Add interactive functionality for Usecase diagrams exported to SVG

src/net/sourceforge/plantuml/graphic/UGraphicDelegator.java

@@ -86,6 +86,10 @@ public abstract class UGraphicDelegator implements UGraphic {
 		ug.startGroup(groupId);
 	}
 
+	public void startGroupWithClass(String groupClasses) {
+		ug.startGroupWithClass(groupClasses);
+	}
+
 	public void closeGroup() {
 		ug.closeGroup();
 	}

src/net/sourceforge/plantuml/svek/Line.java

@@ -624,6 +624,7 @@ public class Line implements Moveable, Hideable, GuideLine {
 			return;
 		}
 		ug.draw(link.commentForSvg());
+		ug.startGroupWithClass("link " + link.getEntity1().getCode() + " " + link.getEntity2().getCode() + " selected");
 		double x = 0;
 		double y = 0;
 		final Url url = link.getUrl();
@@ -750,6 +751,8 @@ public class Line implements Moveable, Hideable, GuideLine {
 			link.getLinkConstraint().setPosition(link, minPt);
 			link.getLinkConstraint().drawMe(ug, skinParam);
 		}
+
+		ug.closeGroup();
 	}
 
 	private List<Point2D> getSquare(double x, double y) {

src/net/sourceforge/plantuml/svek/image/EntityImageDescription.java

@@ -294,6 +294,8 @@ public class EntityImageDescription extends AbstractEntityImage {
 
 	final public void drawU(UGraphic ug) {
 		ug.draw(new UComment("entity " + getEntity().getCodeGetName()));
+		ug.startGroupWithClass("elem " + getEntity().getCode() + " selected");
+
 		if (url != null) {
 			ug.startUrl(url);
 		}
@@ -320,6 +322,8 @@ public class EntityImageDescription extends AbstractEntityImage {
 		if (url != null) {
 			ug.closeUrl();
 		}
+
+		ug.closeGroup();
 	}
 
 	private void drawHexagon(UGraphic ug) {

src/net/sourceforge/plantuml/svek/image/EntityImageNote.java

@@ -201,6 +201,9 @@ public class EntityImageNote extends AbstractEntityImage implements Stencil {
 
 	final public void drawU(UGraphic ug) {
 		final Url url = getEntity().getUrl99();
+
+		ug.startGroupWithClass("elem " + getEntity().getCode() + " selected");
+
 		if (url != null) {
 			ug.startUrl(url);
 		}
@@ -236,6 +239,8 @@ public class EntityImageNote extends AbstractEntityImage implements Stencil {
 		if (url != null) {
 			ug.closeUrl();
 		}
+
+		ug.closeGroup();
 	}
 
 	private double getRoundCorner() {

src/net/sourceforge/plantuml/svek/image/EntityImageUseCase.java

@@ -5,12 +5,12 @@
  * (C) Copyright 2009-2020, Arnaud Roques
  *
  * Project Info:  http://plantuml.com
- * 
+ *
  * If you like this project or if you find it useful, you can support us at:
- * 
+ *
  * http://plantuml.com/patreon (only 1$ per month!)
  * http://plantuml.com/paypal
- * 
+ *
  * This file is part of PlantUML.
  *
  * PlantUML is free software; you can redistribute it and/or modify it
@@ -30,7 +30,7 @@
  *
  *
  * Original Author:  Arnaud Roques
- * 
+ *
  *
  */
 package net.sourceforge.plantuml.svek.image;
@@ -143,7 +143,10 @@ public class EntityImageUseCase extends AbstractEntityImage {
 		ug = ug.apply(backcolor.bg());
 		final UGraphic ug2 = new MyUGraphicEllipse(ug, 0, 0, ellipse.getUEllipse());
 
+		ug2.startGroupWithClass("elem " + getEntity().getCode() + " selected");
 		ellipse.drawU(ug2);
+		ug2.closeGroup();
+
 		if (getEntity().getLeafType() == LeafType.USECASE_BUSINESS) {
 			specialBusiness(ug, ellipse.getUEllipse());
 		}

src/net/sourceforge/plantuml/svg/SvgGraphics.java

@@ -158,12 +158,141 @@ public class SvgGraphics {
 			if (hover != null) {
 				defs.appendChild(getPathHover(hover));
 			}
+
+			// Add styles and script for interactive SVG
+			defs.appendChild(getStylesForInteractiveMode());
+			defs.appendChild(getScriptForInteractiveMode());
 		} catch (ParserConfigurationException e) {
 			e.printStackTrace();
 			throw new IllegalStateException(e);
 		}
 	}
 
+	private Element getStylesForInteractiveMode() {
+		final Element style = simpleElement("style");
+		final CDATASection cdata = document.createCDATASection(
+			".elem {cursor: pointer;} " + "\n" +
+			".elem, .link {opacity: 0.3;}" + "\n" +
+			".elem.selected, .link.selected {opacity: 1;}"
+		);
+		style.setAttribute("type", "text/css");
+		style.appendChild(cdata);
+		return style;
+	}
+
+	private Element getScriptForInteractiveMode() {
+		final Element script = document.createElement("script");
+		script.setTextContent(
+			"function addItemToMapOfLists(mapOfLists, name, item) {" + "\n" +
+            "  // mapOfLists = {" + "\n" +
+            "  //   'key1': [item1, item2, ...]," + "\n" +
+            "  //   'key2': [item3, item4, ...]," + "\n" +
+            "  // }" + "\n" +
+            "  if (mapOfLists[name].length > 0) {" + "\n" +
+            "    if (!mapOfLists[name].includes(item)) {" + "\n" +
+            "      mapOfLists[name].push(item);" + "\n" +
+            "    }" + "\n" +
+            "  } else {" + "\n" +
+            "    mapOfLists[name] = [item];" + "\n" +
+            "  }" + "\n" +
+            "}" + "\n" +
+			"" + "\n" +
+            "function main() {" + "\n" +
+            "  let elems = Array.from(document.getElementsByClassName('elem'));" + "\n" +
+            "  let links = Array.from(document.getElementsByClassName('link'));" + "\n" +
+			"" + "\n" +
+            "  let elemsMap = {};" + "\n" +
+            "  let linkedElems = {};" + "\n" +
+            "  let linkedLinks = {};" + "\n" +
+			"" + "\n" +
+            "  elems.forEach(elem => {" + "\n" +
+            "    let name = elem.classList[1];" + "\n" +
+            "    elemsMap[name] = elem;" + "\n" +
+            "    linkedElems[name] = [];" + "\n" +
+            "    linkedLinks[name] = [];" + "\n" +
+            "  });" + "\n" +
+			"" + "\n" +
+            "  links.forEach(link => {" + "\n" +
+            "    let name1 = link.classList[1];" + "\n" +
+            "    let name2 = link.classList[2];" + "\n" +
+			"" + "\n" +
+            "    let elem1 = elemsMap[name1];" + "\n" +
+            "    let elem2 = elemsMap[name2];" + "\n" +
+			"" + "\n" +
+            "    addItemToMapOfLists(linkedElems, name1, elem2);" + "\n" +
+            "    addItemToMapOfLists(linkedElems, name2, elem1);" + "\n" +
+			"" + "\n" +
+            "    addItemToMapOfLists(linkedLinks, name1, link);" + "\n" +
+            "    addItemToMapOfLists(linkedLinks, name2, link);" + "\n" +
+            "  });" + "\n" +
+			"" + "\n" +
+            "  let selectedElems = [];" + "\n" +
+            "  let selectedLinks = [];" + "\n" +
+            "  let selectedElemName = null;" + "\n" +
+			"" + "\n" +
+            "  function clearSelected() {" + "\n" +
+            "    selectedElems.forEach(item => {" + "\n" +
+            "      item.classList.remove('selected');" + "\n" +
+            "    });" + "\n" +
+            "    selectedElems = [];" + "\n" +
+			"" + "\n" +
+            "    selectedLinks.forEach(item => {" + "\n" +
+            "      item.classList.remove('selected');" + "\n" +
+            "    });" + "\n" +
+            "    selectedLinks = [];" + "\n" +
+            "  }" + "\n" +
+			"" + "\n" +
+            "  function selectAll() {" + "\n" +
+            "    selectedElemName = null;" + "\n" +
+			"" + "\n" +
+            "    selectedElems = Array.from(elems);" + "\n" +
+            "    selectedElems.forEach(item => {" + "\n" +
+            "      item.classList.add('selected');" + "\n" +
+            "    });" + "\n" +
+			"" + "\n" +
+            "    selectedLinks = Array.from(links);" + "\n" +
+            "    selectedLinks.forEach(item => {" + "\n" +
+            "      item.classList.add('selected');" + "\n" +
+            "    });" + "\n" +
+            "  }" + "\n" +
+			"" + "\n" +
+            "  function selectElem(elemName) {" + "\n" +
+            "    if (elemName === selectedElemName) {" + "\n" +
+            "      selectAll();" + "\n" +
+			"" + "\n" +
+            "    } else {" + "\n" +
+            "      clearSelected();" + "\n" +
+            "      selectedElemName = elemName;" + "\n" +
+			"" + "\n" +
+            "      elemsMap[elemName].classList.add('selected');" + "\n" +
+            "      selectedElems.push(elemsMap[elemName]);" + "\n" +
+			"" + "\n" +
+            "      linkedElems[elemName].forEach(linkedElem => {" + "\n" +
+            "        selectedElems.push(linkedElem);" + "\n" +
+            "        linkedElem.classList.add('selected');" + "\n" +
+            "      });" + "\n" +
+			"" + "\n" +
+            "      linkedLinks[elemName].forEach(linkedLink => {" + "\n" +
+            "        selectedLinks.push(linkedLink);" + "\n" +
+            "        linkedLink.classList.add('selected');" + "\n" +
+            "      });" + "\n" +
+            "    }" + "\n" +
+            "  }" + "\n" +
+			"" + "\n" +
+            "  Object.keys(elemsMap).forEach(name => {" + "\n" +
+            "    elemsMap[name].onclick = () => { selectElem(name); };" + "\n" +
+            "  });" + "\n" +
+			"" + "\n" +
+            "  selectAll();" + "\n" +
+            "}" + "\n" +
+			"" + "\n" +
+            "document.addEventListener('DOMContentLoaded', (event) => {" + "\n" +
+            "  main();" + "\n" +
+            "});"
+		);
+		return script;
+	}
+
 	private Element getPathHover(String hover) {
 		final Element style = simpleElement("style");
 		final CDATASection cdata = document.createCDATASection("path:hover { stroke: " + hover + " !important;}");
@@ -932,6 +1061,11 @@ public class SvgGraphics {
 		pendingAction.get(0).setAttribute("id", groupId);
 	}
 
+	public void startGroupWithClass(String groupClasses) {
+		pendingAction.add(0, (Element) document.createElement("g"));
+		pendingAction.get(0).setAttribute("class", groupClasses);
+	}
+
 	public void closeGroup() {
 		closeLink();
 	}

src/net/sourceforge/plantuml/ugraphic/AbstractCommonUGraphic.java

@@ -173,6 +173,9 @@ public abstract class AbstractCommonUGraphic implements UGraphic {
 	public void startGroup(String groupId) {
 	}
 
+	public void startGroupWithClass(String groupClasses) {
+	}
+
 	public void closeGroup() {
 	}
 

src/net/sourceforge/plantuml/ugraphic/UGraphic.java

@@ -57,6 +57,8 @@ public interface UGraphic {
 
 	public void startGroup(String id);
 
+	public void startGroupWithClass(String groupClasses);
+
 	public void closeGroup();
 
 	public void flushUg();

src/net/sourceforge/plantuml/ugraphic/UGraphicNo.java

@@ -45,6 +45,9 @@ public abstract class UGraphicNo {
 	final public void startGroup(String groupId) {
 	}
 
+	final public void startGroupWithClass(String groupClasses) {
+	}
+
 	final public void closeUrl() {
 	}
 

src/net/sourceforge/plantuml/ugraphic/svg/UGraphicSvg.java

@@ -178,7 +178,11 @@ public class UGraphicSvg extends AbstractUGraphic<SvgGraphics> implements ClipCo
 	@Override
 	public void startGroup(String groupId) {
 		getGraphicObject().startGroup(groupId);
+	}
 
+	@Override
+	public void startGroupWithClass(String groupClasses) {
+		getGraphicObject().startGroupWithClass(groupClasses);
 	}
 
 	@Override