ControlBuilderAttribute Class
.NET Framework 2.0
Specifies a ControlBuilder class for building a custom control within the ASP.NET parser. This class cannot be inherited.
Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)
Assembly: System.Web (in system.web.dll)
This attribute specifies the builder Type to be used to create a custom control as shown in the following code:
[ControlBuilderAttribute(typeof(ControlBuilderType))]
The following code example creates a customized selection list that is used to display a message based on the SelectedIndex and the Message values defined at run time. The following command line is used to build the executable.
package CustomControls;
/* File name: controlBuilderAttribute.jsl. */
import System.*;
import System.Web.*;
import System.Web.UI.*;
import System.Web.UI.WebControls.*;
import System.Collections.*;
public class MyJSL_Item extends Control
{
/* Class name: MyJSL_Item.
Defines the child control class.
*/
private String _message;
/** @property
*/
public String get_Message()
{
return _message;
} //get_Message
/** @property
*/
public void set_Message(String value)
{
_message = value;
} //set_Message
} //MyJSL_Item
public class CustomParseControlBuilder extends ControlBuilder
{
/* Class name: CustomParserControlBuilder.
Defines the functions and data to be used in building custom controls.
This class is referenced using the ControlBuilderAttribute class.
See class below.
*/
public Type GetChildControlType(String tagName, IDictionary attributes)
{
if (String.Compare(tagName, "customitem", true) == 0) {
return MyJSL_Item.class.ToType();
}
return null;
} //GetChildControlType
} //CustomParseControlBuilder
/** @attribute ControlBuilderAttribute(CustomParseControlBuilder.class)
*/
public class MyJSL_CustomParse extends Control
{
/* Class name: MyJSL_CustomParse.
Performs custom parsing of a MyJSL_CustomParse control type
child control.
If the child control is of the allowed type, it is added to an
array list. This list is accessed, using the container control attribute
SelectedIndex, to obtain the related child control Message attribute
to be displayed.
*/
private ArrayList _items = new ArrayList();
private int _selectedIndex = 0;
/** @property
*/
public int get_SelectedIndex()
{
return _selectedIndex;
} //get_SelectedIndex
/** @property
*/
public void set_SelectedIndex(int value)
{
_selectedIndex = value;
} //set_SelectedIndex
protected void AddParsedSubObject(Object obj)
{
/* Function name: AddParsedSubObject.
Updates the array list with the allowed child objects.
This function is called during the parsing of the child controls and
after the GetChildControlType function defined in the associated control
builder class.
*/
if (obj instanceof MyJSL_Item) {
_items.Add(obj);
}
} //AddParsedSubObject
protected void Render(HtmlTextWriter output)
{
/* Function name: Render.
Establishes the rules to render the built control. In this case,
a message is rendered that is a function of the parent control
SelectedIndex attribute and the related child Message attribute.
*/
if (get_SelectedIndex() < _items.get_Count()) {
output.Write("<span style='background-color:aqua; color:red;"
+ " font:8pt tahoma, verdana;'><b>"
+ ((MyJSL_Item)_items.get_Item(get_SelectedIndex())).get_Message()
+ "</b></span>");
}
} //Render
} //MyJSL_CustomParse
The following example uses the custom control defined above. In particular, it assigns the SelectedIndex and Message values at run time to determine the message to be rendered. Notice that the values shown in the Register directive reflect the previous command line.
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