WebPartChrome Class (System.Web.UI.WebControls.WebParts)

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Microsoft Visual Studio 2005/.NET Framework 2.0

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.NET Framework Class Library

WebPartChrome Class

Note: This class is new in the .NET Framework version 2.0.

Enables developers to override the rendering for only the selected sections of WebPart or server controls in a WebPartZoneBase zone.

Namespace: System.Web.UI.WebControls.WebParts
Assembly: System.Web (in system.web.dll)

Syntax

Visual Basic (Declaration)

Public Class WebPartChrome

Visual Basic (Usage)

Dim instance As WebPartChrome

public class WebPartChrome

C++

public ref class WebPartChrome

public class WebPartChrome

JScript

public class WebPartChrome

Remarks

Web Parts chrome refers to the peripheral user interface (UI) elements that frame each WebPart control or server control contained in a WebPartZoneBase zone. The chrome for a control includes its border, its title bar, and the icons, title text, and verbs menu that appear within the title bar. The appearance of the chrome is set at the zone level, and applies to all the server controls in the zone.

The Web Parts control set uses the WebPartChrome class to render the chrome for WebPart controls. Additionally, this class provides a way for developers to customize the rendering of any individual section (such as the header or footer) of the WebPart controls in a WebPartZoneBase zone without having to handle all the rendering for those controls. For example, you can override the CreateWebPartChromeStyle method to customize some specific style attributes applied to the WebPartZoneBase zone, but you can rely on the default rendering to handle the rest.

The WebPartChrome class contains several important methods that are useful when you want to override the rendering of WebPart controls. One is the CreateWebPartChromeStyle method, which enables you to change the style attributes of the Style object associated with the WebPartChrome object used to render a control. Another is the WebPartChrome constructor, which you use when you override the CreateWebPartChrome method in a custom WebPartZoneBase class to create an instance of your custom WebPartChrome object. Another useful method is the RenderPartContents method, which you can use to control the rendering of the content area of controls in a zone (as opposed to chrome elements such as headers, footers, and title bars). The GetWebPartVerbs method enables you to exclude certain verbs from being rendered, if for some reason you do not want users to see those verbs in the UI. Finally, if you want complete programmatic control over all aspects of rendering the WebPart controls, you can override the RenderWebPart method.

Several properties of the WebPartChrome class are also useful. The Zone and WebPartManager properties provide references to the zone associated with the WebPartChrome object and the current WebPartManager instance, respectively.

Notes to Inheritors Inherit from the WebPartChrome class when you want to override the default rendering of certain sections of WebPart or server controls. You can optionally override the CreateWebPartChromeStyle method, the GetWebPartVerbs method, and especially the RenderPartContents or RenderWebPart methods, to customize the rendering. To use your custom WebPartChrome class for the WebPart controls in a zone, develop a custom zone derived from the WebPartZoneBase class, and override its CreateWebPartChrome method. For details on how to use a child WebPartChrome object in a zone, see the Example section.

Example

The following code example demonstrates how to use the WebPartChrome class to override the default rendering of WebPart controls in a WebPartZoneBase zone.

The code example has four parts:

A user control that enables you to change display modes on a Web Parts page.
A Web page that hosts all the controls in the example.
A class that contains the source code for a custom WebPartZoneBase zone and a WebPartChrome class.
An explanation of how the example works.

The first part of the code example is the user control. The source code for the user control comes from another topic. For this code example to work, you need to obtain the .ascx file for the user control from the Walkthrough: Changing Display Modes on a Web Parts Page topic, and place the file in the same folder as the .aspx page in this code example.

The second part of the example is the Web page. Note that there is a Register directive near the top of the file to register the compiled component and a tag prefix. Also note that the page references the custom zone using the element <aspSample:MyZone> and includes several standard ASP.NET server controls within the zone. The server controls do not implement any actual functionality; they are used here only to illustrate how the WebPartChrome class features apply to rendering zones. Note that these server controls, though they are not actual WebPart controls, are each automatically wrapped (by ASP.NET) with a GenericWebPart object at run time, so they will have the same functionality as WebPart controls.

Visual Basic

<%@ Page Language="vb" %>
<%@ Register TagPrefix="uc1" 
  TagName="DisplayModeMenuVB"
  Src="~/DisplayModeMenuVB.ascx" %>
<%@ Register TagPrefix="aspSample" 
  Namespace="Samples.AspNet.VB.Controls" 
  Assembly="MyChromeVB" %>

<html  >
<head runat="server">
</head>
<body>
  <form id="form1" runat="server">
    <asp:WebPartManager ID="WebPartManager1" runat="server" />
    <uc1:DisplayModeMenuVB id="menu1" runat="server" />
    <aspSample:MyZone ID="WebPartZone1" runat="server"
      RenderVerbsInMenu="true">
      <PartTitleStyle Font-Bold="true"
        BorderWidth="1" 
        BackColor="lightblue"/>
      <ZoneTemplate>
        <asp:Panel runat="server" id="panel1" 
          title="Vote on Issues" >
          <asp:RadioButtonList ID="RadioButtonList1" runat="server" >
            <asp:ListItem Value="1">Issue 1</asp:ListItem>
            <asp:ListItem Value="2">Issue 2</asp:ListItem>
            <asp:ListItem Value="3">Issue 3</asp:ListItem>
          </asp:RadioButtonList>
          <asp:Button ID="Button1" runat="server" Text="Cast Vote" />
        </asp:Panel>
        <asp:FileUpload ID="FileUpload1" runat="server" 
          title="Upload Files" />
      </ZoneTemplate>
    </aspSample:MyZone>
    <asp:WebPartZone ID="WebPartZone2" runat="server" />
    <asp:EditorZone ID="EditorZone1" runat="server">
      <ZoneTemplate>
        <asp:AppearanceEditorPart ID="AppearanceEditorPart1" runat="server" />
      </ZoneTemplate>
    </asp:EditorZone>
  </form>
</body>
</html>

<%@ Page Language="C#" %>
<%@ Register TagPrefix="uc1" 
  TagName="DisplayModeMenuCS"
  Src="~/DisplayModeMenuCS.ascx" %>
<%@ Register TagPrefix="aspSample" 
  Namespace="Samples.AspNet.CS.Controls" 
  Assembly="MyChromeCS" %>

<html  >
<head runat="server">
</head>
<body>
  <form id="form1" runat="server">
    <asp:WebPartManager ID="WebPartManager1" runat="server" />
    <uc1:DisplayModeMenuCS id="menu1" runat="server" />
    <aspSample:MyZone ID="WebPartZone1" runat="server"
      RenderVerbsInMenu="true">
      <PartTitleStyle Font-Bold="true"
        BorderWidth="1" 
        BackColor="lightblue"/>
      <ZoneTemplate>
        <asp:Panel runat="server" id="panel1" 
          title="Vote on Issues" >
          <asp:RadioButtonList ID="RadioButtonList1" runat="server" >
            <asp:ListItem Value="1">Issue 1</asp:ListItem>
            <asp:ListItem Value="2">Issue 2</asp:ListItem>
            <asp:ListItem Value="3">Issue 3</asp:ListItem>
          </asp:RadioButtonList>
          <asp:Button ID="Button1" runat="server" Text="Cast Vote" />
        </asp:Panel>
        <asp:FileUpload ID="FileUpload1" runat="server" 
          title="Upload Files" />
      </ZoneTemplate>
    </aspSample:MyZone>
    <asp:WebPartZone ID="WebPartZone2" runat="server" />
    <asp:EditorZone ID="EditorZone1" runat="server">
      <ZoneTemplate>
        <asp:AppearanceEditorPart ID="AppearanceEditorPart1" runat="server" />
      </ZoneTemplate>
    </asp:EditorZone>
  </form>
</body>
</html>

The third part of the code example is the source for the custom WebPartZoneBase zone and a WebPartChrome class. In the constructor for the custom zone class, the code checks the MyZone.RenderVerbsInMenu property. If the value is true, verbs are rendered in a menu for each of the WebPart controls in the zone. This is the normal, default behavior in the Web Parts controls set. If the MyZone.RenderVerbsInMenu property value is false, which is the default in this custom zone, the verbs are rendered individually as links in the title bar of each control. Notice that in the Web page code where the <aspSample:MyZone> element is declared, there is a RenderVerbsInMenu attribute set to true, so that the verbs will appear in menus on the controls. To experiment with this feature, you can set the declarative RenderVerbsInMenu attribute to false, and note how the verbs are rendered as links.

The custom WebPartChrome class overrides the rendering on several methods, and the custom zone creates an instance of the MyWebPartChrome class in its CreateWebPartChrome method. This applies the custom rendering to the page. For the code example to run, you must compile this source code. You can compile it explicitly and put the resulting assembly in your Web site's Bin folder or the global assembly cache. Alternatively, you can put the source code in your site's App_Code folder, where it will be dynamically compiled at run time. For a walkthrough that demonstrates both methods of compiling, see Walkthrough: Developing and Using a Custom Server Control.

Visual Basic

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts

Namespace Samples.AspNet.VB.Controls

  <AspNetHostingPermission(SecurityAction.Demand, _
    Level:=AspNetHostingPermissionLevel.Minimal)> _
  <AspNetHostingPermission(SecurityAction.InheritanceDemand, _
    Level:=AspNetHostingPermissionLevel.Minimal)> _
  Public Class MyZone
    Inherits WebPartZone
    Private _renderVerbsInMenu As Boolean

    Protected Overrides Function CreateWebPartChrome() As WebPartChrome
      Dim theChrome As WebPartChrome = _
        New MyWebPartChrome(Me, Me.WebPartManager)
      If RenderVerbsInMenu Then
        Me.WebPartVerbRenderMode = WebPartVerbRenderMode.Menu
      Else
        Me.WebPartVerbRenderMode = WebPartVerbRenderMode.TitleBar
      End If
      Return theChrome
    End Function

    Public Property RenderVerbsInMenu() As Boolean
      Get
        Return _renderVerbsInMenu
      End Get
      Set(ByVal value As Boolean)
        _renderVerbsInMenu = value
      End Set
    End Property

  End Class

  <AspNetHostingPermission(SecurityAction.Demand, _
    Level:=AspNetHostingPermissionLevel.Minimal)> _
  <AspNetHostingPermission(SecurityAction.InheritanceDemand, _
    Level:=AspNetHostingPermissionLevel.Minimal)> _
  Public Class MyWebPartChrome
    Inherits WebPartChrome
    Dim theManager As WebPartManager
    Dim theZone As WebPartZoneBase

    Public Sub New(ByVal aZone As WebPartZoneBase, _
      ByVal aManager As WebPartManager)

      MyBase.New(aZone, aManager)
      theManager = aManager
      theZone = aZone
    End Sub

    Protected Overrides Function GetWebPartVerbs _
      (ByVal webPart As WebPart) As WebPartVerbCollection

      Dim verbSet As New ArrayList()
      Dim verb As WebPartVerb
      For Each verb In MyBase.GetWebPartVerbs(webPart)
        If verb.Text <> "Close" Then
          verbSet.Add(verb)
        End If
      Next verb

      Dim reducedVerbSet As WebPartVerbCollection = _
        New WebPartVerbCollection(verbSet)

      Return reducedVerbSet
    End Function

    Protected Overrides Function CreateWebPartChromeStyle _
      (ByVal part As WebPart, ByVal chromeType As PartChromeType) As Style

      Dim finalStyle As New Style()
      finalStyle.CopyFrom(MyBase.CreateWebPartChromeStyle(Part, chromeType))
      finalStyle.Font.Name = "Verdana"
      Return finalStyle
    End Function

    Protected Overrides Sub RenderPartContents _
      (ByVal writer As HtmlTextWriter, ByVal part As WebPart)

      If part Is Me.WebPartManager.SelectedWebPart Then
        HttpContext.Current.Response.Write("<span>Not rendered</span>")
      Else
        If (Me.Zone.GetType() Is GetType(MyZone)) Then
          part.RenderControl(writer)
        End If
      End If

    End Sub

  End Class

End Namespace

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace Samples.AspNet.CS.Controls
{
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  public class MyZone : WebPartZone
  {
    private Boolean _renderVerbsInMenu;

    protected override WebPartChrome CreateWebPartChrome()
    {
      WebPartChrome theChrome = new MyWebPartChrome(this, 
        this.WebPartManager);
      if (RenderVerbsInMenu)
        this.WebPartVerbRenderMode = WebPartVerbRenderMode.Menu;
      else
        this.WebPartVerbRenderMode = WebPartVerbRenderMode.TitleBar;
      return theChrome;
    }

    public Boolean RenderVerbsInMenu
    {
      get { return _renderVerbsInMenu; }
      set { _renderVerbsInMenu = value; }
    }
  }

  
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  public class MyWebPartChrome : WebPartChrome
  {
    WebPartZoneBase theZone;
    WebPartManager theManager;

    public MyWebPartChrome(WebPartZoneBase aZone, WebPartManager aManager) : 
      base(aZone, aManager)
    {
      theZone = aZone;
      theManager = aManager;
    }

    protected override WebPartVerbCollection GetWebPartVerbs(WebPart webPart)
    {
      ArrayList verbSet = new ArrayList();
      foreach (WebPartVerb verb in base.GetWebPartVerbs(webPart))
      {
        if (verb.Text != "Close")
          verbSet.Add(verb);
      }
      WebPartVerbCollection reducedVerbSet = 
        new WebPartVerbCollection(verbSet);
      return reducedVerbSet;
    }

    protected override Style CreateWebPartChromeStyle(WebPart part, 
      PartChromeType chromeType)
    {
      Style finalStyle = new Style();
      finalStyle.CopyFrom(base.CreateWebPartChromeStyle(part, chromeType));
      finalStyle.Font.Name = "Verdana";
      return finalStyle;
    }

    protected override void RenderPartContents(HtmlTextWriter writer, 
      WebPart part)
    {

        if (part == this.WebPartManager.SelectedWebPart)
          HttpContext.Current.Response.Write("<span>Not rendered</span>");
        else
          if(this.Zone.GetType() == typeof(MyZone))
            part.RenderControl(writer);
    }

  }
}

When you load the Web page in a browser, you can see how the various stylistic and other rendering customizations made in the source code of the MyWebPartChrome class appear on the WebPart controls rendered in the zone.

.NET Framework Security

AspNetHostingPermission for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.
AspNetHostingPermission for operating in a hosted environment. Demand value: InheritanceDemand; Permission value: Minimal.

Inheritance Hierarchy

System.Object
System.Web.UI.WebControls.WebParts.WebPartChrome

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

Version Information

.NET Framework

Supported in: 2.0

Reference

WebPartChrome Members
System.Web.UI.WebControls.WebParts Namespace
WebPart Class
WebPartZoneBase

Other Resources

Web Parts Control Set Overview
ASP.NET Web Parts Pages

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