DXAccessible.QueryAccessibleInfo Event

Allows you to supply accessibility information to DevExpress UI elements dynamically.

Namespace: DevExpress.Accessibility

Assembly: DevExpress.Utils.v23.2.dll

NuGet Packages: DevExpress.Utils, DevExpress.Wpf.Core

Declaration

C#

public static event EventHandler<DXAccessible.QueryAccessibleInfoEventArgs> QueryAccessibleInfo

VB.NET

Public Shared Event QueryAccessibleInfo As EventHandler(Of DXAccessible.QueryAccessibleInfoEventArgs)

Event Data

The QueryAccessibleInfo event's data class is DXAccessible.QueryAccessibleInfoEventArgs. The following properties provide information specific to this event:

Property	Description
AccessibleObject	Gets the System.Windows.Forms.AccessibleObject that allows you to return the standard accessibility information about the currently processed UI element.
DefaultAction	Gets or sets a string that describes the UI element’s default action.
Description	Gets or sets a string that describes the visual appearance of the currently processed UI element.
Name	Gets or sets the name of the Accessible Object associated with a UI element.
Owner	Gets the QueryAccessibleInfoEventArgs.Owner control’s child object that contains the currently processed UI element.
OwnerControl	Gets the control that contains the currently processed UI element.
Role	Gets or sets the accessible role of the currently processed UI element.

The event data class exposes the following methods:

Method	Description
GetDXAccessible<DXAccessible>()	Returns a BaseAccessible object (or its descendant) that stores additional accessibility information about the currently processed UI element.
ToString()	Returns a string representing the current object.

Remarks

DevExpress controls and components expose AccessibleName, AccessibleDescription, and AccessibleRole properties (for example, BarItem.AccessibleName, BarItem.AccessibleDescription, and BarItem.AccessibleRole) that allow you to explicitly assign accessibility information to most of their UI elements. Accessibility information for some UI elements (for instance, grid cells) is formed automatically, and there are no public properties to override the default accessibility information.

Handle the QueryAccessibleInfo event to supply/modify the accessibility information for UI elements, regardless of whether they have corresponding public AccessibleName, AccessibleDescription, and AccessibleRole settings. The QueryAccessibleInfo event fires for each DevExpress UI element that has associated accessibility information when this information is requested by screen readers.

Note

Declare your QueryAccessibleInfo event handler as a form’s method. For instance, do not use a lambda expression to subscribe to the event in the Program.cs file. Otherwise, the garbage collector may release the memory allocated for your event handler.

You can use the WindowsFormsSettings.DisableAccessibility property to disable the accessibility feature for DevExpress controls.

Example

The following example handles the QueryAccessibleInfo event to modify the default value of the AccessibleName setting for cells in DevExpress grid controls. The new value is formed as a column’s caption followed by the “cell” word.

C#

using DevExpress.Accessibility;
using static DevExpress.XtraGrid.Accessibility.GridViewAccessibleObject.GridViewDataPanel;

public Form1() {
    InitializeComponent();
    DXAccessible.QueryAccessibleInfo += DXAccessible_QueryAccessibleInfo;
}

private void DXAccessible_QueryAccessibleInfo(object sender, DXAccessible.QueryAccessibleInfoEventArgs e) {
    if (e.Role == AccessibleRole.Cell) {
        GridCellAccessibleObject cellAccessible = e.GetDXAccessible<GridCellAccessibleObject>();
        if (cellAccessible != null) {
            e.Name = cellAccessible.Column.Caption + " cell";
        }
    }
}

VB.NET

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    AddHandler DXAccessible.QueryAccessibleInfo, AddressOf DXAccessible_QueryAccessibleInfo
End Sub

Private Sub DXAccessible_QueryAccessibleInfo(sender As Object, e As DXAccessible.QueryAccessibleInfoEventArgs)
    If e.Role = AccessibleRole.Cell Then
        Dim cellAccessible As GridCellAccessibleObject = e.GetDXAccessible(Of GridCellAccessibleObject)()
        If cellAccessible IsNot Nothing Then
            e.Name = cellAccessible.Column.Caption & " cell"
        End If
    End If
End Sub

Example

The following QueryAccessibleInfo event handler supplies the AccessibleName and AccessibleDescription settings for tiles in a TileControl.

C#

public Form1() {
    InitializeComponent();
    DXAccessible.QueryAccessibleInfo += DXAccessible_QueryAccessibleInfo;
}

private void DXAccessible_QueryAccessibleInfo(object sender, DXAccessible.QueryAccessibleInfoEventArgs e) {
    if (e.Role == AccessibleRole.ListItem && e.OwnerControl == tileControl1) {
        TileItem item = e.Owner as TileItem;
        if (item != null && item.Elements.Count > 1) {
            e.Name = item.Elements[0].Text;
            e.Description = item.Elements[1].Text;
        }
    }
}

VB.NET

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    AddHandler DXAccessible.QueryAccessibleInfo, AddressOf DXAccessible_QueryAccessibleInfo
End Sub

Private Sub DXAccessible_QueryAccessibleInfo(sender As Object, e As DXAccessible.QueryAccessibleInfoEventArgs)
    If e.Role = AccessibleRole.ListItem AndAlso e.OwnerControl Is TileControl1 Then
        Dim item As TileItem = TryCast(e.Owner, TileItem)
        If item IsNot Nothing AndAlso item.Elements.Count > 1 Then
            e.Name = item.Elements(0).Text
            e.Description = item.Elements(1).Text
        End If
    End If
End Sub