[转]使用iPhone三轴感应器的代码例子

最新推荐文章于 2021-04-30 11:35:14 发布

cnhome

最新推荐文章于 2021-04-30 11:35:14 发布

阅读量1.1k

点赞数

分类专栏：移动开发文章标签： iphone struct float io null 2010

移动开发专栏收录该内容

9 篇文章

订阅专栏

本文提供了一个关于如何在iPhone应用中使用内置三轴加速度传感器的代码示例。通过具体的C语言代码实现，介绍了如何获取并处理加速度数据。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

转自：http://www.cocoachina.com/iphonedev/sdk/2010/0624/1749.html

很多应用里都要用到苹果iPhone自带的三轴感应器（加速度传感器），希望下面这段代码例子能为您使用iPhone三轴感应器打开思路。

#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: %s/n", #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 );
}