C# 自定义控件：LED指示灯

下面我将介绍如何创建一个自定义的LED指示灯控件，它可以显示不同颜色（红、黄、绿等）和状态（亮、灭、闪烁），适用于工业监控、状态指示等场景。

1. 创建基础LED控件

1.1 创建自定义控件类

csharp
using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

public class LedIndicator : Control
{
// 字段
private Color ledColor = Color.Red;
private bool ledState = false;
private bool blinking = false;
private int blinkInterval = 500; // 闪烁间隔(毫秒)
private Timer blinkTimer;
private int ledSize = 20;
private bool threeState = false;
private Color offColor = Color.DarkGray;

// 构造函数
public LedIndicator()
{
// 设置控件样式
SetStyle(ControlStyles.SupportsTransparentBackColor |
ControlStyles.OptimizedDoubleBuffer |
ControlStyles.ResizeRedraw |
ControlStyles.UserPaint, true);

// 初始化定时器
blinkTimer = new Timer();
blinkTimer.Interval = blinkInterval;
blinkTimer.Tick += BlinkTimer_Tick;

// 默认大小
this.Size = new Size(24, 24);
}

// 属性
[Category("LED属性")]
[Description("获取或设置LED颜色")]
public Color LedColor
{
get { return ledColor; }
set { ledColor = value; Invalidate(); }
}

[Category("LED属性")]
[Description("获取或设置LED状态")]
public bool LedState
{
get { return ledState; }
set { ledState = value; Invalidate(); }
}

[Category("LED属性")]
[Description("获取或设置是否闪烁")]
public bool Blinking
{
get { return blinking; }
set 
{
blinking = value;
blinkTimer.Enabled = blinking && ledState;
Invalidate();
}
}

[Category("LED属性")]
[Description("获取或设置闪烁间隔(毫秒)")]
public int BlinkInterval
{
get { return blinkInterval; }
set 
{
blinkInterval = Math.Max(50, value); // 最小50ms
blinkTimer.Interval = blinkInterval;
}
}

[Category("LED属性")]
[Description("获取或设置LED大小")]
public int LedSize
{
get { return ledSize; }
set { ledSize = Math.Max(10, value); Invalidate(); }
}

[Category("LED属性")]
[Description("启用三态模式(亮/灭/闪烁)")]
public bool ThreeState
{
get { return threeState; }
set { threeState = value; }
}

[Category("LED属性")]
[Description("LED关闭时的颜色")]
public Color OffColor
{
get { return offColor; }
set { offColor = value; Invalidate(); }
}

// 方法
public void SetState(bool state)
{
LedState = state;
if (blinking)
{
blinkTimer.Enabled = state;
}
}

// 事件处理
private void BlinkTimer_Tick(object sender, EventArgs e)
{
ledState = !ledState;
Invalidate();
}

// 重写OnPaint方法
protected override void OnPaint(PaintEventArgs e)
{
base.onPaint(e);

Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;

// 计算LED位置和大小
int diameter = Math.Min(ledSize, Math.Min(Width, Height) - 2);
int x = (Width - diameter) / 2;
int y = (Height - diameter) / 2;
Rectangle rect = new Rectangle(x, y, diameter, diameter);

// 绘制LED
using (GraphicsPath path = new GraphicsPath())
{
path.AddEllipse(rect);

// 绘制LED主体
Color drawColor = (ledState || threeState) ? ledColor : offColor;
using (PathGradientBrush pgb = new PathGradientBrush(path))
{
pgb.CenterPoint = new PointF(rect.Left + rect.Width / 3, rect.Top + rect.Height / 3);
pgb.CenterColor = Color.FromArgb(200, drawColor);
pgb.SurroundColors = new Color[] { drawColor };

g.FillEllipse(pgb, rect);
}

// 绘制高光
using (GraphicsPath highlightPath = new GraphicsPath())
{
highlightPath.AddEllipse(rect.X + rect.Width / 4, rect.Y + rect.Height / 4,
rect.Width / 2, rect.Height / 2);
using (SolidBrush highlightBrush = new SolidBrush(Color.FromArgb(128, Color.White)))
{
g.FillEllipse(highlightBrush, rect.X + rect.Width / 4, rect.Y + rect.Height / 4,
rect.Width / 2, rect.Height / 2);
}
}

// 绘制边框
using (Pen pen = new Pen(Color.DarkGray, 1f))
{
g.DrawEllipse(pen, rect);
}
}
}

// 重写大小相关方法
protected override void OnResize(EventArgs e)
{
base.onResize(e);
// 保持控件为正方形
int size = Math.Min(Width, Height);
this.Size = new Size(size, size);
}

// 清理资源
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (blinkTimer != null)
{
blinkTimer.Stop();
blinkTimer.Dispose();
}
}
base.Dispose(disposing);
}
}