因在项目中需要使用定时器播放帧动画,系统自带的定时器每秒最多执行60帧,因为误差较大,如果用于计时的任务,则会随着时间的增加,误差会变的越来越大。
好在Windows系统提供了一种精度更高的定时器:多媒体定时器(Multimedia Timers),最高可以精确至1毫秒。
微软官方文档:https://docs.microsoft.com/zh-cn/windows/win32/multimedia/multimedia-timers
为了方便使用,我封装了一个库,下面是主要代码(完整代码请参考附件):
namespace HighPrecisionTimer
{
/// <summary>
/// 定时器分辨率:毫秒
/// </summary>
struct TimerCaps
{
/// <summary>最小周期</summary>
public int periodMin;
/// <summary>最大周期</summary>
public int periodMax;
}
/// <summary>
/// 高精度定时器
/// </summary>
public class HPTimer
{
static HPTimer()
{
TimeGetDevCaps(ref _caps, Marshal.SizeOf(_caps));
}
public HPTimer()
{
Running = false;
_interval = _caps.periodMin;
_resolution = _caps.periodMin;
_callback = new TimerCallback(TimerEventCallback);
}
~HPTimer()
{
TimeKillEvent(_id);
}
/// <summary>
/// 系统定时器回调
/// </summary>
/// <param name="id">定时器编号</param>
/// <param name="msg">预留,不使用</param>
/// <param name="user">用户实例数据</param>
/// <param name="param1">预留,不使用</param>
/// <param name="param2">预留,不使用</param>
private delegate void TimerCallback(int id, int msg, int user, int param1, int param2);
#region 动态库接口
/// <summary>
/// 查询设备支持的定时器分辨率
/// </summary>
/// <param name="ptc">定时器分辨率结构体指针</param>
/// <param name="cbtc">定时器分辨率结构体大小</param>
/// <returns></returns>
[DllImport("winmm.dll", EntryPoint = "timeGetDevCaps")]
private static extern TimerError TimeGetDevCaps(ref TimerCaps ptc, int cbtc);
/// <summary>
/// 绑定定时器事件
/// </summary>
/// <param name="delay">延时:毫秒</param>
/// <param name="resolution">分辨率</param>
/// <param name="callback">回调接口</param>
/// <param name="user">用户提供的回调数据</param>
/// <param name="eventType"></param>
[DllImport("winmm.dll", EntryPoint = "timeSetEvent")]
private static extern int TimeSetEvent(int delay, int resolution, TimerCallback callback, int user, int eventType);
/// <summary>
/// 终止定时器
/// </summary>
/// <param name="id">定时器编号</param>
[DllImport("winmm.dll", EntryPoint = "timeKillEvent")]
private static extern TimerError TimeKillEvent(int id);
#endregion
#region 属性
/// <summary>时间间隔:毫秒</summary>
public int Interval
{
get { return _interval; }
set
{
if (value < _caps.periodMin || value > _caps.periodMax)
throw new Exception("无效的计时间隔");
_interval = value;
}
}
public bool Running { get; private set; }
#endregion
#region 事件
public event Action Ticked;
#endregion
#region 公开方法
public void Start()
{
if (!Running)
{
_id = TimeSetEvent(_interval, _resolution, _callback, 0,
(int)EventType01.TIME_PERIODIC | (int)EventType02.TIME_KILL_SYNCHRONOUS);
if (_id == 0) throw new Exception("启动定时器失败");
Running = true;
}
}
public void Stop()
{
if (Running)
{
TimeKillEvent(_id);
Running = false;
}
}
#endregion
#region 内部方法
private void TimerEventCallback(int id, int msg, int user, int param1, int param2)
{
Ticked?.Invoke();
}
#endregion
#region 字段
// 系统定时器分辨率
private static TimerCaps _caps;
// 定时器间隔
private int _interval;
// 定时器分辨率
private int _resolution;
// 定时器回调
private TimerCallback _callback;
// 定时器编号
private int _id;
#endregion
}
}
完整项目:https://pan.baidu.com/s/1Lz6PbGsj4If0Y8jbdaQigg
提取码:jkl2
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