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C#自定义事件之天意何问起
这是一个自定义事件的例子。C#、WinForm、Visual Studio 2017。
在HoverTreeForm中画一块草地,上面有许多草(模拟)。
HewenqiTianyi类模拟天气,会引发“风”事件(HoverTreeWindEvent),风有东风或西风,或静止。
当吹东风,草往西边倒,吹西风则往东边到。静止则草不会东歪西倒。
草地上每一颗草都监听HoverTreeWindEvent事件,根据风向(WindDdirection)调整姿态。
HewenqiTianyi中有定时器,每隔一段时间触发调整风向的事件。
由于监听到的“风”事件不是WinForm中的线程,要改变WinForm中“草”的姿态,
使用了BeginInvoke方法和委托,在WinForm线程外访问控件。具体看HoverTreeGrass用户控件。
by 何问起
参考:http://hovertree.com/h/bjag/k0qps1iw.htm
http://hovertree.com/h/bjag/cm8k4ja1.htm
效果图:

HewenqiTianyi类代码:
using System;
using System.Timers;

namespace TianYiHeWenQi
{
class HewenqiTianyi
{
public static event ActionEventHandler HoverTreeWindEvent;
WindEventArgs _arg = new WindEventArgs();
public HewenqiTianyi()
{
Timer h_timer = new Timer();
h_timer.Interval = 3000;
h_timer.Elapsed += H_timer_Elapsed;
h_timer.Start();
}
Random _HoverClock=new Random ();
private void H_timer_Elapsed(object sender, ElapsedEventArgs e)
{
_arg.WindType = (WindDdirection)(_HoverClock.Next(3));
OnAction(_arg);
}

protected void OnAction(WindEventArgs ev)
{
HoverTreeWindEvent?.Invoke(ev);
//相当于以下代码
//if (HoverTreeWindEvent != null)
//{
// HoverTreeWindEvent(ev);
//}
}
}

class WindEventArgs : EventArgs
{
public WindDdirection WindType { get; set; }
}

enum WindDdirection
{
East,
West,
Static
}

delegate void ActionEventHandler(WindEventArgs ev);

}
自定义用户控件代码:
using System;
using System.Windows.Forms;

namespace TianYiHeWenQi
{
public partial class HoverTreeGrass : UserControl
{
delegate void MySetText(string text);
public HoverTreeGrass()
{
InitializeComponent();
HewenqiTianyi.HoverTreeWindEvent += HewenqiTianyi_HoverTreeWindEvent;
}

private void UpdateLabel(WindDdirection wd)
{
if (label_grass.InvokeRequired)
{
// 当一个控件的InvokeRequired属性值为真时,说明有一个创建它以外的线程想访问它
Action<WindDdirection> actionDelegate = (x) => {
switch (x)
{
case WindDdirection.East:
label_grass.Location = new System.Drawing.Point(40 - 9, label_grass.Location.Y);
label_grass.Text="\\";
break;
case WindDdirection.West:
label_grass.Location = new System.Drawing.Point(40+9, label_grass.Location.Y);
label_grass.Text = "/";
break;
case WindDdirection.Static:
label_grass.Location = new System.Drawing.Point(40, label_grass.Location.Y);
label_grass.Text = "|";
break;
}
};
// 或者
// Action<string> actionDelegate = delegate(string txt) { this.label_grass.Text = txt; };
this.label_grass.BeginInvoke(actionDelegate, wd);
}
else
{
switch (wd)
{
case WindDdirection.East:
label_grass.Text = "\\";
break;
case WindDdirection.West:
label_grass.Text = "/";
break;
case WindDdirection.Static:
label_grass.Text = "|";
break;
}
}
}

private void HewenqiTianyi_HoverTreeWindEvent(WindEventArgs ev)
{
UpdateLabel(ev.WindType);
}
}
}
HoverTreeForm窗体代码:
using System.Windows.Forms;

namespace TianYiHeWenQi
{
public partial class HoverTreeForm : Form
{
public HoverTreeForm()
{
InitializeComponent();

for (int i = 0; i < tableLayoutPanel_hovertree.ColumnCount; i++) {
for (int j = 0; j < tableLayoutPanel_hovertree.RowCount; j++) {
tableLayoutPanel_hovertree.Controls.Add(new HoverTreeGrass(), i, j);
}
}
HewenqiTianyi h_ty = new HewenqiTianyi();

}
}
}

TianYiHeWenQi项目源码下载

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