How can I prevent the firing of multiple events of the same kind triggered by a single action?
For example, I have a ListView containing some items. When I select or deselect all items, the SelectedIndexChanged event is fired once for each item. Rather, I would like to receive a single event indication the user's action (selection/deselection of items), regardless of the number of items.
Is there any way to achieve this?
Only by by coming at the problem from a slightly different direction. E.g. subscribe loss of focus.
In the end, the application or runtime cannot raise an event on "all selection changes done" without actually using something else because there is no way for the application to predict whether the user will perform another click on the control while it retains focus.
Even using focus, the user could switch back to that control.
If your ListView is in virtual mode, you could use the
VirtualItemsSelectionRangeChanged event. This event will be fired only once for the user's action (selection/deseclection).
You can't change the ListView code, and subclassing it doesn't provide many options.
I would suggest that you simply add a small delay (200ms or similar) to your code - i.e. you only do the calculation a little while after the last update. Something like:
using System;
using System.Windows.Forms;
static class Program {
[STAThread]
static void Main() {
Application.EnableVisualStyles();
ListView list;
TextBox txt;
Timer tmr = new Timer();
tmr.Interval = 200;
Form form = new Form {
Controls = {
(txt = new TextBox { Dock = DockStyle.Fill, Multiline = true}),
(list = new ListView { Dock = DockStyle.Right, View = View.List,
Items = { "abc", "def" , "ghi", "jkl", "mno" , "pqr"}})
}
};
list.SelectedIndexChanged += delegate {
tmr.Stop();
tmr.Start();
};
tmr.Tick += delegate {
tmr.Stop();
txt.Text += "do work on " + list.SelectedItems.Count + " items"
+ Environment.NewLine;
};
Application.Run(form);
}
}
i had a same type of problem n did't found a solution yet...plz help...i'm a new bee in c#.net.this is my code........
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Registration.aspx.cs" Inherits="_Default" %>
<%@ Register assembly="DevExpress.Web.ASPxEditors.v9.2, Version=9.2.9.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" namespace="DevExpress.Web.ASPxEditors" tagprefix="dxe" %>
Registration Page
.style1
{
width: 100%;
height: 501px;
}
.style2
{
width: 112px;
}
.style3
{
width: 112px;
height: 8px;
}
.style4
{
height: 8px;
}
.style9
{
width: 112px;
height: 3px;
}
.style10
{
height: 3px;
}
.style11
{
width: 112px;
height: 2px;
}
.style12
{
height: 2px;
}
.style13
{
width: 112px;
height: 5px;
}
.style14
{
height: 5px;
}
.style15
{
width: 112px;
height: 1px;
}
.style16
{
height: 1px;
}
.style17
{
width: 112px;
height: 9px;
}
.style18
{
height: 9px;
}
.style19
{
width: 112px;
height: 16px;
}
.style20
{
height: 16px;
}
.style21
{
width: 112px;
height: 10px;
}
.style22
{
height: 10px;
}
                               
<asp:Menu
ID="Menu1" runat="server" BackColor="#B5C7DE" DynamicHorizontalOffset="2"
Font-Names="Verdana" Font-Size="Small" ForeColor="#284E98"
onmenuitemclick="Menu1_MenuItemClick" Orientation="Horizontal"
StaticSubMenuIndent="10px">
<StaticSelectedStyle BackColor="#507CD1" />
<StaticMenuItemStyle HorizontalPadding="5px" VerticalPadding="2px" />
<DynamicHoverStyle BackColor="#284E98" ForeColor="White" />
<DynamicMenuStyle BackColor="#B5C7DE" />
<DynamicSelectedStyle BackColor="#507CD1" />
<DynamicMenuItemStyle HorizontalPadding="5px" VerticalPadding="2px" />
<StaticHoverStyle BackColor="#284E98" ForeColor="White" />
<Items>
<asp:MenuItem Text="Quiz Select" Value="Quiz Select"></asp:MenuItem>
<asp:MenuItem Text="Log Out" Value="Log Out"></asp:MenuItem>
</Items>
</asp:Menu>
<table class="style1" width="70%">
<tr>
<td class="style9">
<asp:Label ID="lblName" runat="server" Text="Name"></asp:Label>
</td>
<td class="style10">
<asp:TextBox ID="txtName" runat="server" Width="200px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
ControlToValidate="txtName" ErrorMessage="*" ValidationGroup="A"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style11">
<asp:Label ID="lblEmail" runat="server" Text="Email"></asp:Label>
</td>
<td class="style12">
<asp:TextBox ID="txtEmail" runat="server" Width="200px"
ontextchanged="Button1_Click"></asp:TextBox>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"
ControlToValidate="txtEmail" ErrorMessage="*"
ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"
ValidationGroup="A"></asp:RegularExpressionValidator>
<asp:Label ID="lblEmailNM" runat="server"></asp:Label>
</td>
</tr>
<tr>
<td class="style13">
<asp:Label ID="lblPassword" runat="server" Text="Password"></asp:Label>
</td>
<td class="style14">
<asp:TextBox ID="txtPassword" runat="server" TextMode="Password" Width="200px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server"
ControlToValidate="txtPassword" ErrorMessage="*" ValidationGroup="A"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style15">
<asp:Label ID="lblConfirmPassword" runat="server" Text="Confirm Password"></asp:Label>
</td>
<td class="style16">
<asp:TextBox ID="txtConfirmPassword" runat="server" TextMode="Password"
Width="200px"></asp:TextBox>
<asp:CompareValidator ID="CompareValidator1" runat="server"
ControlToCompare="txtPassword" ControlToValidate="txtConfirmPassword"
ErrorMessage="*" ValidationGroup="A"></asp:CompareValidator>
</td>
</tr>
<tr>
<td class="style17">
<asp:Label ID="lblGender" runat="server" Text="Gender"></asp:Label>
</td>
<td class="style18">
<asp:RadioButtonList ID="rbGender" runat="server" RepeatDirection="Horizontal">
<asp:ListItem>Male</asp:ListItem>
<asp:ListItem>Female</asp:ListItem>
</asp:RadioButtonList>
</td>
</tr>
<tr>
<td class="style17">
<asp:Label ID="lblDOB" runat="server" Text="DOB"></asp:Label>
</td>
<td class="style18">
<dxe:ASPxDateEdit ID="ASPxDateEdit1" runat="server">
</dxe:ASPxDateEdit>
</td>
</tr>
<tr>
<td class="style19">
<asp:Label ID="lblAddress1" runat="server" Text="Address1"></asp:Label>
</td>
<td class="style20">
<asp:TextBox ID="txtAddress1" runat="server" TextMode="MultiLine" Width="200px"
Height="20px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server"
ControlToValidate="txtAddress1" ErrorMessage="*" ValidationGroup="A"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style3">
<asp:Label ID="lblAddress2" runat="server" Text="Address2"></asp:Label>
</td>
<td class="style4">
<asp:TextBox ID="txtAddress2" runat="server" TextMode="MultiLine" Width="200px"
Height="20px"></asp:TextBox>
</td>
</tr>
<tr>
<td class="style21">
<asp:Label ID="lblCountry" runat="server" Text="Country"></asp:Label>
</td>
<td class="style22">
<asp:DropDownList ID="ddlCountry" runat="server" Height="20px" Width="200px"
onselectedindexchanged="ddlCountry_SelectedIndexChanged">
<asp:ListItem>India</asp:ListItem>
<asp:ListItem>USA</asp:ListItem>
<asp:ListItem>China</asp:ListItem>
<asp:ListItem>France</asp:ListItem>
<asp:ListItem>German</asp:ListItem>
<asp:ListItem>Japan</asp:ListItem>
</asp:DropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server"
ControlToValidate="ddlCountry" ErrorMessage="*" ValidationGroup="A"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style9">
<asp:Label ID="lblState" runat="server" Text="State"></asp:Label>
</td>
<td class="style10">
<asp:DropDownList ID="ddlState" runat="server" Height="20px" Width="200px">
<asp:ListItem>Delhi</asp:ListItem>
<asp:ListItem>Punjab</asp:ListItem>
<asp:ListItem>UP</asp:ListItem>
<asp:ListItem>Haryana</asp:ListItem>
<asp:ListItem>New York</asp:ListItem>
<asp:ListItem>Paris</asp:ListItem>
<asp:ListItem>Tokyo</asp:ListItem>
<asp:ListItem>Bejing</asp:ListItem>
</asp:DropDownList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server"
ControlToValidate="ddlState" ErrorMessage="*" ValidationGroup="A"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style17">
<asp:Label ID="lblCity" runat="server" Text="City"></asp:Label>
</td>
<td class="style18">
<asp:DropDownList ID="ddlCity" runat="server" Height="20px" Width="200px">
<asp:ListItem>New delhi</asp:ListItem>
<asp:ListItem>Amritsar</asp:ListItem>
<asp:ListItem>Gurgaon</asp:ListItem>
<asp:ListItem>Noida</asp:ListItem>
<asp:ListItem>Chandigarh</asp:ListItem>
<asp:ListItem>New York</asp:ListItem>
<asp:ListItem>Paris</asp:ListItem>
</asp:DropDownList>
</td>
</tr>
<tr>
<td class="style2">
</td>
<td>
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Save"
Width="100px" ValidationGroup="A" />
<asp:Label ID="lblRegister" runat="server" Font-Bold="True" Font-Italic="True"
ForeColor="#999966"></asp:Label><asp:LinkButton ID="lnkLogin"
runat="server" onclick="lnkLogin_Click">Back to Login</asp:LinkButton>
<asp:HiddenField ID="HiddenField1" runat="server" />
</td>
</tr>
</table>
</div>
</form>