[RGEOS]绘制多边形Polygon

合集 - RGeos(10)
1.[RGEOS]几何对象定义基础2.[RGEOS]空间量测3.[RGEOS]空间分析4.[RGEOS]空间拓扑操作5.[RGEOS]数学基础6.[RGEOS]空间拓扑关系7.[RGEOS]支持栅格数据读取和显示
8.[RGEOS]绘制多边形Polygon
9.[RGeos]手簿10.使用GitHub开源一个项目RGEOS
收起

 绘制OGIS定义的Polygon

复制代码
 1    public void DrawPolygon(Polygon pol, Brush brush, Pen pen, bool clip)
 2         {
 3             gc = Graphics.FromHwnd(Handle);
 4             if (pol.ExteriorRing == null)
 5                 return;
 6             if (pol.ExteriorRing.Vertices.Count > 2)
 7             {
 8                 //Use a graphics path instead of DrawPolygon. DrawPolygon has a problem with several interior holes
 9                 GraphicsPath gp = new GraphicsPath();
10 
11                 //Add the exterior polygon
12                 PointF[] pts = TransformLineString(pol.ExteriorRing);
13                 if (!clip)
14                     gp.AddPolygon(LimitValues(pts, extremeValueLimit));
15                 else
16                     DrawPolygonClipped(gp, pts, (int)100, (int)100);
17 
18                 //Add the interior polygons (holes)
19 
20                 for (int i = 0; i < pol.InteriorRings.Count; i++)
21                 {
22                     PointF[] pts1 = TransformLineString(pol.InteriorRings[i]);
23                     if (!clip)
24                         gp.AddPolygon(LimitValues(pts1, extremeValueLimit));
25                     else
26                         DrawPolygonClipped(gp, pts1, (int)100, (int)100);
27                 }
28 
29                 // Only render inside of polygon if the brush isn't null or isn't transparent
30                 if (brush != null && brush != Brushes.Transparent)
31                     gc.FillPath(brush, gp);
32                 // Create an outline if a pen style is available
33                 if (pen != null)
34                     gc.DrawPath(pen, gp);
35                 gc.Dispose();
36             }
37         }
复制代码

 

1   public static PointF[] TransformLineString(LineString line)
2         {
3             PointF[] v = new PointF[line.Vertices.Count];
4             for (int i = 0; i < line.Vertices.Count; i++)
5                 v[i] = new PointF((float)line.Vertices[i].X, (float)line.Vertices[i].Y);
6             return v;
7         }

 

复制代码
  1         internal static PointF[] clipPolygon(PointF[] vertices, int width, int height)
  2         {
  3             float deltax, deltay, xin, xout, yin, yout;
  4             float tinx, tiny, toutx, touty, tin1, tin2, tout;
  5             float x1, y1, x2, y2;
  6 
  7             List<PointF> line = new List<PointF>();
  8             if (vertices.Length <= 1) /* nothing to clip */
  9                 return vertices;
 10 
 11             for (int i = 0; i < vertices.Length - 1; i++)
 12             {
 13                 x1 = vertices[i].X;
 14                 y1 = vertices[i].Y;
 15                 x2 = vertices[i + 1].X;
 16                 y2 = vertices[i + 1].Y;
 17 
 18                 deltax = x2 - x1;
 19                 if (deltax == 0)
 20                 {
 21                     // bump off of the vertical
 22                     deltax = (x1 > 0) ? -nearZero : nearZero;
 23                 }
 24                 deltay = y2 - y1;
 25                 if (deltay == 0)
 26                 {
 27                     // bump off of the horizontal
 28                     deltay = (y1 > 0) ? -nearZero : nearZero;
 29                 }
 30 
 31                 if (deltax > 0)
 32                 {
 33                     //  points to right
 34                     xin = 0;
 35                     xout = width;
 36                 }
 37                 else
 38                 {
 39                     xin = width;
 40                     xout = 0;
 41                 }
 42 
 43                 if (deltay > 0)
 44                 {
 45                     //  points up
 46                     yin = 0;
 47                     yout = height;
 48                 }
 49                 else
 50                 {
 51                     yin = height;
 52                     yout = 0;
 53                 }
 54 
 55                 tinx = (xin - x1) / deltax;
 56                 tiny = (yin - y1) / deltay;
 57 
 58                 if (tinx < tiny)
 59                 {
 60                     // hits x first
 61                     tin1 = tinx;
 62                     tin2 = tiny;
 63                 }
 64                 else
 65                 {
 66                     // hits y first
 67                     tin1 = tiny;
 68                     tin2 = tinx;
 69                 }
 70 
 71                 if (1 >= tin1)
 72                 {
 73                     if (0 < tin1)
 74                         line.Add(new PointF(xin, yin));
 75 
 76                     if (1 >= tin2)
 77                     {
 78                         toutx = (xout - x1) / deltax;
 79                         touty = (yout - y1) / deltay;
 80 
 81                         tout = (toutx < touty) ? toutx : touty;
 82 
 83                         if (0 < tin2 || 0 < tout)
 84                         {
 85                             if (tin2 <= tout)
 86                             {
 87                                 if (0 < tin2)
 88                                 {
 89                                     if (tinx > tiny)
 90                                         line.Add(new PointF(xin, y1 + tinx * deltay));
 91                                     else
 92                                         line.Add(new PointF(x1 + tiny * deltax, yin));
 93                                 }
 94 
 95                                 if (1 > tout)
 96                                 {
 97                                     if (toutx < touty)
 98                                         line.Add(new PointF(xout, y1 + toutx * deltay));
 99                                     else
100                                         line.Add(new PointF(x1 + touty * deltax, yout));
101                                 }
102                                 else
103                                     line.Add(new PointF(x2, y2));
104                             }
105                             else
106                             {
107                                 if (tinx > tiny)
108                                     line.Add(new PointF(xin, yout));
109                                 else
110                                     line.Add(new PointF(xout, yin));
111                             }
112                         }
113                     }
114                 }
115             }
116             if (line.Count > 0)
117                 line.Add(new PointF(line[0].X, line[0].Y));
118 
119             return line.ToArray();
120         }
121 
122         private void DrawPolygonClipped(GraphicsPath gp, PointF[] polygon, int width, int height)
123         {
124             ClipState clipState = DetermineClipState(polygon, width, height);
125             if (clipState == ClipState.Within)
126             {
127                 gp.AddPolygon(polygon);
128             }
129             else if (clipState == ClipState.Intersecting)
130             {
131                 PointF[] clippedPolygon = clipPolygon(polygon, width, height);
132                 if (clippedPolygon.Length > 2)
133                     gp.AddPolygon(clippedPolygon);
134             }
135         }
复制代码

 

posted @   太一吾鱼水  阅读(1205)  评论(0)  编辑  收藏  举报
编辑推荐：
· 基于Microsoft.Extensions.AI核心库实现RAG应用
· Linux系列：如何用heaptrack跟踪.NET程序的非托管内存泄露
· 开发者必知的日志记录最佳实践
· SQL Server 2025 AI相关能力初探
· Linux系列：如何用 C#调用 C方法造成内存泄露
阅读排行：
· 震惊！C++程序真的从main开始吗？99%的程序员都答错了
· 【硬核科普】Trae如何「偷看」你的代码？零基础破解AI编程运行原理
· 单元测试从入门到精通
· 上周热点回顾（3.3-3.9）
· winform 绘制太阳，地球，月球 运作规律
历史上的今天：
2013-04-07 VS下Qt4.8.4安装
2012-04-07 手动添加数据源时DataGridViewComboBoxCell值出问题解决方法
点击右上角即可分享
微信分享提示
AI IDE Trae