Merge pull request #533 from lvntky/fix-arrayviz-stack

Fix: Array Visualizer handleText stack usage

src/QImageViewer.cpp

@@ -9,6 +9,7 @@
 #include <QtGui/QImageReader>
 #include <QtGui/QImageWriter>
 #include <QtGui/QPainter>
+#include <QtGui/QWheelEvent>
 #include <QtCore/QDebug>
 #include <QtPrintSupport/QPrintDialog>
 
@@ -19,6 +20,8 @@
 
 QImageViewer::QImageViewer (QWidget* parent) : QWidget(parent) {
 
+    setFocusPolicy(Qt::StrongFocus); // So the widget can take focus and receive the +/-/ESC zoom keys.
+
     _zoomFactor = 1.0;
 
     // Setup the widgets
@@ -34,6 +37,10 @@ QImageViewer::QImageViewer (QWidget* parent) : QWidget(parent) {
     _scrollArea->setWidget(_imageLabel);
     _scrollArea->setWidgetResizable(false);
 
+    // The scroll area consumes wheel events for scrolling, so watch its
+    // viewport to catch Ctrl+wheel for zooming.
+    _scrollArea->viewport()->installEventFilter(this);
+
     layout->addWidget(_scrollArea);
 
     clearImage();
@@ -174,7 +181,30 @@ void QImageViewer::keyPressEvent (QKeyEvent* event) {
     }
 }
 
-void QImageViewer::enterEvent (QEvent* event) {
+bool QImageViewer::eventFilter (QObject* object, QEvent* event) {
+
+    // Ctrl+wheel over the image zooms in or out. A plain wheel keeps
+    // scrolling the image as usual.
+    if (object == _scrollArea->viewport() && event->type() == QEvent::Wheel) {
+
+        QWheelEvent* wheelEvent = static_cast<QWheelEvent*>(event);
+
+        if (wheelEvent->modifiers() & Qt::ControlModifier) {
+
+            if (wheelEvent->angleDelta().y() > 0) {
+                zoomIn();
+            }else if (wheelEvent->angleDelta().y() < 0) {
+                zoomOut();
+            }
+
+            return true;
+        }
+    }
+
+    return QWidget::eventFilter(object, event);
+}
+
+void QImageViewer::enterEvent (QEnterEvent* event) {
 
     Q_UNUSED(event);
 

src/QImageViewer.h

@@ -38,8 +38,9 @@ class QImageViewer : public QWidget {
 
     protected slots:
         void                    keyPressEvent           (QKeyEvent* event);
-        void                    enterEvent              (QEvent*    event);
-        void                    leaveEvent              (QEvent*    event);
+        bool                    eventFilter             (QObject* object, QEvent* event) override;
+        void                    enterEvent              (QEnterEvent* event) override;
+        void                    leaveEvent              (QEvent*    event) override;
 
     private:
         QImage                  _image;

src/SeerArrayVisualizerWidget.cpp

@@ -398,7 +398,10 @@ void SeerArrayVisualizerWidget::handleText (const QString& text) {
 
     //qDebug() << text;
 
-    if (text.contains(QRegularExpression("^([0-9]+)\\^done,value="))) {
+    static const QRegularExpression valueResponse = QRegularExpression("^([0-9]+)\\^done,value=");
+    static const QRegularExpression memoryResponse = QRegularExpression("^([0-9]+)\\^done,memory=");
+	static const QRegularExpression errorResponse = QRegularExpression("^([0-9]+)\\^error,msg=");
+    if (text.contains(valueResponse)) {
 
         // 11^done,value="1"
         // 11^done,value="0x7fffffffd538"
@@ -430,8 +433,10 @@ void SeerArrayVisualizerWidget::handleText (const QString& text) {
                 }
             }
 
-            // Set the variable address.
+            // Set the variable address and read the memory there.
             setAVariableAddress(address);
+
+            readaMemory();
         }
 
         if (id_text.toInt() == _aLengthId) {
@@ -489,8 +494,10 @@ void SeerArrayVisualizerWidget::handleText (const QString& text) {
                 }
             }
 
-            // Set the variable address.
+            // Set the variable address and read the memory there.
             setBVariableAddress(address);
+
+            readbMemory();
         }
 
         if (id_text.toInt() == _bLengthId) {
@@ -523,7 +530,7 @@ void SeerArrayVisualizerWidget::handleText (const QString& text) {
             handlebRefreshButton();
         }
 
-    }else if (text.contains(QRegularExpression("^([0-9]+)\\^done,memory="))) {
+    }else if (text.contains(memoryResponse)) {
 
         // 3^done,memory=[{begin="0x0000000000613e70",offset="0x0000000000000000",end="0x0000000000613e71",contents="00"}]
         // 4^done,memory=[{begin="0x0000000000613e70",offset="0x0000000000000000",end="0x0000000000613ed4",contents="000000000000000000000000"}]
@@ -628,7 +635,7 @@ void SeerArrayVisualizerWidget::handleText (const QString& text) {
             }
         }
 
-    }else if (text.contains(QRegularExpression("^([0-9]+)\\^error,msg="))) {
+    }else if (text.contains(errorResponse)) {
 
         // 12^error,msg="No symbol \"return\" in current context."
         // 13^error,msg="No symbol \"cout\" in current context."
@@ -742,6 +749,26 @@ void SeerArrayVisualizerWidget::handleaRefreshButton () {
         return;
     }
 
+    // Re-evaluate the variable's address first: it may have changed since the
+    // last stop (or the variable may not have existed yet). The answer then
+    // reads the memory at the fresh address. See readaMemory().
+    emit evaluateVariableExpression(_aVariableId, aVariableNameLineEdit->text());
+}
+
+void SeerArrayVisualizerWidget::handlebRefreshButton () {
+
+    if (bVariableNameLineEdit->text() == "") {
+        return;
+    }
+
+    // Re-evaluate the variable's address first: it may have changed since the
+    // last stop (or the variable may not have existed yet). The answer then
+    // reads the memory at the fresh address. See readbMemory().
+    emit evaluateVariableExpression(_bVariableId, bVariableNameLineEdit->text());
+}
+
+void SeerArrayVisualizerWidget::readaMemory () {
+
     if (aVariableAddressLineEdit->text() == "") {
         return;
     }
@@ -750,18 +777,25 @@ void SeerArrayVisualizerWidget::handleaRefreshButton () {
         return;
     }
 
+    // A null address can't be read (a std::vector before its construction,
+    // for example). Keep the "0x0" visible but don't ask gdb.
+    if (aVariableAddressLineEdit->text() == "0x0") {
+        return;
+    }
+
     int bytes = aArrayLengthLineEdit->text().toInt() * Seer::typeBytes(aArrayDisplayFormatComboBox->currentText());
 
+    // Nothing to read yet (no length).
+    if (bytes <= 0) {
+        return;
+    }
+
     //qDebug() << _aMemoryId << aVariableAddressLineEdit->text() << aArrayLengthLineEdit->text() << aArrayDisplayFormatComboBox->currentText() << bytes;
 
     emit evaluateMemoryExpression(_aMemoryId, aVariableAddressLineEdit->text(), bytes);
 }
 
-void SeerArrayVisualizerWidget::handlebRefreshButton () {
-
-    if (bVariableNameLineEdit->text() == "") {
-        return;
-    }
+void SeerArrayVisualizerWidget::readbMemory () {
 
     if (bVariableAddressLineEdit->text() == "") {
         return;
@@ -771,8 +805,19 @@ void SeerArrayVisualizerWidget::handlebRefreshButton () {
         return;
     }
 
+    // A null address can't be read (a std::vector before its construction,
+    // for example). Keep the "0x0" visible but don't ask gdb.
+    if (bVariableAddressLineEdit->text() == "0x0") {
+        return;
+    }
+
     int bytes = bArrayLengthLineEdit->text().toInt() * Seer::typeBytes(bArrayDisplayFormatComboBox->currentText());
 
+    // Nothing to read yet (no length).
+    if (bytes <= 0) {
+        return;
+    }
+
     //qDebug() << _bMemoryId << bVariableAddressLineEdit->text() << bArrayLengthLineEdit->text() << bArrayDisplayFormatComboBox->currentText() << bytes;
 
     emit evaluateMemoryExpression(_bMemoryId, bVariableAddressLineEdit->text(), bytes);

src/SeerArrayVisualizerWidget.h

@@ -76,6 +76,8 @@ class SeerArrayVisualizerWidget : public QWidget, protected Ui::SeerArrayVisuali
         void                resizeEvent                         (QResizeEvent* event);
 
     private:
+        void                readaMemory                         ();
+        void                readbMemory                         ();
         void                createASeries                       ();
         void                createBSeries                       ();
 

src/SeerMatrixVisualizerWidget.cpp

@@ -238,8 +238,10 @@ void SeerMatrixVisualizerWidget::handleText (const QString& text) {
                 }
             }
 
-            // Set the variable address.
+            // Set the variable address and read the memory there.
             setVariableAddress(address);
+
+            readMemory();
         }
 
         if (id_text.toInt() == _rowsId) {
@@ -436,6 +438,14 @@ void SeerMatrixVisualizerWidget::handleRefreshButton () {
         return;
     }
 
+    // Re-evaluate the variable's address first: it may have changed since the
+    // last stop (or the variable may not have existed yet). The answer then
+    // reads the memory at the fresh address. See readMemory().
+    emit evaluateVariableExpression(_variableId, variableNameLineEdit->text());
+}
+
+void SeerMatrixVisualizerWidget::readMemory () {
+
     if (variableAddressLineEdit->text() == "") {
         return;
     }
@@ -444,8 +454,19 @@ void SeerMatrixVisualizerWidget::handleRefreshButton () {
         return;
     }
 
+    // A null address can't be read (a matrix before its construction, for
+    // example). Keep the "0x0" visible but don't ask gdb.
+    if (variableAddressLineEdit->text() == "0x0") {
+        return;
+    }
+
     int bytes = matrixRowsLineEdit->text().toInt() * matrixColumnsLineEdit->text().toInt() * Seer::typeBytes(matrixDisplayFormatComboBox->currentText());
 
+    // Nothing to read yet (no rows/columns).
+    if (bytes <= 0) {
+        return;
+    }
+
     // qDebug() << "Asking for" << bytes << "bytes of matrix data.";
 
     emit evaluateMemoryExpression(_memoryId, variableAddressLineEdit->text(), bytes);

src/SeerMatrixVisualizerWidget.h

@@ -55,6 +55,8 @@ class SeerMatrixVisualizerWidget : public QWidget, protected Ui::SeerMatrixVisua
         void                resizeEvent                             (QResizeEvent* event);
 
     private:
+        void                readMemory                              ();
+
         int                 _variableId;
         int                 _memoryId;
         int                 _rowsId;

src/SeerParallelStacksCommon.cpp

@@ -43,6 +43,15 @@ const QString& SeerParallelStacksFrame::function () const {
     return _function;
 }
 
+QString SeerParallelStacksFrame::functionOrAddr () const {
+
+    if (_function == "??") {
+        return _addr;
+    }
+
+    return _function;
+}
+
 const QString& SeerParallelStacksFrame::arch () const {
     return _arch;
 }
@@ -206,19 +215,26 @@ SeerParallelStacksStack SeerParallelStacksFillStack(const SeerParallelStacksNode
         stack.threadIds.append(t.id());
     }
 
-    if (node.function.function().isEmpty() == false) {
-        stack.frames.append(node.function);
-    }
-
     if (node.children.size() == 1) {
         // Merge single child into this stack (chain of frames).
         // Keep the IDs from the leaf (most specific) node.
+        // Children are deeper (more toward the top of the call stack) than
+        // this node, so their frames go first — the resulting list reads
+        // top of stack (innermost) to bottom of stack (outermost).
         auto child = SeerParallelStacksFillStack(node.children[0]);
-        stack.frames     += child.frames;
-        stack.stacks      = child.stacks;
-        stack.threadCount = child.threadCount;
-        stack.threadIds   = child.threadIds;
+        stack.frames       = child.frames;
+        stack.stacks       = child.stacks;
+        stack.threadCount  = child.threadCount;
+        stack.threadIds    = child.threadIds;
+
+        if (node.function.function().isEmpty() == false) {
+            stack.frames.append(node.function);
+        }
     } else {
+        if (node.function.function().isEmpty() == false) {
+            stack.frames.append(node.function);
+        }
+
         for (const auto& childNode : node.children) {
             stack.stacks.append(SeerParallelStacksFillStack(childNode));
         }

src/SeerParallelStacksCommon.h

@@ -19,6 +19,7 @@ class SeerParallelStacksFrame {
         int                 level           () const;
         const QString&      addr            () const;
         const QString&      function        () const;
+        QString             functionOrAddr  () const;
         const QString&      arch            () const;
         const QString&      from            () const;
         const QString&      file            () const;

src/SeerParallelStacksGraphicsView.cpp

@@ -87,6 +87,12 @@ SeerParallelStacksStackBoxItem::SeerParallelStacksStackBoxItem(const SeerParalle
     setFlag(QGraphicsItem::ItemSendsGeometryChanges, true);
     setAcceptHoverEvents(true);
 
+    _hoverTimer = new QTimer(this);
+    _hoverTimer->setSingleShot(true);
+    _hoverTimer->setInterval(_kHoverDelayMs);
+
+    QObject::connect(_hoverTimer, &QTimer::timeout, this, &SeerParallelStacksStackBoxItem::handleShowPopup);
+
     _headerLeft = QString("%1 Thread%2") .arg(stack.threadCount) .arg(stack.threadCount == 1 ? "" : "s");
 
     _threadIds.resize(0);
@@ -118,15 +124,15 @@ SeerParallelStacksStackBoxItem::SeerParallelStacksStackBoxItem(const SeerParalle
     QFont        normFont;
     QFontMetrics normFm(normFont);
 
-    qreal headerW  = boldFm.horizontalAdvance(_headerLeft) + boldFm.horizontalAdvance(_headerRight) + kHeaderGap;
+    qreal headerW  = boldFm.horizontalAdvance(_headerLeft) + boldFm.horizontalAdvance(_headerRight) + _kHeaderGap;
     qreal maxTextW = headerW;
 
     for (const auto& frame : _stack.frames) {
-        maxTextW = std::max(maxTextW, (qreal)normFm.horizontalAdvance(frame.function()));
+        maxTextW = std::max(maxTextW, (qreal)normFm.horizontalAdvance(frame.functionOrAddr()));
     }
 
-    _width  = maxTextW + 2 * kPadX;
-    _height = kPadY + kRowH * (1 + (int)_stack.frames.size()) + kPadY;
+    _width  = maxTextW + 2 * _kPadX;
+    _height = _kPadY + _kRowH * (1 + (int)_stack.frames.size()) + _kPadY;
 
     qDebug() << _stack.stacks.size();
 }
@@ -163,19 +169,19 @@ void SeerParallelStacksStackBoxItem::paint(QPainter* painter, const QStyleOption
 
     QFont boldFont;  boldFont.setBold(true);
     QFont normFont;
-    const qreal innerW = _width - 2 * kPadX;
-    qreal y = kPadY;
+    const qreal innerW = _width - 2 * _kPadX;
+    qreal y = _kPadY;
 
     painter->setFont(boldFont);
     painter->setPen(colors.headerText);
-    painter->drawText(QRectF(kPadX, y, innerW, kRowH), Qt::AlignLeft | Qt::AlignVCenter, _headerLeft);
+    painter->drawText(QRectF(_kPadX, y, innerW, _kRowH), Qt::AlignLeft | Qt::AlignVCenter, _headerLeft);
 
     if (!_headerRight.isEmpty()) {
         painter->setPen(colors.threadIdsText);
-        painter->drawText(QRectF(kPadX, y, innerW, kRowH), Qt::AlignRight | Qt::AlignVCenter, _headerRight);
+        painter->drawText(QRectF(_kPadX, y, innerW, _kRowH), Qt::AlignRight | Qt::AlignVCenter, _headerRight);
     }
 
-    y += kRowH;
+    y += _kRowH;
 
     painter->setPen(QPen(colors.divider, 1));
     painter->drawLine(QPointF(0, y), QPointF(_width, y));
@@ -184,8 +190,8 @@ void SeerParallelStacksStackBoxItem::paint(QPainter* painter, const QStyleOption
     painter->setPen(colors.frameText);
 
     for (const auto& frame : _stack.frames) {
-        painter->drawText(QRectF(kPadX, y, innerW, kRowH), Qt::AlignLeft | Qt::AlignVCenter, frame.function());
-        y += kRowH;
+        painter->drawText(QRectF(_kPadX, y, innerW, _kRowH), Qt::AlignLeft | Qt::AlignVCenter, frame.functionOrAddr());
+        y += _kRowH;
     }
 
     if (_dragging) {
@@ -269,37 +275,82 @@ void SeerParallelStacksStackBoxItem::hoverEnterEvent(QGraphicsSceneHoverEvent* e
     QGraphicsItem::hoverEnterEvent(event);
 
     if (_popup == nullptr) {
-
-        QString frame;
-
-        if (_stack.frames.size() > 0) {
-            frame = _stack.frames[0].function();
-        }
-
-        _popup = new SeerParallelStacksPopupTableWidget();
-
-        for (const auto& id : _threadIds) {
-            _popup->addRow(id, frame);
-        }
-
-        QGraphicsView* view = scene()->views().first(); // scene() is always valid here
-
-        // Position below the item, aligned to its left edge
-        QRectF sceneRect  = mapToScene(boundingRect()).boundingRect();
-        QPoint viewportPt = view->mapFromScene(sceneRect.bottomLeft());
-        QPoint globalPt   = view->viewport()->mapToGlobal(viewportPt);
-        _popup->move(globalPt);
-
-        _popup->show();
-
-        // Connect things.
-        QObject::connect(_popup, &SeerParallelStacksPopupTableWidget::mouseLeftPopup,      this, &SeerParallelStacksStackBoxItem::handleDeletePopup);
+        _hoverTimer->start();
     }
 }
 
 void SeerParallelStacksStackBoxItem::hoverLeaveEvent(QGraphicsSceneHoverEvent* event) {
 
     QGraphicsItem::hoverLeaveEvent(event);
+
+    // Cancel a pending popup if the mouse left before the delay elapsed.
+    _hoverTimer->stop();
+
+    // A popup that's already showing stays up if the mouse just moved onto
+    // it — give handleMaybeClosePopup() a moment to check for that.
+    handleMaybeClosePopup();
+}
+
+QRect SeerParallelStacksStackBoxItem::globalRect() const {
+
+    QGraphicsView* view = scene()->views().first(); // scene() is always valid here
+
+    QRectF sceneRect    = mapToScene(boundingRect()).boundingRect();
+    QPoint topLeft      = view->viewport()->mapToGlobal(view->mapFromScene(sceneRect.topLeft()));
+    QPoint bottomRight  = view->viewport()->mapToGlobal(view->mapFromScene(sceneRect.bottomRight()));
+
+    return QRect(topLeft, bottomRight);
+}
+
+void SeerParallelStacksStackBoxItem::handleShowPopup() {
+
+    if (_popup != nullptr) {
+        return;
+    }
+
+    QString frame;
+
+    if (_stack.frames.size() > 0) {
+        frame = _stack.frames[0].functionOrAddr();
+    }
+
+    _popup = new SeerParallelStacksPopupTableWidget();
+
+    for (const auto& id : _threadIds) {
+        _popup->addRow(id, frame);
+    }
+
+    // Position below the item, aligned to its left edge
+    _popup->move(globalRect().bottomLeft());
+
+    _popup->show();
+
+    QObject::connect(_popup, &SeerParallelStacksPopupTableWidget::mouseLeftPopup, this, &SeerParallelStacksStackBoxItem::handleMaybeClosePopup);
+}
+
+void SeerParallelStacksStackBoxItem::handleMaybeClosePopup() {
+
+    if (_popup == nullptr) {
+        return;
+    }
+
+    // The mouse may have simply crossed from the node onto the popup (or
+    // vice versa) — give that a moment to register before deciding the
+    // mouse has truly left both, then re-check with the cursor's live
+    // position rather than relying on possibly-stale hover state.
+    QTimer::singleShot(_kCloseGraceMs, this, [this]() {
+
+        if (_popup == nullptr) {
+            return;
+        }
+
+        bool overNode  = globalRect().contains(QCursor::pos());
+        bool overPopup = _popup->frameGeometry().contains(QCursor::pos());
+
+        if (overNode == false && overPopup == false) {
+            handleDeletePopup();
+        }
+    });
 }
 
 void SeerParallelStacksStackBoxItem::handleDeletePopup() {
@@ -358,7 +409,7 @@ QRectF SeerParallelStacksLiveEdge::boundingRect() const {
     QPointF f = _from->sceneBottom();
     QPointF t = _to->sceneTop();
 
-    qreal pad = kArrow + kVCtrl + 4;
+    qreal pad = _kArrow + _kVCtrl + 4;
 
     return QRectF(f, t).normalized().adjusted(-pad, -pad, pad, pad);
 }
@@ -382,39 +433,8 @@ void SeerParallelStacksLiveEdge::paint(QPainter* painter, const QStyleOptionGrap
     QPointF from = _from->sceneBottom();
     QPointF to   = _to->sceneTop();
 
-    /*
-    // Bezier: control points pull vertically toward each other
-    QPainterPath path;
-    path.moveTo(from);
-    path.cubicTo(from + QPointF(0,  kVCtrl), to   + QPointF(0, -kVCtrl), to);
-
-    painter->setPen(QPen(QColor(0x55, 0x55, 0x55), 1.5));
-    painter->setBrush(Qt::NoBrush);
-    painter->drawPath(path);
-
-    // Arrowhead at `to` pointing downward (into the parent box)
-    // The tangent direction at the end of the cubic is (to - cp2)
-    QPointF cp2  = to + QPointF(0, -kVCtrl);
-    QPointF dir  = to - cp2;
-    double  len  = std::hypot(dir.x(), dir.y());
-    if (len < 1e-6) return;
-    dir /= len;   // normalise
-
-    // Perpendicular
-    QPointF perp(-dir.y(), dir.x());
-
-    QPointF a1 = to - dir * kArrow + perp * (kArrow * 0.5);
-    QPointF a2 = to - dir * kArrow - perp * (kArrow * 0.5);
-
-    QPolygonF arrowHead;
-    arrowHead << to << a1 << a2;
-    painter->setPen(Qt::NoPen);
-    painter->setBrush(QColor(0x55, 0x55, 0x55));
-    painter->drawPolygon(arrowHead);
-    */
-
     // --- Arrowhead: tip touches the child box bottom (`from`),
-    //     base is kArrow further along toward `to`.
+    //     base is _kArrow further along toward `to`.
     //     The bezier starts at the base so the line never overlaps the head.
     QPointF delta = to - from;
     double  len   = std::hypot(delta.x(), delta.y());
@@ -425,16 +445,16 @@ void SeerParallelStacksLiveEdge::paint(QPainter* painter, const QStyleOptionGrap
     QPointF perp(-dir.y(), dir.x());      // perpendicular
 
     QPointF tip  = from;                  // touches child box
-    QPointF base = from + dir * kArrow;   // where the line begins
+    QPointF base = from + dir * _kArrow;   // where the line begins
 
-    QPointF a1 = base + perp * (kArrow * 0.5);
-    QPointF a2 = base - perp * (kArrow * 0.5);
+    QPointF a1 = base + perp * (_kArrow * 0.5);
+    QPointF a2 = base - perp * (_kArrow * 0.5);
 
     // Bezier runs from the arrowhead base to the parent box top.
     QPainterPath path;
 
     path.moveTo(base);
-    path.cubicTo(base + QPointF(0,  kVCtrl), to   + QPointF(0, -kVCtrl), to);
+    path.cubicTo(base + QPointF(0,  _kVCtrl), to   + QPointF(0, -_kVCtrl), to);
 
     const QColor color = edgeColor();
 
@@ -641,15 +661,6 @@ SeerParallelStacksPopupTableWidget::SeerParallelStacksPopupTableWidget(QWidget*
     QVBoxLayout* layout = new QVBoxLayout(this);
     layout->setContentsMargins(6, 6, 6, 6);
     layout->addWidget(_table);
-
-    _closeTimer = new QTimer(this);
-    _closeTimer->setSingleShot(true); // Ensures it only fires once
-    _closeTimer->setInterval(1500);   // Delay
-
-    // Connect things.
-    QObject::connect(_closeTimer, &QTimer::timeout,      this, &SeerParallelStacksPopupTableWidget::handleCloseTimer);
-
-    _closeTimer->start();
 }
 
 void SeerParallelStacksPopupTableWidget::addRow (int threadid, const QString& frame) {
@@ -673,31 +684,13 @@ void SeerParallelStacksPopupTableWidget::addRow (int threadid, const QString& fr
     _table->resizeColumnToContents(1);
 }
 
-void SeerParallelStacksPopupTableWidget::enterEvent(QEnterEvent* event) {
-
-    // If the user moves the cursor into the table, cancel the timer.
-    if (_closeTimer->isActive()) {
-        _closeTimer->stop();
-    }
-
-    QFrame::enterEvent(event);
-}
-
 void SeerParallelStacksPopupTableWidget::leaveEvent(QEvent* event) {
 
-    // If the user leaves the table, ask for the table to be closed.
     QFrame::leaveEvent(event);
 
     emit mouseLeftPopup();
 }
 
-void SeerParallelStacksPopupTableWidget::handleCloseTimer() {
-
-    // If the user doesn't move the cursor into the table in the default time,
-    // ask the table to be closed.
-    emit mouseLeftPopup();
-}
-
 // ================================================================
 // SeerParallelStacksPopupTableWidget
 // ================================================================

src/SeerParallelStacksGraphicsView.h

@@ -52,26 +52,32 @@ class SeerParallelStacksStackBoxItem : public QObject, public QGraphicsItem {
         void                    hoverLeaveEvent     (QGraphicsSceneHoverEvent* event) override;
 
     private slots:
-        void                    handleDeletePopup   ();
+        void                    handleDeletePopup       ();
+        void                    handleShowPopup         ();
+        void                    handleMaybeClosePopup   ();
 
     private:
+        // Global (screen) rect this box occupies, used to test whether the
+        // cursor is still over the node.
+        QRect                                    globalRect      () const;
+
+        QVector<SeerParallelStacksLiveEdge*>    _edges;   // non-owning
         QVector<int>                            _threadIds;
         SeerParallelStacksStack                 _stack;
         QString                                 _headerLeft;
         QString                                 _headerRight;
-        qreal                                   _width  = 0;
-        qreal                                   _height = 0;
-        SeerParallelStacksPopupTableWidget*     _popup  = 0;
-
-        bool                                    _dragging  = false;
+        qreal                                   _width          = 0;
+        qreal                                   _height         = 0;
+        SeerParallelStacksPopupTableWidget*     _popup          = 0;
+        QTimer*                                 _hoverTimer     = 0;
+        static constexpr int                    _kHoverDelayMs  = 1000;
+        static constexpr int                    _kCloseGraceMs  =  150;
+        bool                                    _dragging       = false;
         QPointF                                 _dragOffset;
-
-        QVector<SeerParallelStacksLiveEdge*>    _edges;   // non-owning
-
-        static constexpr qreal  kPadX      = 12;
-        static constexpr qreal  kPadY      =  8;
-        static constexpr qreal  kRowH      = 20;
-        static constexpr qreal  kHeaderGap = 16;
+        static constexpr qreal                  _kPadX          = 12;
+        static constexpr qreal                  _kPadY          =  8;
+        static constexpr qreal                  _kRowH          = 20;
+        static constexpr qreal                  _kHeaderGap     = 16;
 };
 
 // ---------------------------------------------------------------
@@ -82,7 +88,7 @@ class SeerParallelStacksLiveEdge : public QGraphicsItem {
 
     public:
         SeerParallelStacksLiveEdge(SeerParallelStacksStackBoxItem* from, SeerParallelStacksStackBoxItem* to, QGraphicsItem* parent = nullptr);
-        ~SeerParallelStacksLiveEdge() override;
+       ~SeerParallelStacksLiveEdge() override;
 
         QRectF          boundingRect     () const override;
         QPainterPath    shape            () const override;
@@ -95,11 +101,11 @@ class SeerParallelStacksLiveEdge : public QGraphicsItem {
 
 
     private:
-        SeerParallelStacksStackBoxItem*           _from;   // child  (bottom anchor)
-        SeerParallelStacksStackBoxItem*           _to;     // parent (top anchor)
+        SeerParallelStacksStackBoxItem*     _from;   // child  (bottom anchor)
+        SeerParallelStacksStackBoxItem*     _to;     // parent (top anchor)
 
-        static constexpr qreal  kArrow = 8.0;
-        static constexpr qreal  kVCtrl = 60.0 * 0.4;   // bezier control-point stretch
+        static constexpr qreal              _kArrow = 8.0;
+        static constexpr qreal              _kVCtrl = 60.0 * 0.4;   // bezier control-point stretch
 };
 
 
@@ -142,7 +148,8 @@ class SeerParallelStacksMiniMapWidget : public QWidget {
 };
 
 // A frameless popup window that wraps a QTableWidget inside a small
-// bordered frame, and closes/deletes itself when the mouse leaves it.
+// bordered frame. Its lifetime is owned by the SeerParallelStacksStackBoxItem
+// that created it — it stays up for as long as the mouse is in that node.
 class SeerParallelStacksPopupTableWidget : public QFrame {
 
     Q_OBJECT
@@ -153,18 +160,13 @@ class SeerParallelStacksPopupTableWidget : public QFrame {
         void            addRow                          (int threadid, const QString& function);
 
     protected:
-        void            enterEvent                      (QEnterEvent* event) override;
         void            leaveEvent                      (QEvent* event) override;
 
-    protected slots:
-        void            handleCloseTimer                ();
-
     signals:
         void            mouseLeftPopup                  ();
 
     private:
         QTableWidget*   _table;
-        QTimer*         _closeTimer;
 };
 
 class SeerParallelStacksGraphicsView : public QGraphicsView {

src/resources/help/ImageVisualizer.md

@@ -78,5 +78,6 @@ Available Quick keys while in the Image Visualizer:
     '+'   zoom in
     '-'   zoom out
     ESC   reset to default zoom level.
+    Ctrl+mouse wheel   zoom in or out.
 ```