From ffdf7eceed26c99c81accaf1529024bd0bf40f44 Mon Sep 17 00:00:00 2001
From: Peter Varga <pvarga@inf.u-szeged.hu>
Date: Tue, 12 Nov 2019 10:57:12 +0100
Subject: Fix widget accessibility on macOS
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macOS Accessibility queries the window for the focused accessibility
element. The window forwards the query to the widget with active focus.
This widget is the RWHVQtDelegateWidget if a web element is focused
in QWebEngineView. Therefore, a QAccessibleWidget interface has been
implemented for the RWHVQtDelegateWidget to forward the request to the
QWebEngineView.

The focused accessibility element expected to be returned by the
QAccessibleInterface::focusChild() method. In case of the macOS accessibility
backend, it is called by the accessibilityFocusedUIElement() NSAccessibility
API function. It expects the focused web accessibility element otherwise
VoiceOver won't focus properly.

The focused web accessiblity element is looked up by the new
BrowserAccessibilityQt::focusChild() method.
RenderWidgetHostviewQtDelegateWidget::focusChild() and
QWebengineViewAccessible::focusChild() methods have been also implemented
to forward it.

This patch depends on a focusChild() fix in qtbase:
a132e02540 Fix QAccessibleWidget::focusChild() to return focused descendant

Microsoft Narrator also uses focusChild() to query the current focused
element when it starts but it is still functional without this fix.

Task-number: QTBUG-78284
Task-number: QTBUG-81539
Change-Id: I3c4861e58622ccbb5046c60c4efcc19842400a88
Reviewed-by: Michael Brüning <michael.bruning@qt.io>
---
 .../widgets/accessibility/tst_accessibility.cpp    | 80 ++++++++++++++++++++++
 1 file changed, 80 insertions(+)

(limited to 'tests')

diff --git a/tests/auto/widgets/accessibility/tst_accessibility.cpp b/tests/auto/widgets/accessibility/tst_accessibility.cpp
index b5def4cd7..117a9e573 100644
--- a/tests/auto/widgets/accessibility/tst_accessibility.cpp
+++ b/tests/auto/widgets/accessibility/tst_accessibility.cpp
@@ -20,9 +20,13 @@
 #include <qtest.h>
 #include "../util.h"
 
+#include <QHBoxLayout>
+#include <QMainWindow>
+
 #include <qaccessible.h>
 #include <qwebengineview.h>
 #include <qwebenginepage.h>
+#include <qwebenginesettings.h>
 #include <qwidget.h>
 
 class tst_Accessibility : public QObject
@@ -38,6 +42,8 @@ public Q_SLOTS:
 private Q_SLOTS:
     void noPage();
     void hierarchy();
+    void focusChild();
+    void focusChild_data();
     void text();
     void value();
     void roles_data();
@@ -142,6 +148,80 @@ void tst_Accessibility::hierarchy()
     QCOMPARE(input, child);
 }
 
+void tst_Accessibility::focusChild_data()
+{
+    QTest::addColumn<QString>("interfaceName");
+    QTest::addColumn<QVector<QAccessible::Role>>("ancestorRoles");
+
+    QTest::newRow("QWebEngineView") << QString("QWebEngineView") << QVector<QAccessible::Role>({QAccessible::Client});
+    QTest::newRow("RenderWidgetHostViewQtDelegate") << QString("RenderWidgetHostViewQtDelegate") << QVector<QAccessible::Role>({QAccessible::Client});
+    QTest::newRow("QMainWindow") << QString("QMainWindow") << QVector<QAccessible::Role>({QAccessible::Window, QAccessible::Client /* central widget */, QAccessible::Client /* view */});
+}
+
+void tst_Accessibility::focusChild()
+{
+    auto traverseToWebDocumentAccessibleInterface = [](QAccessibleInterface *iface) -> QAccessibleInterface * {
+        QFETCH(QVector<QAccessible::Role>, ancestorRoles);
+        for (int i = 0; i < ancestorRoles.size(); ++i) {
+            if (iface->childCount() == 0 || iface->role() != ancestorRoles[i])
+                return nullptr;
+            iface = iface->child(0);
+        }
+
+        if (iface->role() != QAccessible::WebDocument)
+            return nullptr;
+
+        return iface;
+    };
+
+    QMainWindow mainWindow;
+    QWebEngineView *webView = new QWebEngineView;
+    QWidget *centralWidget = new QWidget;
+    QHBoxLayout *centralLayout = new QHBoxLayout;
+    centralWidget->setLayout(centralLayout);
+    mainWindow.setCentralWidget(centralWidget);
+    centralLayout->addWidget(webView);
+
+    mainWindow.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&mainWindow));
+
+    webView->settings()->setAttribute(QWebEngineSettings::FocusOnNavigationEnabled, true);
+    webView->setHtml("<html><body>" \
+        "<input id='input1' type='text' value='some text'/>" \
+        "</body></html>");
+    webView->show();
+    QSignalSpy spyFinished(webView, &QWebEngineView::loadFinished);
+    QVERIFY(spyFinished.wait());
+
+    QVERIFY(webView->focusWidget());
+    QAccessibleInterface *iface = nullptr;
+    QFETCH(QString, interfaceName);
+    if (interfaceName == "QWebEngineView")
+        iface = QAccessible::queryAccessibleInterface(webView);
+    else if (interfaceName == "RenderWidgetHostViewQtDelegate")
+        iface = QAccessible::queryAccessibleInterface(webView->focusWidget());
+    else if (interfaceName == "QMainWindow")
+        iface = QAccessible::queryAccessibleInterface(&mainWindow);
+    QVERIFY(iface);
+
+    // Make sure the input field does not have the focus.
+    evaluateJavaScriptSync(webView->page(), "document.getElementById('input1').blur()");
+    QTRY_VERIFY(evaluateJavaScriptSync(webView->page(), "document.activeElement.id").toString().isEmpty());
+
+    QVERIFY(iface->focusChild());
+    QTRY_COMPARE(iface->focusChild()->role(), QAccessible::WebDocument);
+    QCOMPARE(traverseToWebDocumentAccessibleInterface(iface), iface->focusChild());
+
+    // Set active focus on the input field.
+    evaluateJavaScriptSync(webView->page(), "document.getElementById('input1').focus()");
+    QTRY_COMPARE(evaluateJavaScriptSync(webView->page(), "document.activeElement.id").toString(), QStringLiteral("input1"));
+
+    QVERIFY(iface->focusChild());
+    QTRY_COMPARE(iface->focusChild()->role(), QAccessible::EditableText);
+    // <html> -> <body> -> <input>
+    QCOMPARE(traverseToWebDocumentAccessibleInterface(iface)->child(0)->child(0), iface->focusChild());
+}
+
 void tst_Accessibility::text()
 {
     QWebEngineView webView;
-- 
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