[QtUtils] Add parent lookup, layout clearing, scroll area and monospace helpers (#7617)

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_utility/CMakeLists.txt

@@ -27,6 +27,7 @@ set(UTILITY_HEADERS
     libcockatrice/utility/macros.h
     libcockatrice/utility/passwordhasher.h
     libcockatrice/utility/playmat_params.h
+    libcockatrice/utility/qt_utils.h
     libcockatrice/utility/report_categories.h
     libcockatrice/utility/string_limits.h
     libcockatrice/utility/dice_limits.h

libcockatrice_utility/libcockatrice/utility/qt_utils.h

@@ -1,13 +1,29 @@
 #ifndef COCKATRICE_QT_UTILS_H
 #define COCKATRICE_QT_UTILS_H
+#include <QFont>
+#include <QFontDatabase>
 #include <QLayout>
 #include <QObject>
+#include <QScrollArea>
+#include <QString>
+#include <QWidget>
 
 namespace QtUtils
 {
-template <typename T> T *findParentOfType(const QObject *obj)
+/**
+ * @brief Returns the nearest ancestor of @p obj that casts to @c T.
+ *
+ * Walks the QObject parent chain. QWidget::parentWidget() is the same pointer as
+ * QObject::parent() for widgets, so this also covers the common "find the parent tab,
+ * splitter or scroll area" lookups.
+ *
+ * @param obj         Object to start from. May be null.
+ * @param includeSelf Also test @p obj itself before walking upwards.
+ * @return The first matching ancestor, or nullptr if there is none.
+ */
+template <typename T> T *findParentOfType(const QObject *obj, bool includeSelf = false)
 {
-    const QObject *p = obj ? obj->parent() : nullptr;
+    const QObject *p = includeSelf ? obj : (obj ? obj->parent() : nullptr);
     while (p) {
         if (auto casted = qobject_cast<T *>(const_cast<QObject *>(p))) {
             return casted;
@@ -17,22 +33,80 @@ template <typename T> T *findParentOfType(const QObject *obj)
     return nullptr;
 }
 
-static inline void clearLayoutRec(QLayout *l)
+/**
+ * @brief How clearLayoutRec() disposes of the widgets it removes.
+ *
+ * Deferred is the safe default: deleteLater() lets a widget finish handling the event that
+ * triggered the rebuild. Use Immediate when the caller rebuilds the same layout right away
+ * and a lingering widget would be visible or otherwise in the way until the next event loop
+ * turn.
+ */
+enum class DeletePolicy
+{
+    Deferred,
+    Immediate
+};
+
+/**
+ * @brief Removes and deletes every item in @p l, recursing into nested layouts.
+ *
+ * Widgets are disposed of according to @p policy; spacers and nested layouts are simply
+ * deleted.
+ */
+static inline void clearLayoutRec(QLayout *l, DeletePolicy policy = DeletePolicy::Deferred)
 {
     if (!l) {
         return;
     }
-    QLayoutItem *it;
-    while ((it = l->takeAt(0)) != nullptr) {
+    while (QLayoutItem *it = l->takeAt(0)) {
         if (QWidget *w = it->widget()) {
-            w->deleteLater();
+            if (policy == DeletePolicy::Immediate) {
+                delete w;
+            } else {
+                w->deleteLater();
+            }
         }
         if (QLayout *sub = it->layout()) {
-            clearLayoutRec(sub);
+            clearLayoutRec(sub, policy);
         }
         delete it;
     }
 }
+
+/**
+ * @brief Creates a QScrollArea using the conventions the client applies nearly everywhere:
+ *        the inner widget resizes with the viewport and the horizontal bar is disabled.
+ *
+ * @param parent           Parent widget, or nullptr for a parentless scroll area.
+ * @param verticalPolicy   Vertical scroll bar policy.
+ * @param horizontalPolicy Horizontal scroll bar policy.
+ */
+static inline QScrollArea *makeScrollArea(QWidget *parent = nullptr,
+                                          Qt::ScrollBarPolicy verticalPolicy = Qt::ScrollBarAsNeeded,
+                                          Qt::ScrollBarPolicy horizontalPolicy = Qt::ScrollBarAlwaysOff)
+{
+    auto *scrollArea = new QScrollArea(parent);
+    scrollArea->setWidgetResizable(true);
+    scrollArea->setVerticalScrollBarPolicy(verticalPolicy);
+    scrollArea->setHorizontalScrollBarPolicy(horizontalPolicy);
+    return scrollArea;
+}
+
+/**
+ * @brief A monospace font at the system UI font's point size.
+ *
+ * Used for log dumps, deck codes and other text that has to line up.
+ */
+static inline QFont monospaceFont()
+{
+    QFont font(QStringLiteral("monospace"));
+    font.setStyleHint(QFont::Monospace);
+    const int systemPointSize = QFontDatabase::systemFont(QFontDatabase::GeneralFont).pointSize();
+    if (systemPointSize > 0) {
+        font.setPointSize(systemPointSize);
+    }
+    return font;
+}
 } // namespace QtUtils
 
 #endif // COCKATRICE_QT_UTILS_H