[Shapefile C Library]读取shp图形（.net Wapper）

ShapeLib的.net Wapper版可以在官网下载到，在WorldWind中也有使用。ORG据说也是使用的ShapeLib实现的shp文件的读写。

官网：http://shapelib.maptools.org/

1. C++读取shpfile文件代码

int main()
{
	//读取shp
	const char * pszShapeFile = "data\\LineSegments2.shp";
	SHPHandle hShp= SHPOpen(pszShapeFile, "r");
	int nShapeType, nVertices;
	int nEntities = 0;
	double* minB = new double[4];
	double* maxB = new double[4];
	SHPGetInfo(hShp, &nEntities, &nShapeType, minB, maxB);
	printf("ShapeType:%d\n", nShapeType);
	printf("Entities:%d\n", nEntities);
	for (int i = 0; i < nEntities;i++)
	{
		int iShape = i;
		SHPObject *obj = SHPReadObject(hShp, iShape);
		printf("--------------Feature:%d------------\n",iShape);
		int parts = obj->nParts;
		int verts=obj->nVertices;
		printf("nParts:%d\n", parts);
		printf("nVertices:%d\n", verts);
		for (size_t i = 0; i < verts; i++)
		{
			double x=obj->padfX[i];
			double y = obj->padfY[i];
			printf("%f,%f;", x,y);
		}
		printf("\n");
	}
	SHPClose(hShp);
	system("pause");

}

输出结果：

---

2. 以下是.net读取Shp文件中图形的代码：

  private void button1_Click(object sender, EventArgs e)
         {
             OpenFileDialog dlg = new OpenFileDialog();
             dlg.Filter = "(*.shp)|*.shp";
             if (dlg.ShowDialog() == DialogResult.OK)
             {
                 string fileName = dlg.FileName;
                 txtFilePath.Text = fileName;
                 ReadSHP(fileName);
             }
         }

         private void ReadSHP(string FILENAME)
         {
             IntPtr hShp;
             hShp = ShapeLib.SHPOpen(FILENAME, "rb+");

             // get shape info and verify shapes were created correctly
             double[] minB = new double[];
             double[] maxB = new double[];
             int nEntities = ;
             ShapeLib.ShapeType shapeType = ;
             ShapeLib.SHPGetInfo(hShp, ref nEntities, ref shapeType, minB, maxB);
             listBox1.Items.Add(string.Format("Number Entries: {0}", nEntities));
             listBox1.Items.Add(string.Format("ShapeType: {0}", shapeType));
             listBox1.Items.Add(string.Format("Min XY: {0}, {1}", minB[], minB[]));
             listBox1.Items.Add(string.Format("Max XY: {0}, {1}", maxB[], maxB[]));

             // test SHPReadObject on the first shape
             for (int i = ; i < nEntities; i++)
             {
                 int iShape = i;
                 listBox1.Items.Add(string.Format("Shape({0}): ", iShape));
                 IntPtr pshpObj = ShapeLib.SHPReadObject(hShp, iShape);

                 // Get the SHPObject associated with our IntPtr pshpObj
                 // We create a new SHPObject in managed code, then use Marshal.PtrToStructure
                 // to copy the unmanaged memory pointed to by pshpObj into our managed copy.
                 ShapeLib.SHPObject shpObj = new ShapeLib.SHPObject();
                 Marshal.PtrToStructure(pshpObj, shpObj);

                 listBox1.Items.Add(string.Format("Min XY of shape({0}): ({1}, {2})", iShape, shpObj.dfXMin, shpObj.dfYMin));
                 listBox1.Items.Add(string.Format("Max XY of shape({0}): ({1}, {2})", iShape, shpObj.dfXMax, shpObj.dfYMax));
                 listBox1.Items.Add(string.Format("Points of shape({0}): ({1})", iShape, shpObj.nVertices));
                 int parts = shpObj.nParts;
                 listBox1.Items.Add(string.Format("Parts of shape({0}): ({1})", iShape, parts));
                 if (parts>)
                 {
                     int[] partStart = new int[parts];
                     Marshal.Copy(shpObj.paPartStart, partStart, , parts);
                     for (int j = ; j < partStart.Length; j++)
                     {
                         listBox1.Items.Add(string.Format("FirstPart of shape({0}): ({1})", iShape, partStart[j]));
                     }
                     int[] partType = new int[parts];
                     Marshal.Copy(shpObj.paPartType, partType, , parts);
                     for (int j = ; j < partType.Length; j++)
                     {
                         listBox1.Items.Add(string.Format("FirstPartType of shape({0}): ({1})", iShape, (MapTools.ShapeLib.PartType)partType[j]));
                     }
                 }

                 ShapeLib.SHPDestroyObject(pshpObj);
             }
             ShapeLib.SHPClose(hShp);
             Console.WriteLine("\nPress any key to continue...");
             Console.ReadLine();
         }

3.新建shp并保存属性

//简化后保存
	const char* saveFileName = "data\\simplyRoom.shp";
	int nShpTpyeSave = SHPT_POLYGON;
	SHPHandle outShp = SHPCreate(saveFileName, nShpTpyeSave);
	DBFHandle dbf_h = DBFCreate(saveFileName);
	int fieldIdx=DBFAddField(dbf_h, "Shape", FTInteger, 2, 0);
	SHPObject *psShape;

	for (int ir=0;ir<rooms_.size();ir++)
	{
		printf("--------------Room:%d------------\n",ir);
		std::vector<Coordinate> coords=rooms_[ir].simplyCoords_;
		double *xCoords = new double[coords.size()];
		double *yCoords = new double[coords.size()];
		for (int ip=0;ip<coords.size();ip++)
		{
			double x=coords[ip].x;
			double y=coords[ip].y;
			xCoords[ip] = x;
			yCoords[ip] = y;
			printf("%f,%f;\n", x,y);
		}
		printf("\n");
		psShape = SHPCreateObject(nShpTpyeSave, -1, 0, NULL, NULL, coords.size(), xCoords, yCoords, NULL, NULL);

		std::cout << std::endl;
		int ishape=SHPWriteObject(outShp, -1, psShape);
		SHPDestroyObject(psShape);
		DBFWriteIntegerAttribute(dbf_h, ishape, 0, ishape);
	}
	SHPClose(outShp);
	DBFClose(dbf_h);