TechDraw: improve draw performance

call 'boundingRect' only after all items have been drawn, using a custom 'addToGroup' function that does not trigger an update.

src/Mod/TechDraw/Gui/QGIViewPart.cpp

@@ -22,6 +22,7 @@
 
 #include <QPainterPath>
 #include <QKeyEvent>
+#include <QGraphicsTransform>
 #include <cstdio>
 #include <qmath.h>
 
@@ -259,6 +260,8 @@ void QGIViewPart::draw()
     //this is old C/L
     drawCenterLines(true);//have to draw centerlines after border to get size correct.
     drawAllSectionLines();//same for section lines
+    
+    prepareGeometryChange();
 }
 
 void QGIViewPart::drawViewPart()
@@ -390,7 +393,7 @@ void QGIViewPart::drawAllEdges()
         }
 
         item = new QGIEdge(iEdge);
-        addToGroup(item);      //item is created at scene(0, 0), not group(0, 0)
+        addToGroupWithoutUpdate(item);      //item is created at scene(0, 0), not group(0, 0)
         item->setPath(drawPainterPath(*itGeom));
         item->setSource((*itGeom)->source());
 
@@ -474,7 +477,7 @@ void QGIViewPart::drawAllVertexes()
     for (int i = 0; vert != verts.end(); ++vert, i++) {
         if ((*vert)->isCenter()) {
             auto* cmItem = new QGICMark(i);
-            addToGroup(cmItem);
+            addToGroupWithoutUpdate(cmItem);
             cmItem->setPos(Rez::guiX((*vert)->x()), Rez::guiX((*vert)->y()));
             cmItem->setThick(0.5F * getLineWidth());    //need minimum?
             cmItem->setSize(getVertexSize() * vp->CenterScale.getValue());
@@ -488,7 +491,7 @@ void QGIViewPart::drawAllVertexes()
             //regular Vertex
             if (showVertices()) {
                 auto* item = new QGIVertex(i);
-                addToGroup(item);
+                addToGroupWithoutUpdate(item);
                 item->setPos(Rez::guiX((*vert)->x()), Rez::guiX((*vert)->y()));
                 item->setNormalColor(vertexColor);
                 item->setFillColor(vertexColor);
@@ -606,7 +609,7 @@ QGIFace* QGIViewPart::drawFace(TechDraw::FacePtr f, int idx)
     facePath.setFillRule(Qt::OddEvenFill);
 
     QGIFace* gFace = new QGIFace(idx);
-    addToGroup(gFace);
+    addToGroupWithoutUpdate(gFace);
     gFace->setPos(0.0, 0.0);
     gFace->setOutline(facePath);
     //debug a path
@@ -712,7 +715,7 @@ void QGIViewPart::drawSectionLine(TechDraw::DrawViewSection* viewSection, bool b
         }
 
         QGISectionLine* sectionLine = new QGISectionLine();
-        addToGroup(sectionLine);
+        addToGroupWithoutUpdate(sectionLine);
         sectionLine->setSymbol(const_cast<char*>(viewSection->SectionSymbol.getValue()));
         Base::Color color = Preferences::getAccessibleColor(vp->SectionLineColor.getValue());
         sectionLine->setSectionColor(color.asValue<QColor>());
@@ -807,7 +810,7 @@ void QGIViewPart::drawComplexSectionLine(TechDraw::DrawViewSection* viewSection,
 
 
     QGISectionLine* sectionLine = new QGISectionLine();
-    addToGroup(sectionLine);
+    addToGroupWithoutUpdate(sectionLine);
     sectionLine->setSymbol(const_cast<char*>(viewSection->SectionSymbol.getValue()));
     Base::Color color = Preferences::getAccessibleColor(vp->SectionLineColor.getValue());
     sectionLine->setSectionColor(color.asValue<QColor>());
@@ -867,7 +870,7 @@ void QGIViewPart::drawCenterLines(bool b)
         double xVal, yVal;
         if (horiz) {
             centerLine = new QGICenterLine();
-            addToGroup(centerLine);
+            addToGroupWithoutUpdate(centerLine);
             centerLine->setPos(0.0, 0.0);
             double width = Rez::guiX(viewPart->getBoxX());
             sectionSpan = width + sectionFudge;
@@ -884,7 +887,7 @@ void QGIViewPart::drawCenterLines(bool b)
         }
         if (vert) {
             centerLine = new QGICenterLine();
-            addToGroup(centerLine);
+            addToGroupWithoutUpdate(centerLine);
             centerLine->setPos(0.0, 0.0);
             double height = Rez::guiX(viewPart->getBoxY());
             sectionSpan = height + sectionFudge;
@@ -946,7 +949,7 @@ void QGIViewPart::drawHighlight(TechDraw::DrawViewDetail* viewDetail, bool b)
 
         highlight->setInteractive(false);
 
-        addToGroup(highlight);
+        addToGroupWithoutUpdate(highlight);
         highlight->setPos(0.0, 0.0);//sb setPos(center.x, center.y)?
 
         Base::Vector3d center = viewDetail->AnchorPoint.getValue() * viewPart->getScale();
@@ -1011,7 +1014,7 @@ void QGIViewPart::drawMatting()
     double scale = dvd->getScale();
     double radius = dvd->Radius.getValue() * scale;
     QGIMatting* mat = new QGIMatting();
-    addToGroup(mat);
+    addToGroupWithoutUpdate(mat);
     mat->setRadius(Rez::guiX(radius));
     mat->setPos(0.0, 0.0);
     mat->draw();
@@ -1038,7 +1041,7 @@ void QGIViewPart::drawBreakLines()
     auto breaks = dbv->Breaks.getValues();
     for (auto& breakObj : breaks) {
         QGIBreakLine* breakLine = new QGIBreakLine();
-        addToGroup(breakLine);
+        addToGroupWithoutUpdate(breakLine);
 
         Base::Vector3d direction = dbv->guiDirectionFromObj(*breakObj);
         breakLine->setDirection(direction);
@@ -1250,6 +1253,40 @@ QGraphicsItem *QGIViewPart::getQGISubItemByName(const std::string &subName) cons
     return nullptr;
 }
 
+void QGIViewPart::addToGroupWithoutUpdate(QGraphicsItem* item)
+{
+    // Implementation taken from QGraphicsItemGroup::addToGroup,
+    // But delaying the costly bounding box calculation and update until all items are added
+
+    bool ok;
+    QTransform itemTransform = item->itemTransform(this, &ok);
+    if (!ok) {
+        qWarning("QGIViewPart::addToGroup: could not find a valid transformation from item to group coordinates");
+        return;
+    }
+    QTransform newItemTransform(itemTransform);
+    item->setPos(mapFromItem(item, 0, 0));
+    item->setParentItem(this);
+    if (!item->pos().isNull()) {
+        newItemTransform *= QTransform::fromTranslate(-item->x(), -item->y());
+    }
+
+    // removing additional transformations properties applied with itemTransform()
+    QPointF origin = item->transformOriginPoint();
+    QMatrix4x4 m;
+    QList<QGraphicsTransform*> transformList = item->transformations();
+    for (int i = 0; i < transformList.size(); ++i)
+    {
+        transformList.at(i)->applyTo(&m);
+    }
+    newItemTransform *= m.toTransform().inverted();
+    newItemTransform.translate(origin.x(), origin.y());
+    newItemTransform.rotate(-item->rotation());
+    newItemTransform.scale(1/item->scale(), 1/item->scale());
+    newItemTransform.translate(-origin.x(), -origin.y());
+    item->setTransform(newItemTransform);
+}
+
 bool QGIViewPart::getGroupSelection() {
     return DrawGuiUtil::isSelectedInTree(this);
 }

src/Mod/TechDraw/Gui/QGIViewPart.h

@@ -115,6 +115,7 @@ public:
                                      double x, double y,
                                      double curx, double cury);
 
+    void addToGroupWithoutUpdate(QGraphicsItem* item);
     bool getGroupSelection() override;
     void setGroupSelection(bool isSelected) override;
     void setGroupSelection(bool isSelected, const std::vector<std::string> &subNames) override;