asp.net 的ComboBox 可输入可选择下拉列表
using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Collections;
using System.Web.UI.Design;
[assembly: TagPrefix("AtomNet.Web.UI.WebControls", "AtomNet")]
namespace AtomNet.Web.UI.WebControls
{
/// <summary>
/// Represents a control that allows the user to select a single item from a drop-down list,
/// or type in a new value that is not in the list.
/// </summary>
/// <remarks>
/// Since the ComboBox control inherits from <see cref="System.Web.UI.WebControls.ListBox"/>,
/// you can use it in exactly the same manner (including DataBinding).
/// For older browsers that do not support the functionality required to render this control,
/// a normal dropdown box will be emitted instead.
/// </remarks>
[ToolboxData("<{0}:ComboBox runat=\"server\"></{0}:ComboBox>")]
[ValidationPropertyAttribute("SelectedValue")]
[Designer(typeof(AtomNet.Web.UI.WebControls.ComboBoxDesigner))]
public class ComboBox : System.Web.UI.WebControls.ListBox
{
#region 私有属性
/// <summary>
/// The <see cref="System.Web.UI.WebControls.TextBox"/> used internally to allow the user
/// to type in new values.
/// </summary>
TextBox textBox = new TextBox();
/// <summary>
/// Indicates if the current browser supports rendering the ComboBox.
/// </summary>
bool isSupportedBrowser = false;
/// <summary>
/// The maximum number of characters that a user can manually type in
/// </summary>
int maxLength = 0;
/// <summary>
/// Indicates if the ComboBox control should use the AutoFill technique
/// </summary>
bool enableAutoFill = false;
/// <summary>
/// The path to an external .js file that contains all of the javascript functions
/// needed by this control. If this is not set (the default behavior), then the
/// javascript is emitted inline.
/// </summary>
string externalResourcePath = null;
/// <summary>
/// The ID of the containing control
/// </summary>
string masterID = "combobox";
/// <summary>
/// The client ID of the containing control
/// </summary>
string masterClientID;
#endregion
#region 公共属性
/// <summary>
/// Gets or sets the index of the selected item in the DropDownList control.
/// </summary>
/// <value>
/// The index of the selected item in the control. The default value is 0, which
/// selects the first item in the list.
/// </value>
/// <remarks>
/// If the current browser supports rendering this control as a ComboBox,
/// then this property will always return '-1'. Since the value can be typed
/// in, the value may not exist in the Items collection, so SelectedIndex
/// does not apply.
/// If you set the SelectedIndex property, the value will be set even if the
/// control is rendered as a ComboBox.
/// </remarks>
public override int SelectedIndex
{
get
{
if (this.isSupportedBrowser)
return -1;
else
return base.SelectedIndex;
}
set
{
base.SelectedIndex = value;
}
}
/// <summary>
/// Gets the selected item with the lowest index in the list control.
/// </summary>
/// <remarks>
/// If the current browser supports rendering this control as a ComboBox,
/// then this property will always return <c>null</c>. Since the value can be typed
/// in, the value may not exist in the Items collection, so SelectedItem
/// does not apply.
/// </remarks>
public override ListItem SelectedItem
{
get
{
if (this.isSupportedBrowser)
{
if (base.Items.FindByText(this.textBox.Text) != null)
{
return base.Items.FindByText(this.textBox.Text);
}
else
{
return null;
}
}
else
{
return base.SelectedItem;
}
}
}
/// <summary>
/// Gets the value of the selected item in the list control, or selects the item
/// in the list control that contains the specified value.
/// </summary>
public override string SelectedValue
{
get
{
if (this.isSupportedBrowser)
{
if (this.SelectedItem != null)
{
return this.SelectedItem.Value;
}
else
{
return this.textBox.Text;
}
}
else
{
return base.SelectedValue;
}
}
set
{
if (this.isSupportedBrowser)
this.textBox.Text = value;
else
{
// we need a try...catch here in case the selected value was typed
// in and thus does not exist in the Items collection
try
{
base.SelectedValue = value;
}
catch
{
// swallow the exception
}
}
}
}
#endregion
#region ComboBox构造函数
/// <summary>
/// Initializes a new instance of the ComboBox control
/// </summary>
public ComboBox()
{
// determine if the current browser supports rendering the ComboBox
// (this wont work in design-time, so lets skip it)
CheckBrowserCapabilities();
}
#endregion
#region 重写 OnInit
/// <summary>
/// Initializes the ComboBox control
/// </summary>
/// <param name="e">The <see cref="EventArgs"/> passed to this method</param>
protected override void OnInit(EventArgs e)
{
base.OnInit(e);
this.masterID = this.ID;
this.masterClientID = this.ClientID;
// this makes the ListBox act like a DropDownList
// (we cant just use DropDownList because it does not support adding child controls)
this.SelectionMode = ListSelectionMode.Single;
this.Rows = 1;
// if the current browser supports rendering of the ComboBox, we need to set up
// the internal TextBox control
if (this.isSupportedBrowser)
{
// if we are rendering a ComboBox, we change the ID of the dropdown so
// that we can give the ID to the TextBox (this is required so that the control
// works with validators)
this.ID = String.Format("{0}_dropdown", this.masterID);
this.textBox.ID = String.Format("{0}", this.masterID);
this.Controls.Add(textBox);
}
}
#endregion
#region 重写OnPreRender
/// <summary>
/// Raises the PreRender event.
/// </summary>
/// <remarks>
/// The common javascript functions must be dealt with here because 'RegisterClientScriptBlock'
/// cannot be called from the Render method (it is too late in the lifesycle).
/// </remarks>
/// <param name="e">An <see cref="EventArgs"/> object that contains the event data.</param>
protected override void OnPreRender(EventArgs e)
{
if (this.Visible && this.isSupportedBrowser)
{
// if the javascript is in an external file, render a link to it.
// otherwise, emit the javascript inline.
if (this.externalResourcePath != null)
{
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(),"combobox_external_functions", String.Format("<script language='javascript' type='text/javascript' src='{0}'></script>", this.ResolveUrl(this.externalResourcePath)));
}
else
{
// however, if another control has already linked in the external file, we
// cant emit the inline javascript because it will conflict. if that is the case,
// we dont have to do anything because it is already all handled.
if (!this.Page.ClientScript.IsClientScriptBlockRegistered("combobox_external_functions"))
{
// register the common javascript needed by all instances of the ComboBox control
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(),"combobox_basic_functions", javascriptBasicFunctions);
// if autofill is on, emit the necessary javascript
// (we dont emit it if we dont need it to save on bandwidth)
if (this.enableAutoFill)
{
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(),"combobox_autofill_functions", javascriptAutoFillFunctions);
}
}
}
}
else
{
base.OnPreRender(e);
}
}
#endregion
#region 重写Render
/// <summary>
/// Renders the control as HTML.
/// </summary>
/// <remarks>
/// If the current browser does not support the functionality required to render the
/// ComboBox, a normal <see cref="ListBox"/> will be rendered instead.
/// </remarks>
/// <param name="writer">The <see cref="HtmlTextWriter"/> to which to emit the resulting HTML.</param>
protected override void Render(HtmlTextWriter writer)
{
if (this.Visible && this.isSupportedBrowser)
{
// to make the control look correct, we have to pass all of the dropdown's
// visual properties to the textbox as well.
this.textBox.BackColor = this.BackColor;
this.textBox.BorderColor = this.BorderColor;
this.textBox.BorderStyle = this.BorderStyle;
this.textBox.BorderWidth = this.BorderWidth;
this.textBox.CssClass = this.CssClass;
this.textBox.Enabled = this.Enabled;
this.textBox.Font.Bold = this.Font.Bold;
this.textBox.Font.Italic = this.Font.Italic;
this.textBox.Font.Name = this.Font.Name;
this.textBox.Font.Names = this.Font.Names;
this.textBox.Font.Overline = this.Font.Overline;
this.textBox.Font.Size = this.Font.Size;
this.textBox.Font.Strikeout = this.Font.Strikeout;
this.textBox.Font.Underline = this.Font.Underline;
this.textBox.ForeColor = this.ForeColor;
this.textBox.Height = this.Height;
this.textBox.TabIndex = this.TabIndex;
this.textBox.Width = this.Width;
// handle the default value
if (this.SelectedItem != null)
this.textBox.Text = this.SelectedItem.Text;
// handle the maximum length
this.textBox.MaxLength = this.maxLength;
// dont allow the dropdown box to get the focus if this is a ComboBox
this.TabIndex = -1;
// register the javascript specific to this instance of the ComboBox
this.Page.ClientScript.RegisterStartupScript(this.GetType(),this.masterClientID, String.Format(initializationScriptFormat, this.masterClientID));
// hook up the javascript 'onchange' event of the dropdown.
string onChangeCommand = String.Format("combobox_dropdown_onchange('{0}');", this.masterClientID);
this.Attributes.Add("onchange", onChangeCommand);
// hook up the javascript 'onkeyup' event of the textbox, if we are using autofill
if (this.enableAutoFill)
{
this.textBox.Attributes.Add("onkeyup", String.Format("return combobox_textbox_autofill_onkeyup('{0}', event);", this.masterClientID));
}
// hook up the javascript 'onkeydown' event of the text box. this makes sure the
// selectedIndex gets removed properly if a new value is typed in
this.textBox.Attributes.Add("onkeydown", String.Format("return combobox_textbox_onkeydown('{0}', event);", this.masterClientID));
// this is mainly used with 'GridLayout' where the designer has already set some
// styles that position this element
string existingStyle = this.Attributes["style"];
// these 'style' attributes are responsible (with some of the javascript initialization)
// for making sure the control renders properly
this.Attributes.Add("style", String.Format("position:absolute;top:0px;left:0px;visibility:hidden;{0}", (!this.Width.IsEmpty ? String.Format("width:{0};", this.Width.ToString()) : "")));
this.textBox.Attributes.Add("style", String.Format("position:relative;top:0px;left:0px;z-index:200;{0}", (!this.Width.IsEmpty ? String.Format("width:{0};", this.Width.ToString()) : "")));
// render the control
writer.Write(String.Format("<table cellpadding=\"0\" cellspacing=\"0\" border=\"0\" id=\"{2}_container\" name=\"{2}_container\" style=\"margin:0px;padding:0px;display:inline;vertical-align:-4px;{0}{1}\"><tr><td><div style=\"position:relative;\">", (!this.Width.IsEmpty ? String.Format("width:{0};", this.Width.ToString()) : ""), existingStyle, this.masterClientID));
base.Render(writer);
this.textBox.RenderControl(writer);
writer.Write("</div></td></tr></table>");
}
else
{
// if the ComboBox is not supported by the current browser, just render
// a plain old ListBox. we also do this if the control is in design-mode
base.Render(writer);
}
}
#endregion
#region CheckBrowserCapabilities()
/// <summary>
/// Checks the current browser to determine if it supports the functionality required
/// to render the ComboBox.
/// </summary>
/// <remarks>
/// This is currently coded to emit the ComboBox in IE 5+, Netscape 6+, Mozilla 1+,
/// and Firefox 1+. These were the only browsers that I could accurately verify that
/// the ComboBox rendered correctly in.
/// All other browsers will get a standard <see cref="ListBox"/> control.
/// If you can verify that other browsers support the rendering requirements (like Opera,
/// etc), then you can modify this method OR your browser capabilities section in the
/// machine.config.
/// </remarks>
private void CheckBrowserCapabilities()
{
bool result = false;
if (HttpContext.Current != null)
{
if (HttpContext.Current.Request.Browser.JavaScript)
{
// allow IE 5+
if (HttpContext.Current.Request.Browser.W3CDomVersion.Major >= 1)
{
result = true;
}
else
{
// allow NS 5+, MZ 1+, and FireFox 1+
if (HttpContext.Current.Request.Browser.Browser == "Netscape" && HttpContext.Current.Request.Browser.MajorVersion >= 5)
{
result = true;
}
}
}
}
this.isSupportedBrowser = result;
}
#endregion
#region 放在工具箱上的属性
/// <summary>
/// Indicates if the current browser supports rendering the control as a ComboBox or not
/// </summary>
/// <value>
/// <c>true</c> if the browser supports rendering the ComboBox control;
/// <c>false</c> if the browser is incapable of rendering the ComboBox control.
/// </value>
/// <remarks>
/// If the current browser does NOT support rendering the ComboBox control, a simple
/// <see cref="ListBox"/> control will be rendered instead.
/// </remarks>
[Description("Indicates if the current browser supports rendering the control as a ComboBox or not."),
Browsable(true),
Category("Behavior")]
public bool IsSupportedBrowser
{
get
{
return this.isSupportedBrowser;
}
set
{
this.isSupportedBrowser = value;
}
}
/// <summary>
/// Indicates if the ComboBox should use the AutoFill technique
/// </summary>
/// <value>
/// <c>true</c> if the control should AutoFill;
/// <c>false</c> otherwise [default].
/// </value>
/// <remarks>
/// If the current browser does NOT support rendering the ComboBox control, this
/// property has no effect.
/// </remarks>
[Description("Indicates if the ComboBox should use the AutoFill technique."),
Browsable(true),
Category("Behavior")]
public bool EnableAutoFill
{
get
{
return this.enableAutoFill;
}
set
{
this.enableAutoFill = value;
}
}
/// <summary>
/// Gets or sets the maximum number of characters allowed to be manually entered.
/// </summary>
/// <value>
/// The maxumum number of characters allowed to be manually entered.
/// The default is 0, which indicates that the property is not set.
/// </value>
/// <remarks>
/// If the current browser does not support rendering of the ComboBox, this
/// property has no effect.
/// </remarks>
[Description("Gets or sets the maximum number of characters allowed to be manually entered."),
Browsable(true),
Category("Behavior")]
public int MaxLength
{
get
{
return this.maxLength;
}
set
{
this.maxLength = value;
}
}
/// <summary>
/// Sets the path to an external .js file that contains all of the javascript
/// required by this control. If not set, the javascript will be emitted inline.
/// </summary>
/// <value>
/// The valid path to the .js file, or <c>null</c>.
/// </value>
/// <remarks>
/// If the current browser does not support rendering of the ComboBox, this
/// property has no effect.
/// </remarks>
[Description("Sets the path to an external .js file that contains all of the javascript required by this control. If not set, the javascript will be emitted inline."),
Browsable(true),
Category("Behavior")]
public string ExternalResourcePath
{
get
{
return this.externalResourcePath;
}
set
{
this.externalResourcePath = value;
}
}
#endregion
#region js脚本
/// <summary>
/// The format of the javascript that will be emitted for each ComboBox control that
/// is placed on the page.
/// </summary>
private static string initializationScriptFormat = "<script type='text/javascript'>combobox_initialize('{0}');</script>";
/// <summary>
/// The basic javascript that needs to be emitted once per page that contains any ComboBox
/// controls.
/// (This would be nice if it were not in the compiled code so that it could be edited/
/// updated with out a recompile. However, in the interest of making this control self-
/// contained and simple for the demo, it is just included here. It could easily be moved
/// to a seperate .js file that is referenced here.)
/// </summary>
private static string javascriptBasicFunctions = @"
<script type='text/javascript'>
<!--
function combobox_initialize(comboboxID)
{
var DROPDOWN_DOWN_ARROW_WIDTH = 18;
var combobox = document.getElementById(comboboxID + '_container');
var combobox_textbox = document.getElementById(comboboxID + '');
var combobox_dropdown = document.getElementById(comboboxID + '_dropdown');
var controlWidth = combobox_dropdown.offsetWidth;
var controlHeight = combobox_dropdown.offsetHeight-6;
var visibleWidth = controlWidth - DROPDOWN_DOWN_ARROW_WIDTH;
var visibleHeight = controlHeight;
combobox_textbox.offsetParent.style.width = (controlWidth) + 'px';
combobox.style.width = (controlWidth) + 'px';
combobox_textbox.style.width = (visibleWidth + 1) + 'px';
combobox_textbox.style.height = visibleHeight + 'px';
combobox_textbox.style.visibility = 'visible';
var szClippingRegion = 'rect (auto auto auto ' + (visibleWidth - 1) + 'px)';
combobox_dropdown.style.overflow = 'hidden';
combobox_dropdown.style.clip = szClippingRegion;
combobox_dropdown.selectedIndex = -1;
combobox_dropdown.style.visibility = 'visible';
// browser specific hacks
if(document.all)
{
combobox_dropdown.style.marginTop = '1px';
}
else
{
combobox.style.verticalAlign = '-6px;'
combobox_textbox.style.paddingLeft = '3px';
}
}
function combobox_dropdown_onchange(comboboxID)
{
var combobox_textbox = document.getElementById(comboboxID + '');
var combobox_dropdown = document.getElementById(comboboxID + '_dropdown');
combobox_textbox.value = combobox_dropdown[combobox_dropdown.selectedIndex].text;
}
function combobox_textbox_onkeydown(comboboxID, e)
{
var combobox_textbox = document.getElementById(comboboxID + '');
var combobox_dropdown = document.getElementById(comboboxID + '_dropdown');
combobox_dropdown.selectedIndex = -1;
return true;
}
//-->
</script>
";
/// <summary>
/// The auto-fill javascript that needs to be emitted once per page that contains any ComboBox
/// controls.
/// (This would be nice if it were not in the compiled code so that it could be edited/
/// updated with out a recompile. However, in the interest of making this control self-
/// contained and simple for the demo, it is just included here. It could easily be moved
/// to a seperate .js file that is referenced here.)
/// </summary>
private static string javascriptAutoFillFunctions = @"
<script type='text/javascript'>
<!--
function combobox_textbox_autofill_onkeyup(comboboxID, e)
{
var charCode = (e.charCode ? e.charCode : e.keyCode);
if(charCode < 32 || (charCode >= 33 && charCode <= 46) || (charCode >= 112 && charCode <= 123))
{
return true;
}
var combobox_textbox = document.getElementById(comboboxID + '');
var combobox_dropdown = document.getElementById(comboboxID + '_dropdown');
combobox_dropdown.selectedIndex = -1;
var searchString = combobox_textbox.value.toUpperCase();
var currentLength = searchString.length;
for(i=0;i<combobox_dropdown.options.length;i++)
{
var option = combobox_dropdown.options[i];
var optionText = option.text.toUpperCase();
if(optionText.indexOf(searchString) == 0)
{
var optionLength = option.text.length;
combobox_textbox.value = option.text;
combobox_selectrange(combobox_textbox, currentLength, optionLength - currentLength);
return false;
break;
}
}
return true;
}
function combobox_selectrange(element, start, length)
{
if(element.createTextRange)
{
var oRange = element.createTextRange();
oRange.moveStart('character', start);
oRange.moveEnd('character', length);
oRange.select();
}
else if(element.setSelectionRange)
{
element.setSelectionRange(start, start + length);
}
element.focus();
};
//-->
</script>
";
#endregion
}
public class ComboBoxDesigner : ControlDesigner, IDataSourceProvider
{
public ComboBoxDesigner()
{
//
// TODO: Add constructor logic here
//
}
#region ControlDesigner
public override string GetDesignTimeHtml()
{
ComboBox component = (ComboBox)base.Component;
return @"<table cellspacing=0 cellpadding=0 border=0>
<tr>
<td style='background-color:white;border:ridge 1px buttonface;' ><input style='border:none;margin-right:1px;margin-left:1px;font-size:9pt;' size='" + component.Width + "' value='" + component.SelectedValue + @"'></td>
<td style='background-color:buttonface;border-top:ridge 1px buttonface;border-bottom:ridge 1px buttonface;border-right:ridge 1px buttonface;'> .. </td>
</tr>
</table>";
}
#endregion
#region Proxies of the properties that are involved in DataBinding
/// <summary>
/// This is a proxy for the DataMember field that is required to attach the DataMemberConverter to.
/// </summary>
public string DataMember
{
get
{
return ((ComboBox)base.Component).DataMember;
}
set
{
((ComboBox)base.Component).DataMember = value;
}
}
/// <summary>
/// This is a proxy for the DataTextField field that is required to attach the DataFieldConverter to.
/// </summary>
public string DataTextField
{
get
{
return ((ComboBox)base.Component).DataTextField;
}
set
{
((ComboBox)base.Component).DataTextField = value;
}
}
/// <summary>
/// This is a proxy for the DataValueField field that is required to attach the DataFieldConverter to.
/// </summary>
public string DataValueField
{
get
{
return ((ComboBox)base.Component).DataValueField;
}
set
{
((ComboBox)base.Component).DataValueField = value;
}
}
/// <summary>
/// This is a proxy for the DataSource field that is required to attach the DataSourceConverter to.
/// This is especially required as it allows us to represent the DataSource property as a string
/// rather then as an object.
/// </summary>
public string DataSource
{
get
{
DataBinding binding = DataBindings["DataSource"];
if (binding != null)
return binding.Expression;
return string.Empty;
}
set
{
if ((value == null) || (value.Length == 0))
base.DataBindings.Remove("DataSource");
else
{
DataBinding binding = DataBindings["DataSource"];
if (binding == null)
binding = new DataBinding("DataSource",
typeof(IEnumerable), value);
else
binding.Expression = value;
DataBindings.Add(binding);
}
OnBindingsCollectionChanged("DataSource");
}
}
#endregion
#region Overrides
/// <summary>
/// Set to false so that the control can't be resized on the form.
/// </summary>
public override bool AllowResize
{
get
{
return false;
}
}
/// <summary>
/// Used to modify the Attributes of the 'Data' related fields such that
/// the correct TypeConverters are added to the Attributes. For some reason
/// adding the attributes directly doesn't work.
/// </summary>
/// <param name="properties">The dictionary</param>
protected override void PreFilterProperties(IDictionary properties)
{
base.PreFilterProperties(properties);
PropertyDescriptor prop = (PropertyDescriptor)properties["DataSource"];
if (prop != null)
{
System.ComponentModel.AttributeCollection runtimeAttributes = prop.Attributes;
// make a copy of the original attributes but make room for one extra attribute ie the TypeConverter attribute
Attribute[] attrs = new Attribute[runtimeAttributes.Count + 1];
runtimeAttributes.CopyTo(attrs, 0);
attrs[runtimeAttributes.Count] = new TypeConverterAttribute(typeof(DataSourceConverter));
prop = TypeDescriptor.CreateProperty(this.GetType(), "DataSource", typeof(string), attrs);
properties["DataSource"] = prop;
}
prop = (PropertyDescriptor)properties["DataMember"];
if (prop != null)
{
System.ComponentModel.AttributeCollection runtimeAttributes = prop.Attributes;
Attribute[] attrs = new Attribute[runtimeAttributes.Count + 1];
// make a copy of the original attributes but make room for one extra attribute ie the TypeConverter attribute
runtimeAttributes.CopyTo(attrs, 0);
attrs[runtimeAttributes.Count] = new TypeConverterAttribute(typeof(DataMemberConverter));
prop = TypeDescriptor.CreateProperty(this.GetType(), "DataMember", typeof(string), attrs);
properties["DataMember"] = prop;
}
prop = (PropertyDescriptor)properties["DataValueField"];
if (prop != null)
{
System.ComponentModel.AttributeCollection runtimeAttributes = prop.Attributes;
Attribute[] attrs = new Attribute[runtimeAttributes.Count + 1];
// make a copy of the original attributes but make room for one extra attribute ie the TypeConverter attribute
runtimeAttributes.CopyTo(attrs, 0);
attrs[runtimeAttributes.Count] = new TypeConverterAttribute(typeof(DataFieldConverter));
prop = TypeDescriptor.CreateProperty(this.GetType(), "DataValueField", typeof(string), attrs);
properties["DataValueField"] = prop;
}
prop = (PropertyDescriptor)properties["DataTextField"];
if (prop != null)
{
System.ComponentModel.AttributeCollection runtimeAttributes = prop.Attributes;
Attribute[] attrs = new Attribute[runtimeAttributes.Count + 1];
// make a copy of the original attributes but make room for one extra attribute ie the TypeConverter attribute
runtimeAttributes.CopyTo(attrs, 0);
attrs[runtimeAttributes.Count] = new TypeConverterAttribute(typeof(DataFieldConverter));
prop = TypeDescriptor.CreateProperty(this.GetType(), "DataTextField", typeof(string), attrs);
properties["DataTextField"] = prop;
}
}
#endregion
#region IDataSourceProvider methods
/// <summary>
/// Used by the DataFieldConverter to resolve the DataSource and DataMember combination
/// so that it can populate a dropdown with a list of available fields.
/// </summary>
IEnumerable IDataSourceProvider.GetResolvedSelectedDataSource()
{
DataBinding binding;
binding = this.DataBindings["DataSource"];
if (binding != null)
return DesignTimeData.GetSelectedDataSource(this.Component, binding.Expression, this.DataMember);
return null;
}
/// <summary>
/// Used by the DataMemberConverter to resolve the DataSource which it can then use
/// to populate a drop down box containing a list of available tables.
/// </summary>
/// <returns>The object that is our DataSource</returns>
object IDataSourceProvider.GetSelectedDataSource()
{
DataBinding binding;
binding = this.DataBindings["DataSource"];
if (binding != null)
return DesignTimeData.GetSelectedDataSource(this.Component, binding.Expression);
return null;
}
#endregion
}
}
