src/joystick/iphoneos/SDL_sysjoystick.m
author Ryan C. Gordon <icculus@icculus.org>
Wed, 24 Dec 2014 22:22:35 -0500
changeset 9289 5f857c00d25d
parent 8921 4a9feef61c85
child 9311 a4b031e28de8
child 9489 6cd0275146b3
permissions -rw-r--r--
Maybe actually patched to compile this time?
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2014 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 #include "../../SDL_internal.h"
    22 
    23 /* This is the iOS implementation of the SDL joystick API */
    24 
    25 #include "SDL_joystick.h"
    26 #include "SDL_stdinc.h"
    27 #include "../SDL_sysjoystick.h"
    28 #include "../SDL_joystick_c.h"
    29 
    30 #import <CoreMotion/CoreMotion.h>
    31 
    32 /* needed for SDL_IPHONE_MAX_GFORCE macro */
    33 #import "SDL_config_iphoneos.h"
    34 
    35 const char *accelerometerName = "iOS accelerometer";
    36 
    37 static CMMotionManager *motionManager = nil;
    38 
    39 /* Function to scan the system for joysticks.
    40  * This function should set SDL_numjoysticks to the number of available
    41  * joysticks.  Joystick 0 should be the system default joystick.
    42  * It should return 0, or -1 on an unrecoverable fatal error.
    43  */
    44 int
    45 SDL_SYS_JoystickInit(void)
    46 {
    47     return (1);
    48 }
    49 
    50 int SDL_SYS_NumJoysticks()
    51 {
    52     return 1;
    53 }
    54 
    55 void SDL_SYS_JoystickDetect()
    56 {
    57 }
    58 
    59 /* Function to get the device-dependent name of a joystick */
    60 const char *
    61 SDL_SYS_JoystickNameForDeviceIndex(int device_index)
    62 {
    63     return accelerometerName;
    64 }
    65 
    66 /* Function to perform the mapping from device index to the instance id for this index */
    67 SDL_JoystickID SDL_SYS_GetInstanceIdOfDeviceIndex(int device_index)
    68 {
    69     return device_index;
    70 }
    71 
    72 /* Function to open a joystick for use.
    73    The joystick to open is specified by the index field of the joystick.
    74    This should fill the nbuttons and naxes fields of the joystick structure.
    75    It returns 0, or -1 if there is an error.
    76  */
    77 int
    78 SDL_SYS_JoystickOpen(SDL_Joystick * joystick, int device_index)
    79 {
    80     joystick->naxes = 3;
    81     joystick->nhats = 0;
    82     joystick->nballs = 0;
    83     joystick->nbuttons = 0;
    84 
    85     if (motionManager == nil) {
    86         motionManager = [[CMMotionManager alloc] init];
    87     }
    88 
    89     /* Shorter times between updates can significantly increase CPU usage. */
    90     motionManager.accelerometerUpdateInterval = 0.1;
    91     [motionManager startAccelerometerUpdates];
    92 
    93     return 0;
    94 }
    95 
    96 /* Function to determine is this joystick is attached to the system right now */
    97 SDL_bool SDL_SYS_JoystickAttached(SDL_Joystick *joystick)
    98 {
    99     return SDL_TRUE;
   100 }
   101 
   102 static void SDL_SYS_AccelerometerUpdate(SDL_Joystick * joystick)
   103 {
   104     const float maxgforce = SDL_IPHONE_MAX_GFORCE;
   105     const SInt16 maxsint16 = 0x7FFF;
   106     CMAcceleration accel;
   107 
   108     if (!motionManager.accelerometerActive) {
   109         return;
   110     }
   111 
   112     accel = [[motionManager accelerometerData] acceleration];
   113 
   114     /*
   115      Convert accelerometer data from floating point to Sint16, which is what
   116      the joystick system expects.
   117 
   118      To do the conversion, the data is first clamped onto the interval
   119      [-SDL_IPHONE_MAX_G_FORCE, SDL_IPHONE_MAX_G_FORCE], then the data is multiplied
   120      by MAX_SINT16 so that it is mapped to the full range of an Sint16.
   121 
   122      You can customize the clamped range of this function by modifying the
   123      SDL_IPHONE_MAX_GFORCE macro in SDL_config_iphoneos.h.
   124 
   125      Once converted to Sint16, the accelerometer data no longer has coherent
   126      units. You can convert the data back to units of g-force by multiplying
   127      it in your application's code by SDL_IPHONE_MAX_GFORCE / 0x7FFF.
   128      */
   129 
   130     /* clamp the data */
   131     accel.x = SDL_min(SDL_max(accel.x, -maxgforce), maxgforce);
   132     accel.y = SDL_min(SDL_max(accel.y, -maxgforce), maxgforce);
   133     accel.z = SDL_min(SDL_max(accel.z, -maxgforce), maxgforce);
   134 
   135     /* pass in data mapped to range of SInt16 */
   136     SDL_PrivateJoystickAxis(joystick, 0, (accel.x / maxgforce) * maxsint16);
   137     SDL_PrivateJoystickAxis(joystick, 1, -(accel.y / maxgforce) * maxsint16);
   138     SDL_PrivateJoystickAxis(joystick, 2, (accel.z / maxgforce) * maxsint16);
   139 }
   140 
   141 /* Function to update the state of a joystick - called as a device poll.
   142  * This function shouldn't update the joystick structure directly,
   143  * but instead should call SDL_PrivateJoystick*() to deliver events
   144  * and update joystick device state.
   145  */
   146 void
   147 SDL_SYS_JoystickUpdate(SDL_Joystick * joystick)
   148 {
   149     SDL_SYS_AccelerometerUpdate(joystick);
   150 }
   151 
   152 /* Function to close a joystick after use */
   153 void
   154 SDL_SYS_JoystickClose(SDL_Joystick * joystick)
   155 {
   156     [motionManager stopAccelerometerUpdates];
   157     joystick->closed = 1;
   158 }
   159 
   160 /* Function to perform any system-specific joystick related cleanup */
   161 void
   162 SDL_SYS_JoystickQuit(void)
   163 {
   164     if (motionManager != nil) {
   165         [motionManager release];
   166         motionManager = nil;
   167     }
   168 }
   169 
   170 SDL_JoystickGUID SDL_SYS_JoystickGetDeviceGUID( int device_index )
   171 {
   172     SDL_JoystickGUID guid;
   173     /* the GUID is just the first 16 chars of the name for now */
   174     const char *name = SDL_SYS_JoystickNameForDeviceIndex( device_index );
   175     SDL_zero( guid );
   176     SDL_memcpy( &guid, name, SDL_min( sizeof(guid), SDL_strlen( name ) ) );
   177     return guid;
   178 }
   179 
   180 SDL_JoystickGUID SDL_SYS_JoystickGetGUID(SDL_Joystick * joystick)
   181 {
   182     SDL_JoystickGUID guid;
   183     /* the GUID is just the first 16 chars of the name for now */
   184     const char *name = joystick->name;
   185     SDL_zero( guid );
   186     SDL_memcpy( &guid, name, SDL_min( sizeof(guid), SDL_strlen( name ) ) );
   187     return guid;
   188 }
   189 
   190 /* vi: set ts=4 sw=4 expandtab: */