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/**
* Namespace: System.Web.UI.WebControls
* Class: CheckBox
*
* Author: Gaurav Vaish
* Maintainer: gvaish@iitk.ac.in
* Contact: <my_scripts2001@yahoo.com>, <gvaish@iitk.ac.in>
* Implementation: yes
* Status: 100%
*
* (C) Gaurav Vaish (2001)
* Thanks to Leen Toelen (toelen@hotmail.com)'s classes that helped me
* to write the contents of the function LoadPostData(...)
*/
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Globalization;
using System.Web;
using System.Web.UI;
using System.ComponentModel;
namespace System.Web.UI.WebControls
{
[DefaultEvent("CheckedChanged")]
[DefaultProperty("Text")]
//[DataBindingHanlder("??")]
//[Designer("??")]
public class CheckBox : WebControl, IPostBackDataHandler
{
private static readonly object CheckedChangedEvent = new object();
public CheckBox(): base(HtmlTextWriterTag.Input)
{
}
public virtual bool AutoPostBack
{
get {
object o = ViewState ["AutoPostBack"];
return (o == null) ? false : (bool) o;
}
set { ViewState ["AutoPostBack"] = value; }
}
public virtual bool Checked
{
get {
object o = ViewState ["Checked"];
return (o == null) ? false : (bool) o;
}
set { ViewState ["Checked"] = value; }
}
public virtual string Text
{
get {
object o = ViewState ["Text"];
return (o == null) ? String.Empty : (string) o;
}
set { ViewState ["Text"] = value; }
}
private bool SaveCheckedViewState
{
get {
if (Events [CheckedChangedEvent] != null){
if (!Enabled)
return true;
Type type = GetType ();
if (type == typeof (CheckBox))
return false;
if (type == typeof (RadioButton))
return false;
}
return true;
}
}
public virtual TextAlign TextAlign
{
get {
object o = ViewState ["TextAlign"];
return (o == null) ? TextAlign.Right : (TextAlign) o;
}
set {
if (!System.Enum.IsDefined (typeof (TextAlign), value))
throw new ArgumentException ();
ViewState ["TextAlign"] = value;
}
}
public event EventHandler CheckedChanged
{
add { Events.AddHandler (CheckedChangedEvent, value); }
remove { Events.RemoveHandler (CheckedChangedEvent, value); }
}
protected virtual void OnCheckedChanged(EventArgs e)
{
if(Events != null){
EventHandler eh = (EventHandler) (Events [CheckedChangedEvent]);
if(eh != null)
eh (this, e);
}
}
protected override void OnPreRender(EventArgs e)
{
if (Page != null && Enabled)
Page.RegisterRequiresPostBack (this);
if (SaveCheckedViewState)
ViewState.SetItemDirty ("checked", false);
}
protected override void Render (HtmlTextWriter writer)
{
bool hasBeginRendering = false;
if(ControlStyleCreated && !ControlStyle.IsEmpty){
hasBeginRendering = true;
ControlStyle.AddAttributesToRender (writer, this);
}
if (!Enabled){
hasBeginRendering = true;
writer.AddAttribute (HtmlTextWriterAttribute.Disabled, "disabled");
}
if (ToolTip.Length > 0){
hasBeginRendering = true;
writer.AddAttribute (HtmlTextWriterAttribute.Title, ToolTip);
}
if (Attributes.Count > 0){
string val = Attributes ["value"];
Attributes.Remove ("value");
if (Attributes.Count > 0){
hasBeginRendering = true;
Attributes.AddAttributes (writer);
}
if (val != null)
Attributes ["value"] = val;
}
if (hasBeginRendering)
writer.RenderBeginTag (HtmlTextWriterTag.Span);
if (Text.Length > 0){
TextAlign ta = TextAlign;
if(ta == TextAlign.Right)
RenderInputTag (writer, ClientID);
writer.AddAttribute (HtmlTextWriterAttribute.For, ClientID);
writer.RenderBeginTag (HtmlTextWriterTag.Label);
writer.Write (Text);
writer.RenderEndTag ();
if(ta == TextAlign.Left)
RenderInputTag (writer, ClientID);
}
else
RenderInputTag (writer, ClientID);
if (hasBeginRendering)
writer.RenderEndTag ();
}
internal virtual void RenderInputTag (HtmlTextWriter writer, string clientId)
{
writer.AddAttribute (HtmlTextWriterAttribute.Id, clientId);
writer.AddAttribute( HtmlTextWriterAttribute.Type, "checkbox");
writer.AddAttribute (HtmlTextWriterAttribute.Name, UniqueID);
if (Checked)
writer.AddAttribute (HtmlTextWriterAttribute.Checked, "checked");
if (AutoPostBack){
writer.AddAttribute (HtmlTextWriterAttribute.Onclick,
Page.GetPostBackClientEvent (this, String.Empty));
writer.AddAttribute ("language", "javascript");
}
if (AccessKey.Length > 0)
writer.AddAttribute (HtmlTextWriterAttribute.Accesskey, AccessKey);
if (TabIndex != 0)
writer.AddAttribute (HtmlTextWriterAttribute.Tabindex,
TabIndex.ToString (NumberFormatInfo.InvariantInfo));
writer.RenderBeginTag (HtmlTextWriterTag.Input);
writer.RenderEndTag ();
}
bool IPostBackDataHandler.LoadPostData (string postDataKey, NameValueCollection postCollection)
{
string postedVal = postCollection [postDataKey];
bool postChecked = false;
if(postedVal != null)
postChecked = postedVal.Length > 0;
Checked = postChecked;
return (postChecked == false);
}
void IPostBackDataHandler.RaisePostDataChangedEvent()
{
OnCheckedChanged (EventArgs.Empty);
}
}
}
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