Calendar.OnVisibleMonthChanged(DateTime, DateTime) 方法

定义

引发 VisibleMonthChanged 控件的 Calendar 事件并使您可以为 VisibleMonthChanged 事件提供自定义处理程序。Raises the VisibleMonthChanged event of the Calendar control and allows you to provide a custom handler for the VisibleMonthChanged event.

protected:
 virtual void OnVisibleMonthChanged(DateTime newDate, DateTime previousDate);
protected virtual void OnVisibleMonthChanged (DateTime newDate, DateTime previousDate);
abstract member OnVisibleMonthChanged : DateTime * DateTime -> unit
override this.OnVisibleMonthChanged : DateTime * DateTime -> unit
Protected Overridable Sub OnVisibleMonthChanged (newDate As DateTime, previousDate As DateTime)

参数

newDate
DateTime

一个 DateTime,表示 Calendar 中当前显示的月份。A DateTime that represents the month currently displayed in the Calendar.

previousDate
DateTime

一个 DateTime,表示由 Calendar 显示的前一月。A DateTime that represents the previous month displayed by the Calendar.

示例

下面的代码示例演示如何为事件指定和编写处理程序, VisibleMonthChanged 以显示该事件是 Calendar 向前还是向后移动一个月。The following code example demonstrates how to specify and code a handler for the VisibleMonthChanged event to display whether the Calendar has moved forward or backward one month.

<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">
    <title> Calendar VisibleMonthChanged Example </title>
<script runat="server">

      void MonthChange(Object sender, MonthChangedEventArgs e) 
      {

         if (e.NewDate.Month > e.PreviousDate.Month)
         { 
            Message.Text = "You moved forward one month.";
         }
         else
         {
            Message.Text = "You moved backwards one month.";
         }

      }
         
   </script>
 
</head>
 
<body>
 
   <form id="form1" runat="server">

      <h3> Calendar VisibleMonthChanged Example </h3>
       
      Select a different month on the calendar. 
      <br /><br />
 
      <asp:Calendar id="Calendar1" runat="server"
           OnVisibleMonthChanged="MonthChange">

         <WeekendDayStyle BackColor="gray">
         </WeekendDayStyle>

      </asp:Calendar>

      <hr /> 

      <table border="1">

         <tr style="background-color:Silver">

            <th>

               Month navigation direction

            </th>
         </tr>

         <tr>

            <td>
           
               <asp:Label id="Message" 
                    Text="Starting month." 
                    runat="server"/>

            </td>

         </tr>

      </table>
                   
   </form>
         
</body>

</html>
   
<%@ Page Language="VB" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">
    <title> Calendar VisibleMonthChanged Example </title>
<script runat="server">

      Sub MonthChange(sender As Object, e As MonthChangedEventArgs) 

         If e.NewDate.Month > e.PreviousDate.Month Then
         
            Message.Text = "You moved forward one month."
         
         Else
         
            Message.Text = "You moved backwards one month."
       
         End If

      End Sub
         
   </script>
 
</head>
 
<body>
 
   <form id="form1" runat="server">

      <h3> Calendar VisibleMonthChanged Example </h3>
       
      Select a different month on the calendar. 
      <br /><br />
 
      <asp:Calendar id="Calendar1" runat="server"
           OnVisibleMonthChanged="MonthChange">

         <WeekendDayStyle BackColor="gray">
         </WeekendDayStyle>

      </asp:Calendar>

      <hr /> 

      <table border="1">

         <tr style="background-color:Silver">

            <th>

               Month navigation direction

            </th>
         </tr>

         <tr>

            <td>
           
               <asp:Label id="Message" 
                    Text="Starting Month." 
                    runat="server"/>

            </td>

         </tr>

      </table>
                   
   </form>
         
</body>

</html>
   
<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">
    <title> Calendar VisibleMonthChanged Example </title>
<script runat="server">

      void MonthChange(Object sender, MonthChangedEventArgs e) 
      {

         if (e.NewDate.Month > e.PreviousDate.Month)
         { 
            Message.Text = "You moved forward one month.";
         }
         else
         {
            Message.Text = "You moved backwards one month.";
         }

      }
         
   </script>
 
</head>
 
<body>
 
   <form id="form1" runat="server">

      <h3> Calendar VisibleMonthChanged Example </h3>
       
      Select a different month on the calendar. 
      <br /><br />
 
      <asp:Calendar id="Calendar1" runat="server"
           OnVisibleMonthChanged="MonthChange">

         <WeekendDayStyle BackColor="gray">
         </WeekendDayStyle>

      </asp:Calendar>

      <hr /> 

      <table border="1">

         <tr style="background-color:Silver">

            <th>

               Month navigation direction

            </th>
         </tr>

         <tr>

            <td>
           
               <asp:Label id="Message" 
                    Text="Starting month." 
                    runat="server"/>

            </td>

         </tr>

      </table>
                   
   </form>
         
</body>

</html>
   
<%@ Page Language="VB" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">
    <title> Calendar VisibleMonthChanged Example </title>
<script runat="server">

      Sub MonthChange(sender As Object, e As MonthChangedEventArgs) 

         If e.NewDate.Month > e.PreviousDate.Month Then
         
            Message.Text = "You moved forward one month."
         
         Else
         
            Message.Text = "You moved backwards one month."
       
         End If

      End Sub
         
   </script>
 
</head>
 
<body>
 
   <form id="form1" runat="server">

      <h3> Calendar VisibleMonthChanged Example </h3>
       
      Select a different month on the calendar. 
      <br /><br />
 
      <asp:Calendar id="Calendar1" runat="server"
           OnVisibleMonthChanged="MonthChange">

         <WeekendDayStyle BackColor="gray">
         </WeekendDayStyle>

      </asp:Calendar>

      <hr /> 

      <table border="1">

         <tr style="background-color:Silver">

            <th>

               Month navigation direction

            </th>
         </tr>

         <tr>

            <td>
           
               <asp:Label id="Message" 
                    Text="Starting Month." 
                    runat="server"/>

            </td>

         </tr>

      </table>
                   
   </form>
         
</body>

</html>
   

注解

VisibleMonthChanged当用户单击标题部分中的下个月或上个月导航元素时,将引发事件。The VisibleMonthChanged event is raised when the user clicks the next or previous month navigation elements on the title section.

引发事件时,将通过委托调用事件处理程序。Raising an event invokes the event handler through a delegate. 有关详细信息,请参阅 处理和引发事件For more information, see Handling and Raising Events.

OnVisibleMonthChanged 方法还允许派生类对事件进行处理而不必附加委托。The OnVisibleMonthChanged method also allows derived classes to handle the event without attaching a delegate. 这是在派生类中处理事件的首选技术。This is the preferred technique for handling the event in a derived class.

继承者说明

在派生类中重写 OnVisibleMonthChanged(DateTime, DateTime) 时,一定要调用基类的 OnVisibleMonthChanged(DateTime, DateTime) 方法,以便已注册的委托对事件进行接收。When overriding OnVisibleMonthChanged(DateTime, DateTime) in a derived class, be sure to call the base class's OnVisibleMonthChanged(DateTime, DateTime) method so that registered delegates receive the event.

适用于

另请参阅