Fix QAccessible name and description calculation

The logic was removed in
1881f56d

.

There is no platform independent implementation in Chromium for
calculating Accessible name which follow the W3C Accessibility standard.
We need to apply this logic in order to get Accessible name
and description correctly.

It also fixes the QWebEngineAccessibility test cases.

Change-Id: I733c6311301c43610b7a9aaf22c73c2e5d368c70
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

src/core/browser_accessibility_qt.cpp

@@ -59,6 +59,84 @@ BrowserAccessibilityQt::BrowserAccessibilityQt()
     QAccessible::registerAccessibleInterface(this);
 }
 
+// This function is taken from chromium/content/browser/accessibility/browser_accessibility_win.cc
+// see also http://www.w3.org/TR/html-aapi
+void BrowserAccessibilityQt::OnDataChanged()
+{
+    BrowserAccessibility::OnDataChanged();
+
+    // The calculation of the accessible name of an element has been
+    // standardized in the HTML to Platform Accessibility APIs Implementation
+    // Guide (http://www.w3.org/TR/html-aapi/). In order to return the
+    // appropriate accessible name on Windows, we need to apply some logic
+    // to the fields we get from WebKit.
+    //
+    // TODO(dmazzoni): move most of this logic into WebKit.
+    //
+    // WebKit gives us:
+    //
+    //   name: the default name, e.g. inner text
+    //   title ui element: a reference to a <label> element on the same
+    //       page that labels this node.
+    //   description: accessible labels that override the default name:
+    //       aria-label or aria-labelledby or aria-describedby
+    //   help: the value of the "title" attribute
+    //
+    // On Windows, the logic we apply lets some fields take precedence and
+    // always returns the primary name in "name" and the secondary name,
+    // if any, in "description".
+
+    int title_elem_id = GetIntAttribute(ui::AX_ATTR_TITLE_UI_ELEMENT);
+    base::string16 name = GetString16Attribute(ui::AX_ATTR_NAME);
+    base::string16 description = GetString16Attribute(ui::AX_ATTR_DESCRIPTION);
+    base::string16 help = GetString16Attribute(ui::AX_ATTR_HELP);
+    base::string16 value = GetString16Attribute(ui::AX_ATTR_VALUE);
+
+    // WebKit annoyingly puts the title in the description if there's no other
+    // description, which just confuses the rest of the logic. Put it back.
+    // Now "help" is always the value of the "title" attribute, if present.
+    base::string16 title_attr;
+    if (GetHtmlAttribute("title", &title_attr) &&
+        description == title_attr &&
+        help.empty()) {
+        help = description;
+        description.clear();
+    }
+
+    // Now implement the main logic: the descripion should become the name if
+    // it's nonempty, and the help should become the description if
+    // there's no description - or the name if there's no name or description.
+    if (!description.empty()) {
+        name = description;
+        description.clear();
+    }
+    if (!help.empty() && description.empty()) {
+        description = help;
+        help.clear();
+    }
+    if (!description.empty() && name.empty() && !title_elem_id) {
+        name = description;
+        description.clear();
+    }
+
+    // If it's a text field, also consider the placeholder.
+    base::string16 placeholder;
+    if (GetRole() == ui::AX_ROLE_TEXT_FIELD &&
+        HasState(ui::AX_STATE_FOCUSABLE) &&
+        GetHtmlAttribute("placeholder", &placeholder)) {
+        if (name.empty() && !title_elem_id) {
+            name = placeholder;
+        } else if (description.empty()) {
+            description = placeholder;
+        }
+    }
+
+    m_name = toQt(name);
+    m_description = toQt(description);
+    m_help = toQt(help);
+    m_value = toQt(value);
+}
+
 bool BrowserAccessibilityQt::isValid() const
 {
     return true;
@@ -151,13 +229,13 @@ QString BrowserAccessibilityQt::text(QAccessible::Text t) const
 {
     switch (t) {
     case QAccessible::Name:
-        return toQt(GetStringAttribute(ui::AX_ATTR_NAME));
+        return name();
     case QAccessible::Description:
-        return toQt(GetStringAttribute(ui::AX_ATTR_DESCRIPTION));
+        return description();
     case QAccessible::Help:
-        return toQt(GetStringAttribute(ui::AX_ATTR_HELP));
+        return help();
     case QAccessible::Value:
-        return toQt(GetStringAttribute(ui::AX_ATTR_VALUE));
+        return value();
     case QAccessible::Accelerator:
         return toQt(GetStringAttribute(ui::AX_ATTR_SHORTCUT));
     default:

src/core/browser_accessibility_qt.h

@@ -55,6 +55,9 @@ class BrowserAccessibilityQt
 public:
     BrowserAccessibilityQt();
 
+    // BrowserAccessibility
+    virtual void OnDataChanged() Q_DECL_OVERRIDE;
+
     // QAccessibleInterface
     virtual bool isValid() const Q_DECL_OVERRIDE;
     virtual QObject *object() const Q_DECL_OVERRIDE;
@@ -139,6 +142,18 @@ public:
     virtual QAccessibleInterface* table() const Q_DECL_OVERRIDE;
 
     virtual void modelChange(QAccessibleTableModelChangeEvent *event) Q_DECL_OVERRIDE;
+
+    QString name() const { return m_name; }
+    QString description() const { return m_description; }
+    QString help() const { return m_help; }
+    QString value() const { return m_value; }
+
+private:
+    // IAccessible name, description, help, value.
+    QString m_name;
+    QString m_description;
+    QString m_help;
+    QString m_value;
 };
 
 }