shp系列（二）——利用C++进行shp文件的读（打开）

int OnChangeByteOrder(int indata)
{
	char ss[9];
	char ee[8];
	unsigned long val = unsigned long(indata);
	ultoa(val, ss, 16);// 将十六进制的数(val)转到一个字符串(ss)中,itoa(val,ss,16);  
	int i;
	int length = strlen(ss);
	if (length != 8){
		for (i = 0; i<8 - length; i++)
			ee[i] = ‘0‘;
		for (i = 0; i<length; i++)
			ee[i + 8 - length] = ss[i];
		for (i = 0; i<8; i++)
			ss[i] = ee[i];
	}
	//****** 进行倒序  
	int t;
	t = ss[0]; ss[0] = ss[6]; ss[6] = t;
	t = ss[1]; ss[1] = ss[7]; ss[7] = t;
	t = ss[2]; ss[2] = ss[4]; ss[4] = t;
	t = ss[3]; ss[3] = ss[5]; ss[5] = t;

	//****** 将存有十六进制数 (val) 的字符串 (ss) 中的十六进制数转成十进制数  
	int value = 0;
	for (i = 0; i<8; i++){
		int k;
		if (ss[i] == ‘a‘ || ss[i] == ‘b‘ || ss[i] == ‘c‘ || ss[i] == ‘d‘ || ss[i] == ‘e‘ || ss[i] == ‘f‘)
			k = 10 + ss[i] - ‘a‘;
		else
			k = ss[i] - ‘0‘;
		value = value + int(k*(int)pow((DOUBLE)16, 7 - i));
	} 
	return(value);
}

void readShp(void)
{
	//****打开坐标文件 
	CFileDialog fDLG(true);
	if (fDLG.DoModal() != IDOK)
		return;
	filename = fDLG.GetPathName();
	FILE* m_ShpFile_fp = fopen(filename, "rb");
	if (m_ShpFile_fp == NULL) {
		MessageBox("Open File Failed");
		exit(0);
	}

	CGeoMap* map = new CGeoMap();      //创建地图对象
	CGeoLayer* layer = new CGeoLayer();//新建图层						   

	//****定义读取坐标文件头的变量 
	int i;
	int FileCode = -1;
	int Unused = -1;
	int FileLength = -1;
	int Version = -1;
	int ShapeType = -1;
	double Xmin;
	double Ymin;
	double Xmax;
	double Ymax;
	double Zmin;
	double Zmax;
	double Mmin;
	double Mmax;

	//****读取坐标头文件
	fread(&FileCode, sizeof(int), 1, m_ShpFile_fp);  //从m_ShpFile_fp里面的值读到Filecode里面去，每次读一个int型字节的长度，读取一次  
	FileCode = OnChangeByteOrder(FileCode);          //将读取的FileCode的值转化为十进制的数  
	for (i = 0; i<5; i++)
		fread(&Unused, sizeof(int), 1, m_ShpFile_fp);
	fread(&FileLength, sizeof(int), 1, m_ShpFile_fp);//读取FileLength  
	FileLength = OnChangeByteOrder(FileLength);      //将FileLength转化为十进制的数  
	fread(&Version, sizeof(int), 1, m_ShpFile_fp);   //读取Version的值  
	fread(&ShapeType, sizeof(int), 1, m_ShpFile_fp);//读取ShapeType的值  
	fread(&Xmin, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Xmin里面去，每次读取一个double型字节长度，读取一次  
	fread(&Ymin, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Ymin里面去，每次读取一个double型字节长度，读取一次  
	fread(&Xmax, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Xmax里面去，每次读取一个double型字节长度，读取一次  
	fread(&Ymax, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Ymax里面去，每次读取一个double型字节长度，读取一次  

	CRect rect(Xmin, Ymin, Xmax, Ymax);
	layer->setRect(rect);                         //设置图层的边界

	fread(&Zmin, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Zmin里面去，每次读取一个double型字节长度，读取一次  
	fread(&Zmax, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Zmax里面去，每次读取一个double型字节长度，读取一次  
	fread(&Mmin, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Mmin里面去，每次读取一个double型字节长度，读取一次  
	fread(&Mmax, sizeof(double), 1, m_ShpFile_fp);//从m_ShpFile_fp里面的值读到Mmax里面去，每次读取一个double型字节长度，读取一次  
	//****读取坐标文件头的内容结束

	//****读取面状目标的实体信息
	int RecordNumber;
	int ContentLength;
	switch (ShapeType) {
	case 5: {  //polygon
		while ((fread(&RecordNumber, sizeof(int), 1, m_ShpFile_fp) != 0)) { //从第一个开始循环读取每一个Polygon
			fread(&ContentLength, sizeof(int), 1, m_ShpFile_fp);            //读取ContentLength
			RecordNumber = OnChangeByteOrder(RecordNumber);                 //转换为10进制
			ContentLength = OnChangeByteOrder(ContentLength);
			//****记录头读取结束

			//****读取记录内容
			int shapeType;   //当前Polygon几何类型
			double Box[4];   //当前Polygon的上下左右边界
			int NumParts;    //当前Polygon所包含的子环的个数
			int NumPoints;   //当前Polygon所包含的点的个数
			int *Parts;      //当前Polygon所包含的子环的起点在NumPoints的编号
			fread(&shapeType, sizeof(int), 1, m_ShpFile_fp);
			for (i = 0; i < 4; i++)                         //读Box
				fread(Box + i, sizeof(double), 1, m_ShpFile_fp);
			fread(&NumParts, sizeof(int), 1, m_ShpFile_fp); //表示构成当前Polygon的子环的个数
			fread(&NumPoints, sizeof(int), 1, m_ShpFile_fp);//表示构成当前Polygon所包含的坐标点个数
			Parts = new int[NumParts];                      //记录了每个子环的坐标在Points数组中的起始位置
			for (i = 0; i < NumParts; i++)
				fread(Parts + i, sizeof(int), 1, m_ShpFile_fp);

			int pointNum;
			CGeoPolygon* polygon = new CGeoPolygon();
			polygon->circleNum = NumParts;                   //设定多边形的点数

			//****读取面中子环
			for (i = 0; i < NumParts; i++) {  
				if (i != NumParts - 1)  pointNum = Parts[i + 1] - Parts[i];//每个子环的长度 ，非最后一个环
				else  pointNum = NumPoints - Parts[i];       //最后一个环
				double* PointsX = new double[pointNum];      //用于存放读取的点坐标x值;
				double* PointsY = new double[pointNum];      //用于存放y值
				CGeoPolyline* polyline = new CGeoPolyline(); //每个环实际上就是首尾坐标相同的Polyline
				polyline->circleID = i; 

				for (int j = 0; j < pointNum; j++) {
					fread(PointsX + j, sizeof(double), 1, m_ShpFile_fp);
					fread(PointsY + j, sizeof(double), 1, m_ShpFile_fp);
					double a = PointsX[j];
					double b = PointsY[j];
					CPoint* point = new CPoint(a, b);
					polyline->AddPoint(point);               //把该子环所有的点添加到一条链上
				}

				CPoint pt1 = polyline->pts[0]->GetCPoint();
				CPoint pt2 = polyline->pts[polyline->pts.size() - 1]->GetCPoint();
				if (pt1 != pt2) {  //若首位点不一致
					CString str;
					str.Format("%d数据首尾点不一致", RecordNumber);
					polyline->pts.push_back(p1);
				}
				polygon->AddCircle(polyline);                 //将polyline链添加到对应polygon中
				delete[] PointsX;
				delete[] PointsY;
			}
			//****一个面的某个子环循环结束，同时该子环已加入到polygon
			 
			layer->AddObject((CGeoObject*)polygon);           //将该polygon加入到图层中
			delete[] Parts;
		}
		map->AddLayer(layer);
	}
		break;
	case 1://point
		break;
	case 3://polyline
		break;
	default:
		break;
	}
}