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Gtk.PadController

class — extends EventController

Handles input from the pads found in drawing tablets.

Pads are the collection of buttons and tactile sensors often found around the stylus-sensitive area.

These buttons and sensors have no implicit meaning, and by default they perform no action. GtkPadController is provided to map those to Gio.Action objects, thus letting the application give them a more semantic meaning.

Buttons and sensors are not constrained to triggering a single action, some Gdk.InputSource.TABLET_PAD devices feature multiple "modes". All these input elements have one current mode, which may determine the final action being triggered.

Pad devices often divide buttons and sensors into groups. All elements in a group share the same current mode, but different groups may have different modes. See Gdk.DevicePad.get_n_groups and Gdk.DevicePad.get_group_n_modes.

Each of the actions that a given button/strip/ring performs for a given mode is defined by a PadActionEntry. It contains an action name that will be looked up in the given Gio.ActionGroup and activated whenever the specified input element and mode are triggered.

A simple example of GtkPadController usage: Assigning button 1 in all modes and pad devices to an "invert-selection" action:

GtkPadActionEntry *pad_actions[] = {
  { GTK_PAD_ACTION_BUTTON, 1, -1, "Invert selection", "pad-actions.invert-selection" },
  …
};

…
action_group = g_simple_action_group_new ();
action = g_simple_action_new ("pad-actions.invert-selection", NULL);
g_signal_connect (action, "activate", on_invert_selection_activated, NULL);
g_action_map_add_action (G_ACTION_MAP (action_group), action);
…
pad_controller = gtk_pad_controller_new (action_group, NULL);

The actions belonging to rings/strips/dials will be activated with a parameter of type G_VARIANT_TYPE_DOUBLE bearing the value of the given axis, it is required that those are made stateful and accepting this GVariantType. For rings the value is the angle of the ring position in degrees with 0 facing up. For strips the value is the absolute position on the strip, normalized to the [0.0, 1.0] range. For dials the value is the relative movement of the dial, normalized so that the value 120 represents one logical scroll wheel detent in the positive direction. Devices that support high-resolution scrolling may send events with fractions of 120 to signify a smaller motion.

Constructors

new

@classmethod
def new(cls, group: Gio.ActionGroup, pad: Gdk.Device | None = ...) -> PadController

Creates a new GtkPadController that will associate events from pad to actions.

A None pad may be provided so the controller manages all pad devices generically, it is discouraged to mix GtkPadController objects with None and non-None pad argument on the same toplevel window, as execution order is not guaranteed.

The GtkPadController is created with no mapped actions. In order to map pad events to actions, use PadController.set_action_entries or PadController.set_action.

Be aware that pad events will only be delivered to GtkWindows, so adding a pad controller to any other type of widget will not have an effect.

Parameters:

Methods

set_action

def set_action(self, type: PadActionType | int, index: int, mode: int, label: str, action_name: str) -> None

Adds an individual action to controller.

This action will only be activated if the given button/ring/strip number in index is interacted while the current mode is mode. -1 may be used for simple cases, so the action is triggered on all modes.

The given label should be considered user-visible, so internationalization rules apply. Some windowing systems may be able to use those for user feedback.

Parameters:

  • type — the type of pad feature that will trigger this action
  • index — the 0-indexed button/ring/strip number that will trigger this action
  • mode — the mode that will trigger this action, or -1 for all modes.
  • label — Human readable description of this action, this string should be deemed user-visible.
  • action_name — action name that will be activated in the GActionGroup

set_action_entries

def set_action_entries(self, entries: list[PadActionEntry]) -> None

A convenience function to add a group of action entries on controller.

See PadActionEntry and PadController.set_action.

Parameters:

  • entries — the action entries to set on controller

Properties

action_group

action_group: Gio.ActionGroup  # read/write

The action group of the controller.

pad

pad: Gdk.Device  # read/write

The pad of the controller.