SDL  2.0
SDL_sensor.h
Go to the documentation of this file.
1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2020 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
134  * the API functions that take a sensor index will be valid, and sensor
135  * events will not be delivered.
136  */
137 extern DECLSPEC void SDLCALL SDL_LockSensors(void);
138 extern DECLSPEC void SDLCALL SDL_UnlockSensors(void);
139 
140 /**
141  * \brief Count the number of sensors attached to the system right now
142  */
143 extern DECLSPEC int SDLCALL SDL_NumSensors(void);
144 
145 /**
146  * \brief Get the implementation dependent name of a sensor.
147  *
148  * This can be called before any sensors are opened.
149  *
150  * \return The sensor name, or NULL if device_index is out of range.
151  */
152 extern DECLSPEC const char *SDLCALL SDL_SensorGetDeviceName(int device_index);
153 
154 /**
155  * \brief Get the type of a sensor.
156  *
157  * This can be called before any sensors are opened.
158  *
159  * \return The sensor type, or SDL_SENSOR_INVALID if device_index is out of range.
160  */
161 extern DECLSPEC SDL_SensorType SDLCALL SDL_SensorGetDeviceType(int device_index);
162 
163 /**
164  * \brief Get the platform dependent type of a sensor.
165  *
166  * This can be called before any sensors are opened.
167  *
168  * \return The sensor platform dependent type, or -1 if device_index is out of range.
169  */
170 extern DECLSPEC int SDLCALL SDL_SensorGetDeviceNonPortableType(int device_index);
171 
172 /**
173  * \brief Get the instance ID of a sensor.
174  *
175  * This can be called before any sensors are opened.
176  *
177  * \return The sensor instance ID, or -1 if device_index is out of range.
178  */
179 extern DECLSPEC SDL_SensorID SDLCALL SDL_SensorGetDeviceInstanceID(int device_index);
180 
181 /**
182  * \brief Open a sensor for use.
183  *
184  * The index passed as an argument refers to the N'th sensor on the system.
185  *
186  * \return A sensor identifier, or NULL if an error occurred.
187  */
188 extern DECLSPEC SDL_Sensor *SDLCALL SDL_SensorOpen(int device_index);
189 
190 /**
191  * Return the SDL_Sensor associated with an instance id.
192  */
193 extern DECLSPEC SDL_Sensor *SDLCALL SDL_SensorFromInstanceID(SDL_SensorID instance_id);
194 
195 /**
196  * \brief Get the implementation dependent name of a sensor.
197  *
198  * \return The sensor name, or NULL if the sensor is NULL.
199  */
200 extern DECLSPEC const char *SDLCALL SDL_SensorGetName(SDL_Sensor *sensor);
201 
202 /**
203  * \brief Get the type of a sensor.
204  *
205  * This can be called before any sensors are opened.
206  *
207  * \return The sensor type, or SDL_SENSOR_INVALID if the sensor is NULL.
208  */
209 extern DECLSPEC SDL_SensorType SDLCALL SDL_SensorGetType(SDL_Sensor *sensor);
210 
211 /**
212  * \brief Get the platform dependent type of a sensor.
213  *
214  * This can be called before any sensors are opened.
215  *
216  * \return The sensor platform dependent type, or -1 if the sensor is NULL.
217  */
218 extern DECLSPEC int SDLCALL SDL_SensorGetNonPortableType(SDL_Sensor *sensor);
219 
220 /**
221  * \brief Get the instance ID of a sensor.
222  *
223  * This can be called before any sensors are opened.
224  *
225  * \return The sensor instance ID, or -1 if the sensor is NULL.
226  */
227 extern DECLSPEC SDL_SensorID SDLCALL SDL_SensorGetInstanceID(SDL_Sensor *sensor);
228 
229 /**
230  * Get the current state of an opened sensor.
231  *
232  * The number of values and interpretation of the data is sensor dependent.
233  *
234  * \param sensor The sensor to query
235  * \param data A pointer filled with the current sensor state
236  * \param num_values The number of values to write to data
237  *
238  * \return 0 or -1 if an error occurred.
239  */
240 extern DECLSPEC int SDLCALL SDL_SensorGetData(SDL_Sensor * sensor, float *data, int num_values);
241 
242 /**
243  * Close a sensor previously opened with SDL_SensorOpen()
244  */
245 extern DECLSPEC void SDLCALL SDL_SensorClose(SDL_Sensor * sensor);
246 
247 /**
248  * Update the current state of the open sensors.
249  *
250  * This is called automatically by the event loop if sensor events are enabled.
251  *
252  * This needs to be called from the thread that initialized the sensor subsystem.
253  */
254 extern DECLSPEC void SDLCALL SDL_SensorUpdate(void);
255 
256 
257 /* Ends C function definitions when using C++ */
258 #ifdef __cplusplus
259 /* *INDENT-OFF* */
260 }
261 /* *INDENT-ON* */
262 #endif
263 #include "close_code.h"
264 
265 #endif /* SDL_sensor_h_ */
266 
267 /* 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)
Get the type of a sensor.
const char * SDL_SensorGetDeviceName(int device_index)
Get the implementation dependent name of a sensor.
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)
Get the implementation dependent name of a sensor.
SDL_SensorType SDL_SensorGetType(SDL_Sensor *sensor)
Get the type of a sensor.
SDL_Sensor * SDL_SensorOpen(int device_index)
Open a sensor for use.
SDL_SensorID SDL_SensorGetDeviceInstanceID(int device_index)
Get the instance ID of a sensor.
SDL_SensorID SDL_SensorGetInstanceID(SDL_Sensor *sensor)
Get the instance ID of a sensor.
int SDL_SensorGetNonPortableType(SDL_Sensor *sensor)
Get the platform dependent type of a sensor.
int SDL_NumSensors(void)
Count the number of sensors attached to the system right now.
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)
Get the platform dependent type of a sensor.
int32_t Sint32
Definition: SDL_stdinc.h:203