| gdk-Input-Devices {RGtk2} | R Documentation |
Functions for handling extended input devices
gdkDevicesList()
gdkDeviceSetSource(object, source)
gdkDeviceSetMode(object, mode)
gdkDeviceSetKey(object, index, keyval, modifiers)
gdkDeviceSetAxisUse(object, index, use)
gdkDeviceGetCorePointer()
gdkDeviceGetState(object, window)
gdkDeviceGetHistory(object, window, start, stop)
gdkDeviceGetAxis(object, axes, use)
gdkInputSetExtensionEvents(object, mask, mode)
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 gdkInputSetExtensionEvents.
(Or, more typically, for GtkWidgets, using gtkWidgetSetExtensionEvents).
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
gdkInputSetExtensionEvents. Otherwise, the application
must retrieve the device information using gdkDevicesList,
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 gdkDevicesList.
Each device must be activated using gdkDeviceSetMode, 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
gdkDeviceSetAxisUse. And the source type for each device
can be set with gdkDeviceSetSource.
Devices may also have associated keys
or function buttons. Such keys can be globally set to map
into normal X keyboard events. The mapping is set using
gdkDeviceSetKey.
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.
GdkDeviceGdkDevice structure contains
a detailed description of an extended input device. All
fields are read-only; but you can use gdkDeviceSetSource,
gdkDeviceSetMode, gdkDeviceSetKey and gdkDeviceSetAxisUse
to configure various aspects of the device.
namesourceGdkInputSource] the name of this device.modeGdkInputMode] the type of this device.hasCursornumAxesTRUE if the pointer follows device motion.axesGdkDeviceAxis] the length of the axes list.numKeysGdkDeviceAxis, describing the axes of this device.keysGdkDeviceKey] the length of the keys list.
GdkDeviceKeyGdkDeviceKey structure contains information
about the mapping of one device function button onto a normal X key event.
It has the following fields:
keyvalmodifiersGdkModifierType] the modifiers set for the generated key event.
GdkDeviceAxisGdkDeviceAxis structure contains information
about the range and mapping of a device axis.
useGdkAxisUse] specifies how the axis is used.minmax
GdkTimeCoordGdkTimeCoord structure stores a single event in a
motion history. It contains the following fields:
GdkTimeCoord is a transparent-type.
timeaxes
GdkInputSourcemousepenerasercursor
GdkInputModedisabledscreenwindow
GdkAxisUseignorexypressurextiltytiltwheellast
GdkExtensionModenoneallcursor
Derived by RGtkGen from GTK+ documentation
http://developer.gnome.org/doc/API/2.0/gdk/gdk-Input-Devices.html