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Fixed bug 2603 - iOS: update joystick accelerometer code to use CoreMotion instead of the deprecated UIAccelerometer

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Alex Szpakowski

SDL's code for exposing the accelerometer as a joystick on iOS currently uses UIAccelerometer, which was superseded by the CoreMotion framework and deprecated since iOS 5.

The UIAccelerometer code still works (for now), but it also throws deprecation warnings whenever SDL is built for iOS, since SDL's deployment target is no longer below iOS 5.

I've created a patch which replaces the old UIAccelerometer code with a replacement based on the CoreMotion framework. It has identical functionality (to SDL users), however iOS apps are now required to link to the CoreMotion framework when using SDL.
This commit is contained in:
Sam Lantinga 2014-06-25 00:20:21 -07:00
parent dc434901da
commit ff201dbea2
6 changed files with 67 additions and 217 deletions
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86
src/joystick/iphoneos/SDL_sysjoystick.m
View file

@ -23,11 +23,18 @@
/* This is the iOS implementation of the SDL joystick API */
#include "SDL_joystick.h"
#include "SDL_stdinc.h"
#include "../SDL_sysjoystick.h"
#include "../SDL_joystick_c.h"
#import "SDLUIAccelerationDelegate.h"
const char *accelerometerName = "iPhone accelerometer";
#import <CoreMotion/CoreMotion.h>
/* needed for SDL_IPHONE_MAX_GFORCE macro */
#import "SDL_config_iphoneos.h"
const char *accelerometerName = "iOS accelerometer";
static CMMotionManager *motionManager = nil;
/* Function to scan the system for joysticks.
* This function should set SDL_numjoysticks to the number of available
@ -74,7 +81,15 @@ SDL_SYS_JoystickOpen(SDL_Joystick * joystick, int device_index)
joystick->nhats = 0;
joystick->nballs = 0;
joystick->nbuttons = 0;
[[SDLUIAccelerationDelegate sharedDelegate] startup];
if (motionManager == nil) {
motionManager = [[CMMotionManager alloc] init];
}
/* Shorter times between updates can significantly increase CPU usage. */
motionManager.accelerometerUpdateInterval = 0.1;
[motionManager startAccelerometerUpdates];
return 0;
}
@ -84,6 +99,45 @@ SDL_bool SDL_SYS_JoystickAttached(SDL_Joystick *joystick)
return SDL_TRUE;
}
static void SDL_SYS_AccelerometerUpdate(SDL_Joystick * joystick)
{
const float maxgforce = SDL_IPHONE_MAX_GFORCE;
const SInt16 maxsint16 = 0x7FFF;
CMAcceleration accel;
if (!motionManager.accelerometerActive) {
return;
}
accel = [[motionManager accelerometerData] acceleration];
/*
Convert accelerometer data from floating point to Sint16, which is what
the joystick system expects.
To do the conversion, the data is first clamped onto the interval
[-SDL_IPHONE_MAX_G_FORCE, SDL_IPHONE_MAX_G_FORCE], then the data is multiplied
by MAX_SINT16 so that it is mapped to the full range of an Sint16.
You can customize the clamped range of this function by modifying the
SDL_IPHONE_MAX_GFORCE macro in SDL_config_iphoneos.h.
Once converted to Sint16, the accelerometer data no longer has coherent
units. You can convert the data back to units of g-force by multiplying
it in your application's code by SDL_IPHONE_MAX_GFORCE / 0x7FFF.
*/
/* clamp the data */
accel.x = SDL_min(SDL_max(accel.x, -maxgforce), maxgforce);
accel.y = SDL_min(SDL_max(accel.y, -maxgforce), maxgforce);
accel.z = SDL_min(SDL_max(accel.z, -maxgforce), maxgforce);
/* pass in data mapped to range of SInt16 */
SDL_PrivateJoystickAxis(joystick, 0, (accel.x / maxgforce) * maxsint16);
SDL_PrivateJoystickAxis(joystick, 1, -(accel.y / maxgforce) * maxsint16);
SDL_PrivateJoystickAxis(joystick, 2, (accel.z / maxgforce) * maxsint16);
}
/* Function to update the state of a joystick - called as a device poll.
* This function shouldn't update the joystick structure directly,
* but instead should call SDL_PrivateJoystick*() to deliver events
@ -92,37 +146,25 @@ SDL_bool SDL_SYS_JoystickAttached(SDL_Joystick *joystick)
void
SDL_SYS_JoystickUpdate(SDL_Joystick * joystick)
{
Sint16 orientation[3];
if ([[SDLUIAccelerationDelegate sharedDelegate] hasNewData]) {
[[SDLUIAccelerationDelegate sharedDelegate] getLastOrientation: orientation];
[[SDLUIAccelerationDelegate sharedDelegate] setHasNewData: NO];
SDL_PrivateJoystickAxis(joystick, 0, orientation[0]);
SDL_PrivateJoystickAxis(joystick, 1, -orientation[1]);
SDL_PrivateJoystickAxis(joystick, 2, orientation[2]);
}
return;
SDL_SYS_AccelerometerUpdate(joystick);
}
/* Function to close a joystick after use */
void
SDL_SYS_JoystickClose(SDL_Joystick * joystick)
{
if ([[SDLUIAccelerationDelegate sharedDelegate] isRunning]) {
[[SDLUIAccelerationDelegate sharedDelegate] shutdown];
}
SDL_SetError("No joystick open with that index");
[motionManager stopAccelerometerUpdates];
joystick->closed = 1;
}
/* Function to perform any system-specific joystick related cleanup */
void
SDL_SYS_JoystickQuit(void)
{
if (motionManager != nil) {
[motionManager release];
motionManager = nil;
}
}
SDL_JoystickGUID SDL_SYS_JoystickGetDeviceGUID( int device_index )