From: Mathieu Baudier <mbaudier@argeo.org>
Date: Tue, 17 May 2022 11:55:52 +0000 (+0200)
Subject: Generate SVG from a polygon.
X-Git-Tag: v2.3.8~103
X-Git-Url: https://git.argeo.org/?p=gpl%2Fargeo-suite.git;a=commitdiff_plain;h=0d802e48f2cafd249149f9b322fd11f96a83a947

Generate SVG from a polygon.
---

diff --git a/org.argeo.app.core/src/org/argeo/app/geo/GeoUtils.java b/org.argeo.app.core/src/org/argeo/app/geo/GeoUtils.java
index 8da7c4e..1b9ce72 100644
--- a/org.argeo.app.core/src/org/argeo/app/geo/GeoUtils.java
+++ b/org.argeo.app.core/src/org/argeo/app/geo/GeoUtils.java
@@ -1,11 +1,19 @@
 package org.argeo.app.geo;
 
+import java.io.IOException;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.List;
+
 import javax.measure.Quantity;
 import javax.measure.quantity.Area;
 
+import org.geotools.data.simple.SimpleFeatureCollection;
+import org.geotools.data.simple.SimpleFeatureIterator;
 import org.geotools.geometry.jts.JTS;
 import org.geotools.referencing.CRS;
 import org.geotools.referencing.crs.DefaultGeographicCRS;
+import org.locationtech.jts.geom.Coordinate;
 import org.locationtech.jts.geom.Point;
 import org.locationtech.jts.geom.Polygon;
 import org.opengis.feature.simple.SimpleFeature;
@@ -38,6 +46,63 @@ public class GeoUtils {
 		}
 	}
 
+	public static void exportToSvg(SimpleFeatureCollection features, Writer out, int width, int height) {
+		try {
+			double minY = Double.POSITIVE_INFINITY;
+			double maxY = Double.NEGATIVE_INFINITY;
+			double minX = Double.POSITIVE_INFINITY;
+			double maxX = Double.NEGATIVE_INFINITY;
+			List<String> shapes = new ArrayList<>();
+			for (SimpleFeatureIterator it = features.features(); it.hasNext();) {
+				SimpleFeature feature = it.next();
+				StringBuffer sb = new StringBuffer();
+				sb.append("<polyline style=\"stroke-width:1;stroke:#000000;fill:none;\" points=\"");
+
+				Polygon p = (Polygon) feature.getDefaultGeometry();
+				Point centroid = p.getCentroid();
+				String code = "AUTO:42001," + centroid.getX() + "," + centroid.getY();
+				CoordinateReferenceSystem auto = CRS.decode(code);
+
+				MathTransform transform = CRS.findMathTransform(DefaultGeographicCRS.WGS84, auto);
+
+				Polygon projed = (Polygon) JTS.transform(p, transform);
+
+				for (Coordinate coord : projed.getCoordinates()) {
+					double x = coord.x;
+					if (x < minX)
+						minX = x;
+					if (x > maxX)
+						maxX = x;
+					double y = -coord.y;
+					if (y < minY)
+						minY = y;
+					if (y > maxY)
+						maxY = y;
+					sb.append(x + "," + y + " ");
+				}
+				sb.append("\">");
+				sb.append("</polyline>\n");
+				shapes.add(sb.toString());
+
+			}
+			double viewportHeight = maxY - minY;
+			double viewportWidth = maxX - minX;
+			out.write("<svg xmlns=\"http://www.w3.org/2000/svg\"\n");
+			out.write(" width=\"" + width + "\"\n");
+			out.write(" height=\"" + height + "\"\n");
+			out.write(" viewBox=\"" + minX + " " + minY + " " + viewportWidth + " " + viewportHeight + "\"\n");
+			out.write(" preserveAspectRatio=\"xMidYMid meet\"\n");
+			out.write(">\n");
+			for (String shape : shapes) {
+				out.write(shape);
+				out.write("\n");
+			}
+			out.write("</svg>");
+		} catch (IOException | FactoryException | MismatchedDimensionException | TransformException e) {
+			throw new RuntimeException("Cannot export to SVG", e);
+		}
+	}
+
 	/** Singleton. */
 	private GeoUtils() {
 	}