Input Devices Functions for handling extended input devices In addition to the normal keyboard and mouse input devices, GTK+ also contains support for extended input devices. In particular, this support is targeted at graphics tablets. Graphics tablets typically return sub-pixel positioning information and possibly information about the pressure and tilt of the stylus. Under X, the support for extended devices is done through the XInput extension. Because handling extended input devices may involve considerable overhead, they need to be turned on for each #GdkWindow individually using gdk_input_set_extension_events(). (Or, more typically, for GtkWidgets, using gtk_widget_set_extension_events()). As an additional complication, depending on the support from the windowing system, its possible that a normal mouse cursor will not be displayed for a particular extension device. If an application does not want to deal with displaying a cursor itself, it can ask only to get extension events from devices that will display a cursor, by passing the %GDK_EXTENSION_EVENTS_CURSOR value to gdk_input_set_extension_events(). Otherwise, the application must retrieve the device information using gdk_devices_list(), check the has_cursor field, and, if it is %FALSE, draw a cursor itself when it receives motion events. Each pointing device is assigned a unique integer ID; events from a particular device can be identified by the deviceid field in the event structure. The events generated by pointer devices have also been extended to contain pressure, xtilt and ytilt fields which contain the extended information reported as additional valuators from the device. The pressure field is a a double value ranging from 0.0 to 1.0, while the tilt fields are double values ranging from -1.0 to 1.0. (With -1.0 representing the maximum tilt to the left or up, and 1.0 representing the maximum tilt to the right or down.) One additional field in each event is the source field, which contains an enumeration value describing the type of device; this currently can be one of %GDK_SOURCE_MOUSE, %GDK_SOURCE_PEN, %GDK_SOURCE_ERASER, or %GDK_SOURCE_CURSOR. This field is present to allow simple applications to (for instance) delete when they detect eraser devices without having to keep track of complicated per-device settings. Various aspects of each device may be configured. The easiest way of creating a GUI to allow the user to configure such a device is to use the #GtkInputDialog widget in GTK+. However, even when using this widget, application writers will need to directly query and set the configuration parameters in order to save the state between invocations of the application. The configuration of devices is queried using gdk_devices_list(). Each device must be activated using gdk_device_set_mode(), which also controls whether the device's range is mapped to the entire screen or to a single window. The mapping of the valuators of the device onto the predefined valuator types is set using gdk_device_set_axis_use(). And the source type for each device can be set with gdk_device_set_source(). Devices may also have associated keys or macro buttons. Such keys can be globally set to map into normal X keyboard events. The mapping is set using gdk_device_set_key(). The interfaces in this section will most likely be considerably modified in the future to accomodate devices that may have different sets of additional valuators than the pressure xtilt and ytilt. A GdkDevice structure contains a detailed description of an extended input device. All fields are read-only; but you can use gdk_device_set_source(), gdk_device_set_mode(), gdk_device_set_key() and gdk_device_set_axis_use() to configure various aspects of the device. @parent_instance: the parent instance @name: the name of this device. @source: the type of this device. @mode: the mode of this device @has_cursor: %TRUE if the pointer follows device motion. @num_axes: the length of the @axes array. @axes: an array of #GdkDeviceAxis, describing the axes of this device. @num_keys: the length of the @keys array. @keys: an array of #GdkDeviceKey, describing the mapped macro buttons of this device. An enumeration describing the type of an input device in general terms. @GDK_SOURCE_MOUSE: the device is a mouse. (This will be reported for the core pointer, even if it is something else, such as a trackball.) @GDK_SOURCE_PEN: the device is a stylus of a graphics tablet or similar device. @GDK_SOURCE_ERASER: the device is an eraser. Typically, this would be the other end of a stylus on a graphics tablet. @GDK_SOURCE_CURSOR: the device is a graphics tablet "puck" or similar device. An enumeration that describes the mode of an input device. @GDK_MODE_DISABLED: the device is disabled and will not report any events. @GDK_MODE_SCREEN: the device is enabled. The device's coordinate space maps to the entire screen. @GDK_MODE_WINDOW: the device is enabled. The device's coordinate space is mapped to a single window. The manner in which this window is chosen is undefined, but it will typically be the same way in which the focus window for key events is determined. The GdkDeviceKey structure contains information about the mapping of one device macro button onto a normal X key event. It has the following fields: @keyval: the keyval to generate when the macro button is pressed. If this is 0, no keypress will be generated. @modifiers: the modifiers set for the generated key event. The GdkDeviceAxis structure contains information about the range and mapping of a device axis. @use: specifies how the axis is used. @min: the minimal value that will be reported by this axis. @max: the maximal value that will be reported by this axis. An enumeration describing the way in which a device axis (valuator) maps onto the predefined valuator types that GTK+ understands. @GDK_AXIS_IGNORE: the axis is ignored. @GDK_AXIS_X: the axis is used as the x axis. @GDK_AXIS_Y: the axis is used as the y axis. @GDK_AXIS_PRESSURE: the axis is used for pressure information. @GDK_AXIS_XTILT: the axis is used for x tilt information. @GDK_AXIS_YTILT: the axis is used for x tilt information. @GDK_AXIS_WHEEL: the axis is used for wheel information. @GDK_AXIS_LAST: a constant equal to the numerically highest axis value. @Returns: Sets the source type for an input device. @device: a #GdkDevice. @source: the source type. Sets a the mode of an input device. The mode controls if the device is active and whether the device's range is mapped to the entire screen or to a single window. @device: a #GdkDevice. @mode: the input mode. @Returns: %TRUE if the mode was successfully changed. Specifies the X key event to generate when a macro button of a device is pressed. @device: a #GdkDevice. @index_: the index of the macro button to set. @keyval: the keyval to generate. @modifiers: the modifiers to set. Specifies how an axis of a device is used. @device: a #GdkDevice. @index_: the index of the axis. @use: specifies how the axis is used. @Returns: Gets the current state of a device. @device: a #GdkDevice. @window: a #GdkWindow. @axes: an array of doubles to store the values of the axes of @device in, or %NULL. @mask: location to store the modifiers, or %NULL. @device: @window: @start: @stop: @events: @n_events: @Returns: Frees an array of #GdkTimeCoord that was returned by gdk_device_get_history(). @events: an array of #GdkTimeCoord. @n_events: the length of the array. The #GdkTimeCoord structure stores a single event in a motion history. It contains the following fields: @time: The timestamp for this event. @axes: the values of the device's axes. @device: @axes: @use: @value: @Returns: Turns extension events on or off for a particular window, and specifies the event mask for extension events. @window: a #GdkWindow. @mask: the event mask @mode: the type of extension events that are desired. An enumeration used to specify which extension events are desired for a particular widget. @GDK_EXTENSION_EVENTS_NONE: no extension events are desired. @GDK_EXTENSION_EVENTS_ALL: all extension events are desired. @GDK_EXTENSION_EVENTS_CURSOR: extension events are desired only if a cursor will be displayed for the device.