Qt: Improve tcptrace graph drag responsiveness

Subclass QCPErrorBars with implementation that never accepts clicks.
This prevents a lot of square root computations in QCustomPlot
mousePressEvent handle and results in usable tcptrace graph.

An alternative solution to the poor performance problem could be using
QCP::srmCustom SelectionRectMode. I don't know how to implement graph
drag with QCP::srmCustom, and thus I went with simple subclass approach.

Bug: 16281
Change-Id: Id4178e59bdbd2222db4669d0635ff741ebde839f
Reviewed-on: https://code.wireshark.org/review/36413
Petri-Dish: Tomasz Moń <desowin@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

2 files changed, 32 insertions, 3 deletions

diff --git a/ui/qt/tcp_stream_dialog.cpp b/ui/qt/tcp_stream_dialog.cpp
index 9c761158c8..5c64180c69 100644
--- a/ui/qt/tcp_stream_dialog.cpp
+++ b/ui/qt/tcp_stream_dialog.cpp
@@ -74,6 +74,23 @@ const QString sequence_number_label_ = QObject::tr("Sequence Number (B)");
 const QString time_s_label_ = QObject::tr("Time (s)");
 const QString window_size_label_ = QObject::tr("Window Size (B)");
 
+QCPErrorBarsNotSelectable::QCPErrorBarsNotSelectable(QCPAxis *keyAxis, QCPAxis *valueAxis) :
+    QCPErrorBars(keyAxis, valueAxis)
+{
+}
+
+QCPErrorBarsNotSelectable::~QCPErrorBarsNotSelectable()
+{
+}
+
+double QCPErrorBarsNotSelectable::selectTest(const QPointF &pos, bool onlySelectable, QVariant *details) const
+{
+    Q_UNUSED(pos);
+    Q_UNUSED(onlySelectable);
+    Q_UNUSED(details);
+    return -1.0;
+}
+
 TCPStreamDialog::TCPStreamDialog(QWidget *parent, capture_file *cf, tcp_graph_type graph_type) :
     GeometryStateDialog(parent),
     ui(new Ui::TCPStreamDialog),
@@ -247,7 +264,7 @@ TCPStreamDialog::TCPStreamDialog(QWidget *parent, capture_file *cf, tcp_graph_ty
     seg_graph_ = sp->addGraph();
     seg_graph_->setLineStyle(QCPGraph::lsNone);
     seg_graph_->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDot, Qt::transparent, 0));
-    seg_eb_ = new QCPErrorBars(sp->xAxis, sp->yAxis);
+    seg_eb_ = new QCPErrorBarsNotSelectable(sp->xAxis, sp->yAxis);
     seg_eb_->setErrorType(QCPErrorBars::etValueError);
     seg_eb_->setPen(QPen(QBrush(graph_color_1), pen_width));
     seg_eb_->setSymbolGap(0.0); // draw error spine as single line
@@ -264,7 +281,7 @@ TCPStreamDialog::TCPStreamDialog(QWidget *parent, capture_file *cf, tcp_graph_ty
     sack_graph_ = sp->addGraph();
     sack_graph_->setLineStyle(QCPGraph::lsNone);
     sack_graph_->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDot, Qt::transparent, 0));
-    sack_eb_ = new QCPErrorBars(sp->xAxis, sp->yAxis);
+    sack_eb_ = new QCPErrorBarsNotSelectable(sp->xAxis, sp->yAxis);
     sack_eb_->setErrorType(QCPErrorBars::etValueError);
     sack_eb_->setPen(QPen(QBrush(graph_color_4), pen_width));
     sack_eb_->setSymbolGap(0.0); // draw error spine as single line
@@ -276,7 +293,7 @@ TCPStreamDialog::TCPStreamDialog(QWidget *parent, capture_file *cf, tcp_graph_ty
     sack2_graph_ = sp->addGraph();
     sack2_graph_->setLineStyle(QCPGraph::lsNone);
     sack2_graph_->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDot, Qt::transparent, 0));
-    sack2_eb_ = new QCPErrorBars(sp->xAxis, sp->yAxis);
+    sack2_eb_ = new QCPErrorBarsNotSelectable(sp->xAxis, sp->yAxis);
     sack2_eb_->setErrorType(QCPErrorBars::etValueError);
     sack2_eb_->setPen(QPen(QBrush(graph_color_5), pen_width));
     sack2_eb_->setSymbolGap(0.0); // draw error spine as single line
diff --git a/ui/qt/tcp_stream_dialog.h b/ui/qt/tcp_stream_dialog.h
index edd6133a15..6cd5bb4fec 100644
--- a/ui/qt/tcp_stream_dialog.h
+++ b/ui/qt/tcp_stream_dialog.h
@@ -29,8 +29,20 @@
 
 namespace Ui {
 class TCPStreamDialog;
+class QCPErrorBarsNotSelectable;
 }
 
+class QCPErrorBarsNotSelectable : public QCPErrorBars
+{
+    Q_OBJECT
+
+public:
+    explicit QCPErrorBarsNotSelectable(QCPAxis *keyAxis, QCPAxis *valueAxis);
+    virtual ~QCPErrorBarsNotSelectable();
+
+    virtual double selectTest(const QPointF &pos, bool onlySelectable, QVariant *details = 0) const Q_DECL_OVERRIDE;
+};
+
 class TCPStreamDialog : public GeometryStateDialog
 {
     Q_OBJECT