Accessibility

Accessibility

Screen readers

Every element has an accessibility peer — its role, name, value, states and actions — made the first time something asks for it. The built-in controls know theirs: a list box is a list of list items, a data grid a table of rows and cells, a tree view a tree.

Platform	Bridge
Windows	UI Automation: Narrator, NVDA, JAWS
Browser	An ARIA mirror of the tree beside the canvas, for the browser's screen readers

The name is worked out from what the control shows — a button's text, a check box's caption, the label in front of a field. Where nothing on screen says it, give it:

var search = new TextBox { AccessibleName = "Search orders" };
var icon = new SvgIcon { PathData = "…", IsAccessibilityHidden = true };    // decoration
var status = new Label { LiveSetting = AccessibilityLiveSetting.Polite };   // changes are read out

Member
AccessibleName, AccessibleDescription	What a screen reader says
AccessibleRole	A role other than the control's own
IsAccessibilityHidden	Left out of the tree: decoration
LiveSetting	Changes of the element are announced
CreateAccessibilityPeer()	Overridden by a control of your own to give its peer

The audit

F12 opens the inspector; its audit lists what a screen reader or a keyboard user would trip over — a control with no name, a picture with no name that isn't hidden as decoration, text below the WCAG contrast minimum, a target smaller than 24×24. From code:

foreach (AccessibilityIssue issue in AccessibilityAudit.Run(form))
    Console.WriteLine(issue);

The keyboard

Every control is reachable with Tab and Shift+Tab, in TabIndex order, and works from the keyboard: lists and grids with the arrows, Home, End, PageUp and PageDown, a tree with Left and Right, a menu with the arrows and Escape. The focus ring is shown only while the user works from the keyboard (:focus-visible in style sheets), not after a mouse click.

Access keys: & in a caption underlines the next letter and makes Alt with it a shortcut — on by default for menu items, UseMnemonic = true for other controls.

var save = new Button { Text = "&Save", UseMnemonic = true };   // Alt+S

High contrast and text scale

The system's high contrast mode takes over every theme with its own colors — opt out with App.RespectHighContrast = false. App.IsHighContrastActive tells whether it is on.

App.UseSystemTextScale() follows the system's text size setting; App.TextScale is the factor in effect, and App.TextScaleChanged tells when it changes.

Motion

With the system's reduced-motion setting (Motion.Preference), transitions and animations are instant; scroll inertia and loading indicators keep moving.