[TD]fix area calculation

src/Mod/TechDraw/App/DrawViewDimension.cpp

@@ -34,6 +34,7 @@
 #include <BRepGProp.hxx>
 #include <GProp_GProps.hxx>
 #include <BRep_Tool.hxx>
+#include <BRepTools.hxx>
 #include <BRepAdaptor_Curve.hxx>
 #include <BRepBuilderAPI_MakeEdge.hxx>
 #include <BRepBuilderAPI_MakeVertex.hxx>
@@ -47,6 +48,7 @@
 #include <Geom_Plane.hxx>
 #include <Geom2d_Curve.hxx>
 #include <Geom2dAPI_ProjectPointOnCurve.hxx>
+#include <ShapeAnalysis.hxx>
 #include <TopExp.hxx>
 #include <TopExp_Explorer.hxx>
 #include <TopoDS_Edge.hxx>
@@ -224,6 +226,11 @@ DrawViewDimension::DrawViewDimension()
     UnderTolerance.setStatus(App::Property::ReadOnly, true);
     FormatSpecUnderTolerance.setStatus(App::Property::ReadOnly, true);
 
+    // legacy behaviour if this is false
+    ADD_PROPERTY_TYPE(UseActualArea, (true), "Area", App::Prop_Output,
+                      "If true, area dimensions return the area of the face minus the areas of any enclosed faces. \
+                       If false, the area of the face's outer boundary is returned.");
+
     measurement = new Measure::Measurement();
     // TODO: should have better initial datumLabel position than (0, 0) in the DVP?? something
     // closer to the object being measured?
@@ -277,6 +284,7 @@ void DrawViewDimension::resetArea()
 {
     m_areaPoint.center = Base::Vector3d(0, 0, 0);
     m_areaPoint.area = 0.0;
+    m_areaPoint.actualArea = 0.0;
 }
 
 void DrawViewDimension::onChanged(const App::Property* prop)
@@ -686,7 +694,6 @@ double DrawViewDimension::getDimValue()
 //! retrieve the dimension value for "true" dimensions. The returned value is in internal units (mm).
 double DrawViewDimension::getTrueDimValue() const
 {
-    //    Base::Console().Message("DVD::getTrueDimValue()\n");
     double result = 0.0;
 
     if (Type.isValue("Distance") || Type.isValue("DistanceX") || Type.isValue("DistanceY")) {
@@ -763,7 +770,17 @@ double DrawViewDimension::getProjectedDimValue() const
         result = legAngle;
     }
     else if (Type.isValue("Area")) {
-        result = m_areaPoint.area / scale / scale;
+        // 2d reference makes scaled values in areaPoint
+        // 3d reference makes actual values in areaPoint :p
+        double divisor{scale / scale};
+        if (has3DReferences()) {
+            divisor = 1.0;
+        }
+        if (UseActualArea.getValue()) {
+           result = m_areaPoint.actualArea / divisor;
+        } else {
+            result = m_areaPoint.area / divisor;
+        }
     }
 
     return result;
@@ -1383,27 +1400,71 @@ areaPoint DrawViewDimension::getAreaParameters(ReferenceVector references)
             ssMessage << getNameInDocument() << " can not find geometry for 2d reference (4)";
             throw Base::RuntimeError(ssMessage.str());
         }
+        auto dvp = static_cast<DrawViewPart*>(refObject);
 
-        pts.area = face->getArea();
-        pts.center = face->getCenter();
+        auto filteredFaces  = GeometryUtils::findHolesInFace(dvp, references.front().getSubName());
+        auto perforatedFace = GeometryUtils::makePerforatedFace(face, filteredFaces);
+
+        // these areas are scaled because the source geometry is scaled, but it makes no sense to
+        // report a scaled area.
+        auto unscale = getViewPart()->getScale() * getViewPart()->getScale();
+        pts.area = face->getArea() / unscale;     // this will be the 2d area as projected onto the page? not really filled area?
+        pts.actualArea = getActualArea(perforatedFace)  / unscale;
+        pts.center = getFaceCenter(perforatedFace);
+        pts.invertY();      // geometry class is over, back to -Y up/.
     }
     else {
-        // this is a 3d reference
+        // this is a 3d reference. perforations should be handled for us by OCC
         TopoDS_Shape geometry = references[0].getGeometry();
         if (geometry.IsNull() || geometry.ShapeType() != TopAbs_FACE) {
             throw Base::RuntimeError("Geometry for dimension reference is null.");
         }
         const TopoDS_Face& face = TopoDS::Face(geometry);
 
-        GProp_GProps props;
-        BRepGProp::SurfaceProperties(face, props);
-        pts.area = props.Mass();
-        pts.center = DrawUtil::toVector3d(props.CentreOfMass());
+        // these areas are unscaled as the source is 3d geometry.
+        pts.area = getFilledArea(face);
+        pts.actualArea = getActualArea(face);
+        pts.center = getFaceCenter(face);
+        pts.move(getViewPart()->getCurrentCentroid());
+        pts.project(getViewPart());
     }
 
     return pts;
 }
 
+
+//! returns the center of mass of a face (density = k)
+Base::Vector3d DrawViewDimension::getFaceCenter(const TopoDS_Face& face)
+{
+    GProp_GProps props;
+    BRepGProp::SurfaceProperties(face, props);
+    auto center = DrawUtil::toVector3d(props.CentreOfMass());
+    return center;
+}
+
+
+//! returns the "net" area of a face (area of the face's outer boundary less the area of any holes)
+double DrawViewDimension::getActualArea(const TopoDS_Face& face)
+{
+    GProp_GProps props;
+    BRepGProp::SurfaceProperties(face, props);
+    return props.Mass();
+}
+
+
+//! returns the "gross" area of a face (area of the face's outer boundary)
+double DrawViewDimension::getFilledArea(const TopoDS_Face& face)
+{
+    TopoDS_Wire outerwire = ShapeAnalysis::OuterWire(face);
+    if (outerwire.IsNull()) {
+        return 0.0;
+    }
+
+    double area = ShapeAnalysis::ContourArea(outerwire);
+    return area;
+}
+
+
 DrawViewPart* DrawViewDimension::getViewPart() const
 {
     if (References2D.getValues().empty()) {