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Accordion Control

  • 16 minutes to read

The Accordion Control (the AccordionControl class object) is a side navigation control whose items can be organized into groups.

Accordion 2018 - Head image

The main Accordion features include:

Examples

Demos (DevExpress Demo Center)

Items and Groups

To add Accordion Control groups and items, click the “Run Designer” link on the control’s surface and switch to the designer’s “Elements” tab.

Accordion 2018 - Add Elements

Tip

You can drag-and-drop elements in the “AccordionControl Elements” panel to rearrange and categorize them.

Alternatively, you can invoke the control’s smart tag and click the corresponding links:

Accordion 2018 - Add Elements 2

In code, groups and items are AccordionControlElement class objects with different AccordionControlElement.Style property values. Root groups are stored in the Accordion’s AccordionControl.Elements collection, and individual groups store their child groups and/or items in AccordionControlElement.Elements collections.

Tip

See the following topic for an example: How To: Create AccordionControl in code.

To allow an element to have checked/unchecked states, enable the AccordionControl.AllowItemSelection setting.

Accordion 2018 - Selected Item

Items with Content Containers

A regular item is a button that raises the AccordionControlElementBase.Click and AccordionControl.ElementClick events when clicked. In addition to these regular items, you can add items with content containers.

Click an item’s smart tag and select “Add ContentContainer”. To populate a content container, drag and drop controls from Visual Studio’s Toolbox onto this container.

Accordion 2018 - Content Container

Win-Accordion-ItemWithContainer.gif

Tip

Set a content container’s Padding property to -1 to use paddings based on the applied skin.

To populate a content container in code, specify the AccordionControlElementBase.ContentContainer property…

userControlPhoto uc = new userControlPhoto() { Dock = DockStyle.Fill };
AccordionContentContainer container = new AccordionContentContainer();
container.Controls.Add(uc);
// Assign the required content container to an item
acePhoto.ContentContainer = container;

…or handle the AccordionControl.HasContentContainer and AccordionControl.GetContentContainer events.

// Specify which items should raise the GetContentContainer event
private void accordionControl1_HasContentContainer(object sender, HasContentContainerEventArgs e) {
    if (e.Element.Text == "Photo") e.HasContentContainer = true;
}

// Assign a content container to the item that fired this event
private void accordionControl1_GetContentContainer(object sender, GetContentContainerEventArgs e) {
    if (e.Element.Text == "Photo") {
        userControlPhoto uc = new userControlPhoto() { Dock = DockStyle.Fill };
        AccordionContentContainer container = new AccordionContentContainer();
        container.Controls.Add(uc);
        e.ContentContainer = container;
    }
}

Important

Expand and Collapse Elements

API

Description

AccordionControlElementBase.Expanded

Gets or sets whether the element is expanded.

AccordionControl.ExpandAll

AccordionControl.CollapseAll

Call these methods to expand and collapse all Accordion elements at once.

AccordionControl.ExpandGroupOnHeaderClick

AccordionControl.ExpandItemOnHeaderClick

If these settings are enabled, users can click element headers to expand and collapse elements.

AccordionControl.ExpandStateChanging

AccordionControl.ExpandStateChanged

Handle these events to perform certain actions when the element is about to collapse or expand, and after the element’s state changes.

You can handle the AccordionControl.ExpandStateChanging event and clear the e.ElementsToExpandCollapse collection to abort the expand/collapse operation. For instance, the following code does not allow users to collapse the “Options” group:

private void accordionControl1_ExpandStateChanging(object sender, ExpandStateChangingEventArgs e) {
    if (e.Element.Style == ElementStyle.Group && e.Element.Text == "Options" && e.NewState == AccordionElementState.Collapsed)
        e.ElementsToExpandCollapse.Clear();
}

Alternatively, you can cancel the AccordionControl.ElementClick event to do the same.

private void AccordionControl1_ElementClick(object sender, ElementClickEventArgs e) {
    if (e.Element.Style == ElementStyle.Group && e.Element.Text == "Options" && e.Element.Expanded == true)
        e.Handled = true;
}

Note that the code samples above do not allow users to collapse the Accordion group, but leave this group’s expand/collapse button visible. See the following table row to learn how to hide this button.

AccordionControl.ShowGroupExpandButtons

AccordionControl.ShowItemExpandButtons

Use these properties to hide expand/collapse buttons for all items or groups at once. Initially, all groups — even if they are empty — display these buttons. Items show them only when they have content containers assigned.

If you need to hide the expand/collapse button for individual elements, handle the AccordionControl.CustomDrawElement event. This event allows you to call various e.Draw… methods, each method paints the specific element part. For instance, the sample below does not call the DrawExpandCollapseButton method for the “Options” group.

private void AccordionControl1_CustomDrawElement(object sender, CustomDrawElementEventArgs e) {
    if (e.Element.Style == ElementStyle.Group && e.Element.Text == "Options") {
        e.DrawImage();
        e.DrawText();
        e.DrawContextButtons();
        // Uncomment the following line to draw the expand/collapse button
        //e.DrawExpandCollapseButton();
        e.Handled = true;
    }
}

AccordionControl.ExpandElementMode

Gets or sets whether a single element or multiple elements can be expanded simultaneously.

AccordionControl.ElementPositionOnExpanding

Gets or sets whether expandable groups and elements are scrolled (if required) to make their contents visible when they are expanded.

You can move root Accordion elements (groups and items from the AccordionControl.Elements collection) to the control’s footer. Footer elements act like tabs in a Tabbed UI: when a user clicks a footer element, the Accordion displays this element’s child items in the control’s main area. In the following figure, root items are displayed in the control’s footer. The ‘Mail’ item is active.

Accordion_RootElementsInFooterMenu

To enable this item display style, set the AccordionControl.RootDisplayMode property to Footer.

accordionControl1.RootDisplayMode = DevExpress.XtraBars.Navigation.AccordionControlRootDisplayMode.Footer;

Additional API

  • AccordionOptionsFooter.ActiveGroupDisplayMode - Gets or sets whether the accordion control’s main menu displays the active group’s content, but not the header, or both the content and the header.
  • AccordionControlElement.ControlFooterAlignment - Gets or sets whether the element is aligned at the near or far side of the control footer in the accordion control’s expanded state.

    accordionControl1.OptionsFooter.ActiveGroupDisplayMode = DevExpress.XtraBars.Navigation.ActiveGroupDisplayMode.GroupHeaderAndContent;
    accordionControlElementSetting.ControlFooterAlignment = AccordionItemFooterAlignment.Far;
    

    AccordionControl_GroupContentAndHeader

  • OptionsMinimizing.FooterHeight - Gets or sets the control footer height in the accordion control’s minimized state.
  • OptionsMinimizing.AllowFooterResizing - Gets or sets whether users can resize the control’s footer when the Accordion control is minimized.

Search Panel

The embedded search panel allows end users to locate a required element. If the found element belongs to a group, this group is also visible. If the element is a group, it shows its child elements.

AccordionControl - Search Panel

When the AccordionControl.ShowFilterControl property equals Always, the search panel is always visible. The Auto value allows end users to press CTRL+F to invoke the search panel, and ESC to close it.

You can make a custom filter control for the Accordion. To do that, declare a class that implements the DevExpress.XtraBars.Navigation.IFilterContent interface and assign this class instance to the AccordionControl.FilterControl property.

Element Header Layout

Accordion groups and items can display four types of content within their headers:

Accordion - Default Header Layout

See the following topic to learn how to rearrange these content blocks: Element Header Layout.

Customize Appearance Settings

You can use the control’s properties (for example, AccordionControl.Appearance, AccordionControlElement.Appearance, and AccordionControlElement.HeaderTemplate) and events (for example, AccordionControl.CustomDrawElement) to customize the contents, layout, and appearance settings of the control’s elements.

Use HTML-CSS Templates to Render UI Elements

AccordionControl allows you to use your knowledge of HTML and CSS markup to render the control’s UI elements. A template’s HTML markup specifies an element’s contents, while the template’s CSS code specifies style, display, and layout settings applied to the element.

Custom HTML Templates for the Accordion Control

AccordionControl exposes a set of properties (accessible from the AccordionControl.HtmlTemplates object) to specify HTML-CSS templates to render the control’s elements:

Display Element’s Text, Images, and Custom Data

When you specify templates for AccordionControl elements, you can use the data binding syntax (${PropertyName}) to display text, images, and custom values (AccordionControlElementBase.Tag) of these elements.

${Text} — Inserts an element’s text (AccordionControlElementBase.Text).

${Image} — Inserts an element’s image specified in the AccordionControlElementBase.ImageOptions object. Use the img tag to insert an image, for example, as follows: <img src="${Image}".

For example, the following HTML markup defines a div container that displays an element’s image followed by its text:

<div class="item">
    <div class="item_layout">
        <img class="item_image" src="${Image}">
        <div class="item_text">${Text}</div>
    </div>
</div>

You can also use the ${MyField1} syntax to mark an element as bound to a custom data source. The actual data for this element is set in the QueryHtmlElementData event handler.

<div class="acc_item">${MyField1}</div>
private void OnQueryHtmlElementData(object sender, QueryAccordionHtmlElementDataEventArgs e) {
    if (e.FieldName == "MyField1") {
        e.Value = "CustomData";
    }
}

Interaction with Office Navigation Bar

The Office Navigation Bar can show items retrieved from the Accordion Control. Use the OfficeNavigationBar.NavigationClient property to attach an Office Navigation Bar to an Accordion.

officeNavigationBar1.NavigationClient = accordionControl1;

Interaction with Fluent Design Form

The FluentDesignForm is a Windows 10-inspired form that includes the following features:

  • Embedded Hamburger Menu (AccordionControl with the HamburgerMenu view type)
  • Adaptive Layout mode for the Hamburger Menu (automatically switches between Inline, Overlay, and Minimal display modes when you resize the form)
  • Acrylic Material effect (a partially transparent texture)
  • Reveal Highlight visual effect

See Fluent Design Form for more information.

Example - How to Create Side Navigation

This example demonstrates how to implement a side navigation. Drop the WinForms Accordion and Navigation Frame controls onto a Form. Use the following code to create the accordion elements, customize their settings, and implement the navigation between frames/pages.

Side Navigation - WinForms Accordion Control and Navigation Frame

using System;
using DevExpress.XtraBars.Navigation;

private void Form1_Load(object sender, EventArgs e) {
    InitAccordion(accordionControl1);
}

void InitAccordion(AccordionControl accordion) {
    AccordionControlElement group = new AccordionControlElement(ElementStyle.Group) {
        Name = "accordionGroup1",
        Text = "Pages",
        Expanded = true
    };
    AccordionControlElement item1 = new AccordionControlElement(ElementStyle.Item) {
        Name = "accordionItem1",
        Text = "Page 1"
    };
    AccordionControlElement item2 = new AccordionControlElement(ElementStyle.Item) {
        Name = "accordionItem2",
        Text = "Page 2"
    };

    item1.Click += new EventHandler(this.accordionElement_Click);
    item2.Click += new EventHandler(this.accordionElement_Click);

    group.Elements.AddRange(new AccordionControlElement[] { item1, item2 });
    accordion.Elements.Add(group);
}

void accordionElement_Click(object sender, EventArgs e) {
    AccordionControlElement item = sender as AccordionControlElement;
    navigationFrame1.SelectedPage = item.Text == "Page 1" ? navigationPage1 : navigationPage2;
}

Example: How to Create a Multi-Level Element Hierarchy

Accordion Control allows you to create an unlimited number of element hierarchy levels. To do that, you need to create group elements, populate them with other groups that have their own child groups, etc.

accordionControl1.Elements.Clear();
// Root level elements
AccordionControlElement gr1 = new AccordionControlElement(ElementStyle.Group) { Text = "Root Group 1" };
AccordionControlElement i1 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 1" };
AccordionControlElement i2 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 2" };
AccordionControlElement gr2 = new AccordionControlElement(ElementStyle.Group) { Text = "Root Group 2" };
AccordionControlElement i3 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 3" };
AccordionControlElement i4 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 4" };
AccordionControlElement gr3 = new AccordionControlElement(ElementStyle.Group) { Text = "Root Group 3" };
AccordionControlElement i5 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 5" };
AccordionControlElement i6 = new AccordionControlElement(ElementStyle.Item) { Text = "Item 6" };

// Level 2 elements
AccordionControlElement gr4 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 2 Group 1" };
AccordionControlElement i7 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 1" };
AccordionControlElement i8 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 2" };
AccordionControlElement gr5 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 2 Group 2" };
AccordionControlElement i9 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 3" };
AccordionControlElement i10 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 4" };
AccordionControlElement gr6 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 2 Group 1" };
AccordionControlElement i11 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 5" };
AccordionControlElement i12 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 2 Item 6" };

// Level 3 elements
AccordionControlElement gr7 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 3 Group 1" };
AccordionControlElement i13 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 1" };
AccordionControlElement i14 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 2" };
AccordionControlElement gr8 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 3 Group 2" };
AccordionControlElement i15 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 3" };
AccordionControlElement i16 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 4" };
AccordionControlElement gr9 = new AccordionControlElement(ElementStyle.Group) { Text = "Level 3 Group 1" };
AccordionControlElement i17 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 5" };
AccordionControlElement i18 = new AccordionControlElement(ElementStyle.Item) { Text = "Level 3 Item 6" };

gr7.Elements.AddRange(new AccordionControlElement[] { i13, i14 });
gr8.Elements.AddRange(new AccordionControlElement[] { i15, i16 });
gr9.Elements.AddRange(new AccordionControlElement[] { i17, i18 });

gr4.Elements.AddRange(new AccordionControlElement[] { i7, i8, gr7 });
gr5.Elements.AddRange(new AccordionControlElement[] { i9, i10, gr8 });
gr6.Elements.AddRange(new AccordionControlElement[] { i11, i12, gr9 });

gr1.Elements.AddRange(new AccordionControlElement[] { i1, i2, gr4 });
gr2.Elements.AddRange(new AccordionControlElement[] { i3, i4, gr5 });
gr3.Elements.AddRange(new AccordionControlElement[] { i5, i6, gr6 });

accordionControl1.Elements.AddRange(new AccordionControlElement[] { gr1, gr2, gr3 });
accordionControl1.AllowItemSelection = true;
accordionControl1.ExpandAll();
See Also