From b1fb1114a79b032e225fabebe13499686fa7d1c8 Mon Sep 17 00:00:00 2001
From: Colomban Wendling <cwendling@hypra.fr>
Date: Wed, 26 Jun 2024 11:05:47 +0200
Subject: a11y: Announce status changes

If the equation status changes and the status message is not the
focused element, ask the screen reader to speak the status change
because it's likely to be relevant for the user to be notified.

Fixes #223.
---
 src/math-display.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/math-display.c b/src/math-display.c
index b0f3e0e..949d5c3 100644
--- a/src/math-display.c
+++ b/src/math-display.c
@@ -14,6 +14,11 @@
 
 #include "math-display.h"
 
+/* compatibility with ATK < 2.50 */
+#if ! ATK_CHECK_VERSION(2, 49, 2)
+# define ATK_LIVE_POLITE ((gint) 1)
+#endif
+
 enum {
     PROP_0,
     PROP_EQUATION
@@ -27,8 +32,8 @@ struct MathDisplayPrivate
     /* Display widget */
     GtkWidget *text_view;
 
-    /* Buffer that shows errors etc */
-    GtkTextBuffer *info_buffer;
+    /* Display for errors etc */
+    GtkWidget *info_view;
 
     /* Spinner widget that shows if we're calculating a response */
     GtkWidget *spinner;
@@ -302,7 +307,9 @@ key_press_cb(MathDisplay *display, GdkEventKey *event)
 static void
 status_changed_cb(MathEquation *equation, GParamSpec *spec, MathDisplay *display)
 {
-    gtk_text_buffer_set_text(display->priv->info_buffer, math_equation_get_status(equation), -1);
+    const gchar *status = math_equation_get_status(equation);
+
+    gtk_text_buffer_set_text(gtk_text_view_get_buffer(GTK_TEXT_VIEW(display->priv->info_view)), status, -1);
     if (math_equation_in_solve(equation) && !gtk_widget_get_visible(display->priv->spinner)) {
         gtk_widget_show(display->priv->spinner);
         gtk_spinner_start(GTK_SPINNER(display->priv->spinner));
@@ -311,6 +318,24 @@ status_changed_cb(MathEquation *equation, GParamSpec *spec, MathDisplay *display
         gtk_widget_hide(display->priv->spinner);
         gtk_spinner_stop(GTK_SPINNER(display->priv->spinner));
     }
+
+    /* if the info view doesn't have focus yet we want to display a status
+     * update, try and emit an accessible notification so the screen reader can
+     * pick it up */
+    if (status && *status && ! gtk_widget_has_focus(display->priv->info_view)) {
+        AtkObject *obj = gtk_widget_get_accessible(display->priv->info_view);
+
+        if (obj && GTK_IS_ACCESSIBLE(obj)) {
+            guint signal_id;
+
+            /* we're using either signals, which are mostly the same but for
+             * the politeness parameter */
+            if ((signal_id = g_signal_lookup("notification", G_OBJECT_TYPE(obj))))
+                g_signal_emit(obj, (guint) signal_id, 0, status, ATK_LIVE_POLITE);
+            else if ((signal_id = g_signal_lookup("announcement", G_OBJECT_TYPE(obj))))
+                g_signal_emit(obj, (guint) signal_id, 0, status);
+        }
+    }
 }
 
 static void _text_view_override_font (GtkWidget *widget, PangoFontDescription *font)
@@ -395,7 +420,7 @@ create_gui(MathDisplay *display)
     /* TEMP: Disabled for now as GTK+ doesn't properly render a right aligned right margin, see bug #482688 */
     /*gtk_text_view_set_right_margin(GTK_TEXT_VIEW(info_view), 6);*/
     gtk_box_pack_start(GTK_BOX(info_box), info_view, TRUE, TRUE, 0);
-    display->priv->info_buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(info_view));
+    display->priv->info_view = info_view;
 
     display->priv->spinner = gtk_spinner_new();
     gtk_box_pack_end(GTK_BOX(info_box), display->priv->spinner, FALSE, FALSE, 0);
-- 
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