Question

所以不要在点击下拉菜单时显示。

我希望点击时下拉列表就像这样。

非常感谢您的帮助。：）

Answer 1

为什么你需要这样做？如果您只想显示月份，那么更简单的方法是在Combox中显示月份列表。

但是我在msdn上找到了适合你的东西。看看https://social.msdn.microsoft.com/Forums/en-US/7bdca56f-719e-44bf-be6d-a9600dfa8f78/wpf-datepicker-for-months-only?forum=wpf

Answer 2

请尝试以下代码：

DateTime newDateValue = new DateTime(dateTimePicker_month.Value.Year, 1, 1);
dateTimePicker_month.Value = newDateValue;
dateTimePicker_month.Format = DateTimePickerFormat.Custom;
dateTimePicker_month.CustomFormat = "MMM-yyyy";
dateTimePicker_month.ShowUpDown = true;

您必须在2月份添加（1,1），其中有28/29天确定所有月份值。如果您希望查询选择月份。以下是一个示例：

string month = dateTimePicker_month.Value.Month.ToString();
string year = dateTimePicker_month.Value.Year.ToString();

使用以下查询选择月份：

select CAST(date AS DATE) from table where DATEPART(month, date)  = '" + month + "' and DATEPART(year,date) = '" + year + "'

Answer 3

尝试使用格式属性：

 dateTimePicker.Format = DateTimePickerFormat.Custom;
 dateTimePicker.CustomFormat = "MM";

Answer 4

使用windows messages approach，您可以检测月份日历控件的显示并强制执行月份视图，并且可以检测视图更改并在逐月视图更改时（选择月份之后）关闭月份日历控件。

最简单的实现方法是覆盖DateTimePicker。

public class MonthPicker : DateTimePicker
{
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_NOFITY)
        {
            var nmhdr = (NMHDR)Marshal.PtrToStructure(m.LParam, typeof(NMHDR));
            switch (nmhdr.code)
            {
                case -950:
                {
                    var cal = SendMessage(Handle, DTM_GETMONTHCAL, IntPtr.Zero, IntPtr.Zero);
                    SendMessage(cal, MCM_SETCURRENTVIEW, IntPtr.Zero, (IntPtr)1);
                    break;
                }
                case MCN_VIEWCHANGE:
                {
                    var nmviewchange = (NMVIEWCHANGE)Marshal.PtrToStructure(m.LParam, typeof(NMVIEWCHANGE));
                    if (nmviewchange.dwOldView == 1 && nmviewchange.dwNewView == 0)
                    {
                        SendMessage(Handle, DTM_CLOSEMONTHCAL, IntPtr.Zero, IntPtr.Zero);
                    }

                    break;
                }
            }
        }
        base.WndProc(ref m);
    }

    private const int WM_NOFITY = 0x004e;
    private const int DTM_CLOSEMONTHCAL = 0x1000 + 13;
    private const int DTM_GETMONTHCAL = 0x1000 + 8;
    private const int MCM_SETCURRENTVIEW = 0x1000 + 32;
    private const int MCN_VIEWCHANGE = -750;

    [DllImport("user32.dll")]
    public static extern IntPtr SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);

    [StructLayout(LayoutKind.Sequential)]
    private struct NMHDR
    {
        public IntPtr hwndFrom;
        public IntPtr idFrom;
        public int code;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct NMVIEWCHANGE
    {
        public NMHDR nmhdr;
        public uint dwOldView;
        public uint dwNewView;
    }
}

Answer 5

由于在我的情况下不起作用，我修改了Orance的答案，将其放在从DateTimePicker继承的类中：

public partial class Startup
{
    private readonly IConfiguration Configuration;

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers()
            .AddNewtonsoftJson();
        
        //Omited for brevity
        
        services.AddModelBinderErrorHandler();
    }
    
    //Omited for brevity
}

与VB等效：

    protected override void WndProc(ref Message m)
{
    if (_MonthSelectStyle)
    {
        if (m.Msg == 0X204E) // = Win32Messages.WM_REFLECT_NOTIFY
        {
            var nmhdrI = (NMHDR)(Marshal.PtrToStructure(m.LParam, typeof(NMHDR)));
            switch (nmhdrI.code)
            {
                case -754: // Win32Messages.DTN_DROPDOWN
                    var cal = SendMessage(m.HWnd, WinApi.Win32Messages.DTM_GETMONTHCAL, IntPtr.Zero, IntPtr.Zero);
                    SendMessage(cal, WinApi.Win32Messages.MCM_SETCURRENTVIEW, IntPtr.Zero, (IntPtr)1);
                    break;
                case -759: // Win32Messages.DTN_DATETIMECHANGE
                    WinApi.SendMessage(Handle, WinApi.Win32Messages.DTM_CLOSEMONTHCAL, IntPtr.Zero, IntPtr.Zero);
                    break;
            }
        }
    }
    base.WndProc(ref m);
}

如何设置datetimepicker下拉列表以仅显示Months

5 个答案: