Arcengine的工具中实现Snapping(捕捉)
在Engine的工具(ITool)里:
OnClick事件处理函数中:
首先需要获取一个图层,作为Snapping的参照,
IFeatureLayer targetLayer
然后声明一个IMovePointFeedBack作为鼠标移动时捕捉点的显示:
- IMovePointFeedback m_pMovePtFeed = new MovePointFeedback();
- mFeedback = (IDisplayFeedback)m_pMovePtFeed;
- ISimpleMarkerSymbol simpleMarkerSymbol = new SimpleMarkerSymbolClass();
- IRgbColor pRGBColor = new RgbColorClass();
- pRGBColor.Red = 0;
- pRGBColor.Green = 0;
- pRGBColor.Blue = 0;
- simpleMarkerSymbol.Color = pRGBColor;
- simpleMarkerSymbol.Size = 3;
- simpleMarkerSymbol.Style = ESRI.ArcGIS.Display.esriSimpleMarkerStyle.esriSMSSquare;
- ISymbol symbol = simpleMarkerSymbol as ISymbol;
- symbol.ROP2 = esriRasterOpCode.esriROPNotXOrPen;
- //symbol.ROP2 = esriRasterOpCode.;
- m_pMovePtFeed.Symbol = (ISymbol)simpleMarkerSymbol;
然后开始Feedback的显示(tmpPoint是指开始的点,其实影响不大,如果不想要源点在屏幕上的话,可以取一个在屏幕外的点):
- m_pMovePtFeed.Display = mMapControl.ActiveView.ScreenDisplay;
- m_pMovePtFeed.Start(tmpPoint, tmpPoint);
在OnMouseMove事件中:
- IPoint pPoint2 = null;
- IPoint pPoint = pMap.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(x, y);
- pPoint2 = Snapping(pPoint.X, pPoint.Y, targetLayer, pMap, 10);
- if (pPoint2 == null)
- pPoint2 = pPoint;
- ((IMovePointFeedback)mFeedback).MoveTo(pPoint2);
其中Snapping函数即为最主要的查找函数,其功能为根据输入的点坐标在目标图层上查找最为相近的点(也即需要捕捉的点),返回该点,若没有找到则返回NULL,最后一个参数的含义是,在地图控件上,以多少个像素为单位在周边查找捕捉点.
- public IPoint Snapping(double x, double y, IFeatureLayer iFeatureLyr, IMapControl3 axMapControl1,double snappingDis)
- {
- IPoint iHitPoint = null;
- IMap iMap = axMapControl1.Map;
- IActiveView iView = axMapControl1.ActiveView;
- IFeatureClass iFClss = iFeatureLyr.FeatureClass;
- IPoint point = new PointClass();
- point.PutCoords(x, y);
- double length = ConvertPixelsToMapUnits(axMapControl1.ActiveView, snappingDis);
- ITopologicalOperator pTopo = point as ITopologicalOperator;
- IGeometry pGeometry = pTopo.Buffer(length).Envelope as IGeometry;
- ISpatialFilter spatialFilter = new SpatialFilterClass();
- spatialFilter.GeometryField = iFeatureLyr.FeatureClass.ShapeFieldName;
- spatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;
- spatialFilter.Geometry = pGeometry;
- IFeatureCursor cursor = iFClss.Search(spatialFilter, false);
- IFeature iF = cursor.NextFeature();
- if (iF == null) return null;
- IPoint iHitPt = new ESRI.ArcGIS.Geometry.Point();
- IHitTest iHitTest = iF.Shape as IHitTest;
- double hitDist = 0;
- int partIndex = 0;
- int vertexIndex = 0;
- bool bVertexHit = false;
- // Tolerance in pixels for line hits
- double tol = ConvertPixelsToMapUnits(iView, snappingDis);
- if (iHitTest.HitTest(point, tol, esriGeometryHitPartType.esriGeometryPartBoundary,
- iHitPt, ref hitDist, ref partIndex, ref vertexIndex, ref bVertexHit))
- {
- iHitPoint = iHitPt;
- }
- //axMapControl1.ActiveView.Refresh();
- return iHitPoint;
- }
- public double ConvertPixelsToMapUnits(IActiveView pActiveView, double pixelUnits)
- {
- double realWorldDisplayExtent;
- int pixelExtent;
- double sizeOfOnePixel;
- pixelExtent = pActiveView.ScreenDisplay.DisplayTransformation.get_DeviceFrame().right – pActiveView.ScreenDisplay.DisplayTransformation.get_DeviceFrame().left;
- realWorldDisplayExtent = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.Width;
- sizeOfOnePixel = realWorldDisplayExtent / pixelExtent;
- return pixelUnits * sizeOfOnePixel;
- }
此时即可实现鼠标实时地捕捉目标图层上的对象,若需要获取当前位置的捕捉点时,则可以在相应事件(例如OnMouseDown或OnDbClick)中调用:
- IPoint pPoint = ((IMovePointFeedback)mFeedback).Stop();
这时实时捕捉将会停止,若需要重新开始捕捉,则在之后调用这些语句即可:
- //重新开始Snap
- IPoint tmpPoint = new PointClass();
- tmpPoint.PutCoords(pMap.Extent.XMin – 1, pMap.Extent.YMin – 1);
- IMovePointFeedback m_pMovePtFeed = (IMovePointFeedback)mFeedback;
- m_pMovePtFeed.Display = pMap.ActiveView.ScreenDisplay;
- m_pMovePtFeed.Start(tmpPoint, tmpPoint);
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转载自：https://blog.csdn.net/kone0611/article/details/73135729
