environment/org.argeo.geo.ui/src/org/argeo/geo/GeoToSvg.java

   1 package org.argeo.geo;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5 import java.io.Writer;
   6 import java.nio.charset.StandardCharsets;
   7 import java.nio.file.Files;
   8 import java.nio.file.Path;
   9 import java.util.ArrayList;
  10 import java.util.List;
  11
  12 import com.fasterxml.jackson.databind.JsonNode;
  13 import com.fasterxml.jackson.databind.ObjectMapper;
  14
  15 /** Converts a geographical feature to an SVG. */
  16 public class GeoToSvg {
  17         public void convertGeoJsonToSvg(Path source, Path target) {
  18                 ObjectMapper objectMapper = new ObjectMapper();
  19                 try (InputStream in = Files.newInputStream(source);
  20                                 Writer out = Files.newBufferedWriter(target, StandardCharsets.UTF_8)) {
  21                         JsonNode tree = objectMapper.readTree(in);
  22                         JsonNode coord = tree.get("features").get(0).get("geometry").get("coordinates");
  23                         double ratio = 100;
  24                         double minX = Double.POSITIVE_INFINITY;
  25                         double maxX = Double.NEGATIVE_INFINITY;
  26                         double minY = Double.POSITIVE_INFINITY;
  27                         double maxY = Double.NEGATIVE_INFINITY;
  28                         List<String> shapes = new ArrayList<>();
  29                         for (JsonNode shape : coord) {
  30                                 StringBuffer sb = new StringBuffer();
  31                                 sb.append("<polyline style=\"stroke-width:0.00000003;stroke:#000000;\" points=\"");
  32                                 for (JsonNode latlng : shape) {
  33                                         double lat = latlng.get(0).asDouble();
  34                                         double y = lat * ratio;
  35                                         if (y < minY)
  36                                                 minY = y;
  37                                         if (y > maxY)
  38                                                 maxY = y;
  39                                         double lng = latlng.get(1).asDouble();
  40                                         double x = lng * ratio;
  41                                         if (x < minX)
  42                                                 minX = x;
  43                                         if (x > maxX)
  44                                                 maxX = x;
  45                                         sb.append(y + "," + x + " ");
  46                                 }
  47                                 sb.append("\">");
  48                                 sb.append("</polyline>\n");
  49                                 shapes.add(sb.toString());
  50                         }
  51
  52                         double width = maxX - minX;
  53                         double height = maxY - minY;
  54                         out.write("<svg xmlns=\"http://www.w3.org/2000/svg\"\n");
  55                         out.write(" width=\"" + (int) (width * 1000) + "\"\n");
  56                         out.write(" height=\"" + (int) (height * 1000) + "\"\n");
  57                         out.write(" viewBox=\"" + minX + "," + minY + "," + width + "," + height + "\"\n");
  58                         out.write(">\n");
  59                         for (String shape : shapes) {
  60                                 out.write(shape);
  61                                 out.write("\n");
  62                         }
  63                         out.write("</svg>");
  64                 } catch (IOException e) {
  65                         throw new RuntimeException("Cannot convert " + source + " to " + target, e);
  66                 }
  67         }
  68
  69 }