Qt: Show tooltip in sequence diagram for elided comments

If the comment (i.e. Info column) text is elided, show the
full text as a tooltip. We already show it down in the status
hint text, but it's nice not to have to look all the way at
the bottom of the window.

Somewhat related to #4972
(I think, for that one, we will probably need to make the
column width controlled by a different widget rather than a
QSplitter, because making it a QSplitter would make the comments
no longer an axis, and then they wouldn't be printed.)

ui/qt/sequence_diagram.cpp

@@ -149,8 +149,6 @@ void SequenceDiagram::setData(_seq_analysis_info *sainfo)
     double cur_key = 0.0;
     QVector<double> key_ticks, val_ticks;
     QVector<QString> key_labels, val_labels, com_labels;
-    QFontMetrics com_fm(comment_axis_->tickLabelFont());
-    int elide_w = com_fm.height() * max_comment_em_width_;
     char* addr_str;
 
     for (GList *cur = g_queue_peek_nth_link(sainfo->items, 0); cur; cur = gxx_list_next(cur)) {
@@ -165,7 +163,7 @@ void SequenceDiagram::setData(_seq_analysis_info *sainfo)
             key_ticks.append(cur_key);
             key_labels.append(sai->time_str);
 
-            com_labels.append(com_fm.elidedText(sai->comment, Qt::ElideRight, elide_w));
+            com_labels.append(elidedComment(sai->comment));
 
             cur_key++;
         }
@@ -211,6 +209,21 @@ _seq_analysis_item *SequenceDiagram::itemForPosY(int ypos)
     return NULL;
 }
 
+bool SequenceDiagram::inComment(QPoint pos) const
+{
+    return pos.x() >= (comment_axis_->axisRect()->right()
+                        + comment_axis_->padding()
+                        + comment_axis_->tickLabelPadding()
+                        + comment_axis_->offset());
+}
+
+QString SequenceDiagram::elidedComment(const QString &text) const
+{
+    QFontMetrics com_fm(comment_axis_->tickLabelFont());
+    int elide_w = com_fm.height() * max_comment_em_width_;
+    return com_fm.elidedText(text, Qt::ElideRight, elide_w);
+}
+
 double SequenceDiagram::selectTest(const QPointF &pos, bool, QVariant *) const
 {
     double key_pos = qRound(key_axis_->pixelToCoord(pos.y()));

ui/qt/sequence_diagram.h

@@ -53,6 +53,8 @@ public:
 
     // non-property methods:
     struct _seq_analysis_item *itemForPosY(int ypos);
+    bool inComment(QPoint pos) const;
+    QString elidedComment(const QString &text) const;
 
     // reimplemented virtual methods:
     virtual void clearData() { data_->clear(); }

ui/qt/sequence_dialog.cpp

@@ -225,6 +225,23 @@ void SequenceDialog::updateWidgets()
     WiresharkDialog::updateWidgets();
 }
 
+bool SequenceDialog::event(QEvent *event)
+{
+    if (event->type() == QEvent::ToolTip) {
+        QHelpEvent *helpEvent = static_cast<QHelpEvent *>(event);
+        seq_analysis_item_t *sai = seq_diagram_->itemForPosY(helpEvent->pos().y());
+        if (sai && seq_diagram_->inComment(helpEvent->pos()) && (sai->comment != seq_diagram_->elidedComment(sai->comment))) {
+            QToolTip::showText(helpEvent->globalPos(), sai->comment);
+        } else {
+            QToolTip::hideText();
+            event->ignore();
+        }
+
+        return true;
+    }
+    return QWidget::event(event);
+}
+
 void SequenceDialog::showEvent(QShowEvent *)
 {
     QTimer::singleShot(0, this, SLOT(fillDiagram()));

ui/qt/sequence_dialog.h

@@ -54,6 +54,7 @@ public:
     void enableVoIPFeatures();
 
 protected:
+    bool event(QEvent *event);
     void showEvent(QShowEvent *event);
     void resizeEvent(QResizeEvent *event);
     void keyPressEvent(QKeyEvent *event);