[WPF][XamMac][GtkMac] A11y helper

* Allows to check whether accessibility means are in use (Narrator/3rd party tools on Windows, VoiceOver on macOS)
* Adds Accessible.MakeAnnouncement (string message, bool polite = false) method for making a custom announcement for user per request (uses LiveRegion on Windows and NSAccessibility.PostNotification on macOS)

WPF version requires target framework version .NET 4.7.2

1 files changed, 16 insertions, 2 deletions

diff --git a/TestApps/Samples/Samples/ProgressBarSample.cs b/TestApps/Samples/Samples/ProgressBarSample.cs
index 2b0041fc..c2c6678e 100644
--- a/TestApps/Samples/Samples/ProgressBarSample.cs
+++ b/TestApps/Samples/Samples/ProgressBarSample.cs
@@ -25,6 +25,7 @@
 // THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 using System.Timers;
 using Xwt;
 using Xwt.Drawing;
@@ -33,7 +34,7 @@ namespace Samples
 {
 	public class ProgressBarSample : VBox
 	{
-		Timer timer = new Timer (100);
+		Timer timer = new Timer (3000);
 		ProgressBar determinateProgressBar;
 		ProgressBar indeterminateProgressBar;
 
@@ -49,6 +50,9 @@ namespace Samples
 			timer.Elapsed += Increase;
 			determinateProgressBar = new ProgressBar ();
 			determinateProgressBar.Fraction = 0.0;

+

+			determinateProgressBar.Accessible.AccessibilityInUseChanged += Accessible_AccessibilityInUseChanged;

+

 			PackStart(determinateProgressBar, true);
 			timer.Start ();
 
@@ -57,6 +61,11 @@ namespace Samples
 			PackStart (spinner);
 		}
 
+		private void Accessible_AccessibilityInUseChanged (object sender, EventArgs e)
+		{
+			Console.WriteLine ($"Accessible_AccessibilityInUseChanged now the value is {determinateProgressBar.Accessible.AccessibilityInUse}");
+		}
+
 		public void Increase (object sender, ElapsedEventArgs args)
 		{
 			double nextFraction;
@@ -66,7 +75,12 @@ namespace Samples
 			} else {
 				nextFraction = 0.0;
 			}
-			Application.Invoke ( () => determinateProgressBar.Fraction = nextFraction );
+			Application.Invoke ( () =>
+			{
+				determinateProgressBar.Fraction = nextFraction;
+				determinateProgressBar.Accessible.MakeAnnouncement($"My progress is now {nextFraction * 100} percents");
+				Debug.WriteLine($"AccessibilityInUse: {determinateProgressBar.Accessible.AccessibilityInUse}");
+			} );
 		}
 	}
 }