//For "poly" type geometries, this function returns an array of the multipoint parts of a record.
//This multipoint part array is used in the construction of the "poly" type geometry.
private static Multipoint[] GetMultipointParts(byte[] recordContents)
{
//Get the number of parts and number of points and stored inside the PolyRecordFields struct.
PolyRecordFields recordNums = new PolyRecordFields(recordContents);
//Get all the points in the record.
Point[] points = GetPolyPoints(recordNums.NumPoints, recordNums.NumParts, recordContents);
//The points will be divided up into parts and assigned an index here.
Multipoint[] multiparts = new Multipoint[recordNums.NumParts];
//Get the index of each part.
int[] partIndex = GetRecordPartOffsets(recordNums.NumParts, recordContents);
//Loop through all the parts indicies and copy the points of that part to the multipart array.
for (int n = 0; n < partIndex.Length; n++)
{
//Find the number of points between the current index and the next index.
//If this is the last index then find the number of points between it and the length of the point array.
int numPointsInPart = n < partIndex.Length - 1 ? partIndex[n + 1] - partIndex[n] : recordNums.NumPoints - partIndex[n];
//Copy points to new point array sized for that part.
Point[] partPoints = new Point[numPointsInPart];
partPoints = points.Skip(partIndex[n]).Take(numPointsInPart).ToArray <Point>();
//Create a new multipoint object from the new point array and store it at the current part index.
multiparts[n] = new Multipoint(partPoints);
}
return(multiparts);
}
/// <summary>
/// 解析多点要素
/// </summary>
/// <param name="recordContents"></param>
/// <returns></returns>
private static List <PolyLine> GetMultiPolyLineParts(byte[] recordContents)
{
//获取几何分了几部分，以及所有坐标点的数量
PolyRecordFields recordNums = new PolyRecordFields(recordContents);
//获取记录中的所有的坐标点
var points = GetPolyPoints(recordNums.NumPoints, recordNums.NumParts, recordContents);
//按照部分划分这些点
List <PolyLine> multiparts = new List <PolyLine>();
//获取每部分点的开始索引
int[] partIndex = GetRecordPartOffsets(recordNums.NumParts, recordContents);
var partsNum = partIndex.Length;
//循环以生成各个部分的点
for (int n = 0; n < partsNum; n++)
{
//判断这是不是最后一部分点，并计算本部分点共有多少个
int numPointsInPart =
n < partsNum - 1
? partIndex[n + 1] - partIndex[n]
: recordNums.NumPoints - partIndex[n];
//取出当前这部分的点
var partPoints =
points.Skip(partIndex[n]).Take(numPointsInPart).ToList();
PolyLine multiPoint = new PolyLine(partPoints);
multiparts.Add(multiPoint);
}
return(multiparts);
}
