cabana: horizontal scrolling with Shift+wheel (#31929)

tools/cabana/messageswidget.cc

@@ -85,7 +85,9 @@ MessagesWidget::MessagesWidget(QWidget *parent) : menu(new QMenu(this)), QWidget
     <span style="color:gray">Byte color</span><br />
     <span style="color:gray;">■ </span> constant changing<br />
     <span style="color:blue;">■ </span> increasing<br />
-    <span style="color:red;">■ </span> decreasing
+    <span style="color:red;">■ </span> decreasing<br />
+    <span style="color:gray">Shortcuts</span><br />
+    Horizontal Scrolling: <span style="background-color:lightGray;color:gray">&nbsp;shift+wheel&nbsp;</span>
   )"));
 }
 
@@ -391,6 +393,14 @@ void MessageView::updateBytesSectionSize() {
   header()->resizeSection(MessageListModel::Column::DATA, delegate->sizeForBytes(max_bytes).width());
 }
 
+void MessageView::wheelEvent(QWheelEvent *event) {
+  if (event->modifiers() == Qt::ShiftModifier) {
+    QApplication::sendEvent(horizontalScrollBar(), event);
+  } else {
+    QTreeView::wheelEvent(event);
+  }
+}
+
 // MessageViewHeader
 
 MessageViewHeader::MessageViewHeader(QWidget *parent) : QHeaderView(Qt::Horizontal, parent) {

tools/cabana/messageswidget.h

@@ -12,6 +12,7 @@
 #include <QMenu>
 #include <QToolBar>
 #include <QTreeView>
+#include <QWheelEvent>
 
 #include "tools/cabana/dbc/dbcmanager.h"
 #include "tools/cabana/streams/abstractstream.h"
@@ -65,10 +66,13 @@ class MessageView : public QTreeView {
   Q_OBJECT
 public:
   MessageView(QWidget *parent) : QTreeView(parent) {}
+  void updateBytesSectionSize();
+
+protected:
   void drawRow(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
   void drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const override {}
   void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>()) override;
-  void updateBytesSectionSize();
+  void wheelEvent(QWheelEvent *event) override;
 };
 
 class MessageViewHeader : public QHeaderView {