Cache pan/zoom per topology

* remembers canvas position/zoom per topology
* makes it easy to go back to the last position in a prev topology

Fixes #1238

client/app/scripts/charts/nodes-chart.js

@@ -23,6 +23,8 @@ const MARGINS = {
   bottom: 0
 };
 
+const ZOOM_CACHE_FIELDS = ['scale', 'panTranslateX', 'panTranslateY'];
+
 // make sure circular layouts a bit denser with 3-6 nodes
 const radiusDensity = d3.scale.threshold()
   .domain([3, 6]).range([2.5, 3.5, 3]);
@@ -43,7 +45,8 @@ export default class NodesChart extends React.Component {
       panTranslateY: 0,
       scale: 1,
       selectedNodeScale: d3.scale.linear(),
-      hasZoomed: false
+      hasZoomed: false,
+      zoomCache: {}
     };
   }
 
@@ -58,13 +61,25 @@ export default class NodesChart extends React.Component {
 
     // wipe node states when showing different topology
     if (nextProps.topologyId !== this.props.topologyId) {
-      _.assign(state, {
+      // re-apply cached canvas zoom/pan to d3 behavior
+      const nextZoom = this.state.zoomCache[nextProps.topologyId];
+      if (nextZoom) {
+        this.zoom.scale(nextZoom.scale);
+        this.zoom.translate([nextZoom.panTranslateX, nextZoom.panTranslateY]);
+      }
+
+      // saving previous zoom state
+      const prevZoom = _.pick(this.state, ZOOM_CACHE_FIELDS);
+      const zoomCache = _.assign({}, this.state.zoomCache);
+      zoomCache[this.props.topologyId] = prevZoom;
+
+      // clear canvas and apply zoom state
+      _.assign(state, nextZoom, { zoomCache }, {
         nodes: makeMap(),
         edges: makeMap()
       });
     }
-    //
-    // FIXME add PureRenderMixin, Immutables, and move the following functions to render()
+
     // _.assign(state, this.updateGraphState(nextProps, state));
     if (nextProps.forceRelayout || nextProps.nodes !== this.props.nodes) {
       _.assign(state, this.updateGraphState(nextProps, state));

client/app/scripts/charts/nodes-layout.js

@@ -3,7 +3,7 @@ import debug from 'debug';
 import { fromJS, Map as makeMap, Set as ImmSet } from 'immutable';
 
 import { EDGE_ID_SEPARATOR } from '../constants/naming';
-import { updateNodeDegrees } from '../utils/topology-utils';
+import { buildTopologyCacheId, updateNodeDegrees } from '../utils/topology-utils';
 
 const log = debug('scope:nodes-layout');
 
@@ -25,17 +25,6 @@ function fromGraphNodeId(encodedId) {
   return encodedId.replace('<DOT>', '.');
 }
 
-function buildCacheIdFromOptions(options) {
-  if (options) {
-    let id = options.topologyId;
-    if (options.topologyOptions) {
-      id += JSON.stringify(options.topologyOptions);
-    }
-    return id;
-  }
-  return '';
-}
-
 /**
  * Layout engine runner
  * After the layout engine run nodes and edges have x-y-coordinates. Engine is
@@ -348,7 +337,7 @@ function copyLayoutProperties(layout, nodeCache, edgeCache) {
  */
 export function doLayout(immNodes, immEdges, opts) {
   const options = opts || {};
-  const cacheId = buildCacheIdFromOptions(options);
+  const cacheId = buildTopologyCacheId(options.topologyId, options.topologyOptions);
 
   // one engine and node and edge caches per topology, to keep renderings similar
   if (!topologyCaches[cacheId]) {

client/app/scripts/utils/__tests__/topology-utils-test.js

@@ -107,17 +107,27 @@ describe('TopologyUtils', () => {
     expect(nodes.n3.degree).toEqual(0);
   });
 
+  describe('buildTopologyCacheId', () => {
+    it('should generate a cache ID', () => {
+      const fun = TopologyUtils.buildTopologyCacheId;
+      expect(fun()).toEqual('');
+      expect(fun('test')).toEqual('test');
+      expect(fun(undefined, 'test')).toEqual('');
+      expect(fun('test', {a: 1})).toEqual('test{"a":1}');
+    });
+  });
+
   describe('filterHiddenTopologies', () => {
     it('should filter out empty topos that set hide_if_empty=true', () => {
       const topos = [
-        {id: 'a', hide_if_empty: true, stats: {node_count: 0, filtered_nodes:0}},
-        {id: 'b', hide_if_empty: true, stats: {node_count: 1, filtered_nodes:0}},
-        {id: 'c', hide_if_empty: true, stats: {node_count: 0, filtered_nodes:1}},
-        {id: 'd', hide_if_empty: false, stats: {node_count: 0, filtered_nodes:0}}
+        {id: 'a', hide_if_empty: true, stats: {node_count: 0, filtered_nodes: 0}},
+        {id: 'b', hide_if_empty: true, stats: {node_count: 1, filtered_nodes: 0}},
+        {id: 'c', hide_if_empty: true, stats: {node_count: 0, filtered_nodes: 1}},
+        {id: 'd', hide_if_empty: false, stats: {node_count: 0, filtered_nodes: 0}}
       ];
 
       const res = TopologyUtils.filterHiddenTopologies(topos);
       expect(res.map(t => t.id)).toEqual(['b', 'c', 'd']);
     });
-  })
+  });
 });

client/app/scripts/utils/topology-utils.js

@@ -1,5 +1,28 @@
 import _ from 'lodash';
 
+/**
+ * Returns a cache ID based on the topologyId and optionsQuery
+ * @param  {String} topologyId
+ * @param  {object} topologyOptions (optional)
+ * @return {String}
+ */
+export function buildTopologyCacheId(topologyId, topologyOptions) {
+  let id = '';
+  if (topologyId) {
+    id = topologyId;
+    if (topologyOptions) {
+      id += JSON.stringify(topologyOptions);
+    }
+  }
+  return id;
+}
+
+/**
+ * Returns a topology object from the topology tree
+ * @param  {List} subTree
+ * @param  {String} topologyId
+ * @return {Map} topology if found
+ */
 export function findTopologyById(subTree, topologyId) {
   let foundTopology;