C# 阴历，阳历互转

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

namespace WinFormLunisolar
{
    public partial class FormLunisolar : Form
    {
        #region
        private readonly string animals;
        private DateTimePicker lunarPicker, solarPicker;
        private ChineseLunisolarCalendar lunarCalendar;
        #endregion

        public FormLunisolar()
        {
            #region
            InitializeComponent();
            animals = "鼠牛虎兔龙蛇马羊猴鸡狗猪";
            lunarCalendar = new ChineseLunisolarCalendar(); // 中国阴阳历。
            lunarPicker = new DateTimePicker();
            lunarPicker.Dock = DockStyle.Top;
            lunarPicker.Format = DateTimePickerFormat.Custom; // 自定义格式。
            lunarPicker.ShowUpDown = true; // 使用数值调节钮控件。
            lunarPicker.ValueChanged += new EventHandler(lunarPicker_ValueChanged);
            this.Controls.Add(lunarPicker);
            solarPicker = new DateTimePicker();
            solarPicker.Dock = DockStyle.Bottom;
            solarPicker.Format = DateTimePickerFormat.Custom; // 自定义格式。
            solarPicker.CustomFormat = "dddd yyyy'年'M'月'd'日'";
            solarPicker.ShowUpDown = true; // 使用数值调节钮控件。
            solarPicker.MaxDate = lunarCalendar.MaxSupportedDateTime;
            solarPicker.ValueChanged += new EventHandler(solarPicker_ValueChanged);
            solarPicker.Value = DateTime.Today;
            this.Controls.Add(solarPicker);
            this.TopMost = true; // 前端显示。
            this.ShowInTaskbar = false; // 在 Windows 任务栏中隐藏窗体。
            this.HelpButton = true; // 显示“帮助”按钮。
            this.MaximizeBox = false; // 隐藏“最大化”按钮。
            this.MinimizeBox = false; // 隐藏“最小化”按钮。
            this.AutoScaleMode = AutoScaleMode.Font; // 根据字体的维度控制缩放。
            this.Font = new Font(Font.Name, 12F);
            this.ClientSize = new Size(192, 52);
            this.AutoSizeMode = AutoSizeMode.GrowAndShrink; // 禁用手动调整大小。
            this.SizeGripStyle = SizeGripStyle.Hide; // 隐藏调整大小手柄。
            this.StartPosition = FormStartPosition.CenterScreen; // 在桌面居中显示。
            #endregion
        }

        #region 计算阳历
        private void lunarPicker_ValueChanged(object sender, EventArgs e)
        {
            DateTime solar = lunarPicker.Value;
            int year = solar.Year;
            int month = solar.Month;
            int day = Math.Min(solar.Day, lunarCalendar.GetDaysInMonth(year, month));
            int leapMonth = lunarCalendar.GetLeapMonth(year);
            if (0 < leapMonth && leapMonth <= month)
                ++month;
            solarPicker.Value = lunarCalendar.ToDateTime(year, month, day, 0, 0, 0, 0);
        }
        #endregion

        #region 计算阴历
        private void solarPicker_ValueChanged(object sender, EventArgs e)
        {
            DateTime solar = solarPicker.Value;
            int year = lunarCalendar.GetYear(solar);
            int month = lunarCalendar.GetMonth(solar);
            int day = lunarCalendar.GetDayOfMonth(solar);
            int leapMonth = lunarCalendar.GetLeapMonth(year);
            if (0 < leapMonth && leapMonth <= month)
                --month;
            if (month == 2 && day > 28)
                lunarPicker.CustomFormat = string.Format("{0}年 {1}年 {2}月{3}日", animals[(year - 4) % 12], year, month, day);
            else
            {
                lunarPicker.CustomFormat = string.Format("{0}'年' yyyy'年'M'月'd'日'", animals[(year - 4) % 12]);
                lunarPicker.Value = new DateTime(year, month, day);
            }
        }
        #endregion

        #region DesktopBounds
        protected override void OnHelpButtonClicked(System.ComponentModel.CancelEventArgs e)
        {
            base.OnHelpButtonClicked(e);
            e.Cancel = true;
            using (FontDialog fontDialog = new FontDialog())
            {
                fontDialog.Font = this.Font;
                fontDialog.ShowEffects = false;
                if (fontDialog.ShowDialog(this) == DialogResult.OK)
                {
                    this.Font = fontDialog.Font;
                    int sw = TextRenderer.MeasureText("星期日 0000年00月00日", this.Font).Width;
                    this.ClientSize = new Size(sw + 16, lunarPicker.Height + solarPicker.Height);
                    Size ws = Screen.GetWorkingArea(this).Size - this.Size;
                    this.DesktopLocation = new Point(ws.Width / 2, ws.Height / 2);
                }
            }
        }
        #endregion
    }
}