add implementation/realization edge type, fix arrow heads to be hollow

packages/mermaid/src/dagre-wrapper/edges.js

@@ -469,6 +469,7 @@ export const insertEdge = function (elem, e, edge, clusterDb, diagramType, graph
     default:
       strokeClasses = '';
   }
+
   switch (edge.pattern) {
     case 'solid':
       strokeClasses += ' edge-pattern-solid';
@@ -533,6 +534,9 @@ export const insertEdge = function (elem, e, edge, clusterDb, diagramType, graph
     case 'extension':
       svgPath.attr('marker-start', 'url(' + url + '#' + diagramType + '-extensionStart' + ')');
       break;
+    case 'realization':
+      svgPath.attr('marker-start', 'url(' + url + '#' + diagramType + '-realizationStart' + ')');
+      break;
     case 'composition':
       svgPath.attr('marker-start', 'url(' + url + '#' + diagramType + '-compositionStart' + ')');
       break;
@@ -563,6 +567,9 @@ export const insertEdge = function (elem, e, edge, clusterDb, diagramType, graph
     case 'extension':
       svgPath.attr('marker-end', 'url(' + url + '#' + diagramType + '-extensionEnd' + ')');
       break;
+    case 'realization':
+      svgPath.attr('marker-end', 'url(' + url + '#' + diagramType + '-realizationEnd' + ')');
+      break;
     case 'composition':
       svgPath.attr('marker-end', 'url(' + url + '#' + diagramType + '-compositionEnd' + ')');
       break;

packages/mermaid/src/dagre-wrapper/markers.js

@@ -2,6 +2,43 @@
 
 import { log } from '../logger.js';
 
+const getSvgParent = (elem) => {
+  let container = elem;
+
+  // the intent here is to find the first parent element that is NOT part of the SVG element
+  // I know there has to be a better way, but could not find one that worked
+  // tried using checking if elem was instanceof SVGGraphicsElement or SVGElement, but it failed to detect correctly
+  if (container._groups) {
+    container = container._groups[0][0];
+  }
+  if (container.tagName.toLowerCase() === 'g') {
+    container = container.parentElement;
+  }
+  if (container.localName.toLowerCase() === 'svg') {
+    container = container.parentElement;
+  }
+  return container;
+};
+
+const getBackgroundColor = (elem) => {
+  let parent = getSvgParent(elem);
+
+  let backgroundColor;
+  while (parent && parent.tagName.toLowerCase() !== 'body') {
+    if(parent instanceof Element) {
+      const computedStyle = getComputedStyle(parent);
+      backgroundColor = computedStyle.backgroundColor;
+
+      if (backgroundColor !== 'rgba(0, 0, 0, 0)') {
+        break;
+      }
+      parent = parent.parentNode;
+    }
+  }
+
+  return backgroundColor === 'rgba(0, 0, 0, 0)' ? 'white' : backgroundColor;
+};
+
 // Only add the number of markers that the diagram needs
 const insertMarkers = (elem, markerArray, type, id) => {
   markerArray.forEach((markerName) => {
@@ -11,6 +48,8 @@ const insertMarkers = (elem, markerArray, type, id) => {
 
 const extension = (elem, type, id) => {
   log.trace('Making markers for ', id);
+  let backgroundColor = getBackgroundColor(elem);
+
   elem
     .append('defs')
     .append('marker')
@@ -22,7 +61,8 @@ const extension = (elem, type, id) => {
     .attr('markerHeight', 240)
     .attr('orient', 'auto')
     .append('path')
-    .attr('d', 'M 1,7 L18,13 V 1 Z');
+    .attr('d', 'M 1,7 L18,13 V 2 Z')
+    .attr('fill', backgroundColor);
 
   elem
     .append('defs')
@@ -35,7 +75,41 @@ const extension = (elem, type, id) => {
     .attr('markerHeight', 28)
     .attr('orient', 'auto')
     .append('path')
-    .attr('d', 'M 1,1 V 13 L18,7 Z'); // this is actual shape for arrowhead
+    .attr('d', 'M 1,1 V 13 L18,7 Z')
+    .attr('fill', backgroundColor); // this is actual shape for arrowhead
+};
+
+const realization = (elem, type, id) => {
+  log.trace('Making markers for ', id);
+  let backgroundColor = getBackgroundColor(elem);
+
+  elem
+    .append('defs')
+    .append('marker')
+    .attr('id', type + '-realizationStart')
+    .attr('class', 'marker realization ' + type)
+    .attr('refX', 0)
+    .attr('refY', 7)
+    .attr('markerWidth', 190)
+    .attr('markerHeight', 240)
+    .attr('orient', 'auto')
+    .append('path')
+    .attr('d', 'M 1,7 L18,13 V 2 Z')
+    .attr('fill', backgroundColor);
+
+  elem
+    .append('defs')
+    .append('marker')
+    .attr('id', type + '-realizationEnd')
+    .attr('class', 'marker realization ' + type)
+    .attr('refX', 19)
+    .attr('refY', 7)
+    .attr('markerWidth', 20)
+    .attr('markerHeight', 28)
+    .attr('orient', 'auto')
+    .append('path')
+    .attr('d', 'M 1,1 V 13 L18,7 Z')
+    .attr('fill', backgroundColor); // this is actual shape for arrowhead
 };
 
 const composition = (elem, type) => {
@@ -265,6 +339,7 @@ const barb = (elem, type) => {
 // TODO rename the class diagram markers to something shape descriptive and semantic free
 const markers = {
   extension,
+  realization,
   composition,
   aggregation,
   dependency,

packages/mermaid/src/diagrams/class/classDb.ts

@@ -362,6 +362,7 @@ export const relationType = {
   COMPOSITION: 2,
   DEPENDENCY: 3,
   LOLLIPOP: 4,
+  REALIZATION: 5,
 };
 
 const setupToolTips = function (element: Element) {

packages/mermaid/src/diagrams/class/classRenderer-v2.ts

@@ -361,7 +361,7 @@ export const draw = async function (text: string, id: string, _version: string,
   await render(
     element,
     g,
-    ['aggregation', 'extension', 'composition', 'dependency', 'lollipop'],
+    ['aggregation', 'extension', 'realization', 'composition', 'dependency', 'lollipop'],
     'classDiagram',
     id
   );
@@ -413,6 +413,9 @@ function getArrowMarker(type: number) {
     case 4:
       marker = 'lollipop';
       break;
+    case 5:
+      marker = 'realization';
+      break;
     default:
       marker = 'none';
   }

packages/mermaid/src/diagrams/class/parser/classDiagram.jison

@@ -124,7 +124,7 @@ Function arguments are optional: 'call <callback_name>()' simply executes 'callb
 <*>"_top"               return 'LINK_TARGET';
 
 <*>\s*\<\|              return 'EXTENSION';
-<*>\s*\|\>              return 'EXTENSION';
+<*>\s*\|\>              return 'REALIZATION';
 <*>\s*\>                return 'DEPENDENCY';
 <*>\s*\<                return 'DEPENDENCY';
 <*>\s*\*                return 'COMPOSITION';
@@ -370,6 +370,7 @@ relation
 relationType
     : AGGREGATION { $$=yy.relationType.AGGREGATION;}
     | EXTENSION   { $$=yy.relationType.EXTENSION;}
+    | REALIZATION { $$=yy.relationType.REALIZATION;}
     | COMPOSITION { $$=yy.relationType.COMPOSITION;}
     | DEPENDENCY  { $$=yy.relationType.DEPENDENCY;}
     | LOLLIPOP    { $$=yy.relationType.LOLLIPOP;}

packages/mermaid/src/diagrams/class/svgDraw.js

@@ -9,6 +9,8 @@ export const drawEdge = function (elem, path, relation, conf, diagObj) {
     switch (type) {
       case diagObj.db.relationType.AGGREGATION:
         return 'aggregation';
+      case diagObj.db.relationType.REALIZATION:
+        return 'realization';
       case diagObj.db.relationType.EXTENSION:
         return 'extension';
       case diagObj.db.relationType.COMPOSITION: