Touch Support

SDL offers touch input, on platforms that support it. More...

Collaboration diagram for Touch Support:

Classes
struct	SDL::Finger
	Data about a single finger in a multitouch event. More...

Typedefs
using	SDL::FingerRaw = SDL_Finger
	Alias to raw representation for Finger.
using	SDL::TouchID = SDL_TouchID
	A unique ID for a touch device. More...
using	SDL::FingerID = SDL_FingerID
	A unique ID for a single finger on a touch device. More...
using	SDL::TouchDeviceType = SDL_TouchDeviceType
	An enum that describes the type of a touch device. More...

Functions
OwnArray< TouchID >	SDL::GetTouchDevices ()
	Get a list of registered touch devices. More...
const char *	SDL::GetTouchDeviceName (TouchID touchID)
	Get the touch device name as reported from the driver. More...
TouchDeviceType	SDL::GetTouchDeviceType (TouchID touchID)
	Get the type of the given touch device. More...
OwnArray< Finger * >	SDL::GetTouchFingers (TouchID touchID)
	Get a list of active fingers for a given touch device. More...

Variables
constexpr TouchDeviceType	SDL::TOUCH_DEVICE_INVALID
	TOUCH_DEVICE_INVALID. More...
constexpr TouchDeviceType	SDL::TOUCH_DEVICE_DIRECT
	touch screen with window-relative coordinates More...
constexpr TouchDeviceType	SDL::TOUCH_DEVICE_INDIRECT_ABSOLUTE
	trackpad with absolute device coordinates More...
constexpr TouchDeviceType	SDL::TOUCH_DEVICE_INDIRECT_RELATIVE
	trackpad with screen cursor-relative coordinates More...
constexpr MouseID	SDL::TOUCH_MOUSEID = SDL_TOUCH_MOUSEID
	The MouseID for mouse events simulated with touch input. More...
constexpr TouchID	SDL::MOUSE_TOUCHID = SDL_MOUSE_TOUCHID
	The TouchID for touch events simulated with mouse input. More...

Detailed Description

It can manage multiple touch devices and track multiple fingers on those devices.

Touches are mostly dealt with through the event system, in the EVENT_FINGER_DOWN, EVENT_FINGER_MOTION, and EVENT_FINGER_UP events, but there are also functions to query for hardware details, etc.

The touch system, by default, will also send virtual mouse events; this can be useful for making a some desktop apps work on a phone without significant changes. For apps that care about mouse and touch input separately, they should ignore mouse events that have a which field of TOUCH_MOUSEID.

Typedef Documentation

FingerID

using SDL::FingerID = typedef SDL_FingerID

This ID is valid for the time the finger (stylus, etc) is touching and will be unique for all fingers currently in contact, so this ID tracks the lifetime of a single continuous touch. This value may represent an index, a pointer, or some other unique ID, depending on the platform.

The value 0 is an invalid ID.

Since

This datatype is available since SDL 3.2.0.

TouchDeviceType

using SDL::TouchDeviceType = typedef SDL_TouchDeviceType

Since

This enum is available since SDL 3.2.0.

TouchID

using SDL::TouchID = typedef SDL_TouchID

This ID is valid for the time the device is connected to the system, and is never reused for the lifetime of the application.

The value 0 is an invalid ID.

Since

This datatype is available since SDL 3.2.0.

Function Documentation

GetTouchDeviceName()

const char * SDL::GetTouchDeviceName ( TouchID  touchID )

inline

Parameters

touchID

the touch device instance ID.

Returns

touch device name, or nullptr on failure; call GetError() for more information.

Since

This function is available since SDL 3.2.0.

GetTouchDevices()

OwnArray< TouchID > SDL::GetTouchDevices ( )

inline

On some platforms SDL first sees the touch device if it was actually used. Therefore the returned list might be empty, although devices are available. After using all devices at least once the number will be correct.

Returns

a 0 terminated array of touch device IDs or nullptr on failure; call GetError() for more information.

Since

This function is available since SDL 3.2.0.

GetTouchDeviceType()

TouchDeviceType SDL::GetTouchDeviceType ( TouchID  touchID )

inline

Parameters

touchID

the ID of a touch device.

Returns

touch device type.

Since

This function is available since SDL 3.2.0.

GetTouchFingers()

OwnArray< Finger * > SDL::GetTouchFingers ( TouchID  touchID )

inline

Parameters

touchID

the ID of a touch device.

Returns

a nullptr terminated array of Finger pointers or nullptr on failure; call GetError() for more information.

Since

This function is available since SDL 3.2.0.

Variable Documentation

MOUSE_TOUCHID

constexpr TouchID SDL::MOUSE_TOUCHID = SDL_MOUSE_TOUCHID

constexpr

Since

This macro is available since SDL 3.2.0.

TOUCH_DEVICE_DIRECT

constexpr TouchDeviceType SDL::TOUCH_DEVICE_DIRECT

constexpr

Initial value:

=
  SDL_TOUCH_DEVICE_DIRECT

TOUCH_DEVICE_INDIRECT_ABSOLUTE

constexpr TouchDeviceType SDL::TOUCH_DEVICE_INDIRECT_ABSOLUTE

constexpr

Initial value:

=
  SDL_TOUCH_DEVICE_INDIRECT_ABSOLUTE

TOUCH_DEVICE_INDIRECT_RELATIVE

constexpr TouchDeviceType SDL::TOUCH_DEVICE_INDIRECT_RELATIVE

constexpr

Initial value:

=
  SDL_TOUCH_DEVICE_INDIRECT_RELATIVE

TOUCH_DEVICE_INVALID

constexpr TouchDeviceType SDL::TOUCH_DEVICE_INVALID

constexpr

Initial value:

=
  SDL_TOUCH_DEVICE_INVALID

TOUCH_MOUSEID

constexpr MouseID SDL::TOUCH_MOUSEID = SDL_TOUCH_MOUSEID

constexpr

Since

This macro is available since SDL 3.2.0.