/// <summary>
/// 求指定简单多边形的面积
/// </summary>
/// <param name="points"></param>
/// <returns></returns>
internal static double GetPolygonSquare(moPoints points)
{
Int32 sPointCount = points.Count;
double s = 0;
double x0 = points.GetItem(0).X, y0 = points.GetItem(0).Y;
for (Int32 i = 1; i <= sPointCount - 2; i++)
{
s = s + (points.GetItem(i).X - x0) * (points.GetItem(i + 1).Y - y0) - (points.GetItem(i + 1).X - x0) * (points.GetItem(i).Y - y0);
}
s = Math.Abs(s / 2);
return(s);
}
//采用简单线符号绘制简单折线
private static void DrawPolylineBySimpleLine(Graphics g, moRectangle extent, double mapScale, double dpm,
double mpu, moPoints points, moSimpleLineSymbol symbol)
{
double sOffsetX = extent.MinX, sOffsetY = extent.MaxY; //获取投影坐标系相对屏幕坐标系的平移量
//（1）转换为屏幕坐标
GraphicsPath sGraphicPath = new GraphicsPath(); //用于屏幕绘制
Int32 sPointCount = points.Count; //顶点数目
PointF[] sScreenPoints = new PointF[sPointCount];
for (Int32 j = 0; j <= sPointCount - 1; j++)
{
PointF sScreenPoint = new PointF();
moPoint sCurPoint = points.GetItem(j);
sScreenPoint.X = (float)((sCurPoint.X - sOffsetX) * mpu / mapScale * dpm);
sScreenPoint.Y = (float)((sOffsetY - sCurPoint.Y) * mpu / mapScale * dpm);
sScreenPoints[j] = sScreenPoint;
}
sGraphicPath.AddLines(sScreenPoints);
//（2）绘制
Pen sPen = new Pen(symbol.Color, (float)(symbol.Size / 1000 * dpm));
sPen.DashStyle = (DashStyle)symbol.Style;
g.DrawPath(sPen, sGraphicPath);
sPen.Dispose();
}
/// <summary>
/// 指示指定复合折线是否部分或完全位于指定矩形盒内
/// </summary>
/// <param name="multipolyline"></param>
/// <param name="box"></param>
/// <returns></returns>
public static bool IsMultiPolylinePartiallyWithinBox(moMultiPolyline multipolyline, moRectangle box)
{
//思路：先判断矩形盒是否相交，如是，按如下顺序，满足任何一个条件，则返回True
//（1）复合折线任何一个点位于矩形盒内;
//（2）矩形盒与复合折线有交点
moRectangle sBox = multipolyline.GetEnvelope();
if (AreBoxesCross(sBox, box) == false)
{
return(false);
}
//（1）复合折线任何一个点位于矩形盒内;
Int32 sPartCount = multipolyline.Parts.Count;
for (Int32 i = 0; i <= sPartCount - 1; i++)
{
Int32 sPointCount = multipolyline.Parts.GetItem(i).Count;
for (Int32 j = 0; j <= sPointCount - 1; j++)
{
moPoint sCurPoint = multipolyline.Parts.GetItem(i).GetItem(j);
if (IsPointWithinBox(sCurPoint, box) == true)
{
return(true);
}
}
}
//（2）矩形盒与复合折线有交点
for (Int32 i = 0; i <= sPartCount - 1; i++)
{
moPoints sPoints = multipolyline.Parts.GetItem(i);
Int32 sPointCount = sPoints.Count;
for (Int32 j = 0; j <= sPointCount - 2; j++)
{
if (IsSegmentCrossBox(sPoints.GetItem(j), sPoints.GetItem(j + 1), box) == true)
{
return(true);
}
}
}
//（3）都不满足，返回false
return(false);
}
/// <summary>
/// 指示在指定容限下，指定点是否位于指定的折线上
/// </summary>
/// <param name="point"></param>
/// <param name="points"></param>
/// <param name="tolerance"></param>
/// <returns></returns>
public static bool IsPointOnPolyline(moPoint point, moPoints points, double tolerance)
{
moRectangle sBox = new moRectangle(points.MinX - tolerance, points.MaxX + tolerance, points.MinY - tolerance, points.MaxY + tolerance);
if (IsPointWithinBox(point, sBox) == false)
{
return(false);
}
Int32 sPointCount = points.Count;
for (Int32 i = 0; i <= sPointCount - 2; i++)
{
if (GetDistanceFromPointToSegment(point.X, point.Y, points.GetItem(i).X, points.GetItem(i).Y,
points.GetItem(i + 1).X, points.GetItem(i + 1).Y) <= tolerance)
{
return(true);
}
}
return(false);
}
/// <summary>
/// 求一条水平向右的射线与一个多边形的交点个数
/// </summary>
/// <param name="point"></param>
/// <param name="polygon"></param>
/// <returns></returns>
internal static Int32 GetIntersectionCountBetweenRayAndPolygon(moPoint point, moPoints points)
{
Int32 sIntersectionCount = 0;
Int32 sPointCount = points.Count;
if (IsRayCrossSegment(point, points.GetItem(sPointCount - 1), points.GetItem(0)) == true)
{
//起点与最后一点的连线与射线有交点
sIntersectionCount = sIntersectionCount + 1;
}
//求射线与其他边的交点
for (Int32 i = 0; i <= sPointCount - 2; i++)
{
if (IsRayCrossSegment(point, points.GetItem(i), points.GetItem(i + 1)) == true)
{
sIntersectionCount = sIntersectionCount + 1;
}
}
return(sIntersectionCount);
}
/// <summary>
/// 获取指定折线的中点
/// </summary>
/// <param name="points"></param>
/// <returns></returns>
public static moPoint GetMidPointOfPolyline(moPoints points)
{
Int32 sPointCount = points.Count;
List <double> sDises = new List <double>(); //所有顶点至起点的距离
sDises.Add(0); //第一个点至起点的距离
for (Int32 i = 1; i <= sPointCount - 1; i++)
{
double sCurDis = sDises.Last() + GetDistance(points.GetItem(i).X, points.GetItem(i).Y, points.GetItem(i - 1).X, points.GetItem(i - 1).Y);
sDises.Add(sCurDis);
}
//查找中点所在的线段索引号
Int32 sIndex = 0;
double sMidDis = sDises.Last() / 2; //中点与起点的距离
for (Int32 i = 0; i <= sPointCount - 2; i++)
{
if (sMidDis >= sDises[i] && sMidDis < sDises[i + 1])
{
sIndex = i;
break;
}
}
//计算中点
double x1 = points.GetItem(sIndex).X, y1 = points.GetItem(sIndex).Y;
double x2 = points.GetItem(sIndex + 1).X, y2 = points.GetItem(sIndex + 1).Y;
double sSegDis = GetDistance(x1, y1, x2, y2);
double x = x1 + (x2 - x1) * (sMidDis - sDises[sIndex]) / sSegDis;
double y = y1 + (y2 - y1) * (sMidDis - sDises[sIndex]) / sSegDis;
moPoint sMidPoint = new moPoint(x, y);
return(sMidPoint);
}
//绘制点集合（多点）
internal static void DrawPoints(Graphics g, moRectangle extent, double mapScale, double dpm, double mpu, moPoints points, moSymbol symbol)
{
if (symbol.SymbolType == moSymbolTypeConstant.SimpleMarkerSymbol)
{
moSimpleMarkerSymbol sSymbol = (moSimpleMarkerSymbol)symbol;
if (sSymbol.Visible == true)
{
Int32 sPointCount = points.Count;
for (Int32 i = 0; i <= sPointCount - 1; i++)
{
moPoint sPoint = points.GetItem(i);
DrawPointBySimpleMarker(g, extent, mapScale, dpm, mpu, sPoint, sSymbol);
}
}
}
}
//采用简单填充符号绘制简单多边形
private static void DrawPolygonBySimpleFill(Graphics g, moRectangle extent, double mapScale, double dpm,
double mpu, moPoints points, moSimpleFillSymbol symbol)
{
double sOffsetX = extent.MinX, sOffsetY = extent.MaxY; //获取投影坐标系相对屏幕坐标系的平移量
//（1）转换为屏幕坐标
GraphicsPath sGraphicPath = new GraphicsPath(); //用于屏幕绘制
Int32 sPointCount = points.Count; //顶点数目
PointF[] sScreenPoints = new PointF[sPointCount];
for (Int32 j = 0; j <= sPointCount - 1; j++)
{
PointF sScreenPoint = new PointF();
moPoint sCurPoint = points.GetItem(j);
sScreenPoint.X = (float)((sCurPoint.X - sOffsetX) * mpu / mapScale * dpm);
sScreenPoint.Y = (float)((sOffsetY - sCurPoint.Y) * mpu / mapScale * dpm);
sScreenPoints[j] = sScreenPoint;
}
sGraphicPath.AddPolygon(sScreenPoints);
//（2）填充
SolidBrush sBrush = new SolidBrush(symbol.Color);
g.FillPath(sBrush, sGraphicPath);
sBrush.Dispose();
//（3）绘制边界
if (symbol.Outline.SymbolType == moSymbolTypeConstant.SimpleLineSymbol)
{
moSimpleLineSymbol sOutline = symbol.Outline;
if (sOutline.Visible == true)
{
Pen sPen = new Pen(sOutline.Color, (float)(sOutline.Size / 1000 * dpm));
sPen.DashStyle = (DashStyle)sOutline.Style;
g.DrawPath(sPen, sGraphicPath);
sPen.Dispose();
}
}
}
/// <summary>
/// 指示指定复合多边形是否部分或完全位于指定矩形盒内
/// </summary>
/// <param name="multipolygon"></param>
/// <param name="box"></param>
/// <returns></returns>
public static bool IsMultiPolygonPartiallyWithinBox(moMultiPolygon multipolygon, moRectangle box)
{
//思路：先判断矩形盒是否相交，如是，按如下顺序，满足任何一个条件，则返回True
//（1）复合多边形任何一个点位于矩形盒内;
//（2）矩形盒任何一个顶点位于复合多边形内
//（3）矩形盒与复合多边形有交点
moRectangle sBox = multipolygon.GetEnvelope();
if (AreBoxesCross(sBox, box) == false)
{
return(false);
}
//（1）多边形任何一个点位于矩形盒内
Int32 sPartCount = multipolygon.Parts.Count;
for (Int32 i = 0; i <= sPartCount - 1; i++)
{
Int32 sPointCount = multipolygon.Parts.GetItem(i).Count;
for (Int32 j = 0; j <= sPointCount - 1; j++)
{
moPoint sCurPoint = multipolygon.Parts.GetItem(i).GetItem(j);
if (IsPointWithinBox(sCurPoint, box) == true)
{
return(true);
}
}
}
//（2）矩形盒任何一个顶点位于多边形内
moPoint sRectPoint = new moPoint(box.MinX, box.MinY); //左下点
if (IsPointWithinMultiPolygon(sRectPoint, multipolygon) == true)
{
return(true);
}
sRectPoint = new moPoint(box.MinX, box.MaxY); //左上点
if (IsPointWithinMultiPolygon(sRectPoint, multipolygon) == true)
{
return(true);
}
sRectPoint = new moPoint(box.MaxX, box.MaxY); //右上点
if (IsPointWithinMultiPolygon(sRectPoint, multipolygon) == true)
{
return(true);
}
sRectPoint = new moPoint(box.MaxX, box.MinY); //右下点
if (IsPointWithinMultiPolygon(sRectPoint, multipolygon) == true)
{
return(true);
}
//（3）矩形盒与复合多边形有交点
for (Int32 i = 0; i <= sPartCount - 1; i++)
{
moPoints sPoints = multipolygon.Parts.GetItem(i);
Int32 sPointCount = sPoints.Count;
for (Int32 j = 0; j <= sPointCount - 2; j++)
{
if (IsSegmentCrossBox(sPoints.GetItem(j), sPoints.GetItem(j + 1), box) == true)
{
return(true);
}
}
if (IsSegmentCrossBox(sPoints.GetItem(sPointCount - 1), sPoints.GetItem(0), box) == true)
{
return(true);
}
}
//（4）都不满足，返回false
return(false);
}
/// <summary>
/// 获取指定扫描线与指定多边形的交点的X坐标序列
/// </summary>
/// <param name="scanY"></param>
/// <param name="points"></param>
/// <returns></returns>
internal static List <double> GetIntersectionsBetweenScanAndPolygon(double scanY, moPoints points)
{
Int32 sPointCount = points.Count;
List <double> sIntersections = new List <double>(); //交点X坐标序列
if (IsScanCrossSegment(scanY, points.GetItem(sPointCount - 1), points.GetItem(0)) == true)
{ //起点与最后一点的连线与扫描线有交点
double x1 = points.GetItem(sPointCount - 1).X, y1 = points.GetItem(sPointCount - 1).Y;
double x2 = points.GetItem(0).X, y2 = points.GetItem(0).Y;
double x = x1 + (x2 - x1) * (scanY - y1) / (y2 - y1);
sIntersections.Add(x);
}
//求扫描线与其他边的交点
for (Int32 i = 0; i <= sPointCount - 2; i++)
{
if (IsScanCrossSegment(scanY, points.GetItem(i), points.GetItem(i + 1)) == true)
{
double x1 = points.GetItem(i).X, y1 = points.GetItem(i).Y;
double x2 = points.GetItem(i + 1).X, y2 = points.GetItem(i + 1).Y;
double x = x1 + (x2 - x1) * (scanY - y1) / (y2 - y1);
sIntersections.Add(x);
}
}
return(sIntersections);
}