GdkDeviceManager

GdkDeviceManager — Functions for handling input devices

Synopsis

#include <gdk/gdk.h>

                    GdkDeviceManager;
void                gdk_disable_multidevice             (void);
GdkDisplay *        gdk_device_manager_get_display      (GdkDeviceManager *device_manager);
GList *             gdk_device_manager_list_devices     (GdkDeviceManager *device_manager,
                                                         GdkDeviceType type);
GdkDevice *         gdk_device_manager_get_client_pointer
                                                        (GdkDeviceManager *device_manager);

Object Hierarchy

  GObject
   +----GdkDeviceManager

Properties

  "display"                  GdkDisplay*           : Read / Write / Construct Only

Signals

  "device-added"                                   : Run Last
  "device-changed"                                 : Run Last
  "device-removed"                                 : Run Last

Description

In addition to a single pointer and keyboard for user interface input, GDK contains support for a variety of input devices, including graphics tablets, touchscreens and multiple pointers/keyboards interacting simultaneously with the user interface. Under X, the support for multiple input devices is done through the XInput 2 extension, which also supports additional features such as sub-pixel positioning information and additional device-dependent information.

By default, and if the platform supports it, GDK is aware of multiple keyboard/pointer pairs and multitouch devices, this behavior can be changed by calling gdk_disable_multidevice() before gdk_display_open(), although there would rarely be a reason to do that. For a widget or window to be dealt as multipointer aware, gdk_window_set_support_multidevice() or gtk_widget_set_support_multidevice() must have been called on it.

Conceptually, in multidevice mode there are 2 device types. Virtual devices (or master devices) are represented by the pointer cursors and keyboard foci that are seen on the screen. Physical devices (or slave devices) represent the hardware that is controlling the virtual devices, and thus have no visible cursor on the screen.

Virtual devices are always paired, so there is a keyboard device for every pointer device. Associations between devices may be inspected through gdk_device_get_associated_device().

There may be several virtual devices, and several physical devices could be controlling each of these virtual devices. Physical devices may also be "floating", which means they are not attached to any virtual device.

By default, GDK will automatically listen for events coming from all master devices, setting the GdkDevice for all events coming from input devices, [1] Although gdk_window_set_support_multidevice() must be called on GdkWindows in order to support additional features of multiple pointer interaction, such as multiple per-device enter/leave events, the default setting will emit just one enter/leave event pair for all devices on the window. See gdk_window_set_support_multidevice() documentation for more information.

In order to listen for events coming from other than a virtual device, gdk_window_set_device_events() must be called. Generally, this function can be used to modify the event mask for any given device.

Input devices may also provide additional information besides X/Y. For example, graphics tablets may also provide pressure and X/Y tilt information. This information is device-dependent, and may be queried through gdk_device_get_axis(). In multidevice mode, virtual devices will change axes in order to always represent the physical device that is routing events through it. Whenever the physical device changes, the "n-axes" property will be notified, and gdk_device_list_axes() will return the new device axes.

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().

In order to query the device hierarchy and be aware of changes in the device hierarchy (such as virtual devices being created or removed, or physical devices being plugged or unplugged), GDK provides GdkDeviceManager. On X11, multidevice support is implemented through XInput 2. Unless gdk_disable_multidevice() is called, the XInput 2.x GdkDeviceManager implementation will be used as the input source. Otherwise either the core or XInput 1.x implementations will be used.

Details

GdkDeviceManager

typedef struct _GdkDeviceManager GdkDeviceManager;


gdk_disable_multidevice ()

void                gdk_disable_multidevice             (void);

Disables multidevice support in GDK. This call must happen prior to gdk_display_open(), gtk_init(), gtk_init_with_args() or gtk_init_check() in order to take effect.

Most common GTK+ applications won't ever need to call this. Only applications that do mixed GDK/Xlib calls could want to disable multidevice support if such Xlib code deals with input devices in any way and doesn't observe the presence of XInput 2.

Since 3.0


gdk_device_manager_get_display ()

GdkDisplay *        gdk_device_manager_get_display      (GdkDeviceManager *device_manager);

Gets the GdkDisplay associated to device_manager.

device_manager :

a GdkDeviceManager

Returns :

the GdkDisplay to which device_manager is associated to, or NULL. This memory is owned by GDK and must not be freed or unreferenced. [transfer none]

Since 3.0


gdk_device_manager_list_devices ()

GList *             gdk_device_manager_list_devices     (GdkDeviceManager *device_manager,
                                                         GdkDeviceType type);

Returns the list of devices of type type currently attached to device_manager.

device_manager :

a GdkDeviceManager

type :

device type to get.

Returns :

a list of GdkDevices. The returned list must be freed with g_list_free(). The list elements are owned by GTK+ and must not be freed or unreffed. [transfer container][element-type Gdk.Device]

Since 3.0


gdk_device_manager_get_client_pointer ()

GdkDevice *         gdk_device_manager_get_client_pointer
                                                        (GdkDeviceManager *device_manager);

Returns the client pointer, that is, the master pointer that acts as the core pointer for this application. In X11, window managers may change this depending on the interaction pattern under the presence of several pointers.

You should use this function sheldomly, only in code that isn't triggered by a GdkEvent and there aren't other means to get a meaningful GdkDevice to operate on.

device_manager :

a GdkDeviceManager

Returns :

The client pointer. This memory is owned by GDK and must not be freed or unreferenced. [transfer none]

Since 3.0

Property Details

The "display" property

  "display"                  GdkDisplay*           : Read / Write / Construct Only

Display for the device manager.

Signal Details

The "device-added" signal

void                user_function                      (GdkDeviceManager *device_manager,
                                                        GdkDevice        *device,
                                                        gpointer          user_data)           : Run Last

The ::device-added signal is emitted either when a new master pointer is created, or when a slave (Hardware) input device is plugged in.

device_manager :

the object on which the signal is emitted

device :

the newly added GdkDevice.

user_data :

user data set when the signal handler was connected.

The "device-changed" signal

void                user_function                      (GdkDeviceManager *device_manager,
                                                        GdkDevice        *device,
                                                        gpointer          user_data)           : Run Last

The ::device-changed signal is emitted whenever a device has changed in the hierarchy, either slave devices being disconnected from their master device or connected to another one, or master devices being added or removed a slave device.

If a slave device is detached from all master devices (gdk_device_get_associated_device() returns NULL), its GdkDeviceType will change to GDK_DEVICE_TYPE_FLOATING, if it's attached, it will change to GDK_DEVICE_TYPE_SLAVE.

device_manager :

the object on which the signal is emitted

device :

the GdkDevice that changed.

user_data :

user data set when the signal handler was connected.

The "device-removed" signal

void                user_function                      (GdkDeviceManager *device_manager,
                                                        GdkDevice        *device,
                                                        gpointer          user_data)           : Run Last

The ::device-removed signal is emitted either when a master pointer is removed, or when a slave (Hardware) input device is unplugged.

device_manager :

the object on which the signal is emitted

device :

the just removed GdkDevice.

user_data :

user data set when the signal handler was connected.

See Also

GdkDevice, GdkEvent