简单服务器端控件 Simple Server Control

Code

namespace CustomTextBox
{
[DefaultProperty("Text")]
[ToolboxData("<{0}:ServerControl1 runat=server></{0}:ServerControl1>")]
public class MyTextBox : WebControl,IPostBackDataHandler
{
[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Text
{
get
{
String s = (String)ViewState["Text"];
return ((s == null) ? "[" + this.ID + "]" : s);
}

set
{
ViewState["Text"] = value;
}
}

public MyTextBox()
: base(HtmlTextWriterTag.Input)
{
Text = "";
}

protected override void AddAttributesToRender(HtmlTextWriter writer)
{
writer.AddAttribute("type", "text");
writer.AddAttribute("name", this.UniqueID);
writer.AddAttribute(HtmlTextWriterAttribute.Value, Text);
writer.AddAttribute("ondblclick", Page.GetPostBackEventReference(this, string.Empty));
base.AddAttributesToRender(writer);
}

protected override void RenderContents(HtmlTextWriter writer)
{
base.RenderContents(writer);
}

// 返回结果:
// 如果服务器控件的状态由于回发而发生更改，则为 true；否则为 false。
public bool LoadPostData(string postDataKey, NameValueCollection postCollection) {
string postedVal = postCollection[postDataKey];
string strText = Text;
if (strText != postedVal)
{
Text = postedVal;
return true;
}
return false;
}

public event EventHandler TextChanged;

protected virtual void OnTextChanged( EventArgs e)
{
if (TextChanged != null)
{
TextChanged(this, e);
}
}

public void RaisePostDataChangedEvent() {
OnTextChanged( new EventArgs());
}

}
}