[APM] Service Map - Separate overlapping edges by rotating nodes (#60477

)

* Adds rotation transform which does the top->bottom to left->right
transformation + an extra 5 degrees which results in taxi edges
separating when rendered.

* PR feedback to reduce edge width on hover, and assure that connected
edges are highlighted when node is selected/focused

* update disabled kuery bar placeholder text for service map

x-pack/legacy/plugins/apm/public/components/app/ServiceMap/Cytoscape.tsx

@@ -57,6 +57,20 @@ function useCytoscape(options: cytoscape.CytoscapeOptions) {
   return [ref, cy] as [React.MutableRefObject<any>, cytoscape.Core | undefined];
 }
 
+function rotatePoint(
+  { x, y }: { x: number; y: number },
+  degreesRotated: number
+) {
+  const radiansPerDegree = Math.PI / 180;
+  const θ = radiansPerDegree * degreesRotated;
+  const cosθ = Math.cos(θ);
+  const sinθ = Math.sin(θ);
+  return {
+    x: x * cosθ - y * sinθ,
+    y: x * sinθ + y * cosθ
+  };
+}
+
 function getLayoutOptions(
   selectedRoots: string[],
   height: number,
@@ -71,10 +85,11 @@ function getLayoutOptions(
     animate: true,
     animationEasing: animationOptions.easing,
     animationDuration: animationOptions.duration,
-    // Rotate nodes from top -> bottom to display left -> right
     // @ts-ignore
-    transform: (node: any, { x, y }: cytoscape.Position) => ({ x: y, y: -x }),
-    // swap width/height of boundingBox to compensation for the rotation
+    // Rotate nodes counter-clockwise to transform layout from top→bottom to left→right.
+    // The extra 5° achieves the effect of separating overlapping taxi-styled edges.
+    transform: (node: any, pos: cytoscape.Position) => rotatePoint(pos, -95),
+    // swap width/height of boundingBox to compensate for the rotation
     boundingBox: { x1: 0, y1: 0, w: height, h: width }
   };
 }
@@ -109,20 +124,31 @@ export function Cytoscape({
   // is required and can trigger rendering when changed.
   const divStyle = { ...style, height };
 
-  const dataHandler = useCallback<cytoscape.EventHandler>(
-    event => {
+  const resetConnectedEdgeStyle = useCallback(
+    (node?: cytoscape.NodeSingular) => {
       if (cy) {
         cy.edges().removeClass('highlight');
 
-        if (serviceName) {
-          const focusedNode = cy.getElementById(serviceName);
-          focusedNode.connectedEdges().addClass('highlight');
+        if (node) {
+          node.connectedEdges().addClass('highlight');
         }
+      }
+    },
+    [cy]
+  );
 
-        // Add the "primary" class to the node if its id matches the serviceName.
-        if (cy.nodes().length > 0 && serviceName) {
-          cy.nodes().removeClass('primary');
-          cy.getElementById(serviceName).addClass('primary');
+  const dataHandler = useCallback<cytoscape.EventHandler>(
+    event => {
+      if (cy) {
+        if (serviceName) {
+          resetConnectedEdgeStyle(cy.getElementById(serviceName));
+          // Add the "primary" class to the node if its id matches the serviceName.
+          if (cy.nodes().length > 0) {
+            cy.nodes().removeClass('primary');
+            cy.getElementById(serviceName).addClass('primary');
+          }
+        } else {
+          resetConnectedEdgeStyle();
         }
         if (event.cy.elements().length > 0) {
           const selectedRoots = selectRoots(event.cy);
@@ -141,7 +167,7 @@ export function Cytoscape({
         }
       }
     },
-    [cy, serviceName, height, width]
+    [cy, resetConnectedEdgeStyle, serviceName, height, width]
   );
 
   // Trigger a custom "data" event when data changes
@@ -162,12 +188,20 @@ export function Cytoscape({
       event.target.removeClass('hover');
       event.target.connectedEdges().removeClass('nodeHover');
     };
+    const selectHandler: cytoscape.EventHandler = event => {
+      resetConnectedEdgeStyle(event.target);
+    };
+    const unselectHandler: cytoscape.EventHandler = event => {
+      resetConnectedEdgeStyle();
+    };
 
     if (cy) {
       cy.on('data', dataHandler);
       cy.ready(dataHandler);
       cy.on('mouseover', 'edge, node', mouseoverHandler);
       cy.on('mouseout', 'edge, node', mouseoutHandler);
+      cy.on('select', 'node', selectHandler);
+      cy.on('unselect', 'node', unselectHandler);
     }
 
     return () => {
@@ -181,7 +215,7 @@ export function Cytoscape({
         cy.removeListener('mouseout', 'edge, node', mouseoutHandler);
       }
     };
-  }, [cy, dataHandler, serviceName]);
+  }, [cy, dataHandler, resetConnectedEdgeStyle, serviceName]);
 
   return (
     <CytoscapeContext.Provider value={cy}>

x-pack/legacy/plugins/apm/public/components/app/ServiceMap/cytoscapeOptions.ts

@@ -121,15 +121,18 @@ const style: cytoscape.Stylesheet[] = [
   {
     selector: 'edge.nodeHover',
     style: {
-      width: 4,
+      width: 2,
       // @ts-ignore
-      'z-index': zIndexEdgeHover
+      'z-index': zIndexEdgeHover,
+      'line-color': theme.euiColorDarkShade,
+      'source-arrow-color': theme.euiColorDarkShade,
+      'target-arrow-color': theme.euiColorDarkShade
     }
   },
   {
     selector: 'node.hover',
     style: {
-      'border-width': 4
+      'border-width': 2
     }
   },
   {

x-pack/legacy/plugins/apm/public/components/shared/KueryBar/index.tsx

@@ -79,7 +79,7 @@ export function KueryBar() {
   const disabled = /\/service-map$/.test(location.pathname);
   const disabledPlaceholder = i18n.translate(
     'xpack.apm.kueryBar.disabledPlaceholder',
-    { defaultMessage: 'Search is not available for service maps' }
+    { defaultMessage: 'Search is not available for service map' }
   );
 
   async function onChange(inputValue: string, selectionStart: number) {