public static Polygon Clip(CombineMode clipMode, Polygon subject_polygon, Polygon clip_polygon)
{
Validate(clipMode);
NativeConstants.gpc_op gpcOp = Convert(clipMode);
NativeStructs.gpc_polygon gpc_polygon = new NativeStructs.gpc_polygon();
NativeStructs.gpc_polygon gpc_subject_polygon = PolygonTo_gpc_polygon(subject_polygon);
NativeStructs.gpc_polygon gpc_clip_polygon = PolygonTo_gpc_polygon(clip_polygon);
NativeMethods.gpc_polygon_clip(gpcOp, ref gpc_subject_polygon, ref gpc_clip_polygon, ref gpc_polygon);
Polygon polygon = gpc_polygon_ToPolygon(gpc_polygon);
Free_gpc_polygon(gpc_subject_polygon);
Free_gpc_polygon(gpc_clip_polygon);
NativeMethods.gpc_free_polygon(ref gpc_polygon);
return polygon;
}
private static NativeStructs.gpc_polygon PolygonTo_gpc_polygon(Polygon polygon)
{
NativeStructs.gpc_polygon gpc_pol = new NativeStructs.gpc_polygon();
gpc_pol.num_contours = polygon.NofContours;
int[] hole = new int[polygon.NofContours];
for (int i = 0; i < polygon.NofContours; i++)
{
hole[i] = (polygon.ContourIsHole[i] ? 1 : 0);
}
gpc_pol.hole = Marshal.AllocCoTaskMem(polygon.NofContours * Marshal.SizeOf(typeof(int) /*hole[0]*/));
if (polygon.NofContours > 0)
{
Marshal.Copy(hole, 0, gpc_pol.hole, polygon.NofContours);
}
gpc_pol.contour = Marshal.AllocCoTaskMem(polygon.NofContours * Marshal.SizeOf(typeof(NativeStructs.gpc_vertex_list)));
IntPtr ptr = gpc_pol.contour;
for (int i = 0; i < polygon.NofContours; i++)
{
NativeStructs.gpc_vertex_list gpc_vtx_list = new NativeStructs.gpc_vertex_list();
gpc_vtx_list.num_vertices = polygon.Contour[i].NofVertices;
gpc_vtx_list.vertex = Marshal.AllocCoTaskMem(polygon.Contour[i].NofVertices * Marshal.SizeOf(typeof(NativeStructs.gpc_vertex)));
IntPtr ptr2 = gpc_vtx_list.vertex;
for (int j = 0; j < polygon.Contour[i].NofVertices; j++)
{
NativeStructs.gpc_vertex gpc_vtx = new NativeStructs.gpc_vertex();
gpc_vtx.x = polygon.Contour[i].Vertex[j].X;
gpc_vtx.y = polygon.Contour[i].Vertex[j].Y;
Marshal.StructureToPtr(gpc_vtx, ptr2, false);
ptr2 = (IntPtr)(((int)ptr2) + Marshal.SizeOf(gpc_vtx));
}
Marshal.StructureToPtr(gpc_vtx_list, ptr, false);
ptr = (IntPtr)(((int)ptr) + Marshal.SizeOf(gpc_vtx_list));
}
return gpc_pol;
}
