/// <summary>
/// Constructor from grid header
/// </summary>
/// <param name="h">header</param>
public OffSet(MapWinGIS.GridHeader h)
{
// origin (taken as column zero and row zero) is at the top left of the grid
this.origin = new MapWinGIS.Point();
this.origin.x = h.XllCenter - (h.dX / 2);
this.origin.y = h.YllCenter - (h.dY / 2) + h.dY * h.NumberRows;
this.dX = h.dX;
this.dY = h.dY;
this.unitArea = (double)this.dX * this.dY;
}
private bool Multipoint2Grid(MapWinGIS.Shapefile MultipointSf, int FldID, MapWinGIS.Grid Newgrd,
MapWinGIS.GridHeader header, MapWinGIS.GridDataType grType, MapWinGIS.ICallback cback)
{
//count the number of shapes
int s, p;
MapWinGIS.Shape shp;
MapWinGIS.Point pt;
ArrayList pixels = new ArrayList();
object val;
GridPixel px;
int nShps = MultipointSf.NumShapes;
int nPts = 0;
int perc = 1;
int shpsPerc = NumPercentShapes(perc, nShps); //percent of progress
for (s = 0; s < nShps; ++s)
{
//get the shape
shp = MultipointSf.get_Shape(s);
//exclude shapes which are completely outside of the grid extents
if (!IsGridContainsShape(shp, header))
{
continue;
}
//get the shape's value
val = GetCellValue(MultipointSf, FldID, s, header.NodataValue);
nPts = shp.numPoints;
for (p = 0; p < nPts; ++p)
{
//write pixel values
pt = shp.get_Point(p);
Newgrd.ProjToCell(pt.x, pt.y, out px.col, out px.row);
pixels.Add(px);
writePxList(Newgrd, grType, pixels, val, cback);
}
//report the progress
if (s >= shpsPerc)
{
reportProgress(shpsPerc, nShps, "shapefile to grid", cback);
perc = (int)((s * 100) / nShps);
shpsPerc = NumPercentShapes(perc + 1, nShps);
}
}
return(true);
}
/// <summary>
/// convert point shapefile to grid
/// </summary>
private bool Point2Grid(MapWinGIS.Shapefile PointSf, int FldID, MapWinGIS.Grid Newgrd,
MapWinGIS.GridHeader header, MapWinGIS.GridDataType grType, MapWinGIS.ICallback cback)
{
//count the number of shapes
int s;
MapWinGIS.Shape shp;
MapWinGIS.Point pt = new MapWinGIS.Point();
object val;
GridPixel px;
int nShps = PointSf.NumShapes;
int perc = 1;
int shpsPerc = NumPercentShapes(perc, nShps); //percent of progress
for (s = 0; s < nShps; ++s)
{
//get the point
shp = PointSf.get_Shape(s);
//exclude shapes which are completely outside of the grid extents
if (!IsGridContainsShape(shp, header))
{
continue;
}
if (shp.numPoints > 0)
{
pt = shp.get_Point(0);
if (pt != null)
{
//return the shape's value and write the pixel
val = GetCellValue(PointSf, FldID, s, header.NodataValue);
Newgrd.ProjToCell(pt.x, pt.y, out px.col, out px.row);
writePx(Newgrd, grType, px, val, cback);
}
}
//report the progress
if (s >= shpsPerc)
{
perc = (int)((s * 100) / nShps);
shpsPerc = NumPercentShapes(perc + 1, nShps);
reportProgress(shpsPerc, nShps, "shapefile to grid", cback);
}
}
return(true);
}
/// <summary>
/// populate all the grid cells between two consecutive intersections with shape's value
/// </summary>
private bool ScanLine(ArrayList vettore, double xref,
ArrayList pixels, MapWinGIS.GridHeader header,
object value, MapWinGIS.ICallback cback)
{
bool result = false;
bool control;
double xll, yll, ystart, yend, ycellstart;
double dx, dy;
int nrows;
int c, r, v;
r = 0;
GridPixel curPx;
control = false;
xll = header.XllCenter;
yll = header.YllCenter;
dx = header.dX;
dy = header.dY;
nrows = header.NumberRows;
ystart = 0;
for (v = vettore.Count - 1; v >= 0; --v)
{
if (control == false)
{
ystart = (double)vettore[v];
control = true;
}
else
{
yend = (double)vettore[v];
ycellstart = FirstLineXY(ystart, yll, dy, -1);
do
{
Globals.ProjToCell(xref, ycellstart, out c, out r, xll, yll, dx, dy, nrows);
curPx.col = c;
curPx.row = r;
pixels.Add(curPx);
ycellstart = ycellstart - dy;
}while (ycellstart >= yend);
control = false;
}
}
return(result);
}
/// <summary>
/// determine if the shape is partially inside grid extents
/// </summary>
/// <param name="shp"></param>
/// <param name="hdr"></param>
/// <returns>false, if the shape is completely outside grid extents
/// true, if it's at least partially inside</returns>
private bool IsGridContainsShape(MapWinGIS.Shape shp, MapWinGIS.GridHeader hdr)
{
double gridXmin = hdr.XllCenter;
double gridYmin = hdr.YllCenter;
double gridXmax = gridXmin + (hdr.NumberCols * hdr.dX);
double gridYmax = gridYmin + (hdr.NumberRows * hdr.dY);
MapWinGIS.Extents ext = shp.Extents;
if (ext.xMin > gridXmax || ext.yMin > gridYmax ||
ext.xMax < gridXmin || ext.yMax < gridYmin)
{
return(false);
}
else
{
return(true);
}
}
/// <summary>
/// 'Copyright (C) 2008 Enrico Antonio Chiaradia, UNIMI
///'This program is free software; you can redistribute it and/or
///'modify it under the terms of the GNU General Public License
///'version 2, 1991 as published by the Free Software Foundation.
///'This program is distributed in the hope that it will be useful,
///'but WITHOUT ANY WARRANTY; without even the implied warranty of
///'MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
///'GNU General Public License for more details.
///'A copy of the full GNU General Public License is available at:
///'http://www.gnu.org/copyleft/gpl.html
///'or from:
///'The Free Software Foundation, Inc., 59 Temple Place - Suite 330,
///'Boston, MA 02111-1307, USA.
///'If you wish to use or incorporate this program (or parts of it) into
///'other software that does not meet the GNU General Public License
///'conditions contact the author to request permission.
///'If you have any question or suggestion, please contact the author.
///'Enrico A. Chiaradia
///'University of Milan
///'Ist. di Idraulica Agraria
///'via Celoria 2
///'20133, Milan, Italy
///'email: [email protected]
/// </summary>
/// <param name="sfPath">the name of the shapefile</param>
/// <param name="resultGridPath">the name of the new grid</param>
/// <param name="gridFileType">file type of the new grid</param>
/// <param name="gridDataType">data format of the new grid</param>
/// <param name="sfValueField">the name of the field that contains data</param>
/// <param name="resultGridHeader">contains information about dimension of the new grid</param>
/// <param name="callback">(optional) reports progress and error messages</param>
/// <returns></returns>
public bool ShapefileToGrid2(string SfNm, string GrdName,
MapWinGIS.GridFileType GrdFileType, MapWinGIS.GridDataType GrdDataType,
string Fldname, MapWinGIS.GridHeader GrdHd,
MapWinGIS.ICallback cback)
{
int i;
bool flg;
string projStr;
//open the shapefile
MapWinGIS.Shapefile MySf = new MapWinGIS.Shapefile();
flg = MySf.Open(SfNm, cback);
if (flg == false)
{
reportError("ERROR in opening shapefile: " + SfNm, cback);
MySf.Close();
return(false);
}
//get the handle for the field
MapWinGIS.Field field;
int FldId = -1;
int LayFldNum = MySf.NumFields;
i = 0;
for (i = 0; i < LayFldNum; ++i)
{
field = MySf.get_Field(i);
if (field.Name.ToLower() == Fldname.ToLower())
{
FldId = i;
break;
}
}
if (FldId < 0)
{
reportError("The shapefile " + SfNm + " doesn't have a field " + Fldname, cback);
MySf.Close();
return(false);
}
//copy shapefile projection
projStr = MySf.Projection;
if (!MapWinUtility.Strings.IsEmpty(projStr))
{
GrdHd.Projection = projStr;
}
//create a new grid and a new gridheader
MapWinGIS.Grid NewGrd = new MapWinGIS.Grid();
flg = NewGrd.CreateNew(GrdName, GrdHd, GrdDataType, GrdHd.NodataValue, false, GrdFileType, cback);
if (flg == false)
{
reportError("ERROR in grid initialization: " + GrdName, cback);
NewGrd.Close();
MySf.Close();
}
//verify the type of shapefile and call rasterization function
MapWinGIS.ShpfileType SfType = new MapWinGIS.ShpfileType();
SfType = MySf.ShapefileType;
switch (SfType)
{
case ShpfileType.SHP_POLYGON:
case ShpfileType.SHP_POLYGONM:
case ShpfileType.SHP_POLYGONZ:
flg = Poly2Grid(MySf, FldId, NewGrd, GrdHd, GrdDataType, cback);
break;
case ShpfileType.SHP_POLYLINE:
case ShpfileType.SHP_POLYLINEM:
case ShpfileType.SHP_POLYLINEZ:
flg = Line2Grid(MySf, FldId, NewGrd, GrdHd, GrdDataType, cback);
break;
case ShpfileType.SHP_POINT:
case ShpfileType.SHP_POINTM:
case ShpfileType.SHP_POINTZ:
flg = Point2Grid(MySf, FldId, NewGrd, GrdHd, GrdDataType, cback);
break;
case ShpfileType.SHP_MULTIPOINT:
case ShpfileType.SHP_MULTIPOINTM:
case ShpfileType.SHP_MULTIPOINTZ:
flg = Multipoint2Grid(MySf, FldId, NewGrd, GrdHd, GrdDataType, cback);
break;
default:
reportError("The shapefile type " + SfType.ToString() + "is not supported.", cback);
NewGrd.Close();
MySf.Close();
flg = false;
break;
}
//save and close the grid, close shapefile
NewGrd.Save(GrdName, GrdFileType, cback);
NewGrd.Close();
MySf.Close();
return(flg);
}
/// <summary>
/// converts a Line shapefile to grid using Bresenham algorithm
/// </summary>
/// <param name="PolySf">Polygon shapefile object</param>
/// <param name="FldID">Field index</param>
/// <param name="Newgrd">New grid object</param>
/// <param name="header">Grid header</param>
/// <param name="nodatavalue"></param>
/// <param name="cback">optional, for reporting progress</param>
/// <returns>true if successful</returns>
private bool Line2Grid(MapWinGIS.Shapefile LineSf, int FldID, MapWinGIS.Grid Newgrd,
MapWinGIS.GridHeader header, MapWinGIS.GridDataType grType, MapWinGIS.ICallback cback)
{
int numParts, numPoints;
int curPartStart, curPartEnd, vertexCol, vertexRow, lastCol, lastRow;
int nShps = LineSf.NumShapes;
int perc = 1;
int shpsPerc = NumPercentShapes(perc, nShps); //percent of progress
int s = 0; //shape number
int p = 0; //part number
int k = 0; //point number
MapWinGIS.Shape LineShp = new MapWinGIS.Shape();
MapWinGIS.Point curPoint;
//Rasterization ras = new Rasterization(); //rasterization class, contains the code of
//lineToGrid methods independent on MapWinGIS functions
ArrayList vertices = new ArrayList(); //list of line vertex points
ArrayList pixels = new ArrayList(); //list of calculated pixels on the line
GridPixel px;
object val; //the shape's value
for (s = 0; s < nShps; ++s)
{
LineShp = LineSf.get_Shape(s);
numParts = LineShp.NumParts;
numPoints = LineShp.numPoints;
//exclude shapes which are completely outside of the grid extents
if (!IsGridContainsShape(LineShp, header))
{
continue;
}
//get the shape's value
val = GetCellValue(LineSf, FldID, s, header.NodataValue);
//process each part of the polyline
curPartStart = 0;
for (p = 0; p < numParts; ++p)
{
vertices.Clear();
pixels.Clear();
curPartStart = LineShp.get_Part(p);
// check for multi-part lines
if (p < numParts - 1)
{
curPartEnd = LineShp.get_Part(p + 1) - 1;
}
else
{
curPartEnd = numPoints - 1;
}
//go to next part if there's zero points
if (numPoints <= 0)
{
continue;
}
// add all points of current part to rasterization list
// always add the first point of the part (convert its coordinates to
// grid row and column)
curPoint = LineShp.get_Point(curPartStart);
Newgrd.ProjToCell(curPoint.x, curPoint.y,
out vertexCol, out vertexRow);
px.col = vertexCol;
px.row = vertexRow;
vertices.Add(px);
lastCol = vertexCol; lastRow = vertexRow;
// add all other points with different grid coordinates
for (k = curPartStart + 1; k <= curPartEnd; ++k)
{
// (check if it has a different row or column than the previous point)
curPoint = LineShp.get_Point(k);
Newgrd.ProjToCell(curPoint.x, curPoint.y,
out vertexCol, out vertexRow);
if (vertexCol != lastCol || vertexRow != lastRow)
{
px.col = vertexCol;
px.row = vertexRow;
vertices.Add(px);
lastCol = vertexCol;
lastRow = vertexRow;
}
}
// convert the polyline and write pixels to grid
LineBresenham(vertices, pixels);
writePxList(Newgrd, grType, pixels, val, cback);
}
//report the progress
if (s >= shpsPerc)
{
reportProgress(shpsPerc, nShps, "shapefile to grid", cback);
perc = (int)((s * 100) / nShps);
shpsPerc = NumPercentShapes(perc + 1, nShps);
}
}
return(true);
}
/// <summary>
/// populate all the grid cells between two consecutive intersections with shape's value
/// </summary>
private bool ScanLine2(System.Collections.ArrayList vettore, double xref,
ref System.Collections.ArrayList pixels, ref MapWinGIS.Grid gr, MapWinGIS.GridHeader header,
object value, MapWinGIS.ICallback cback)
{
bool result = false;
bool control;
double yll, ystart, yend, ycellstart;
double pxsize;
int c, r, v;
r = 0;
GridPixel curPx;
control = false;
yll = header.YllCenter;
pxsize = header.dX;
ystart = 0;
for (v = vettore.Count - 1; v >= 0; --v)
{
if (control == false)
{
ystart = (double)vettore[v];
control = true;
}
else
{
yend = (double)vettore[v];
ycellstart = FirstLineXY(ystart, yll, pxsize, -1);
do
{
gr.ProjToCell(xref, ycellstart, out c, out r);
curPx.col = c;
curPx.row = r;
pixels.Add(curPx);
ycellstart = ycellstart - pxsize;
}while (ycellstart >= yend);
control = false;
}
}
return(result);
}
/// <summary>
/// This function converts a polygon shapefile to grid. It implements the line-scan algorithm.
/// <param name="PolySf">The polygon shapefile</param>
/// <param name="FldID">The field index</param>
/// <param name="Newgrd">File name of the new grid</param>
/// <param name="header">Header object of the new grid</param>
/// <param name="writePxDeleg">Delegate function for writing the grid pixels</param>
/// <param name="nodatavalue">'no data' value</param>
/// <param name="cback">can be used to report progress (optional)</param>
/// <returns>true if successful</returns>
//
// AUTHOR NAME: Enrico A. Chiaradia
// FROM: University of Milan (Italy)
// e.mail: [email protected]
//
// For details about the line-scan algorithm,
// please refer to http://www.profc.udec.cl/~gabriel/tutoriales/giswb/vol1/cp3/cp3-6.htm
//
// for each shape in PolySf
// 0) get the shape value (in the shapefile table)
// 1) load all the borders in a matrix composed by x(startpoint), x(endpoint), slope and share
// 2) define x of first scan line
// for each scan lines
// 3) calculate intersections with polygon border
// 4) sort intersections from lower Y to the higther
// 5) convert line space between two consecutive intersection to raster
private bool Poly2Grid(MapWinGIS.Shapefile PolySf, int FldID, MapWinGIS.Grid Newgrd,
MapWinGIS.GridHeader header, MapWinGIS.GridDataType grType,
MapWinGIS.ICallback cback)
{
double xMin, xMax;
double x0, x1, x2, y0, y1, y2, m, q;
int nShps, nVs, i, s, nP, p, tempn, v, b;
object val;
bool flg;
bord brd; //struct to keep a border
System.Collections.ArrayList bordi2; //list of borders
int perc = 1; //percent shapes done
int shpsPerc;
MapWinGIS.Shape PolyShp; //the polygon shape
//count the number of shapes
nShps = PolySf.NumShapes;
shpsPerc = NumPercentShapes(perc, nShps); //percent of progress
for (s = 0; s < nShps; ++s)
{
//for each shape, determine the extent and the number of parts
i = 0;
PolyShp = PolySf.get_Shape(s);
nP = PolyShp.NumParts;
xMin = PolyShp.Extents.xMin;
//yMin = PolyShp.Extents.yMin;
xMax = PolyShp.Extents.xMax;
//yMax = PolyShp.Extents.yMax;
//exclude shapes which are completely outside of the grid extents
if (!IsGridContainsShape(PolyShp, header))
{
continue;
}
//return the shape's value
val = GetCellValue(PolySf, FldID, s, header.NodataValue);
//load polygon borders
nVs = PolyShp.numPoints - 1;
bordi2 = new System.Collections.ArrayList(nVs + 1);
b = -1;
tempn = 0;
for (p = 0; p < nP; ++p)
{
x0 = PolyShp.get_Point(tempn).x;
y0 = PolyShp.get_Point(tempn).y;
for (v = tempn; v < nVs; ++v)
{
x1 = PolyShp.get_Point(v).x;
x2 = PolyShp.get_Point(v + 1).x;
y1 = PolyShp.get_Point(v).y;
y2 = PolyShp.get_Point(v + 1).y;
if (x1 != x2) // no vertical lines
{
m = (y2 - y1) / (x2 - x1);
q = y1 - (m * x1);
//add border to the list
b = b + 1;
brd = new bord();
brd.x1 = x1;
brd.x2 = x2;
brd.m = m;
brd.q = q;
bordi2.Add(brd);
}
//in case of multi-parts polygon
if ((x2 == x0) && (y2 == y0))
{
tempn = v + 2;
break;
}
} //Next v
} // next p
//define the first line-scan
double xstart;
// 20 nov 07 added by Enrico A. Chiaradia
//necessary if grid extentions differ from shapefile extentions
if (xMin >= header.XllCenter)
{
xstart = FirstLineXY(xMin, header.XllCenter, header.dX, 1);
}
else
{
xstart = FirstLineXY(xMin, header.XllCenter, header.dX, -1);
}
// the list of intersection y-values
System.Collections.ArrayList y_int = new System.Collections.ArrayList();
System.Collections.ArrayList pixels = new System.Collections.ArrayList();
do
{
flg = Interseca(bordi2, y_int, xstart);
flg = SortArray(y_int);
flg = ScanLine2(y_int, xstart, ref pixels, ref Newgrd, header, val, cback);
xstart = xstart + header.dX;
}while (xstart <= xMax);
writePxList(Newgrd, grType, pixels, val, cback);
//report the progress
if (s >= shpsPerc)
{
reportProgress(shpsPerc, nShps, "shapefile to grid", cback);
perc = (int)((s * 100) / nShps);
shpsPerc = NumPercentShapes(perc + 1, nShps);
}
} // next shape
reportProgress(100, 100, "shapefile to grid", cback); //100 % shapes done
return(true);
}
/// <summary>
/// Constructor, making an empty dictionary, and setting offset
/// from header.
/// </summary>
public ManhattanShapes(MapWinGIS.GridHeader h)
{
ShapesTable = new Dictionary <int, Data>();
offset = new OffSet(h);
}
/// <summary>
/// Converts grid to a shapefile, removing any existing shapefile.
/// Assumed to be an integer grid. Adds attribute headed id with the grid values, and
/// attribute headed "Area" with the area for each polygon.
/// </summary>
/// <param name="gridName">Path of input grid</param>
/// <param name="shapeName">Path of output shapefile</param>
/// <param name="id">String to use for name of grid values attribute</param>
/// <param name="cb">Callback for reporting errors</param>
/// <returns>null if any errors, else shapefile</returns>
public static MapWinGIS.Shapefile GridToShapeManhattan(string gridName, string shapeName,
string id, MapWinGIS.ICallback cb)
{
if (!System.IO.File.Exists(gridName))
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.nogrid + gridName);
}
return(null);
}
MapWinGIS.Grid grid = new MapWinGIS.GridClass();
if (!grid.Open(gridName, GridDataType.UnknownDataType, true, GridFileType.UseExtension, null))
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noopengrid + gridName);
}
return(null);
}
MapWinGIS.GridHeader header = grid.Header;
int numRows = header.NumberRows;
int numCols = header.NumberCols;
MapWinGeoProc.DataManagement.DeleteShapefile(ref shapeName);
string oldProj = System.IO.Path.ChangeExtension(gridName, ".prj");
string newProj = System.IO.Path.ChangeExtension(shapeName, ".prj");
if (System.IO.File.Exists(oldProj) && !oldProj.Equals(newProj))
{
System.IO.File.Copy(oldProj, newProj);
}
MapWinGIS.Shapefile shapeFile = new MapWinGIS.Shapefile();
bool success = shapeFile.CreateNew(shapeName, ShpfileType.SHP_POLYGON);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.nocreateshapefile + shapeName);
}
return(null);
}
success = shapeFile.StartEditingShapes(true, null);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noeditshapefile + shapeName);
}
return(null);
}
ManhattanShapes shapes = new ManhattanShapes(header);
for (int i = 0; i < numRows; i++)
{
shapes.addGridRow(grid, i, numCols);
}
if (!shapes.lastError.Equals(""))
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", shapes.lastError);
}
return(null);
}
grid.Close();
shapes.FinishShapes();
MapWinGIS.Field idField = new MapWinGIS.Field();
idField.Name = id;
idField.Type = FieldType.INTEGER_FIELD;
int idIndex = 0;
success = shapeFile.EditInsertField(idField, ref idIndex, null);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noaddfield + shapeName);
}
shapeFile.Close();
return(null);
}
MapWinGIS.Field areaField = new MapWinGIS.Field();
areaField.Name = "Area";
areaField.Type = FieldType.DOUBLE_FIELD;
int areaIndex = 1;
success = shapeFile.EditInsertField(areaField, ref areaIndex, null);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noaddfield + shapeName);
}
shapeFile.Close();
return(null);
}
int shapeIndex = 0;
foreach (int k in shapes.ShapesTable.Keys)
{
success = shapes.InsertShape(shapeFile, k, ref shapeIndex);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noaddshape + shapeName);
}
shapeFile.Close();
return(null);
}
success = shapeFile.EditCellValue(idIndex, shapeIndex, k);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noeditcell + shapeName);
}
shapeFile.Close();
return(null);
}
double area = shapes.Area(k);
success = shapeFile.EditCellValue(areaIndex, shapeIndex, area);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noeditcell + shapeName);
}
shapeFile.Close();
return(null);
}
}
success = shapeFile.StopEditingShapes(true, true, null);
if (!success)
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.noeditshapefile + shapeName);
}
shapeFile.Close();
return(null);
}
if (!shapeFile.Close())
{
if (cb != null)
{
cb.Error("GridToShapeManhattan", clsUtils.ManhattanShapes.nocloseshapefile + shapeName);
}
return(null);
}
return(shapeFile);
}
private MapWinGIS.Extents GetMaxExtents(MapWinGIS.Extents ex, MapWinGIS.GridHeader header)
{
MapWinGIS.Extents extents = new MapWinGIS.ExtentsClass();
double xMin = 0, xMax = 0, yMin = 0, yMax = 0;
double newXMin = 0, newXMax = 0, newYMin = 0, newYMax = 0;
//find the grid Max and Min extents
xMin = header.XllCenter;
yMin = header.YllCenter;
xMax = header.XllCenter + header.dX * header.NumberCols;
yMax = header.YllCenter + header.dY * header.NumberRows;
if (ex == null)
{
return(null);
}
else if (ex.xMax < xMin || ex.yMax < yMin || ex.xMin > xMax || ex.yMin > yMax)
{
//out of bounds return nothing
return(null);
}
else
{
//check to make sure the selected bounds are within the grid
if (ex.xMin < xMin)
{
newXMin = xMin;
}
else
{
newXMin = ex.xMin;
}
if (ex.yMin < yMin)
{
newYMin = yMin;
}
else
{
newYMin = ex.yMin;
}
if (ex.xMax > xMax)
{
newXMax = xMax;
}
else
{
newXMax = ex.xMax;
}
if (ex.yMax > yMax)
{
newYMax = yMax;
}
else
{
newYMax = ex.yMax;
}
extents.SetBounds(newXMin, newYMin, 0, newXMax, newYMax, 0);
}
return(extents);
}