SDL  2.0
SDL_sensor.h
Go to the documentation of this file.
1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 
22 /**
23  * \file SDL_sensor.h
24  *
25  * Include file for SDL sensor event handling
26  *
27  */
28 
29 #ifndef SDL_sensor_h_
30 #define SDL_sensor_h_
31 
32 #include "SDL_stdinc.h"
33 #include "SDL_error.h"
34 
35 #include "begin_code.h"
36 /* Set up for C function definitions, even when using C++ */
37 #ifdef __cplusplus
38 /* *INDENT-OFF* */
39 extern "C" {
40 /* *INDENT-ON* */
41 #endif
42 
43 /**
44  * \brief SDL_sensor.h
45  *
46  * In order to use these functions, SDL_Init() must have been called
47  * with the ::SDL_INIT_SENSOR flag. This causes SDL to scan the system
48  * for sensors, and load appropriate drivers.
49  */
50 
51 struct _SDL_Sensor;
52 typedef struct _SDL_Sensor SDL_Sensor;
53 
54 /**
55  * This is a unique ID for a sensor for the time it is connected to the system,
56  * and is never reused for the lifetime of the application.
57  *
58  * The ID value starts at 0 and increments from there. The value -1 is an invalid ID.
59  */
61 
62 /* The different sensors defined by SDL
63  *
64  * Additional sensors may be available, using platform dependent semantics.
65  *
66  * Hare are the additional Android sensors:
67  * https://developer.android.com/reference/android/hardware/SensorEvent.html#values
68  */
69 typedef enum
70 {
71  SDL_SENSOR_INVALID = -1, /**< Returned for an invalid sensor */
72  SDL_SENSOR_UNKNOWN, /**< Unknown sensor type */
73  SDL_SENSOR_ACCEL, /**< Accelerometer */
74  SDL_SENSOR_GYRO /**< Gyroscope */
76 
77 /**
78  * Accelerometer sensor
79  *
80  * The accelerometer returns the current acceleration in SI meters per
81  * second squared. This measurement includes the force of gravity, so
82  * a device at rest will have an value of SDL_STANDARD_GRAVITY away
83  * from the center of the earth.
84  *
85  * values[0]: Acceleration on the x axis
86  * values[1]: Acceleration on the y axis
87  * values[2]: Acceleration on the z axis
88  *
89  * For phones held in portrait mode and game controllers held in front of you,
90  * the axes are defined as follows:
91  * -X ... +X : left ... right
92  * -Y ... +Y : bottom ... top
93  * -Z ... +Z : farther ... closer
94  *
95  * The axis data is not changed when the phone is rotated.
96  *
97  * \sa SDL_GetDisplayOrientation()
98  */
99 #define SDL_STANDARD_GRAVITY 9.80665f
100 
101 /**
102  * Gyroscope sensor
103  *
104  * The gyroscope returns the current rate of rotation in radians per second.
105  * The rotation is positive in the counter-clockwise direction. That is,
106  * an observer looking from a positive location on one of the axes would
107  * see positive rotation on that axis when it appeared to be rotating
108  * counter-clockwise.
109  *
110  * values[0]: Angular speed around the x axis (pitch)
111  * values[1]: Angular speed around the y axis (yaw)
112  * values[2]: Angular speed around the z axis (roll)
113  *
114  * For phones held in portrait mode and game controllers held in front of you,
115  * the axes are defined as follows:
116  * -X ... +X : left ... right
117  * -Y ... +Y : bottom ... top
118  * -Z ... +Z : farther ... closer
119  *
120  * The axis data is not changed when the phone or controller is rotated.
121  *
122  * \sa SDL_GetDisplayOrientation()
123  */
124 
125 /* Function prototypes */
126 
127 /**
128  * Locking for multi-threaded access to the sensor API
129  *
130  * If you are using the sensor API or handling events from multiple threads
131  * you should use these locking functions to protect access to the sensors.
132  *
133  * In particular, you are guaranteed that the sensor list won't change, so the
134  * API functions that take a sensor index will be valid, and sensor events
135  * will not be delivered.
136  *
137  * \since This function is available since SDL 2.0.14.
138  */
139 extern DECLSPEC void SDLCALL SDL_LockSensors(void);
140 extern DECLSPEC void SDLCALL SDL_UnlockSensors(void);
141 
142 /**
143  * Count the number of sensors attached to the system right now.
144  *
145  * \returns the number of sensors detected.
146  *
147  * \since This function is available since SDL 2.0.9.
148  */
149 extern DECLSPEC int SDLCALL SDL_NumSensors(void);
150 
151 /**
152  * Get the implementation dependent name of a sensor.
153  *
154  * \param device_index The sensor to obtain name from
155  * \returns the sensor name, or NULL if `device_index` is out of range.
156  *
157  * \since This function is available since SDL 2.0.9.
158  */
159 extern DECLSPEC const char *SDLCALL SDL_SensorGetDeviceName(int device_index);
160 
161 /**
162  * Get the type of a sensor.
163  *
164  * \param device_index The sensor to get the type from
165  * \returns the SDL_SensorType, or `SDL_SENSOR_INVALID` if `device_index` is
166  * out of range.
167  *
168  * \since This function is available since SDL 2.0.9.
169  */
170 extern DECLSPEC SDL_SensorType SDLCALL SDL_SensorGetDeviceType(int device_index);
171 
172 /**
173  * Get the platform dependent type of a sensor.
174  *
175  * \param device_index The sensor to check
176  * \returns the sensor platform dependent type, or -1 if `device_index` is out
177  * of range.
178  *
179  * \since This function is available since SDL 2.0.9.
180  */
181 extern DECLSPEC int SDLCALL SDL_SensorGetDeviceNonPortableType(int device_index);
182 
183 /**
184  * Get the instance ID of a sensor.
185  *
186  * \param device_index The sensor to get instance id from
187  * \returns the sensor instance ID, or -1 if `device_index` is out of range.
188  *
189  * \since This function is available since SDL 2.0.9.
190  */
191 extern DECLSPEC SDL_SensorID SDLCALL SDL_SensorGetDeviceInstanceID(int device_index);
192 
193 /**
194  * Open a sensor for use.
195  *
196  * \param device_index The sensor to open
197  * \returns an SDL_Sensor sensor object, or NULL if an error occurred.
198  *
199  * \since This function is available since SDL 2.0.9.
200  */
201 extern DECLSPEC SDL_Sensor *SDLCALL SDL_SensorOpen(int device_index);
202 
203 /**
204  * Return the SDL_Sensor associated with an instance id.
205  *
206  * \param instance_id The sensor from instance id
207  * \returns an SDL_Sensor object.
208  *
209  * \since This function is available since SDL 2.0.9.
210  */
211 extern DECLSPEC SDL_Sensor *SDLCALL SDL_SensorFromInstanceID(SDL_SensorID instance_id);
212 
213 /**
214  * Get the implementation dependent name of a sensor
215  *
216  * \param sensor The SDL_Sensor object
217  * \returns the sensor name, or NULL if `sensor` is NULL.
218  *
219  * \since This function is available since SDL 2.0.9.
220  */
221 extern DECLSPEC const char *SDLCALL SDL_SensorGetName(SDL_Sensor *sensor);
222 
223 /**
224  * Get the type of a sensor.
225  *
226  * \param sensor The SDL_Sensor object to inspect
227  * \returns the SDL_SensorType type, or `SDL_SENSOR_INVALID` if `sensor` is
228  * NULL.
229  *
230  * \since This function is available since SDL 2.0.9.
231  */
232 extern DECLSPEC SDL_SensorType SDLCALL SDL_SensorGetType(SDL_Sensor *sensor);
233 
234 /**
235  * Get the platform dependent type of a sensor.
236  *
237  * \param sensor The SDL_Sensor object to inspect
238  * \returns the sensor platform dependent type, or -1 if `sensor` is NULL.
239  *
240  * \since This function is available since SDL 2.0.9.
241  */
242 extern DECLSPEC int SDLCALL SDL_SensorGetNonPortableType(SDL_Sensor *sensor);
243 
244 /**
245  * Get the instance ID of a sensor.
246  *
247  * \param sensor The SDL_Sensor object to inspect
248  * \returns the sensor instance ID, or -1 if `sensor` is NULL.
249  *
250  * \since This function is available since SDL 2.0.9.
251  */
252 extern DECLSPEC SDL_SensorID SDLCALL SDL_SensorGetInstanceID(SDL_Sensor *sensor);
253 
254 /**
255  * Get the current state of an opened sensor.
256  *
257  * The number of values and interpretation of the data is sensor dependent.
258  *
259  * \param sensor The SDL_Sensor object to query
260  * \param data A pointer filled with the current sensor state
261  * \param num_values The number of values to write to data
262  * \returns 0 or -1 if an error occurred.
263  *
264  * \since This function is available since SDL 2.0.9.
265  */
266 extern DECLSPEC int SDLCALL SDL_SensorGetData(SDL_Sensor * sensor, float *data, int num_values);
267 
268 /**
269  * Close a sensor previously opened with SDL_SensorOpen().
270  *
271  * \param sensor The SDL_Sensor object to close
272  *
273  * \since This function is available since SDL 2.0.9.
274  */
275 extern DECLSPEC void SDLCALL SDL_SensorClose(SDL_Sensor * sensor);
276 
277 /**
278  * Update the current state of the open sensors.
279  *
280  * This is called automatically by the event loop if sensor events are
281  * enabled.
282  *
283  * This needs to be called from the thread that initialized the sensor
284  * subsystem.
285  *
286  * \since This function is available since SDL 2.0.9.
287  */
288 extern DECLSPEC void SDLCALL SDL_SensorUpdate(void);
289 
290 
291 /* Ends C function definitions when using C++ */
292 #ifdef __cplusplus
293 /* *INDENT-OFF* */
294 }
295 /* *INDENT-ON* */
296 #endif
297 #include "close_code.h"
298 
299 #endif /* SDL_sensor_h_ */
300 
301 /* vi: set ts=4 sw=4 expandtab: */
SDL_Sensor * SDL_SensorFromInstanceID(SDL_SensorID instance_id)
Sint32 SDL_SensorID
Definition: SDL_sensor.h:60
SDL_SensorType SDL_SensorGetDeviceType(int device_index)
const char * SDL_SensorGetDeviceName(int device_index)
void SDL_SensorUpdate(void)
int SDL_SensorGetData(SDL_Sensor *sensor, float *data, int num_values)
struct _SDL_Sensor SDL_Sensor
Definition: SDL_sensor.h:52
void SDL_UnlockSensors(void)
const char * SDL_SensorGetName(SDL_Sensor *sensor)
SDL_SensorType SDL_SensorGetType(SDL_Sensor *sensor)
SDL_Sensor * SDL_SensorOpen(int device_index)
SDL_SensorID SDL_SensorGetDeviceInstanceID(int device_index)
SDL_SensorID SDL_SensorGetInstanceID(SDL_Sensor *sensor)
int SDL_SensorGetNonPortableType(SDL_Sensor *sensor)
int SDL_NumSensors(void)
void SDL_SensorClose(SDL_Sensor *sensor)
void SDL_LockSensors(void)
SDL_SensorType
Definition: SDL_sensor.h:70
@ SDL_SENSOR_INVALID
Definition: SDL_sensor.h:71
@ SDL_SENSOR_GYRO
Definition: SDL_sensor.h:74
@ SDL_SENSOR_UNKNOWN
Definition: SDL_sensor.h:72
@ SDL_SENSOR_ACCEL
Definition: SDL_sensor.h:73
int SDL_SensorGetDeviceNonPortableType(int device_index)
int32_t Sint32
Definition: SDL_stdinc.h:214