Utils: Replace Tooltip hack with another tooltip hack

Instead of fooling moc into believing it operates on a class called
QTipLabel and create a "QTipLabel" class name from that, create a
metaobject with the "QTipLabel" class name directly.

This trades messing around with namespaces for assumptions on
the stability of QMetaObject class layout. Given that this is an
exported class in Qt Core, that's unlikely to break soon.

Change-Id: Iad24dd2a8a7f492e4b238d390888f89c6dd29ea9
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

3 files changed, 35 insertions, 24 deletions

diff --git a/src/libs/utils/tooltip/tips.cpp b/src/libs/utils/tooltip/tips.cpp
index b0aee273f4..d38259518d 100644
--- a/src/libs/utils/tooltip/tips.cpp
+++ b/src/libs/utils/tooltip/tips.cpp
@@ -46,24 +46,41 @@
 namespace Utils {
 namespace Internal {
 
-QTipLabel::QTipLabel(QWidget *parent) :
+TipLabel::TipLabel(QWidget *parent) :
     QLabel(parent, Qt::ToolTip | Qt::BypassGraphicsProxyWidget)
-{}
+{
+}
 
-void QTipLabel::setHelpId(const QString &id)
+void TipLabel::setHelpId(const QString &id)
 {
     m_helpId = id;
     update();
 }
 
-QString QTipLabel::helpId() const
+QString TipLabel::helpId() const
 {
     return m_helpId;
 }
 
+const QMetaObject *TipLabel::metaObject() const
+{
+    // CSS Tooltip styling depends on a the name of this class.
+    // So set up a minimalist QMetaObject to fake a class name "QTipLabel":
+    static const uint tip_label_meta_data[15] = { 8 /* moc revision */ };
+    static const QMetaObject tipMetaObject {
+         &QLabel::staticMetaObject,
+         QByteArrayLiteral("QTipLabel").data_ptr(),
+         tip_label_meta_data,
+         nullptr,
+         nullptr,
+         nullptr
+    };
+
+    return &tipMetaObject;
+}
 
 ColorTip::ColorTip(QWidget *parent)
-    : QTipLabel(parent)
+    : TipLabel(parent)
 {
     resize(40, 40);
 }
@@ -101,7 +118,7 @@ bool ColorTip::equals(int typeId, const QVariant &other, const QString &otherHel
 
 void ColorTip::paintEvent(QPaintEvent *event)
 {
-    QTipLabel::paintEvent(event);
+    TipLabel::paintEvent(event);
 
     QPainter painter(this);
     painter.setBrush(m_color);
@@ -115,7 +132,7 @@ void ColorTip::paintEvent(QPaintEvent *event)
     painter.drawRect(borderRect);
 }
 
-TextTip::TextTip(QWidget *parent) : QTipLabel(parent)
+TextTip::TextTip(QWidget *parent) : TipLabel(parent)
 {
     setForegroundRole(QPalette::ToolTipText);
     setBackgroundRole(QPalette::ToolTipBase);
@@ -210,7 +227,7 @@ void TextTip::resizeEvent(QResizeEvent *event)
 }
 
 WidgetTip::WidgetTip(QWidget *parent) :
-    QTipLabel(parent), m_layout(new QVBoxLayout)
+    TipLabel(parent), m_layout(new QVBoxLayout)
 {
     m_layout->setContentsMargins(0, 0, 0, 0);
     setLayout(m_layout);
@@ -267,8 +284,5 @@ bool WidgetTip::equals(int typeId, const QVariant &other, const QString &otherHe
             && other.value<QWidget *>() == m_widget;
 }
 
-// need to include it here to force it to be inside the namespaces
-#include "moc_tips.cpp"
-
 } // namespace Internal
 } // namespace Utils
diff --git a/src/libs/utils/tooltip/tips.h b/src/libs/utils/tooltip/tips.h
index 844848e796..764e10eb8a 100644
--- a/src/libs/utils/tooltip/tips.h
+++ b/src/libs/utils/tooltip/tips.h
@@ -33,17 +33,13 @@
 #include <QVariant>
 #include <QVBoxLayout>
 
-#ifndef Q_MOC_RUN
 namespace Utils {
 namespace Internal {
-#endif
 
-// Please do not change the name of this class. Detailed comments in tooltip.h.
-class QTipLabel : public QLabel
+class TipLabel : public QLabel
 {
-    Q_OBJECT
 public:
-    QTipLabel(QWidget *parent);
+    TipLabel(QWidget *parent);
 
     virtual void setContent(const QVariant &content) = 0;
     virtual bool isInteractive() const { return false; }
@@ -54,11 +50,14 @@ public:
     virtual void setHelpId(const QString &id);
     virtual QString helpId() const;
 
+protected:
+    const QMetaObject *metaObject() const override;
+
 private:
     QString m_helpId;
 };
 
-class TextTip : public QTipLabel
+class TextTip : public TipLabel
 {
 public:
     TextTip(QWidget *parent);
@@ -76,7 +75,7 @@ private:
     QString m_text;
 };
 
-class ColorTip : public QTipLabel
+class ColorTip : public TipLabel
 {
 public:
     ColorTip(QWidget *parent);
@@ -93,7 +92,7 @@ private:
     QPixmap m_tilePixmap;
 };
 
-class WidgetTip : public QTipLabel
+class WidgetTip : public TipLabel
 {
     Q_OBJECT
 
@@ -113,7 +112,5 @@ private:
     QVBoxLayout *m_layout;
 };
 
-#ifndef Q_MOC_RUN
 } // namespace Internal
 } // namespace Utils
-#endif
diff --git a/src/libs/utils/tooltip/tooltip.h b/src/libs/utils/tooltip/tooltip.h
index ece289b66b..d78623b41f 100644
--- a/src/libs/utils/tooltip/tooltip.h
+++ b/src/libs/utils/tooltip/tooltip.h
@@ -50,7 +50,7 @@ class QWidget;
 QT_END_NAMESPACE
 
 namespace Utils {
-namespace Internal { class QTipLabel; }
+namespace Internal { class TipLabel; }
 
 class QTCREATOR_UTILS_EXPORT ToolTip : public QObject
 {
@@ -110,7 +110,7 @@ private:
     void showTip();
     void hideTipWithDelay();
 
-    QPointer<Internal::QTipLabel> m_tip;
+    QPointer<Internal::TipLabel> m_tip;
     QWidget *m_widget;
     QRect m_rect;
     QTimer m_showTimer;