brushable histogram brush selection responds to state updates (#670)

* add continuousSelection reducer and make histo respond to state changes

* correctly handle uninitialized state for brush move

* PR review tweaks

client/src/components/brushableHistogram/index.js

@@ -13,12 +13,13 @@ import memoize from "memoize-one";
 import * as globals from "../../globals";
 import actions from "../../actions";
 import finiteExtent from "../../util/finiteExtent";
+import { makeContinuousDimensionName } from "../../util/nameCreators";
 
 @connect(state => ({
   world: state.world,
   scatterplotXXaccessor: state.controls.scatterplotXXaccessor,
   scatterplotYYaccessor: state.controls.scatterplotYYaccessor,
-  crossfilter: state.crossfilter,
+  continuousSelection: state.continuousSelection,
   differential: state.differential,
   colorAccessor: state.colors.colorAccessor,
   obsAnnotations: _.get(state.world, "obsAnnotations", null)
@@ -86,12 +87,52 @@ class HistogramBrush extends React.Component {
   }
 
   componentDidUpdate(prevProps) {
-    const { field, obsAnnotations } = this.props;
+    const { field, obsAnnotations, continuousSelection } = this.props;
     const { x, y, bins, numValues, svgRef } = this._histogram;
 
     if (obsAnnotations !== prevProps.obsAnnotations) {
       this.renderAxesBrushBins(x, y, bins, numValues, svgRef, field);
     }
+
+    /*
+    if the selection has changed, ensure that the brush correctly reflects
+    the underlying selection.
+    */
+    if (continuousSelection !== prevProps.continuousSelection) {
+      const { isObs, isUserDefined, isDiffExp } = this.props;
+      const myName = makeContinuousDimensionName(
+        { isObs, isUserDefined, isDiffExp },
+        field
+      );
+      const range = continuousSelection[myName];
+      const { brushXselection, brushX } = this.state;
+      if (brushXselection) {
+        const selection = d3.brushSelection(brushXselection.node());
+        if (!range && selection) {
+          /* no active selection - clear brush */
+          brushXselection.call(brushX.move, null);
+        } else if (range && !selection) {
+          /* there is an active selection, but no brush - set the brush */
+          const x0 = x(range[0]);
+          const x1 = x(range[1]);
+          brushXselection.call(brushX.move, [x0, x1]);
+        } else if (range && selection) {
+          /* there is an active selection and a brush - make sure they match */
+          const moveDeltaThreshold = 1;
+          const x0 = x(range[0]);
+          const x1 = x(range[1]);
+          const dX0 = Math.abs(x0 - selection[0]);
+          const dX1 = Math.abs(x1 - selection[1]);
+          /*
+          only update the brush if it is grossly incorrect, 
+          as defined by the moveDeltaThreshold
+          */
+          if (dX0 > moveDeltaThreshold || dX1 > moveDeltaThreshold) {
+            brushXselection.call(brushX.move, [x0, x1]);
+          }
+        }
+      }
+    }
   }
 
   onBrush(selection, x, eventType) {
@@ -99,6 +140,9 @@ class HistogramBrush extends React.Component {
     return () => {
       const { dispatch, field, isObs, isUserDefined, isDiffExp } = this.props;
 
+      // ignore programmatically generated events
+      if (!d3.event.sourceEvent) return;
+
       if (d3.event.selection) {
         dispatch({
           type,
@@ -128,10 +172,13 @@ class HistogramBrush extends React.Component {
   onBrushEnd(selection, x) {
     return () => {
       const { dispatch, field, isObs, isUserDefined, isDiffExp } = this.props;
-      const { brushX } = this.state;
+      const { brushXselection } = this.state;
       const minAllowedBrushSize = 10;
       const smallAmountToAvoidInfiniteLoop = 0.1;
 
+      // ignore programmatically generated events
+      if (!d3.event.sourceEvent) return;
+
       if (d3.event.selection) {
         let _range;
 
@@ -151,7 +198,7 @@ class HistogramBrush extends React.Component {
 
           _range = [x(d3.event.selection[0]), x(procedurallyResizedBrushWidth)];
 
-          d3.event.target.move(brushX, [
+          d3.event.target.move(brushXselection, [
             d3.event.selection[0],
             procedurallyResizedBrushWidth
           ]);
@@ -283,21 +330,20 @@ class HistogramBrush extends React.Component {
 
     /* BRUSH */
     const brushX = d3
+      .brushX()
+      /*
+      emit start so that the Undoable history can save an undo point
+      upon drag start, and ignore the subsequent intermediate drag events.
+      */
+      .on("start", this.onBrush(field, x.invert, "start").bind(this))
+      .on("brush", this.onBrush(field, x.invert, "brush").bind(this))
+      .on("end", this.onBrushEnd(field, x.invert).bind(this));
+    const brushXselection = d3
       .select(svgRef)
       .append("g")
       .attr("class", "brush")
       .attr("data-testid", `${svgRef.id}-brush`)
-      .call(
+      .call(brushX);
-        d3
-          .brushX()
-          /*
-          emit start so that the Undoable history can save an undo point
-          upon drag start, and ignore the subsequent intermediate drag events.
-          */
-          .on("start", this.onBrush(field, x.invert, "start").bind(this))
-          .on("brush", this.onBrush(field, x.invert, "brush").bind(this))
-          .on("end", this.onBrushEnd(field, x.invert).bind(this))
-      );
 
     /* AXIS */
     d3.select(svgRef)
@@ -318,7 +364,7 @@ class HistogramBrush extends React.Component {
       .selectAll(".axis--x line")
       .style("stroke", "rgb(230,230,230)");
 
-    this.setState({ brushX });
+    this.setState({ brushX, brushXselection });
   }
 
   render() {

client/src/reducers/continuousSelection.js

@@ -0,0 +1,26 @@
+import { makeContinuousDimensionName } from "../util/nameCreators";
+
+const ContinuousSelection = (state = {}, action) => {
+  switch (action.type) {
+    case "reset World to eq Universe": {
+      return {};
+    }
+    case "continuous metadata histogram start":
+    case "continuous metadata histogram brush":
+    case "continuous metadata histogram end": {
+      const name = makeContinuousDimensionName(
+        action.continuousNamespace,
+        action.selection
+      );
+      return {
+        ...state,
+        [name]: action.range
+      };
+    }
+    default: {
+      return state;
+    }
+  }
+};
+
+export default ContinuousSelection;

client/src/reducers/index.js

@@ -7,6 +7,7 @@ import config from "./config";
 import universe from "./universe";
 import world from "./world";
 import categoricalSelection from "./categoricalSelection";
+import continuousSelection from "./continuousSelection";
 import crossfilter from "./crossfilter";
 import colors from "./colors";
 import differential from "./differential";
@@ -63,6 +64,7 @@ const Reducer = undoable(
     ["universe", universe],
     ["world", world],
     ["categoricalSelection", categoricalSelection],
+    ["continuousSelection", continuousSelection],
     ["crossfilter", crossfilter],
     ["colors", colors],
     ["controls", controls],
@@ -73,6 +75,7 @@ const Reducer = undoable(
   [
     "world",
     "categoricalSelection",
+    "continuousSelection",
     "crossfilter",
     "colors",
     "controls",