[MSCE C++] DimensionHandler如何使用

给您一个MSCE C#的例子，您可以仿照着用C++改写一下。CE版的C#和C++对象模型基本一致。

class CreateDimensionCallbacks : DimensionCreateData
    {
        private DimensionStyle m_dimStyle;
        private DgnTextStyle m_textStyle;
        private Symbology m_symbology;
        private LevelId m_levelId;
        private DirectionFormatter m_directionFormatter;

        public CreateDimensionCallbacks(DimensionStyle dimStyle, DgnTextStyle textStyle, Symbology symb, LevelId levelId, DirectionFormatter formatter)
        {
            m_dimStyle = dimStyle;
            m_textStyle = textStyle;
            m_symbology = symb;
            m_levelId = levelId;
            m_directionFormatter = formatter;
        }
        public override DimensionStyle GetDimensionStyle()
        {
            return m_dimStyle;
        }
        public override DgnTextStyle GetTextStyle()
        {
            return m_textStyle;
        }
        public override Symbology GetSymbology()
        {
            return m_symbology;
        }
        public override LevelId GetLevelId()
        {
            return m_levelId;
        }
        public override int GetViewNumber()
        {
            return 0;
        }
        public override DMatrix3d GetDimensionRotation()
        {
            return DMatrix3d.Identity;
        }
        public override DMatrix3d GetViewRotation()
        {
            return DMatrix3d.Identity;
        }
        public override DirectionFormatter GetDirectionFormatter()
        {
            return m_directionFormatter;
        }
    }
    class CreateElement
    {
    public static void LinearAndAngularDimension(string unparsed)
        {
            DgnFile oFile = Session.Instance.GetActiveDgnFile();
            DgnModel oModel = Session.Instance.GetActiveDgnModel();
            double uorPerMast = oModel.GetModelInfo().UorPerMaster;
            
            DimensionStyle dimStyle = new DimensionStyle("DimStyle", oFile);
            dimStyle.SetBooleanProp(true, DimStyleProp.Placement_UseStyleAnnotationScale_BOOLINT);
            dimStyle.SetDoubleProp(1, DimStyleProp.Placement_AnnotationScale_DOUBLE);
            dimStyle.SetBooleanProp(true, DimStyleProp.Text_OverrideHeight_BOOLINT);
            dimStyle.SetDistanceProp(0.5 * uorPerMast, DimStyleProp.Text_Height_DISTANCE, oModel);
            dimStyle.SetBooleanProp(true, DimStyleProp.Text_OverrideWidth_BOOLINT);
            dimStyle.SetDistanceProp(0.4 * uorPerMast, DimStyleProp.Text_Width_DISTANCE, oModel);
            dimStyle.SetBooleanProp(true, DimStyleProp.General_UseMinLeader_BOOLINT);
            dimStyle.SetDoubleProp(0.01, DimStyleProp.Terminator_MinLeader_DOUBLE);
            dimStyle.SetBooleanProp(true, DimStyleProp.Value_AngleMeasure_BOOLINT);
            dimStyle.SetAccuracyProp ((byte)AnglePrecision.Use1Place, DimStyleProp.Value_AnglePrecision_INTEGER);

            DgnTextStyle textStyle = new DgnTextStyle("TestStyle", oFile);
            LevelId lvlId = Settings.GetLevelIdFromName("Default");
            CreateDimensionCallbacks callbacks = new CreateDimensionCallbacks(dimStyle, textStyle, new Symbology(), lvlId, null);
            DimensionElement oDim = new DimensionElement(oModel, callbacks, DimensionType.SizeArrow);
            if (oDim.IsValid)
            {
                DPoint3d pt = new DPoint3d(0, -17 * uorPerMast, 0);
                oDim.InsertPoint(pt, null, dimStyle, -1);
                pt.X += 3*uorPerMast;
                oDim.InsertPoint(pt, null, dimStyle, -1);
                oDim.SetHeight(uorPerMast);
                oDim.AddToModel();
            }
            oDim = new DimensionElement(oModel, callbacks, DimensionType.AngleSize);
            if (oDim.IsValid)
            {
                DPoint3d pt = new DPoint3d(7*uorPerMast, -13 * uorPerMast, 0);
                oDim.InsertPoint(pt, null, dimStyle, -1);
                pt = DPoint3d.FromXY (5*uorPerMast, -15*uorPerMast);
                oDim.InsertPoint(pt, null, dimStyle, -1);
                pt = DPoint3d.FromXY (9*uorPerMast, -15*uorPerMast);
                oDim.InsertPoint(pt, null, dimStyle, -1);
                oDim.SetHeight(uorPerMast);
                oDim.AddToModel();
            }
        }
    }

谢谢符老师的回答，但是不太明白定义IDimCreateData的作用是干什么？

这个IDimCreateData是用来控制你创建出的Dimension元素的样子的。你看代码中需要先new一个派生于此的类的实例，new时需要指定Dimension元素的dimStyle、textStyle等特性。而在真正创建Dimension元素时，new DimensionElement中仅仅有这个实例而没有了dimStyle、textStyle等参数。

同样道理，C++的DimensionHandler::CreateDimensionElement中也只是通过指定IDimCreateData的一个实例来指定Dimension元素的特性的。