a11y atspi: Bridge IA2 strikeout text attrs to AT-SPI

When the text attributes an accessible interface reports
include one of the various "text-line-through-*"
IAccessible2 text attributes with a value that indicates
that strikethrough is applied [1], bridge that to the
AT-SPI layer via the "strikethrough" attribute with a
value of "true".

See also the ATK documentation [2] for the
`ATK_TEXT_ATTR_STRIKETHROUGH` text attribute.

This will not only be used by an upcoming change
that implements reporting that for Qt's own text
widgets, but is also needed for third-party applications.
Change for LibreOffice that makes use of this: [3]

[1] https://wiki.linuxfoundation.org/accessibility/iaccessible2/textattributes
[2] https://gnome.pages.gitlab.gnome.org/atk/AtkText.html#AtkTextAttribute
[3] https://gerrit.libreoffice.org/c/core/+/157939

Task-number: QTBUG-118106
Change-Id: Ieb98584a3c6270d8db508d59994f9ba244e2bc64
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gui/accessible/linux/atspiadaptor.cpp b/src/gui/accessible/linux/atspiadaptor.cpp
index 996523ccf4..6b4c80cf60 100644
--- a/src/gui/accessible/linux/atspiadaptor.cpp
+++ b/src/gui/accessible/linux/atspiadaptor.cpp
@@ -2222,6 +2222,13 @@ namespace
                 // (on which it produces traceback and fails to read any following text attributes),
                 // but that is the default value, so omit it anyway
                 value = QString();
+        } else if (((ia2Name == "text-line-through-style"_L1 || ia2Name == "text-line-through-type"_L1) && (ia2Value != "none"_L1))
+                   || (ia2Name == "text-line-through-text"_L1 && !ia2Value.isEmpty())) {
+            // if any of the above is set, set "strikethrough" to true, but don't explicitly set
+            // to false otherwise, since any of the others might still be set to indicate strikethrough
+            // and no strikethrough is assumed anyway when nothing is explicitly set
+            name = QStringLiteral("strikethrough");
+            value = QStringLiteral("true");
         } else if (ia2Name == "text-position"_L1) {
             name = QStringLiteral("vertical-align");
             if (value != "baseline"_L1 && value != "super"_L1 && value != "sub"_L1) {