TD: implement XMLQuery for Qt6

src/Mod/TechDraw/App/XMLQuery.cpp

@@ -66,11 +66,53 @@ bool XMLQuery::processItems(const QString& queryStr, const std::function<bool(QD
     return true;
 }
 #else
+// A helper function that traverses all child elements recursively and check for
+// elements of name "text" with an attribute "freecad:editable"
+// If the query string contains "tspan" the first sub-element is used or the
+// found text element otherwise.
+static bool processElements(const QDomElement& element, const QString& queryStr,
+                            const std::function<bool(QDomElement&)>& process)
+{
+    bool find_tspan = queryStr.contains(QLatin1String("tspan"));
+    QDomNodeList editable = element.elementsByTagName(QString(QLatin1String("text")));
+    if (editable.count() > 0) {
+        for(int i = 0; i < editable.count(); i++) {
+            QDomNode node = editable.item(i);
+            QDomElement element = node.toElement();
+            if (element.hasAttribute(QString(QLatin1String("freecad:editable")))) {
+                if (find_tspan) {
+                    element = element.firstChildElement();
+                }
+
+                if (!process(element)) {
+                    return false;
+                }
+            }
+        }
+    }
+    else {
+        QDomElement child;
+        child = element.firstChildElement();
+        while (!child.isNull()) {
+            if (!processElements(child, queryStr, process)) {
+                return false;
+            }
+            child = child.nextSiblingElement();
+        }
+    }
+
+    return true;
+}
+
 bool XMLQuery::processItems(const QString& queryStr, const std::function<bool(QDomElement&)>& process)
 {
-    //TODO: Port to Qt6
-    Q_UNUSED(queryStr)
-    Q_UNUSED(process)
-    return false;
+    // The actual query string is of the form "//text[@freecad:editable]"
+    // or "//text[@freecad:editable]/tspan"
+    QDomElement root = domDocument.documentElement();
+    if (!root.isNull()) {
+        processElements(root, queryStr, process);
+    }
+
+    return true;
 }
 #endif