[英]How can I set the DateTimePicker dropdown to select Years or Months only?
Like discussed in How can I set the datetimepicker dropdown to show Months only there was a possibility to overwrite DateTimePicker
to get a MonthPicker
.就像在我如何设置 datetimepicker 下拉列表以仅显示 Months中讨论的那样,有可能覆盖DateTimePicker
以获得MonthPicker
。
I have read a lot of sites but didn't figure out how to do similar to get a YearPicker
.我已经阅读了很多网站,但没有弄清楚如何做类似的事情来获得YearPicker
。
Maybe someone can help out.也许有人可以帮忙。
This Custom Control tweaks a little the standard DateTimePicker to get a Year or Month selection style only.此自定义控件对标准 DateTimePicker 稍作调整,以仅获得年份或月份选择样式。
▶ The standard DateTimePicker's CustomFormat
and Format
properties are disabled , setting internally the former to yyyy
or MMMM
(a simple modification can add different formats) and the latter to DateTimePickerFormat.Custom
. ▶ 标准 DateTimePicker 的CustomFormat
和Format
属性被禁用,在内部将前者设置为yyyy
或MMMM
(简单修改可以添加不同的格式),将后者设置为DateTimePickerFormat.Custom
。 These properties are hidden from the PropertyGrid an cannot be changed.这些属性在 PropertyGrid 中是隐藏的,无法更改。
▶ The browsing functionality is maintained, but limited to the Decade/Year or Decade/Year/Month selection. ▶ 保留浏览功能,但仅限于十年/年或十年/年/月选择。
Clicking the DTP's Title Area, brings on the Decade selector and the previous and next Buttons are of course functional (these can only show years).单击 DTP 的标题区域,打开十年选择器,上一个和下一个按钮当然可以正常工作(这些只能显示年份)。
▶ The DTP is closed and the current value set when a MCN_VIEWCHANGE
notification reveals, passing the current selection level in a NMVIEWCHANGE
structure, that the current selection has reached the View Mode set by the SelectionMode
property. ▶ DTP 关闭并在MCN_VIEWCHANGE
通知显示时设置当前值,通过NMVIEWCHANGE
结构中的当前选择级别,当前选择已达到由SelectionMode
属性设置的查看模式。
This property value is an enumerator which, in turn, reflects the MonthCalendar's MCM_SETCURRENTVIEW
message values.此属性值是一个枚举器,它反过来反映 MonthCalendar 的MCM_SETCURRENTVIEW
消息值。
▶ The current View is set sending a MCM_SETCURRENTVIEW
message to the MonthCalendar control, changing the default View to MCMV_DECADE
or MCMV_YEAR
(depending on the current SelectionMode
) each time the MonthCalendar control is shown. ▶ 当前视图设置为向 MonthCalendar 控件发送MCM_SETCURRENTVIEW
消息,每次显示 MonthCalendar 控件时将默认视图更改为MCMV_DECADE
或MCMV_YEAR
(取决于当前SelectionMode
)。 The opening animation is then preserved.然后保留开口 animation。
▶ The only style changed is MCS_NOTODAY
, set in the OnHandleCreated
method. ▶ 唯一更改的样式是MCS_NOTODAY
,在OnHandleCreated
方法中设置。 It can be switched on/off at any time, calling the ShowMonCalToday()
method.它可以随时打开/关闭,调用ShowMonCalToday()
方法。
This style shows the Today
date, at the bottom of the DateTimerPicker.此样式在 DateTimerPicker 底部显示Today
日期。 It sets the current Year or Month value when clicked.单击时,它会设置当前的年或月值。
This is how it works:这是它的工作原理:
Tested on VisualStudio 2017.在 VisualStudio 2017 上测试。
.Net Framework 4.8 (only). .Net Framework 4.8(仅限)。
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Windows.Forms;
[DesignerCategory("Code")]
public class MonthYearPicker : DateTimePicker
{
private string m_CustomFormat = "yyyy";
private DateTimePickerFormat m_Format = DateTimePickerFormat.Custom;
private SelectionViewMode m_SelectionMode = SelectionViewMode.Year;
private bool m_ShowToday = false;
private IntPtr hWndCal = IntPtr.Zero;
public MonthYearPicker() {
base.CustomFormat = m_CustomFormat;
base.Format = m_Format;
}
[DefaultValue(SelectionViewMode.Year)]
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Appearance"), Description("Set the current selection mode to either Month or Year")]
public SelectionViewMode SelectionMode {
get => m_SelectionMode;
set {
if (value != m_SelectionMode) {
m_SelectionMode = value;
m_CustomFormat = m_SelectionMode == SelectionViewMode.Year ? "yyyy" : "MMMM";
base.CustomFormat = m_CustomFormat;
}
}
}
[DefaultValue(false)]
[Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
[Category("Appearance"), Description("Shows or hides \"Today\" date at the bottom of the Calendar Control")]
public bool ShowToday {
get => m_ShowToday;
set {
if (value != m_ShowToday) {
m_ShowToday = value;
ShowMonCalToday(m_ShowToday);
}
}
}
[DefaultValue("yyyy")]
[Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
public new string CustomFormat {
get => base.CustomFormat;
set => base.CustomFormat = m_CustomFormat;
}
[DefaultValue(DateTimePickerFormat.Custom)]
[Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
public new DateTimePickerFormat Format {
get => base.Format;
set => base.Format = m_Format;
}
protected override void OnHandleCreated(EventArgs e)
{
base.OnHandleCreated(e);
ShowMonCalToday(m_ShowToday);
}
protected override void OnDropDown(EventArgs e)
{
hWndCal = SendMessage(this.Handle, DTM_GETMONTHCAL, 0, 0);
if (hWndCal != IntPtr.Zero) {
SendMessage(hWndCal, MCM_SETCURRENTVIEW, 0, (int)(MonCalStyles)m_SelectionMode);
}
base.OnDropDown(e);
}
private void ShowMonCalToday(bool show)
{
int styles = SendMessage(this.Handle, DTM_GETMCSTYLE, 0, 0).ToInt32();
styles = show ? styles &~(int)MonCalStyles.MCS_NOTODAY : styles | (int)MonCalStyles.MCS_NOTODAY;
SendMessage(this.Handle, DTM_SETMCSTYLE, 0, styles);
}
protected override void WndProc(ref Message m)
{
switch (m.Msg) {
case WM_NOTIFY:
var nmh = (NMHDR)m.GetLParam(typeof(NMHDR));
switch (nmh.code) {
case MCN_VIEWCHANGE:
var nmView = (NMVIEWCHANGE)m.GetLParam(typeof(NMVIEWCHANGE));
if (nmView.dwNewView < (MonCalView)m_SelectionMode) {
SendMessage(this.Handle, DTM_CLOSEMONTHCAL, 0, 0);
}
break;
default:
// NOP: Add more notifications handlers...
break;
}
break;
default:
// NOP: Add more message handlers...
break;
}
base.WndProc(ref m);
}
public enum SelectionViewMode : int
{
Month = MonCalView.MCMV_YEAR,
Year = MonCalView.MCMV_DECADE,
}
// Move to a NativeMethods class, eventually
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
internal static extern IntPtr SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
internal const int WM_NOTIFY = 0x004E;
internal const int MCN_VIEWCHANGE = -750;
internal const int DTM_FIRST = 0x1000;
internal const int DTM_GETMONTHCAL = DTM_FIRST + 8;
internal const int DTM_SETMCSTYLE = DTM_FIRST + 11;
internal const int DTM_GETMCSTYLE = DTM_FIRST + 12;
internal const int DTM_CLOSEMONTHCAL = DTM_FIRST + 13;
internal const int MCM_FIRST = 0x1000;
internal const int MCM_GETCURRENTVIEW = MCM_FIRST + 22;
internal const int MCM_SETCURRENTVIEW = MCM_FIRST + 32;
[StructLayout(LayoutKind.Sequential)]
internal struct NMHDR
{
public IntPtr hwndFrom;
public UIntPtr idFrom;
public int code;
}
[StructLayout(LayoutKind.Sequential)]
internal struct NMVIEWCHANGE
{
public NMHDR nmhdr;
public MonCalView dwOldView;
public MonCalView dwNewView;
}
internal enum MonCalView : int
{
MCMV_MONTH = 0,
MCMV_YEAR = 1,
MCMV_DECADE = 2,
MCMV_CENTURY = 3
}
internal enum MonCalStyles : int
{
MCS_DAYSTATE = 0x0001,
MCS_MULTISELECT = 0x0002,
MCS_WEEKNUMBERS = 0x0004,
MCS_NOTODAYCIRCLE = 0x0008,
MCS_NOTODAY = 0x0010,
MCS_NOTRAILINGDATES = 0x0040,
MCS_SHORTDAYSOFWEEK = 0x0080,
MCS_NOSELCHANGEONNAV = 0x0100
}
}
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