GLFW

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Input guide

This guide introduces the input related functions of GLFW. For details on a specific function in this category, see the Input reference. There are also guides for the other areas of GLFW.

- Introduction to the API
- Window guide
- Context guide
- Vulkan guide
- Monitor guide

GLFW provides many kinds of input. While some can only be polled, like time, or only received via callbacks, like scrolling, many provide both callbacks and polling. Callbacks are more work to use than polling but is less CPU intensive and guarantees that you do not miss state changes.

All input callbacks receive a window handle. By using the window user pointer, you can access non-global structures or objects from your callbacks.

To get a better feel for how the various events callbacks behave, run the `events` test program. It register every callback supported by GLFW and prints out all arguments provided for every event, along with time and sequence information.

# Event processing

GLFW needs to poll the window system for events both to provide input to the application and to prove to the window system that the application hasn't locked up. Event processing is normally done each frame after buffer swapping. Even when you have no windows, event polling needs to be done in order to receive monitor and joystick connection events.

There are three functions for processing pending events. glfwPollEvents, processes only those events that have already been received and then returns immediately.

glfwPollEvents();
glfwPollEvents
void glfwPollEvents(void)
Processes all pending events.

This is the best choice when rendering continuously, like most games do.

If you only need to update the contents of the window when you receive new input, glfwWaitEvents is a better choice.

glfwWaitEvents();
glfwWaitEvents
void glfwWaitEvents(void)
Waits until events are queued and processes them.

It puts the thread to sleep until at least one event has been received and then processes all received events. This saves a great deal of CPU cycles and is useful for, for example, editing tools.

If you want to wait for events but have UI elements or other tasks that need periodic updates, glfwWaitEventsTimeout lets you specify a timeout.

glfwWaitEventsTimeout(0.7);
glfwWaitEventsTimeout
void glfwWaitEventsTimeout(double timeout)
Waits with timeout until events are queued and processes them.

It puts the thread to sleep until at least one event has been received, or until the specified number of seconds have elapsed. It then processes any received events.

If the main thread is sleeping in glfwWaitEvents, you can wake it from another thread by posting an empty event to the event queue with glfwPostEmptyEvent.

glfwPostEmptyEvent();
glfwPostEmptyEvent
void glfwPostEmptyEvent(void)
Posts an empty event to the event queue.

Do not assume that callbacks will only be called in response to the above functions. While it is necessary to process events in one or more of the ways above, window systems that require GLFW to register callbacks of its own can pass events to GLFW in response to many window system function calls. GLFW will pass those events on to the application callbacks before returning.

For example, on Windows the system function that glfwSetWindowSize is implemented with will send window size events directly to the event callback that every window has and that GLFW implements for its windows. If you have set a window size callback GLFW will call it in turn with the new size before everything returns back out of the glfwSetWindowSize call.

# Keyboard input

GLFW divides keyboard input into two categories; key events and character events. Key events relate to actual physical keyboard keys, whereas character events relate to the Unicode code points generated by pressing some of them.

Keys and characters do not map 1:1. A single key press may produce several characters, and a single character may require several keys to produce. This may not be the case on your machine, but your users are likely not all using the same keyboard layout, input method or even operating system as you.

## Key input

If you wish to be notified when a physical key is pressed or released or when it repeats, set a key callback.

glfwSetKeyCallback(window, key_callback);
glfwSetKeyCallback
GLFWkeyfun glfwSetKeyCallback(GLFWwindow *window, GLFWkeyfun callback)
Sets the key callback.

The callback function receives the keyboard key, platform-specific scancode, key action and modifier bits.

void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (key == GLFW_KEY_E && action == GLFW_PRESS)
activate_airship();
}
GLFW_PRESS
#define GLFW_PRESS
The key or mouse button was pressed.
Definition: glfw3.h:339
GLFW_KEY_E
#define GLFW_KEY_E
Definition: glfw3.h:417
GLFWwindow
struct GLFWwindow GLFWwindow
Opaque window object.
Definition: glfw3.h:1186

The action is one of `GLFW_PRESS`, `GLFW_REPEAT` or `GLFW_RELEASE`. The key will be `GLFW_KEY_UNKNOWN` if GLFW lacks a key token for it, for example E-mail and Play keys.

The scancode is unique for every key, regardless of whether it has a key token. Scancodes are platform-specific but consistent over time, so keys will have different scancodes depending on the platform but they are safe to save to disk. You can query the scancode for any named key on the current platform with glfwGetKeyScancode.

const int scancode = glfwGetKeyScancode(GLFW_KEY_X);
set_key_mapping(scancode, swap_weapons);
glfwGetKeyScancode
int glfwGetKeyScancode(int key)
Returns the platform-specific scancode of the specified key.
GLFW_KEY_X
#define GLFW_KEY_X
Definition: glfw3.h:436

The last reported state for every named key is also saved in per-window state arrays that can be polled with glfwGetKey.

int state = glfwGetKey(window, GLFW_KEY_E);
if (state == GLFW_PRESS)
{
activate_airship();
}
glfwGetKey
int glfwGetKey(GLFWwindow *window, int key)
Returns the last reported state of a keyboard key for the specified window.

The returned state is one of `GLFW_PRESS` or `GLFW_RELEASE`.

This function only returns cached key event state. It does not poll the system for the current physical state of the key.

Whenever you poll state, you risk missing the state change you are looking for. If a pressed key is released again before you poll its state, you will have missed the key press. The recommended solution for this is to use a key callback, but there is also the `GLFW_STICKY_KEYS` input mode.

glfwSetInputMode(window, GLFW_STICKY_KEYS, GLFW_TRUE);
GLFW_STICKY_KEYS
#define GLFW_STICKY_KEYS
Definition: glfw3.h:1050
GLFW_TRUE
#define GLFW_TRUE
One.
Definition: glfw3.h:313
glfwSetInputMode
void glfwSetInputMode(GLFWwindow *window, int mode, int value)
Sets an input option for the specified window.

When sticky keys mode is enabled, the pollable state of a key will remain `GLFW_PRESS` until the state of that key is polled with glfwGetKey. Once it has been polled, if a key release event had been processed in the meantime, the state will reset to `GLFW_RELEASE`, otherwise it will remain `GLFW_PRESS`.

If you wish to know what the state of the Caps Lock and Num Lock keys was when input events were generated, set the `GLFW_LOCK_KEY_MODS` input mode.

glfwSetInputMode(window, GLFW_LOCK_KEY_MODS, GLFW_TRUE);
GLFW_LOCK_KEY_MODS
#define GLFW_LOCK_KEY_MODS
Definition: glfw3.h:1052

When this input mode is enabled, any callback that receives modifier bits will have the GLFW_MOD_CAPS_LOCK bit set if Caps Lock was on when the event occurred and the GLFW_MOD_NUM_LOCK bit set if Num Lock was on.

The `GLFW_KEY_LAST` constant holds the highest value of any named key.

## Text input

GLFW supports text input in the form of a stream of Unicode code points, as produced by the operating system text input system. Unlike key input, text input obeys keyboard layouts and modifier keys and supports composing characters using dead keys. Once received, you can encode the code points into UTF-8 or any other encoding you prefer.

Because an `unsigned int` is 32 bits long on all platforms supported by GLFW, you can treat the code point argument as native endian UTF-32.

If you wish to offer regular text input, set a character callback.

glfwSetCharCallback(window, character_callback);
glfwSetCharCallback
GLFWcharfun glfwSetCharCallback(GLFWwindow *window, GLFWcharfun callback)
Sets the Unicode character callback.

The callback function receives Unicode code points for key events that would have led to regular text input and generally behaves as a standard text field on that platform.

void character_callback(GLFWwindow* window, unsigned int codepoint)
{
}

## Key names

If you wish to refer to keys by name, you can query the keyboard layout dependent name of printable keys with glfwGetKeyName.

const char* key_name = glfwGetKeyName(GLFW_KEY_W, 0);
show_tutorial_hint("Press %s to move forward", key_name);
glfwGetKeyName
const char * glfwGetKeyName(int key, int scancode)
Returns the layout-specific name of the specified printable key.
GLFW_KEY_W
#define GLFW_KEY_W
Definition: glfw3.h:435

This function can handle both keys and scancodes. If the specified key is `GLFW_KEY_UNKNOWN` then the scancode is used, otherwise it is ignored. This matches the behavior of the key callback, meaning the callback arguments can always be passed unmodified to this function.

# Mouse input

Mouse input comes in many forms, including mouse motion, button presses and scrolling offsets. The cursor appearance can also be changed, either to a custom image or a standard cursor shape from the system theme.

## Cursor position

If you wish to be notified when the cursor moves over the window, set a cursor position callback.

glfwSetCursorPosCallback(window, cursor_position_callback);
glfwSetCursorPosCallback
GLFWcursorposfun glfwSetCursorPosCallback(GLFWwindow *window, GLFWcursorposfun callback)
Sets the cursor position callback.

The callback functions receives the cursor position, measured in screen coordinates but relative to the top-left corner of the window content area. On platforms that provide it, the full sub-pixel cursor position is passed on.

static void cursor_position_callback(GLFWwindow* window, double xpos, double ypos)
{
}

The cursor position is also saved per-window and can be polled with glfwGetCursorPos.

double xpos, ypos;
glfwGetCursorPos(window, &xpos, &ypos);
glfwGetCursorPos
void glfwGetCursorPos(GLFWwindow *window, double *xpos, double *ypos)
Retrieves the position of the cursor relative to the content area of the window.

## Cursor mode

The `GLFW_CURSOR` input mode provides several cursor modes for special forms of mouse motion input. By default, the cursor mode is `GLFW_CURSOR_NORMAL`, meaning the regular arrow cursor (or another cursor set with glfwSetCursor) is used and cursor motion is not limited.

If you wish to implement mouse motion based camera controls or other input schemes that require unlimited mouse movement, set the cursor mode to `GLFW_CURSOR_DISABLED`.

glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
GLFW_CURSOR_DISABLED
#define GLFW_CURSOR_DISABLED
Definition: glfw3.h:1057
GLFW_CURSOR
#define GLFW_CURSOR
Definition: glfw3.h:1049

This will hide the cursor and lock it to the specified window. GLFW will then take care of all the details of cursor re-centering and offset calculation and providing the application with a virtual cursor position. This virtual position is provided normally via both the cursor position callback and through polling.

Note
  You should not implement your own version of this functionality using other features of GLFW. It is not supported and will not work as robustly as `GLFW_CURSOR_DISABLED`.

If you only wish the cursor to become hidden when it is over a window but still want it to behave normally, set the cursor mode to `GLFW_CURSOR_HIDDEN`.

glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN);
GLFW_CURSOR_HIDDEN
#define GLFW_CURSOR_HIDDEN
Definition: glfw3.h:1056

This mode puts no limit on the motion of the cursor.

To exit out of either of these special modes, restore the `GLFW_CURSOR_NORMAL` cursor mode.

glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
GLFW_CURSOR_NORMAL
#define GLFW_CURSOR_NORMAL
Definition: glfw3.h:1055

## Raw mouse motion

When the cursor is disabled, raw (unscaled and unaccelerated) mouse motion can be enabled if available.

Raw mouse motion is closer to the actual motion of the mouse across a surface. It is not affected by the scaling and acceleration applied to the motion of the desktop cursor. That processing is suitable for a cursor while raw motion is better for controlling for example a 3D camera. Because of this, raw mouse motion is only provided when the cursor is disabled.

Call glfwRawMouseMotionSupported to check if the current machine provides raw motion and set the `GLFW_RAW_MOUSE_MOTION` input mode to enable it. It is disabled by default.

if (glfwRawMouseMotionSupported())
glfwSetInputMode(window, GLFW_RAW_MOUSE_MOTION, GLFW_TRUE);
GLFW_RAW_MOUSE_MOTION
#define GLFW_RAW_MOUSE_MOTION
Definition: glfw3.h:1053
glfwRawMouseMotionSupported
int glfwRawMouseMotionSupported(void)
Returns whether raw mouse motion is supported.

If supported, raw mouse motion can be enabled or disabled per-window and at any time but it will only be provided when the cursor is disabled.

## Cursor objects

GLFW supports creating both custom and system theme cursor images, encapsulated as GLFWcursor objects. They are created with glfwCreateCursor or glfwCreateStandardCursor and destroyed with glfwDestroyCursor, or glfwTerminate, if any remain.

### Custom cursor creation

A custom cursor is created with glfwCreateCursor, which returns a handle to the created cursor object. For example, this creates a 16x16 white square cursor with the hot-spot in the upper-left corner:

unsigned char pixels[16 * 16 * 4];
memset(pixels, 0xff, sizeof(pixels));
GLFWimage image;
image.width = 16;
image.height = 16;
image.pixels = pixels;
GLFWcursor* cursor = glfwCreateCursor(&image, 0, 0);
glfwCreateCursor
GLFWcursor * glfwCreateCursor(const GLFWimage *image, int xhot, int yhot)
Creates a custom cursor.
GLFWcursor
struct GLFWcursor GLFWcursor
Opaque cursor object.
Definition: glfw3.h:1198
GLFWimage
Image data.
Definition: glfw3.h:1722
GLFWimage::height
int height
Definition: glfw3.h:1728
GLFWimage::pixels
unsigned char * pixels
Definition: glfw3.h:1731
GLFWimage::width
int width
Definition: glfw3.h:1725

If cursor creation fails, `NULL` will be returned, so it is necessary to check the return value.

The image data is 32-bit, little-endian, non-premultiplied RGBA, i.e. eight bits per channel with the red channel first. The pixels are arranged canonically as sequential rows, starting from the top-left corner.

### Standard cursor creation

A cursor with a standard shape from the current system cursor theme can be can be created with glfwCreateStandardCursor.

GLFWcursor* cursor = glfwCreateStandardCursor(GLFW_HRESIZE_CURSOR);
glfwCreateStandardCursor
GLFWcursor * glfwCreateStandardCursor(int shape)
Creates a cursor with a standard shape.
GLFW_HRESIZE_CURSOR
#define GLFW_HRESIZE_CURSOR
The horizontal resize arrow shape.
Definition: glfw3.h:1099

These cursor objects behave in the exact same way as those created with glfwCreateCursor except that the system cursor theme provides the actual image.

### Cursor destruction

When a cursor is no longer needed, destroy it with glfwDestroyCursor.

glfwDestroyCursor(cursor);
glfwDestroyCursor
void glfwDestroyCursor(GLFWcursor *cursor)
Destroys a cursor.

Cursor destruction always succeeds. If the cursor is current for any window, that window will revert to the default cursor. This does not affect the cursor mode. All remaining cursors are destroyed when glfwTerminate is called.

### Cursor setting

A cursor can be set as current for a window with glfwSetCursor.

glfwSetCursor(window, cursor);
glfwSetCursor
void glfwSetCursor(GLFWwindow *window, GLFWcursor *cursor)
Sets the cursor for the window.

Once set, the cursor image will be used as long as the system cursor is over the content area of the window and the cursor mode is set to `GLFW_CURSOR_NORMAL`.

A single cursor may be set for any number of windows.

To revert to the default cursor, set the cursor of that window to `NULL`.

glfwSetCursor(window, NULL);

When a cursor is destroyed, any window that has it set will revert to the default cursor. This does not affect the cursor mode.

## Cursor enter/leave events

If you wish to be notified when the cursor enters or leaves the content area of a window, set a cursor enter/leave callback.

glfwSetCursorEnterCallback(window, cursor_enter_callback);
glfwSetCursorEnterCallback
GLFWcursorenterfun glfwSetCursorEnterCallback(GLFWwindow *window, GLFWcursorenterfun callback)
Sets the cursor enter/leave callback.

The callback function receives the new classification of the cursor.

void cursor_enter_callback(GLFWwindow* window, int entered)
{
if (entered)
{
// The cursor entered the content area of the window
}
else
{
// The cursor left the content area of the window
}
}

You can query whether the cursor is currently inside the content area of the window with the GLFW_HOVERED window attribute.

if (glfwGetWindowAttrib(window, GLFW_HOVERED))
{
highlight_interface();
}
GLFW_HOVERED
#define GLFW_HOVERED
Mouse cursor hover window attribute.
Definition: glfw3.h:856
glfwGetWindowAttrib
int glfwGetWindowAttrib(GLFWwindow *window, int attrib)
Returns an attribute of the specified window.

## Mouse button input

If you wish to be notified when a mouse button is pressed or released, set a mouse button callback.

glfwSetMouseButtonCallback(window, mouse_button_callback);
glfwSetMouseButtonCallback
GLFWmousebuttonfun glfwSetMouseButtonCallback(GLFWwindow *window, GLFWmousebuttonfun callback)
Sets the mouse button callback.

The callback function receives the mouse button, button action and modifier bits.

void mouse_button_callback(GLFWwindow* window, int button, int action, int mods)
{
if (button == GLFW_MOUSE_BUTTON_RIGHT && action == GLFW_PRESS)
popup_menu();
}
GLFW_MOUSE_BUTTON_RIGHT
#define GLFW_MOUSE_BUTTON_RIGHT
Definition: glfw3.h:582

The action is one of `GLFW_PRESS` or `GLFW_RELEASE`.

Mouse button states for named buttons are also saved in per-window state arrays that can be polled with glfwGetMouseButton.

int state = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT);
if (state == GLFW_PRESS)
{
upgrade_cow();
}
GLFW_MOUSE_BUTTON_LEFT
#define GLFW_MOUSE_BUTTON_LEFT
Definition: glfw3.h:581
glfwGetMouseButton
int glfwGetMouseButton(GLFWwindow *window, int button)
Returns the last reported state of a mouse button for the specified window.

The returned state is one of `GLFW_PRESS` or `GLFW_RELEASE`.

This function only returns cached mouse button event state. It does not poll the system for the current state of the mouse button.

Whenever you poll state, you risk missing the state change you are looking for. If a pressed mouse button is released again before you poll its state, you will have missed the button press. The recommended solution for this is to use a mouse button callback, but there is also the `GLFW_STICKY_MOUSE_BUTTONS` input mode.

glfwSetInputMode(window, GLFW_STICKY_MOUSE_BUTTONS, GLFW_TRUE);
GLFW_STICKY_MOUSE_BUTTONS
#define GLFW_STICKY_MOUSE_BUTTONS
Definition: glfw3.h:1051

When sticky mouse buttons mode is enabled, the pollable state of a mouse button will remain `GLFW_PRESS` until the state of that button is polled with glfwGetMouseButton. Once it has been polled, if a mouse button release event had been processed in the meantime, the state will reset to `GLFW_RELEASE`, otherwise it will remain `GLFW_PRESS`.

The `GLFW_MOUSE_BUTTON_LAST` constant holds the highest value of any named button.

## Scroll input

If you wish to be notified when the user scrolls, whether with a mouse wheel or touchpad gesture, set a scroll callback.

glfwSetScrollCallback(window, scroll_callback);
glfwSetScrollCallback
GLFWscrollfun glfwSetScrollCallback(GLFWwindow *window, GLFWscrollfun callback)
Sets the scroll callback.

The callback function receives two-dimensional scroll offsets.

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
}

A normal mouse wheel, being vertical, provides offsets along the Y-axis.

# Joystick input

The joystick functions expose connected joysticks and controllers, with both referred to as joysticks. It supports up to sixteen joysticks, ranging from `GLFW_JOYSTICK_1`, `GLFW_JOYSTICK_2` up to and including `GLFW_JOYSTICK_16` or `GLFW_JOYSTICK_LAST`. You can test whether a joystick is present with glfwJoystickPresent.

int present = glfwJoystickPresent(GLFW_JOYSTICK_1);
glfwJoystickPresent
int glfwJoystickPresent(int jid)
Returns whether the specified joystick is present.
GLFW_JOYSTICK_1
#define GLFW_JOYSTICK_1
Definition: glfw3.h:593

Each joystick has zero or more axes, zero or more buttons, zero or more hats, a human-readable name, a user pointer and an SDL compatible GUID.

When GLFW is initialized, detected joysticks are added to the beginning of the array. Once a joystick is detected, it keeps its assigned ID until it is disconnected or the library is terminated, so as joysticks are connected and disconnected, there may appear gaps in the IDs.

Joystick axis, button and hat state is updated when polled and does not require a window to be created or events to be processed. However, if you want joystick connection and disconnection events reliably delivered to the joystick callback then you must process events.

To see all the properties of all connected joysticks in real-time, run the `joysticks` test program.

## Joystick axis states

The positions of all axes of a joystick are returned by glfwGetJoystickAxes. See the reference documentation for the lifetime of the returned array.

int count;
const float* axes = glfwGetJoystickAxes(GLFW_JOYSTICK_5, &count);
glfwGetJoystickAxes
const float * glfwGetJoystickAxes(int jid, int *count)
Returns the values of all axes of the specified joystick.
GLFW_JOYSTICK_5
#define GLFW_JOYSTICK_5
Definition: glfw3.h:597

Each element in the returned array is a value between -1.0 and 1.0.

## Joystick button states

The states of all buttons of a joystick are returned by glfwGetJoystickButtons. See the reference documentation for the lifetime of the returned array.

int count;
const unsigned char* buttons = glfwGetJoystickButtons(GLFW_JOYSTICK_3, &count);
glfwGetJoystickButtons
const unsigned char * glfwGetJoystickButtons(int jid, int *count)
Returns the state of all buttons of the specified joystick.
GLFW_JOYSTICK_3
#define GLFW_JOYSTICK_3
Definition: glfw3.h:595

Each element in the returned array is either `GLFW_PRESS` or `GLFW_RELEASE`.

For backward compatibility with earlier versions that did not have glfwGetJoystickHats, the button array by default also includes all hats. See the reference documentation for glfwGetJoystickButtons for details.

## Joystick hat states

The states of all hats are returned by glfwGetJoystickHats. See the reference documentation for the lifetime of the returned array.

int count;
const unsigned char* hats = glfwGetJoystickHats(GLFW_JOYSTICK_7, &count);
glfwGetJoystickHats
const unsigned char * glfwGetJoystickHats(int jid, int *count)
Returns the state of all hats of the specified joystick.
GLFW_JOYSTICK_7
#define GLFW_JOYSTICK_7
Definition: glfw3.h:599

Each element in the returned array is one of the following:

Name | Value
--- | ---
`GLFW_HAT_CENTERED` | 0
`GLFW_HAT_UP` | 1
`GLFW_HAT_RIGHT` | 2
`GLFW_HAT_DOWN` | 4
`GLFW_HAT_LEFT` | 8
`GLFW_HAT_RIGHT_UP` | `GLFW_HAT_RIGHT` | `GLFW_HAT_UP`
`GLFW_HAT_RIGHT_DOWN` | `GLFW_HAT_RIGHT` | `GLFW_HAT_DOWN`
`GLFW_HAT_LEFT_UP` | `GLFW_HAT_LEFT` | `GLFW_HAT_UP`
`GLFW_HAT_LEFT_DOWN` | `GLFW_HAT_LEFT` | `GLFW_HAT_DOWN`

The diagonal directions are bitwise combinations of the primary (up, right, down and left) directions and you can test for these individually by ANDing it with the corresponding direction.

if (hats[2] & GLFW_HAT_RIGHT)
{
// State of hat 2 could be right-up, right or right-down
}
GLFW_HAT_RIGHT
#define GLFW_HAT_RIGHT
Definition: glfw3.h:358

For backward compatibility with earlier versions that did not have glfwGetJoystickHats, all hats are by default also included in the button array. See the reference documentation for glfwGetJoystickButtons for details.

## Joystick name

The human-readable, UTF-8 encoded name of a joystick is returned by glfwGetJoystickName. See the reference documentation for the lifetime of the returned string.

const char* name = glfwGetJoystickName(GLFW_JOYSTICK_4);
glfwGetJoystickName
const char * glfwGetJoystickName(int jid)
Returns the name of the specified joystick.
GLFW_JOYSTICK_4
#define GLFW_JOYSTICK_4
Definition: glfw3.h:596

Joystick names are not guaranteed to be unique. Two joysticks of the same model and make may have the same name. Only the joystick ID is guaranteed to be unique, and only until that joystick is disconnected.

## Joystick user pointer

Each joystick has a user pointer that can be set with glfwSetJoystickUserPointer and queried with glfwGetJoystickUserPointer. This can be used for any purpose you need and will not be modified by GLFW. The value will be kept until the joystick is disconnected or until the library is terminated.

The initial value of the pointer is `NULL`.

## Joystick configuration changes

If you wish to be notified when a joystick is connected or disconnected, set a joystick callback.

glfwSetJoystickCallback(joystick_callback);
glfwSetJoystickCallback
GLFWjoystickfun glfwSetJoystickCallback(GLFWjoystickfun callback)
Sets the joystick configuration callback.

The callback function receives the ID of the joystick that has been connected and disconnected and the event that occurred.

void joystick_callback(int jid, int event)
{
if (event == GLFW_CONNECTED)
{
// The joystick was connected
}
else if (event == GLFW_DISCONNECTED)
{
// The joystick was disconnected
}
}
GLFW_DISCONNECTED
#define GLFW_DISCONNECTED
Definition: glfw3.h:1108
GLFW_CONNECTED
#define GLFW_CONNECTED
Definition: glfw3.h:1107

For joystick connection and disconnection events to be delivered on all platforms, you need to call one of the event processing functions. Joystick disconnection may also be detected and the callback called by joystick functions. The function will then return whatever it returns for a disconnected joystick.

Only glfwGetJoystickName and glfwGetJoystickUserPointer will return useful values for a disconnected joystick and only before the monitor callback returns.

## Gamepad input

The joystick functions provide unlabeled axes, buttons and hats, with no indication of where they are located on the device. Their order may also vary between platforms even with the same device.

To solve this problem the SDL community crowdsourced the SDL_GameControllerDB project, a database of mappings from many different devices to an Xbox-like gamepad.

GLFW supports this mapping format and contains a copy of the mappings available at the time of release. See Gamepad mappings for how to update this at runtime. Mappings will be assigned to joysticks automatically any time a joystick is connected or the mappings are updated.

You can check whether a joystick is both present and has a gamepad mapping with glfwJoystickIsGamepad.

if (glfwJoystickIsGamepad(GLFW_JOYSTICK_2))
{
// Use as gamepad
}
glfwJoystickIsGamepad
int glfwJoystickIsGamepad(int jid)
Returns whether the specified joystick has a gamepad mapping.
GLFW_JOYSTICK_2
#define GLFW_JOYSTICK_2
Definition: glfw3.h:594

If you are only interested in gamepad input you can use this function instead of glfwJoystickPresent.

You can query the human-readable name provided by the gamepad mapping with glfwGetGamepadName. This may or may not be the same as the joystick name.

const char* name = glfwGetGamepadName(GLFW_JOYSTICK_7);
glfwGetGamepadName
const char * glfwGetGamepadName(int jid)
Returns the human-readable gamepad name for the specified joystick.

To retrieve the gamepad state of a joystick, call glfwGetGamepadState.

GLFWgamepadstate state;
if (glfwGetGamepadState(GLFW_JOYSTICK_3, &state))
{
if (state.buttons[GLFW_GAMEPAD_BUTTON_A])
{
input_jump();
}
input_speed(state.axes[GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER]);
}
GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER
#define GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER
Definition: glfw3.h:654
GLFW_GAMEPAD_BUTTON_A
#define GLFW_GAMEPAD_BUTTON_A
Definition: glfw3.h:619
glfwGetGamepadState
int glfwGetGamepadState(int jid, GLFWgamepadstate *state)
Retrieves the state of the specified joystick remapped as a gamepad.
GLFWgamepadstate
Gamepad input state.
Definition: glfw3.h:1746
GLFWgamepadstate::buttons
unsigned char buttons[15]
Definition: glfw3.h:1750
GLFWgamepadstate::axes
float axes[6]
Definition: glfw3.h:1754

The GLFWgamepadstate struct has two arrays; one for button states and one for axis states. The values for each button and axis are the same as for the glfwGetJoystickButtons and glfwGetJoystickAxes functions, i.e. `GLFW_PRESS` or `GLFW_RELEASE` for buttons and -1.0 to 1.0 inclusive for axes.

The sizes of the arrays and the positions within each array are fixed.

The button indices are `GLFW_GAMEPAD_BUTTON_A`, `GLFW_GAMEPAD_BUTTON_B`, `GLFW_GAMEPAD_BUTTON_X`, `GLFW_GAMEPAD_BUTTON_Y`, `GLFW_GAMEPAD_BUTTON_LEFT_BUMPER`, `GLFW_GAMEPAD_BUTTON_RIGHT_BUMPER`, `GLFW_GAMEPAD_BUTTON_BACK`, `GLFW_GAMEPAD_BUTTON_START`, `GLFW_GAMEPAD_BUTTON_GUIDE`, `GLFW_GAMEPAD_BUTTON_LEFT_THUMB`, `GLFW_GAMEPAD_BUTTON_RIGHT_THUMB`, `GLFW_GAMEPAD_BUTTON_DPAD_UP`, `GLFW_GAMEPAD_BUTTON_DPAD_RIGHT`, `GLFW_GAMEPAD_BUTTON_DPAD_DOWN` and `GLFW_GAMEPAD_BUTTON_DPAD_LEFT`.

For those who prefer, there are also the `GLFW_GAMEPAD_BUTTON_CROSS`, `GLFW_GAMEPAD_BUTTON_CIRCLE`, `GLFW_GAMEPAD_BUTTON_SQUARE` and `GLFW_GAMEPAD_BUTTON_TRIANGLE` aliases for the A, B, X and Y button indices.

The axis indices are `GLFW_GAMEPAD_AXIS_LEFT_X`, `GLFW_GAMEPAD_AXIS_LEFT_Y`, `GLFW_GAMEPAD_AXIS_RIGHT_X`, `GLFW_GAMEPAD_AXIS_RIGHT_Y`, `GLFW_GAMEPAD_AXIS_LEFT_TRIGGER` and `GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER`.

The `GLFW_GAMEPAD_BUTTON_LAST` and `GLFW_GAMEPAD_AXIS_LAST` constants equal the largest available index for each array.

## Gamepad mappings

GLFW contains a copy of the mappings available in SDL_GameControllerDB at the time of release. Newer ones can be added at runtime with glfwUpdateGamepadMappings.

const char* mappings = load_file_contents("game/data/gamecontrollerdb.txt");
glfwUpdateGamepadMappings(mappings);
glfwUpdateGamepadMappings
int glfwUpdateGamepadMappings(const char *string)
Adds the specified SDL_GameControllerDB gamepad mappings.

This function supports everything from single lines up to and including the unmodified contents of the whole `gamecontrollerdb.txt` file.

If you are compiling GLFW from source with CMake you can update the built-in mappings by building the update_mappings target. This runs the `GenerateMappings.cmake` CMake script, which downloads `gamecontrollerdb.txt` and regenerates the `mappings.h` header file.

Below is a description of the mapping format. Please keep in mind that this description is not authoritative. The format is defined by the SDL and SDL_GameControllerDB projects and their documentation and code takes precedence.

Each mapping is a single line of comma-separated values describing the GUID, name and layout of the gamepad. Lines that do not begin with a hexadecimal digit are ignored.

The first value is always the gamepad GUID, a 32 character long hexadecimal string that typically identifies its make, model, revision and the type of connection to the computer. When this information is not available, the GUID is generated using the gamepad name. GLFW uses the SDL 2.0.5+ GUID format but can convert from the older formats.

The second value is always the human-readable name of the gamepad.

All subsequent values are in the form `<field>:<value>` and describe the layout of the mapping. These fields may not all be present and may occur in any order.

The button fields are `a`, `b`, `c`, `d`, `back`, `start`, `guide`, `dpup`, `dpright`, `dpdown`, `dpleft`, `leftshoulder`, `rightshoulder`, `leftstick` and `rightstick`.

The axis fields are `leftx`, `lefty`, `rightx`, `righty`, `lefttrigger` and `righttrigger`.

The value of an axis or button field can be a joystick button, a joystick axis, a hat bitmask or empty. Joystick buttons are specified as `bN`, for example `b2` for the third button. Joystick axes are specified as `aN`, for example `a7` for the eighth button. Joystick hat bit masks are specified as `hN.N`, for example `h0.8` for left on the first hat. More than one bit may be set in the mask.

Before an axis there may be a `+` or `-` range modifier, for example `+a3` for the positive half of the fourth axis. This restricts input to only the positive or negative halves of the joystick axis. After an axis or half-axis there may be the `~` inversion modifier, for example `a2~` or `-a7~`. This negates the values of the gamepad axis.

The hat bit mask match the hat states in the joystick functions.

There is also the special `platform` field that specifies which platform the mapping is valid for. Possible values are `Windows`, `Mac OS X` and `Linux`.

Below is an example of what a gamepad mapping might look like. It is the one built into GLFW for Xbox controllers accessed via the XInput API on Windows. This example has been broken into several lines to fit on the page, but real gamepad mappings must be a single line.

78696e70757401000000000000000000,XInput Gamepad (GLFW),platform:Windows,a:b0,
b:b1,x:b2,y:b3,leftshoulder:b4,rightshoulder:b5,back:b6,start:b7,leftstick:b8,
rightstick:b9,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,
righttrigger:a5,dpup:h0.1,dpright:h0.2,dpdown:h0.4,dpleft:h0.8,

Note
  GLFW does not yet support the output range and modifiers `+` and `-` that were recently added to SDL. The input modifiers `+`, `-` and `~` are supported and described above.

# Time input

GLFW provides high-resolution time input, in seconds, with glfwGetTime.

double seconds = glfwGetTime();
glfwGetTime
double glfwGetTime(void)
Returns the GLFW time.

It returns the number of seconds since the library was initialized with glfwInit. The platform-specific time sources used typically have micro- or nanosecond resolution.

You can modify the base time with glfwSetTime.

glfwSetTime(4.0);
glfwSetTime
void glfwSetTime(double time)
Sets the GLFW time.

This sets the time to the specified time, in seconds, and it continues to count from there.

You can also access the raw timer used to implement the functions above, with glfwGetTimerValue.

uint64_t value = glfwGetTimerValue();
glfwGetTimerValue
uint64_t glfwGetTimerValue(void)
Returns the current value of the raw timer.

This value is in 1 / frequency seconds. The frequency of the raw timer varies depending on the operating system and hardware. You can query the frequency, in Hz, with glfwGetTimerFrequency.

uint64_t frequency = glfwGetTimerFrequency();
glfwGetTimerFrequency
uint64_t glfwGetTimerFrequency(void)
Returns the frequency, in Hz, of the raw timer.

# Clipboard input and output

If the system clipboard contains a UTF-8 encoded string or if it can be converted to one, you can retrieve it with glfwGetClipboardString. See the reference documentation for the lifetime of the returned string.

const char* text = glfwGetClipboardString(NULL);
if (text)
{
insert_text(text);
}
glfwGetClipboardString
const char * glfwGetClipboardString(GLFWwindow *window)
Returns the contents of the clipboard as a string.

If the clipboard is empty or if its contents could not be converted, `NULL` is returned.

The contents of the system clipboard can be set to a UTF-8 encoded string with glfwSetClipboardString.

glfwSetClipboardString(NULL, "A string with words in it");
glfwSetClipboardString
void glfwSetClipboardString(GLFWwindow *window, const char *string)
Sets the clipboard to the specified string.

# Path drop input

If you wish to receive the paths of files and/or directories dropped on a window, set a file drop callback.

glfwSetDropCallback(window, drop_callback);
glfwSetDropCallback
GLFWdropfun glfwSetDropCallback(GLFWwindow *window, GLFWdropfun callback)
Sets the path drop callback.

The callback function receives an array of paths encoded as UTF-8.

void drop_callback(GLFWwindow* window, int count, const char** paths)
{
int i;
for (i = 0; i < count; i++)
handle_dropped_file(paths[i]);
}

The path array and its strings are only valid until the file drop callback returns, as they may have been generated specifically for that event. You need to make a deep copy of the array if you want to keep the paths.