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