed value. A value can still be typed in, with the bonus that it can be checked to ensure it is in a given range.

The main properties of a GtkSpinButton are through an adjustment. See the GtkAdjustment section for more details about an adjustment’s properties. Note that GtkSpinButton will by default make its entry large enough to accomodate the lower and upper bounds of the adjustment, which can lead to surprising results. Best practice is to set both the GtkEntry:width-chars and GtkEntry:max-width-chars poperties to the desired number of characters to display in the entry.

CSS nodes

(plain Language Example):

spinbutton.horizontal
├── undershoot.left
├── undershoot.right
├── entry
│   ╰── ...
├── button.down
╰── button.up

(plain Language Example):

spinbutton.vertical
├── undershoot.left
├── undershoot.right
├── button.up
├── entry
│   ╰── ...
╰── button.down

GtkSpinButtons main CSS node has the name spinbutton. It creates subnodes for the entry and the two buttons, with these names. The button nodes have the style classes .up and .down. The GtkEntry subnodes (if present) are put below the entry node. The orientation of the spin button is reflected in the .vertical or .horizontal style class on the main node.

Using a GtkSpinButton to get an integer

(C Language Example):

// Provides a function to retrieve an integer value from a GtkSpinButton
// and creates a spin button to model percentage values.

gint
grab_int_value (GtkSpinButton *button,
                gpointer       user_data)
{
  return gtk_spin_button_get_value_as_int (button);
}

void
create_integer_spin_button (void)
{

  GtkWidget *window, *button;
  GtkAdjustment *adjustment;

  adjustment = gtk_adjustment_new (50.0, 0.0, 100.0, 1.0, 5.0, 0.0);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_container_set_border_width (GTK_CONTAINER (window), 5);

  // creates the spinbutton, with no decimal places
  button = gtk_spin_button_new (adjustment, 1.0, 0);
  gtk_container_add (GTK_CONTAINER (window), button);

  gtk_widget_show_all (window);
}

Using a GtkSpinButton to get a floating point value

(C Language Example):

// Provides a function to retrieve a floating point value from a
// GtkSpinButton, and creates a high precision spin button.

gfloat
grab_float_value (GtkSpinButton *button,
                  gpointer       user_data)
{
  return gtk_spin_button_get_value (button);
}

void
create_floating_spin_button (void)
{
  GtkWidget *window, *button;
  GtkAdjustment *adjustment;

  adjustment = gtk_adjustment_new (2.500, 0.0, 5.0, 0.001, 0.1, 0.0);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_container_set_border_width (GTK_CONTAINER (window), 5);

  // creates the spinbutton, with three decimal places
  button = gtk_spin_button_new (adjustment, 0.001, 3);
  gtk_container_add (GTK_CONTAINER (window), button);

  gtk_widget_show_all (window);
}

The SpinButtonRef type acts as a lightweight Swift reference to an underlying GtkSpinButton instance. It exposes methods that can operate on this data type through SpinButtonProtocol conformance. Use SpinButtonRef only as an unowned reference to an existing GtkSpinButton instance.