CodeGraphic: Improve cursor rendering performance (#191)

* CodeGraphic: Improve cursor rendering performance
* GraphicsBar: Don't jump to invalid addresses

src/widgets/CodeGraphic.cpp

@@ -87,6 +87,7 @@ void GraphicsBar::fetchData()
 void GraphicsBar::fillData()
 {
     qDeleteAll(graphicsScene->items());
+    cursorGraphicsItem = nullptr;
     int from = blockMaps.first()["from"].toInt();
     int to = blockMaps.first()["to"].toInt();
 
@@ -110,10 +111,6 @@ void GraphicsBar::fillData()
     xToAddress.clear();
     double x_start = 0.0;
 
-
-    bool draw_cursor = false;
-    double cursor_x = 0.0;
-
     for(int i=0; i < sections.length(); i++)
     {
         SectionDescription section = sections[i];
@@ -194,27 +191,32 @@ void GraphicsBar::fillData()
                 graphicsScene->addItem(rect);
             }
 
-            // Check whether this block contains the current address.
-            if ((x2a.address_from <= current_address) && (current_address < x2a.address_to))
-            {
-                draw_cursor = true;
-                RVA cursor_offset = (double)(current_address - x2a.address_from) * width_per_byte;
-                cursor_x = block_x_start + cursor_offset;
-            }
-
             counter += 1;
         }
         x_start = x_end;
     }
 
-    // Draw the red cursor that shows where we are in the file (if we are in one of the rendered sections)
-    if(draw_cursor)
+    drawCursor();
+}
+
+void GraphicsBar::drawCursor()
+{
+    RVA offset = Core()->getOffset();
+    double cursor_x = addressToLocalX(offset);
+    if (cursorGraphicsItem != nullptr)
     {
-        QGraphicsRectItem *rect = new QGraphicsRectItem(cursor_x, 0, 2, h);
-        rect->setPen(Qt::NoPen);
-        rect->setBrush(QBrush(QColor(255, 0, 0)));
-        graphicsScene->addItem(rect);
+        graphicsScene->removeItem(cursorGraphicsItem);
+        delete cursorGraphicsItem;
     }
+    if (cursor_x == nan(""))
+    {
+        return;
+    }
+    int h = this->codeGraphic->height();
+    cursorGraphicsItem = new QGraphicsRectItem(cursor_x, 0, 2, h);
+    cursorGraphicsItem->setPen(Qt::NoPen);
+    cursorGraphicsItem->setBrush(QBrush(QColor(255, 0, 0)));
+    graphicsScene->addItem(cursorGraphicsItem);
 }
 
 QString GraphicsBar::generateTooltip(QString section_name, QMap<QString, QVariant> map)
@@ -237,7 +239,7 @@ void GraphicsBar::on_seekChanged(RVA addr)
 {
     Q_UNUSED(addr);
     // Re-paint, which will also update the cursor.
-    this->fillData();
+    this->drawCursor();
 }
 
 void GraphicsBar::mousePressEvent(QMouseEvent *event)
@@ -245,14 +247,37 @@ void GraphicsBar::mousePressEvent(QMouseEvent *event)
     event->accept();
     // Convert the local X coordinate to an address.
     qreal x = event->localPos().x();
+    RVA address = localXToAddress(x);
+    if(address != 0)
+    {
+        Core()->seek(address);
+    }
+}
+
+RVA GraphicsBar::localXToAddress(double x)
+{
     for(auto x2a : xToAddress)
     {
         if ((x2a.x_start <= x) && (x <= x2a.x_end))
         {
             double offset = (x - x2a.x_start) / (x2a.x_end - x2a.x_start);
             double size = x2a.address_to - x2a.address_from;
-            Core()->seek(x2a.address_from + (offset * size));
-            break;
+            return x2a.address_from + (offset * size);
         }
     }
+    return 0;
+}
+
+double GraphicsBar::addressToLocalX(RVA address)
+{
+    for(auto x2a : xToAddress)
+    {
+        if ((x2a.address_from <= address) && (address < x2a.address_to))
+        {
+            double offset = (double)(address - x2a.address_from) / (double)(x2a.address_to - x2a.address_from);
+            double size = x2a.x_end - x2a.x_start;
+            return x2a.x_start + (offset * size);
+        }
+    }
+    return nan("");
 }

src/widgets/CodeGraphic.h

@@ -30,20 +30,27 @@ private slots:
     void fetchAndPaintData();
     void fetchData();
     void fillData();
+    void drawCursor();
     void on_seekChanged(RVA addr);
 
 private:
     QGraphicsView     *codeGraphic;
     QGraphicsScene    *graphicsScene;
+    QGraphicsRectItem *cursorGraphicsItem;
     MainWindow        *main;
     RVA totalSectionsSize;
     QList<SectionDescription> sections;
     QList<QVariantMap> blockMaps;
     QList<struct xToAddress> xToAddress;
-    QString generateTooltip(QString section_name, QMap<QString, QVariant> map);
 
     // Used to check whether the width changed. If yes we need to re-initialize the scene (slow)
     int previousWidth;
+
+    QString generateTooltip(QString section_name, QMap<QString, QVariant> map);
+
+    RVA localXToAddress(double x);
+    double addressToLocalX(RVA address);
+
     void mousePressEvent(QMouseEvent *event) override;
 };