Pad the compact fitbounds longitude range like getAutoRange

The antimeridian fix replaced the padded naive range with a tight
[min, max], so markers ended up flush against the frame on straddling
maps while every other fitbounds map leaves a margin. Scale the padding
getAutoRange already applied to the naive range down to the narrower
crossing range and apply it. The padding is symmetric, so the
mid-longitude the projection centers on is unchanged. Loosen the
integration test's range assertion to match.

Author: SharadhNaidu

src/plots/geo/geo.js

@@ -261,7 +261,21 @@ proto.updateProjection = function(geoCalcData, fullLayout) {
 
             if(!hasLocationData) {
                 var fitLonRange = getFitboundsLonRange(lons);
-                if(fitLonRange) axLon.range = fitLonRange;
+                if(fitLonRange) {
+                    // getFitboundsLonRange returns a tight [min, max]. getAutoRange
+                    // pads the naive range (for marker size and the standard
+                    // margin), so scale that padding to the narrower crossing range
+                    // and apply it, keeping markers off the frame edge as on any
+                    // other fitbounds map. The padding is symmetric, so the
+                    // mid-longitude the projection centers on is unchanged.
+                    var lonDataSpan = Lib.aggNums(Math.max, null, lons) -
+                        Lib.aggNums(Math.min, null, lons);
+                    var lonPad = lonDataSpan > 0 ?
+                        (axLon.range[1] - axLon.range[0] - lonDataSpan) / 2 *
+                        (fitLonRange[1] - fitLonRange[0]) / lonDataSpan :
+                        0;
+                    axLon.range = [fitLonRange[0] - lonPad, fitLonRange[1] + lonPad];
+                }
             }
         }
 

test/jasmine/tests/geo_test.js

@@ -83,11 +83,18 @@ describe('Test geo fitbounds with antimeridian-straddling points', function() {
 
     it('centers on the compact crossing view when points straddle the antimeridian', function(done) {
         // lon = [131.8855, -179] spans ~311deg the naive way; the compact view
-        // crosses the antimeridian, giving range [131.8855, 181] and a projection
-        // rotated to its mid-longitude (~156.4deg), not to the naive mid (~-24deg).
+        // crosses the antimeridian, giving a range around [131.8855, 181] (padded
+        // for markers like any fitbounds map) and a projection rotated to its
+        // mid-longitude (~156.4deg), not to the naive mid (~-24deg).
         _plot([131.8855, -179]).then(function() {
             var geoLayout = gd._fullLayout.geo;
-            expect(geoLayout.lonaxis._ax.range).toEqual([131.8855, 181]);
+            var lonRange = geoLayout.lonaxis._ax.range;
+            // crosses the antimeridian (upper bound past 180) and stays compact
+            // (~49deg plus a little padding), nowhere near the naive ~311deg.
+            expect(lonRange[0]).toBeLessThan(131.8855);
+            expect(lonRange[1]).toBeGreaterThan(181);
+            expect(lonRange[1] - lonRange[0]).toBeGreaterThan(49);
+            expect(lonRange[1] - lonRange[0]).toBeLessThan(70);
             expect(geoLayout._subplot.projection.rotate()[0]).toBeCloseTo(-156.4, 0);
         })
         .then(done, done.fail);