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. 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

[1] 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 GDK_GRAB_BROKEN