如果用户点击DateTimePicker日历中的日期，如何识别 [英] how to identity if user clicked on a date in DateTimePicker calendar

问题描述

当用户点击日历而不点击日期时，我不希望更改日期。问题是在Datepickercalendar打开时始终选择One Date。我正在寻找类似于日历控件中的DateSelected事件的类型。

I don't want the date to change when user clicks out of the calender without clicking on a date. The problem is One Date is always selected when the datepickercalendar opens up. I am looking for something similar to DateSelected event in the Calender control

我有一个派生自DateTimePicker的类，它使用带有空格键的自定义格式来具有空字段DateTimePicker。

I have a class that derives from DateTimePicker which uses custom format with a spacechar string for to have empty field for DateTimePicker.

我在stackoverflow中找到了一个同样问题的文章，但解决方案不工作。我没有足够的分数来发表评论（无法找到链接现在:(）

I found an article in stackoverflow with same issue but the solution doesnot work. I don't have enough points to place comments either (unable to find the link now :( )

至于代码这是我有的

Public Class CustomDP
    Inherits System.Windows.Forms.DateTimePicker

    Public Sub New()
        CustomFormat = " "
        Format = System.Windows.Forms.DateTimePickerFormat.Custom
    End Sub

    Protected Overrides Sub OnValueChanged(eventargs As System.EventArgs)
        MyBase.OnValueChanged(eventargs)
    End Sub

    Protected Overrides Sub OnCloseUp(eventargs As System.EventArgs)
        Format = DateTimePickerFormat.Short
        MyBase.OnCloseUp(eventargs)
    End Sub

    Protected Overrides Sub OnDropDown(eventargs As System.EventArgs)
        Format = DateTimePickerFormat.Custom
        MyBase.OnDropDown(eventargs)
    End Sub
End Class

推荐答案

CodeProject上已经有至少一个$ code> DateTimePicker 控件，该对象允许一个Nullable Date。但是有一个比这更简单的方法。

There is already at least 1 DateTimePicker control on CodeProject which allows for a Nullable Date. But there is a simpler method than that.

在设计中，将 ShowCheckBox 设置为True。然后当表单加载或重新设置字段时，将选中设置为False。这使得DTP看起来被禁用，这是不幸的，但是当用户打开DTP时，将自动检查复选框。所以，所有你需要做的，看他们是否选择一个日期，是评估检查属性。禁用的外观最终表明，该值无法真正计数，如果它们在选择有效日期后有可能取消选中。

In design, set the ShowCheckBox to True. Then when the form loads or you are resetting fields, set Checked to False. This makes the DTP look disabled which is a little unfortunate, but when the user opens the DTP, the Checkbox is automatically checked. So, all you need to do to see if they picked a date, is to evaluate the Checked property. The disabled appearance ends up indicating that the value doesnt really count, if they should happen to uncheck it after selecting a valid date.

如果您使用较小的版本（ ShowUpDown ），控件 被禁用，直到他们首先点击该复选框，然后选择一个字段来旋转。您仍然可以为每个字段的每个更改获取值更改的事件，但这是如何应用的。控件始终具有有效的日期值，因此您不必检查 Nothing 等。

If you use the smaller version (ShowUpDown), the control is disabled until they first click the checkbox, then select a field to spin thru. You will still get a value changed event for each change of each field, but thats how it is supposed to work. The control always has a valid date value so you dont have to check against Nothing etc.

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