ArcObjects SDK开发 014 MapSurround和普通Element

1、如何获取MapSurround

和获取MapFrame类似，如果你已经获取指北针、比例尺等对象，可以通过IGraphicsContainer的FindFrame函数获取。如果没有，则通过IGraphicsContainer循环所有Element去判断即可。

2、添加MapSurround

指北针、比例尺、图例等都是MapSurround，我们以最简单的指北针为例，把MapSurround添加到PageLayout上。

var myGraphicsContainer = pLayoutApplication.PageLayout as IGraphicsContainer; var myActiveView = pLayoutApplication.PageLayout as IActiveView; var myMap = myActiveView.FocusMap; var myMapFrame = myGraphicsContainer.FindFrame(myMap) as IMapFrame; if (this._MapSurroundFrame == null) {     this._MapSurroundFrame = new MapSurroundFrameClass();     var myMarkerNorthArrow = new MarkerNorthArrowClass();     var myMarkerSymbol = myMarkerNorthArrow.MarkerSymbol;     var myCharacterMarkerSymbol = myMarkerSymbol as ICharacterMarkerSymbol;     myCharacterMarkerSymbol.CharacterIndex = 177;     myMarkerNorthArrow.MarkerSymbol = myCharacterMarkerSymbol;     myMarkerNorthArrow.Size = 30;     this._MapSurroundFrame.MapSurround = myMarkerNorthArrow;     this._MapSurroundFrame.MapFrame = myMapFrame;     var myQuerySize = this._MapSurroundFrame.MapSurround as IQuerySize;     double myWidth = 0;     double myHeight = 0;     myQuerySize.QuerySize(ref myWidth, ref myHeight);     var myUnitConverter = new UnitConverterClass();     this.Width = Math.Round(myUnitConverter.ConvertUnits(myWidth, esriUnits.esriPoints, esriUnits.esriMillimeters), 1);     this.Height = Math.Round(myUnitConverter.ConvertUnits(myHeight, esriUnits.esriPoints, esriUnits.esriMillimeters), 1); } else {     this._MapSurroundFrame.MapFrame = myMapFrame; } var myNewEnvelope = new EnvelopeClass {     XMin = this.X,     YMin = this.Y,     Width = this.Width,     Height = this.Height }; this.GetElment().Geometry = myNewEnvelope; if (GraphicsContainerHelper.Contain(myGraphicsContainer, this.GetElment()) == false) {     myGraphicsContainer.AddElement(this.GetElment(), 0); }

添加MapSurround流程都是一样的，不同的地方主要是在实例化具体MapSurround的代码。例如指北针、比例尺、图例等。实例化比例尺的代码如下。

IGraphicsContainer myGraphicsContainer = pLayoutApplication.PageLayout as IGraphicsContainer; if (this._MapSurroundFrame != null) {     myGraphicsContainer.DeleteElement(this._MapSurroundFrame as IElement);     this._MapSurroundFrame = null; }  IActiveView myActiveView = pLayoutApplication.PageLayout as IActiveView; IMap myMap = myActiveView.FocusMap; IMapFrame myMapFrame = myGraphicsContainer.FindFrame(myMap) as IMapFrame;  this._MapSurroundFrame = new MapSurroundFrameClass(); this._MapSurroundFrame.MapFrame = myMapFrame;  //创建比例尺 this._ScaleBar = this.CreateScaleBar(); this._ScaleBar.Map = myMapFrame.Map; this._ScaleBar.ResizeHint = esriScaleBarResizeHint.esriScaleBarFixed; this._ScaleBar.LabelFrequency = esriScaleBarFrequency.esriScaleBarDivisions; this._MapSurroundFrame.MapSurround = this._ScaleBar;  this._ScaleBar.BarHeight = this.BarHeight; this._ScaleBar.Division = this.Division; this._ScaleBar.Divisions = this.Divisions; this._ScaleBar.Subdivisions = this.Subdivisions; this._ScaleBar.DivisionsBeforeZero = this.DivisionsBeforeZero;  this._ScaleBar.LabelPosition = this.LabelPosition; this._ScaleBar.LabelGap = this.LabelGap; ITextSymbol myLabelSymbol = new TextSymbolClass(); IFontDisp myFontDisp = myLabelSymbol.Font; myFontDisp.Name = "Times New Roman"; myLabelSymbol.Font = myFontDisp; myLabelSymbol.Size = this.LabelSize; this._ScaleBar.LabelSymbol = myLabelSymbol;  //pScaleBar的UnitLabel属性设置需要放在pScaleBar.Units设置代码之后。这样UnitLabel设置才有效果。 this._ScaleBar.Units = esriUnits.esriKilometers; this._ScaleBar.UnitLabel = this.UnitLabel; this._ScaleBar.UnitLabelGap = this.UnitLabelGap; ITextSymbol myUnitLabelSymbol = new TextSymbolClass(); myFontDisp = myUnitLabelSymbol.Font; myFontDisp.Name = "Times New Roman"; myUnitLabelSymbol.Font = myFontDisp; myUnitLabelSymbol.Size = this.UnitLabelFontSize; this._ScaleBar.UnitLabelSymbol = myUnitLabelSymbol; this._ScaleBar.UnitLabelPosition = this.UnitLabelPosition;  IScaleMarks myScaleMarks = this._ScaleBar as IScaleMarks; myScaleMarks.MarkFrequency = esriScaleBarFrequency.esriScaleBarDivisionsAndSubdivisions; myScaleMarks.MarkPosition = this.MarkPosition; myScaleMarks.DivisionMarkHeight = this.DivisionMarkHeight; ILineSymbol myDivisionMarkSymbol = new SimpleLineSymbolClass(); myDivisionMarkSymbol.Color = new RgbColorClass() { Red = 0, Green = 0, Blue = 0 }; myDivisionMarkSymbol.Width = this.DivisionMarkWidth; myScaleMarks.DivisionMarkSymbol = myDivisionMarkSymbol; myScaleMarks.SubdivisionMarkHeight = this.SubdivisionMarkHeight; ILineSymbol mySubdivisionMarkSymbol = new SimpleLineSymbolClass(); mySubdivisionMarkSymbol.Color = new RgbColorClass() { Red = 0, Green = 0, Blue = 0 }; mySubdivisionMarkSymbol.Width = this.SubdivisionMarkWidth; myScaleMarks.SubdivisionMarkSymbol = mySubdivisionMarkSymbol;  IElement myElement = this._MapSurroundFrame as IElement; IGeometry myGeometry = myElement.Geometry; if (myGeometry != null && myGeometry.IsEmpty == false) {     IEnvelope myGeometryEnvelope = myGeometry.Envelope;     this.Width = myGeometryEnvelope.Width;     this.Height = myGeometryEnvelope.Height; } IEnvelope myEnvelope = new EnvelopeClass(); myEnvelope.PutCoords(this.X, this.Y, this.X + this.Width, this.Y + this.Height); myElement.Geometry = myEnvelope; myGraphicsContainer.AddElement(this._MapSurroundFrame as IElement, 0);  /// <summary> /// 创建比例尺 /// </summary> private IScaleBar CreateScaleBar() {     IScaleBar myScaleBar;     if (this.BarType == "AlternatingScaleBar")     {         myScaleBar = new AlternatingScaleBar();     }     else if (this.BarType == "DoubleAlternatingScaleBar")     {         myScaleBar = new DoubleAlternatingScaleBar();     }     else if (this.BarType == "HollowScaleBar")     {         myScaleBar = new HollowScaleBar();     }     else if (this.BarType == "SteppedScaleLine")     {         myScaleBar = new SteppedScaleLine();     }     else     {         myScaleBar = new ScaleLine();     }     myScaleBar.Name = this.BarType;     return myScaleBar; }

3、普通Element

继承IElement接口的类如下图所示。

这个列表中的Elment，除了MapFrame、MapSurroundFrame以及后面带()的外，其他的基本上都是我们常用的，例如点元素、线元素、面元素、圆元素、椭圆元素、各种图片元素等。

IElement有一个关键属性Geometry，如果是MarkerElement或者TextElement，那么Geometry就是IPoint类型，如果是LineElement，那么Geometry是IPolyline类型，PolygonElement的Geometry为IPolygon类型，图片Element一般传入IEnvelope。

一些特殊的Element例如椭圆的Geometry传什么呢？这样不确定的问题，我们可以去SDK帮助中查找，一般帮助中会解释的很清楚。

帮助中说的比较明确，可以传递IEnvelope，这样会在IEnvelope生成 一个椭圆。也可以传由EllipticArc组成的Polygon对象。不过我们一般会传IEnvelope，主要原因是简单直观。

除了Geometry外，很对图形状的元素包含Symbol属性。例如MarkerElement可设置IMarkerSymbol，TextElement可以设置ITextSymbol，IPolylineElement可设置ILineSymbol，PolygonElement、CircleElement和EllipseElement可以设置IFillSymbol。