How to use three-axis sensor code in iPhone applications

IPhone applicationsHow to use iPhoneThree-axis sensorThe code case is the content you will introduce in this article, mainly to understand and learnIphone applications. In many applications, the built-in iPhoneThree-axis sensorAcceleration Sensor), hope the following code example can open your mind for using the iPhone three axis sensor. :

 

 
 

  
  
#include <IOKit/IOKitLib.h> 
  
  
#include <CoreFoundation/CoreFoundation.h> 
  
  
 
  
  
typedef struct {} *IOHIDEventSystemRef;  
  
  
typedef struct {} *IOHIDEventRef;  
  
  
float IOHIDEventGetFloatValue(IOHIDEventRef ref, int param);  
  
  
 
  
  
void handleHIDEvent(int a, int b, int c, IOHIDEventRef ptr) {  
  
  
int type = IOHIDEventGetType(ptr);  
  
  
if (type == 12) {  
  
  
float x,y,z;  
  
  
x = IOHIDEventGetFloatValue(ptr, 0xc0000);  
  
  
y = IOHIDEventGetFloatValue(ptr, 0xc0001);  
  
  
z = IOHIDEventGetFloatValue(ptr, 0xc0002);  
  
  
// do whatever you need to do with the gravity  
  
  
ballSetAccel(x, y);  
  
  
}  
  
  
}  
  
  
#define expect(x) if(!x) { printf("failed: %sn", #x); return; }  
  
  
void initialize(int hz) {  
  
  
mach_port_t master;  
  
  
expect(0 == IOMasterPort(MACH_PORT_NULL, &master));  
  
  
 
  
  
int page = 0xff00, usage = 3;  
  
  
 
  
  
CFNumberRef nums[2];  
  
  
CFStringRef keys[2];  
  
  
keys[0] = CFStringCreateWithCString(0, "PrimaryUsagePage", 0);  
  
  
keys[1] = CFStringCreateWithCString(0, "PrimaryUsage", 0);  
  
  
nums[0] = CFNumberCreate(0, kCFNumberSInt32Type, &page);  
  
  
nums[1] = CFNumberCreate(0, kCFNumberSInt32Type, &usage);  
  
  
CFDictionaryRef dict = CFDictionaryCreate(0, (const void**)keys,  
  
  
(const void**)nums, 2, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);  
  
  
 expect(dict);  
  
  
IOHIDEventSystemRef sys = (IOHIDEventSystemRef) IOHIDEventSystemCreate(0);  
  
  
expect(sys);  
  
  
 CFArrayRef srvs = (CFArrayRef)IOHIDEventSystemCopyMatchingServices(sys, dict, 0, 0, 0);  
  
  
expect(CFArrayGetCount(srvs)==1);  
  
  
   
  
  
io_registry_entry_t serv = (io_registry_entry_t)CFArrayGetValueAtIndex(srvs, 0);  
  
  
expect(serv);  
  
  
   
  
  
CFStringRef cs = CFStringCreateWithCString(0, "ReportInterval", 0);  
  
  
int rv = 1000000/hz;  
  
  
CFNumberRef cn = CFNumberCreate(0, kCFNumberSInt32Type, &rv);  
  
  
   
  
  
int res = IOHIDServiceSetProperty(serv, cs, cn);  
  
  
expect(res == 1);  
  
  
   
  
  
res = IOHIDEventSystemOpen(sys, handleHIDEvent, 0, 0);  
  
  
expect(res != 0);  
  
  
} 
 
 

Summary:IPhone applicationsHow to UseThree-axis sensorThe content of the code case has been introduced. I hope this article will help you!