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//------------------------------------------------------------------------------
// <copyright file="DropDownList.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.UI.WebControls {
using System;
using System.Collections;
using System.ComponentModel;
using System.Collections.Specialized;
using System.Drawing;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls.Adapters;
/// <devdoc>
/// <para>Creates a control that allows the user to select a single item from a
/// drop-down list.</para>
/// </devdoc>
[
SupportsEventValidation,
ValidationProperty("SelectedItem")
]
public class DropDownList : ListControl, IPostBackDataHandler {
/// <devdoc>
/// <para>Initializes a new instance of the <see cref='System.Web.UI.WebControls.DropDownList'/> class.</para>
/// </devdoc>
public DropDownList() {
}
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
[
Browsable(false)
]
public override Color BorderColor {
get {
return base.BorderColor;
}
set {
base.BorderColor = value;
}
}
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
[
Browsable(false)
]
public override BorderStyle BorderStyle {
get {
return base.BorderStyle;
}
set {
base.BorderStyle = value;
}
}
/// <devdoc>
/// <para>[To be supplied.]</para>
/// </devdoc>
[
Browsable(false)
]
public override Unit BorderWidth {
get {
return base.BorderWidth;
}
set {
base.BorderWidth = value;
}
}
public override bool SupportsDisabledAttribute {
get {
return true;
}
}
/// <devdoc>
/// <para>Gets or sets the index of the item selected by the user
/// from the <see cref='System.Web.UI.WebControls.DropDownList'/>
/// control.</para>
/// </devdoc>
[
WebCategory("Behavior"),
DefaultValue(0),
WebSysDescription(SR.WebControl_SelectedIndex),
DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)
]
public override int SelectedIndex {
get {
int selectedIndex = base.SelectedIndex;
if (selectedIndex < 0 && Items.Count > 0) {
Items[0].Selected = true;
selectedIndex = 0;
}
return selectedIndex;
}
set {
base.SelectedIndex = value;
}
}
internal override ArrayList SelectedIndicesInternal {
get {
int sideEffect = SelectedIndex;
return base.SelectedIndicesInternal;
}
}
protected override void AddAttributesToRender(HtmlTextWriter writer) {
string uniqueID = UniqueID;
if (uniqueID != null) {
writer.AddAttribute(HtmlTextWriterAttribute.Name, uniqueID);
}
base.AddAttributesToRender(writer);
}
protected override ControlCollection CreateControlCollection() {
return new EmptyControlCollection(this);
}
/// <internalonly/>
/// <devdoc>
/// <para>Process posted data for the <see cref='System.Web.UI.WebControls.DropDownList'/> control.</para>
/// </devdoc>
bool IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) {
return LoadPostData(postDataKey, postCollection);
}
/// <internalonly/>
/// <devdoc>
/// <para>Process posted data for the <see cref='System.Web.UI.WebControls.DropDownList'/> control.</para>
/// </devdoc>
protected virtual bool LoadPostData(String postDataKey, NameValueCollection postCollection) {
// When a DropDownList is disabled, then there is no postback data for it.
// Since DropDownList doesn't call RegisterRequiresPostBack, this method will
// never be called, so we don't need to worry about ignoring empty postback data.
string [] selectedItems = postCollection.GetValues(postDataKey);
EnsureDataBoundInLoadPostData();
if (selectedItems != null) {
ValidateEvent(postDataKey, selectedItems[0]);
int n = Items.FindByValueInternal(selectedItems[0], false);
if (SelectedIndex != n) {
SetPostDataSelection(n);
return true;
}
}
return false;
}
/// <internalonly/>
/// <devdoc>
/// <para>Raises events for the <see cref='System.Web.UI.WebControls.DropDownList'/> control on post back.</para>
/// </devdoc>
void IPostBackDataHandler.RaisePostDataChangedEvent() {
RaisePostDataChangedEvent();
}
/// <internalonly/>
/// <devdoc>
/// <para>Raises events for the <see cref='System.Web.UI.WebControls.DropDownList'/> control on post back.</para>
/// </devdoc>
protected virtual void RaisePostDataChangedEvent() {
if (AutoPostBack && !Page.IsPostBackEventControlRegistered) {
// VSWhidbey 204824
Page.AutoPostBackControl = this;
if (CausesValidation) {
Page.Validate(ValidationGroup);
}
}
OnSelectedIndexChanged(EventArgs.Empty);
}
protected internal override void VerifyMultiSelect() {
throw new HttpException(SR.GetString(SR.Cant_Multiselect, "DropDownList"));
}
}
}
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