Merge pull request #3915 from plotly/fix2950-parcoords-cannot-select-first-enum

Fix2950 parcoords cannot select first enum

Author: archmoj

src/traces/parcoords/axisbrush.js

@@ -25,37 +25,31 @@ function closeToCovering(v, vAdjacent) { return v * (1 - snapClose) + vAdjacent
 // so it's clear we're covering it
 // find the interval we're in, and snap to 1/4 the distance to the next
 // these two could be unified at a slight loss of readability / perf
-function ordinalScaleSnapLo(a, v, existingRanges) {
+function ordinalScaleSnap(isHigh, a, v, existingRanges) {
     if(overlappingExisting(v, existingRanges)) return v;
 
-    var aPrev = a[0];
-    var aPrevPrev = aPrev;
-    for(var i = 1; i < a.length; i++) {
-        var aNext = a[i];
+    var dir = isHigh ? -1 : 1;
 
-        // very close to the previous - snap down to it
-        if(v < closeToCovering(aPrev, aNext)) return snapOvershoot(aPrev, aPrevPrev);
-        if(v < aNext || i === a.length - 1) return snapOvershoot(aNext, aPrev);
-
-        aPrevPrev = aPrev;
-        aPrev = aNext;
+    var first = 0;
+    var last = a.length - 1;
+    if(dir < 0) {
+        var tmp = first;
+        first = last;
+        last = tmp;
     }
-}
-
-function ordinalScaleSnapHi(a, v, existingRanges) {
-    if(overlappingExisting(v, existingRanges)) return v;
 
-    var aPrev = a[a.length - 1];
-    var aPrevPrev = aPrev;
-    for(var i = a.length - 2; i >= 0; i--) {
-        var aNext = a[i];
+    var aHere = a[first];
+    var aPrev = aHere;
+    for(var i = first; dir * i < dir * last; i += dir) {
+        var nextI = i + dir;
+        var aNext = a[nextI];
 
         // very close to the previous - snap down to it
-        if(v > closeToCovering(aPrev, aNext)) return snapOvershoot(aPrev, aPrevPrev);
-        if(v > aNext || i === a.length - 1) return snapOvershoot(aNext, aPrev);
+        if(dir * v < dir * closeToCovering(aHere, aNext)) return snapOvershoot(aHere, aPrev);
+        if(dir * v < dir * aNext || nextI === last) return snapOvershoot(aNext, aHere);
 
-        aPrevPrev = aPrev;
-        aPrev = aNext;
+        aPrev = aHere;
+        aHere = aNext;
     }
 }
 
@@ -333,8 +327,8 @@ function attachDragBehavior(selection) {
                     var a = d.unitTickvals;
                     if(a[a.length - 1] < a[0]) a.reverse();
                     s.newExtent = [
-                        ordinalScaleSnapLo(a, s.newExtent[0], s.stayingIntervals),
-                        ordinalScaleSnapHi(a, s.newExtent[1], s.stayingIntervals)
+                        ordinalScaleSnap(0, a, s.newExtent[0], s.stayingIntervals),
+                        ordinalScaleSnap(1, a, s.newExtent[1], s.stayingIntervals)
                     ];
                     var hasNewExtent = s.newExtent[1] > s.newExtent[0];
                     s.extent = s.stayingIntervals.concat(hasNewExtent ? [s.newExtent] : []);
@@ -505,8 +499,8 @@ function cleanRanges(ranges, dimension) {
         var sortedTickVals = dimension.tickvals.slice().sort(sortAsc);
         ranges = ranges.map(function(ri) {
             var rSnapped = [
-                ordinalScaleSnapLo(sortedTickVals, ri[0], []),
-                ordinalScaleSnapHi(sortedTickVals, ri[1], [])
+                ordinalScaleSnap(0, sortedTickVals, ri[0], []),
+                ordinalScaleSnap(1, sortedTickVals, ri[1], [])
             ];
             if(rSnapped[1] > rSnapped[0]) return rSnapped;
         })

test/image/baselines/gl2d_parcoords_select_first_last_enum.png

@@ -0,0 +1,85 @@
+{
+    "data": [
+        {
+            "type": "parcoords",
+            "line": {
+                "colorscale": "Portland",
+                "showscale": true,
+                "reversescale": true,
+                "color": [
+                    1,
+                    2,
+                    3,
+                    4,
+                    5,
+                    6,
+                    7,
+                    8
+                ]
+            },
+            "dimensions": [
+                {
+                    "label": "A",
+                    "values": [
+                        1,
+                        2,
+                        3,
+                        4,
+                        5,
+                        6,
+                        7,
+                        8
+                    ],
+                    "tickvals": [
+                        1,
+                        2,
+                        3,
+                        4,
+                        5,
+                        6,
+                        7,
+                        8
+                    ],
+                    "constraintrange": [
+                        [
+                            1,
+                            1
+                        ],
+                        [
+                            3,
+                            3
+                        ],
+                        [
+                            5,
+                            6
+                        ],
+                        [
+                            8,
+                            8
+                        ]
+                    ]
+                },
+                {
+                    "label": "B",
+                    "values": [
+                        1,
+                        2,
+                        3,
+                        5,
+                        8,
+                        13,
+                        22,
+                        35
+                    ]
+                }
+            ]
+        }
+    ],
+    "layout": {
+        "width": 400,
+        "height": 400,
+        "title": {
+            "text": "should select first and last enum"
+        }
+    }
+}