特定のビットを反転する

// ビット0 (LSB) だけを反転する.
Flags ^= 0x00000001;

// ビット1だけを反転する.
Flags ^= 0x00000002;

// ビット2だけを反転する.
Flags ^= 0x00000004;

using System;
using System.Drawing;
using System.Windows.Forms;

namespace aaa
{
	public partial class Form1 : Form
	{

		const uint BIT_R = 0x00000001;
		const uint BIT_G = 0x00000002;
		const uint BIT_B = 0x00000004;

		uint Flags;

		public Form1()
		{
			InitializeComponent();
		}

		private void Form1_Load( object sender, EventArgs e )
		{
			Flags = 0x00000000;
		}

		private void button1_Click( object sender, EventArgs e )
		{
			Flags ^= BIT_B;
			this.Invalidate( true );
		}

		private void button2_Click( object sender, EventArgs e )
		{
			Flags ^= BIT_G;
			this.Invalidate( true );
		}

		private void button3_Click( object sender, EventArgs e )
		{
			Flags ^= BIT_R;
			this.Invalidate( true );
		}

		private void pictureBox1_Paint( object sender, PaintEventArgs e )
		{

			Color c;

			if (( Flags & BIT_B ) == BIT_B )
			{
				c = Color.Blue;
			}
			else
			{
				c = Color.Black;
			}

			pictureBox1.BackColor = c;

		}

		private void pictureBox2_Paint( object sender, PaintEventArgs e )
		{

			Color c;

			if (( Flags & BIT_G ) == BIT_G )
			{
				c = Color.Lime;
			}
			else
			{
				c = Color.Black;
			}

			pictureBox2.BackColor = c;

		}

		private void pictureBox3_Paint( object sender, PaintEventArgs e )
		{

			Color c;

			if (( Flags & BIT_R ) == BIT_R )
			{
				c = Color.Red;
			}
			else
			{
				c = Color.Black;
			}

			pictureBox3.BackColor = c;

		}
	}
}