Revit二次开发之“创建尺寸标注”

运行该命令，选中一个可标注的对象，即实现标注。

[Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)]
[Autodesk.Revit.Attributes.Regeneration(Autodesk.Revit.Attributes.RegenerationOption.Manual)]
public class TestCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, Autodesk.Revit.DB.ElementSet elements)
    {
        UIDocument uiDoc = commandData.Application.ActiveUIDocument;
        Autodesk.Revit.ApplicationServices.Application app = commandData.Application.Application;
        Document doc = uiDoc.Document;
        Autodesk.Revit.DB.View view = doc.ActiveView;
        ViewType vt = view.ViewType;

        if (vt == ViewType.FloorPlan || vt == ViewType.Elevation)
        {
            Reference eRef = uiDoc.Selection.PickObject(ObjectType.Element, "Please pick a curve based element like wall.");
            if (eRef != null && eRef.Element != null)
            {
                XYZ dirVec = new XYZ();
                XYZ viewNormal = view.ViewDirection;

                LocationCurve locCurve = eRef.Element.Location as LocationCurve;
                if (locCurve == null || locCurve.Curve == null)
                {
                    TaskDialog.Show("Prompt", "Selected element isn’t curve based!");
                    return Result.Cancelled;
                }

                // location curve needs to be perpendicular to view normal
                XYZ dirCur = locCurve.Curve.get_EndPoint(0).Subtract(locCurve.Curve.get_EndPoint(1)).Normalize();
                double d = dirCur.DotProduct(viewNormal);
                if (d > -0.000000001 && d < 0.000000001)
                {
                    dirVec = dirCur.CrossProduct(viewNormal);
                    XYZ p1 = locCurve.Curve.get_EndPoint(0);
                    XYZ p2 = locCurve.Curve.get_EndPoint(1);
                    XYZ dirLine = XYZ.Zero.Add(p1);
                    XYZ newVec = XYZ.Zero.Add(dirVec);
                    newVec = newVec.Normalize().Multiply(3);
                    dirLine = dirLine.Subtract(p2);

                    p1 = p1.Add(newVec);
                    p2 = p2.Add(newVec);
                    // move the dimension line a little away the element’s curve
                    Line newLine = app.Create.NewLine(p1, p2, true);

                    ReferenceArray arrRefs = new ReferenceArray();
                    Options options = app.Create.NewGeometryOptions();
                    options.ComputeReferences = true;
                    options.DetailLevel = DetailLevels.Fine;
                    GeometryElement element = eRef.Element.get_Geometry(options);
                    GeometryObjectArray geoObjectArray = element.Objects;
                    //enum the geometry element
                    for (int j = 0; j < geoObjectArray.Size; j++)
                    {
                        GeometryObject geoObject = geoObjectArray.get_Item(j);
                        Solid solid = geoObject as Solid;
                        if (solid == null)
                            continue;

                        FaceArrayIterator fIt = solid.Faces.ForwardIterator();
                        while (fIt.MoveNext())
                        {
                            PlanarFace p = fIt.Current as PlanarFace;
                            if (p == null)
                                continue;

                            p2 = p.Normal.CrossProduct(dirLine);
                            if (p2.IsZeroLength())
                            {
                                arrRefs.Append(p.Reference);
                            }
                            if (2 == arrRefs.Size)
                            {
                                break;
                            }
                        }
                        if (2 == arrRefs.Size)
                        {
                            break;
                        }
                    }
                    if (arrRefs.Size != 2)
                    {
                        TaskDialog.Show("Prompt", "Couldn’t find enough reference for creating dimension");
                        return Result.Cancelled;
                    }

                    Transaction trans = new Transaction(doc, "create dimension");
                    trans.Start();
                    doc.Create.NewDimension(doc.ActiveView, newLine, arrRefs);
                    trans.Commit();
                }
                else
                {
                    TaskDialog.Show("Prompt", "Selected element isn’t curve based!");
                    return Result.Cancelled;
                }
            }
        }
        else
        {
            TaskDialog.Show("Prompt", "Only support Plan View or Elevation View");
        }

        return Result.Succeeded;
    }
}

from:http://revit.5d6d.com/thread-866-1-4.html