Automation Properties in Xamarin.Forms

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Xamarin.Forms allows accessibility values to be set on user interface elements by using attached properties from the AutomationProperties class, which in turn set native accessibility values. This article explains how to use the AutomationProperties class, so that a screen reader can speak about the elements on the page.

Xamarin.Forms allows automation properties to be set on user interface elements via the following attached properties:

  • AutomationProperties.IsInAccessibleTree – indicates whether the element is available to an accessible application. For more information, see AutomationProperties.IsInAccessibleTree.
  • AutomationProperties.Name – a short description of the element that serves as a speakable identifier for the element. For more information, see AutomationProperties.Name.
  • AutomationProperties.HelpText – a longer description of the element, which can be thought of as tooltip text associated with the element. For more information, see AutomationProperties.HelpText.
  • AutomationProperties.LabeledBy – allows another element to define accessibility information for the current element. For more information, see AutomationProperties.LabeledBy.

These attached properties set native accessibility values so that a screen reader can speak about the element. For more information about attached properties, see Attached Properties.

Important

Using the AutomationProperties attached properties may impact UI Test execution on Android. The AutomationId, AutomationProperties.Name and AutomationProperties.HelpText properties will both set the native ContentDescription property, with the AutomationProperties.Name and AutomationProperties.HelpText property values taking precedence over the AutomationId value (if both AutomationProperties.Name and AutomationProperties.HelpText are set, the values will be concatenated). This means that any tests looking for AutomationId will fail if AutomationProperties.Name or AutomationProperties.HelpText are also set on the element. In this scenario, UI Tests should be altered to look for the value of AutomationProperties.Name or AutomationProperties.HelpText, or a concatenation of both.

Each platform has a different screen reader to narrate the accessibility values:

However, the exact behavior of a screen reader depends on the software and on the user's configuration of it. For example, most screen readers read the text associated with a control when it receives focus, enabling users to orient themselves as they move among the controls on the page. Some screen readers also read the entire application user interface when a page appears, which enables the user to receive all of the page's available informational content before attempting to navigate it.

Screen readers also read different accessibility values. In the sample application:

  • VoiceOver will read the Placeholder value of the Entry, followed by instructions for using the control.
  • TalkBack will read the Placeholder value of the Entry, followed by the AutomationProperties.HelpText value, followed by instructions for using the control.
  • Narrator will read the AutomationProperties.LabeledBy value of the Entry, followed by instructions on using the control.

In addition, Narrator will prioritize AutomationProperties.Name, AutomationProperties.LabeledBy, and then AutomationProperties.HelpText. On Android, TalkBack may combine the AutomationProperties.Name and AutomationProperties.HelpText values. Therefore, it's recommended that thorough accessibility testing is carried out on each platform to ensure an optimal experience.

AutomationProperties.IsInAccessibleTree

The AutomationProperties.IsInAccessibleTree attached property is a boolean that determines if the element is accessible, and hence visible, to screen readers. It must be set to true to use the other accessibility attached properties. This can be accomplished in XAML as follows:

<Entry AutomationProperties.IsInAccessibleTree="true" />

Alternatively, it can be set in C# as follows:

var entry = new Entry();
AutomationProperties.SetIsInAccessibleTree(entry, true);

Note

Note that the SetValue method can also be used to set the AutomationProperties.IsInAccessibleTree attached property – entry.SetValue(AutomationProperties.IsInAccessibleTreeProperty, true);

AutomationProperties.Name

The AutomationProperties.Name attached property value should be a short, descriptive text string that a screen reader uses to announce an element. This property should be set for elements that have a meaning that is important for understanding the content or interacting with the user interface. This can be accomplished in XAML as follows:

<ActivityIndicator AutomationProperties.IsInAccessibleTree="true"
                   AutomationProperties.Name="Progress indicator" />

Alternatively, it can be set in C# as follows:

var activityIndicator = new ActivityIndicator();
AutomationProperties.SetIsInAccessibleTree(activityIndicator, true);
AutomationProperties.SetName(activityIndicator, "Progress indicator");

Note

Note that the SetValue method can also be used to set the AutomationProperties.Name attached property – activityIndicator.SetValue(AutomationProperties.NameProperty, "Progress indicator");

AutomationProperties.HelpText

The AutomationProperties.HelpText attached property should be set to text that describes the user interface element, and can be thought of as tooltip text associated with the element. This can be accomplished in XAML as follows:

<Button Text="Toggle ActivityIndicator"
        AutomationProperties.IsInAccessibleTree="true"
        AutomationProperties.HelpText="Tap to toggle the activity indicator" />

Alternatively, it can be set in C# as follows:

var button = new Button { Text = "Toggle ActivityIndicator" };
AutomationProperties.SetIsInAccessibleTree(button, true);
AutomationProperties.SetHelpText(button, "Tap to toggle the activity indicator");

Note

Note that the SetValue method can also be used to set the AutomationProperties.HelpText attached property – button.SetValue(AutomationProperties.HelpTextProperty, "Tap to toggle the activity indicator");

On some platforms, for edit controls such as an Entry, the HelpText property can sometimes be omitted and replaced with placeholder text. For example, "Enter your name here" is a good candidate for the Entry.Placeholder property that places the text in the control prior to the user's actual input.

AutomationProperties.LabeledBy

The AutomationProperties.LabeledBy attached property allows another element to define accessibility information for the current element. For example, a Label next to an Entry can be used to describe what the Entry represents. This can be accomplished in XAML as follows:

<Label x:Name="label" Text="Enter your name: " />
<Entry AutomationProperties.IsInAccessibleTree="true"
       AutomationProperties.LabeledBy="{x:Reference label}" />

Alternatively, it can be set in C# as follows:

var nameLabel = new Label { Text = "Enter your name: " };
var entry = new Entry();
AutomationProperties.SetIsInAccessibleTree(entry, true);
AutomationProperties.SetLabeledBy(entry, nameLabel);

Note

Note that the SetValue method can also be used to set the AutomationProperties.IsInAccessibleTree attached property – entry.SetValue(AutomationProperties.LabeledByProperty, nameLabel);

Accessibility intricacies

The following sections describe the intricacies of setting accessibility values on certain controls.

On Android, to set the text that screen readers will read for the back arrow in the action bar in a NavigationPage, set the AutomationProperties.Name and AutomationProperties.HelpText properties on a Page. However, note that this will not have an effect on OS back buttons.

MasterDetailPage

On iOS and the Universal Windows Platform (UWP), to set the text that screen readers will read for the toggle button on a MasterDetailPage, either set the AutomationProperties.Name, and AutomationProperties.HelpText properties on the MasterDetailPage, or on the Icon property of the Master page.

On Android, to set the text that screen readers will read for the toggle button on a MasterDetailPage, add string resources to the Android project:

<resources>
	    <string name="app_name">Xamarin Forms Control Gallery</string>
	    <string name="btnMDPAutomationID_open">Open Side Menu message</string>
	    <string name="btnMDPAutomationID_close">Close Side Menu message</string>
</resources>

Then set the AutomationId property of the Icon property of the Master page to the appropriate string:

var master = new ContentPage { ... };
master.Icon.AutomationId = "btnMDPAutomationID";

ToolbarItem

On iOS, Android, and UWP, screen readers will read the Text property value of ToolbarItem instances, provided that AutomationProperties.Name or AutomationProperties.HelpText values aren't defined.

On iOS and UWP the AutomationProperties.Name property value will replace the Text property value that is read by the screen reader.

On Android, the AutomationProperties.Name and/or AutomationProperties.HelpText property values will completely replace the Text property value that is both visible and read by the screen reader. Note that this is a limitation of APIs less than 26.