GDK 3 Reference Manual: GdkDeviceManager

## 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. Such input devices often have additional features, such as sub-pixel positioning information and additional device-dependent information.

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.

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()`. There should rarely be a need to do that though, since GDK defaults to a compatibility mode in which it will emit just one enter/leave event pair for all devices on a window. To enable per-device enter/leave events and other multi-pointer interaction features, `gdk_window_set_support_multidevice()` must be called on GdkWindows (or `gtk_widget_set_support_multidevice()` on widgets). window. See the `gdk_window_set_support_multidevice()` documentation for more information.

On X11, multi-device support is implemented through XInput 2. Unless `gdk_disable_multidevice()` is called, the XInput 2 GdkDeviceManager implementation will be used as the input source. Otherwise either the core or XInput 1 implementations will be used.

For simple applications that don't have any special interest in input devices, the so-called client pointer provides a reasonable approximation to a simple setup with a single pointer and keyboard. The device that has been set as the client pointer can be accessed via `gdk_device_manager_get_client_pointer()`.

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.

Example 3. Master and slave devices

    carlossacarino:~$ xinput list
    ⎡ Virtual core pointer                          id=2    [master pointer  (3)]
    ⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
    ⎜   ↳ Wacom ISDv4 E6 Pen stylus                 id=10   [slave  pointer  (2)]
    ⎜   ↳ Wacom ISDv4 E6 Finger touch               id=11   [slave  pointer  (2)]
    ⎜   ↳ SynPS/2 Synaptics TouchPad                id=13   [slave  pointer  (2)]
    ⎜   ↳ TPPS/2 IBM TrackPoint                     id=14   [slave  pointer  (2)]
    ⎜   ↳ Wacom ISDv4 E6 Pen eraser                 id=16   [slave  pointer  (2)]
    ⎣ Virtual core keyboard                         id=3    [master keyboard (2)]
        ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]
        ↳ Power Button                              id=6    [slave  keyboard (3)]
        ↳ Video Bus                                 id=7    [slave  keyboard (3)]
        ↳ Sleep Button                              id=8    [slave  keyboard (3)]
        ↳ Integrated Camera                         id=9    [slave  keyboard (3)]
        ↳ AT Translated Set 2 keyboard              id=12   [slave  keyboard (3)]
        ↳ ThinkPad Extra Buttons                    id=15   [slave  keyboard (3)]

By default, GDK will automatically listen for events coming from all master devices, setting the GdkDevice for all events coming from input devices. Events containing device information are GDK_MOTION_NOTIFY, GDK_BUTTON_PRESS, GDK_2BUTTON_PRESS, GDK_3BUTTON_PRESS, GDK_BUTTON_RELEASE, GDK_SCROLL, GDK_KEY_PRESS, GDK_KEY_RELEASE, GDK_ENTER_NOTIFY, GDK_LEAVE_NOTIFY, GDK_FOCUS_CHANGE, GDK_PROXIMITY_IN, GDK_PROXIMITY_OUT, GDK_DRAG_ENTER, GDK_DRAG_LEAVE, GDK_DRAG_MOTION, GDK_DRAG_STATUS, GDK_DROP_START, GDK_DROP_FINISHED and GDK_GRAB_BROKEN. When dealing with an event on a master device, it is possible to get the source (slave) device that the event originated from via `gdk_event_get_source_device()`.

In order to listen for events coming from devices 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()`.

## 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 seldomly, 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