compute geo.midPt more efficiently

etpinard · etpinard · commit ab059900a1b8 · 2017-09-25T11:19:20.000-04:00
- and update non-clipped scroll test for
  more-pronounced signal
diff --git a/src/plots/geo/geo.js b/src/plots/geo/geo.js
@@ -194,8 +194,8 @@ proto.updateProjection = function(fullLayout, geoLayout) {
     // px coordinates of view mid-point,
     // useful to update `geo.center` after interactions
     var midPt = this.midPt = [
-        b[0][0] + (b[1][0] - b[0][0]) / 2,
-        b[0][1] + (b[1][1] - b[0][1]) / 2
+        (b[0][0] + b[1][0]) / 2,
+        (b[0][1] + b[1][1]) / 2
     ];
 
     // adjust projection to user setting
diff --git a/src/plots/geo/layout/defaults.js b/src/plots/geo/layout/defaults.js
@@ -78,7 +78,7 @@ function handleGeoDefaults(geoLayoutIn, geoLayoutOut, coerce) {
     var lon1 = lonRange[1];
     if(lon0 > 0 && lon1 < 0) lon1 += 360;
 
-    var centerLon = lon0 + (lon1 - lon0) / 2;
+    var centerLon = (lon0 + lon1) / 2;
     var projLon;
 
     if(!isAlbersUsa) {
@@ -109,7 +109,7 @@ function handleGeoDefaults(geoLayoutIn, geoLayoutOut, coerce) {
         centerLatDflt = 38.7;
     } else {
         centerLonDflt = isScoped ? centerLon : projLon;
-        centerLatDflt = latRange[0] + (latRange[1] - latRange[0]) / 2;
+        centerLatDflt = (latRange[0] + latRange[1]) / 2;
     }
 
     coerce('center.lon', centerLonDflt);
diff --git a/test/jasmine/tests/geo_test.js b/test/jasmine/tests/geo_test.js
@@ -1544,13 +1544,13 @@ describe('Test geo zoom/pan/drag interactions:', function() {
             ], [
                 'geo.center.lat'
             ]);
-            return scroll([350, 250], [-200, -200]);
+            return scroll([200, 250], [-200, -200]);
         })
         .then(function() {
-                [-124.4, 0], [-124.4, 29.5], 1.3
             _assert('after off-center scroll', [
+                [-151.2, 0], [-151.2, 29.5], 1.3
             ], [
-                [124.4, 0], [350, 329.2], [0, 0], 134.4
+                [151.2, 0], [350, 329.2], [0, 0], 134.4
             ], [
                 'geo.projection.rotation.lon',
                 'geo.center.lon', 'geo.center.lat',
@@ -1559,8 +1559,8 @@ describe('Test geo zoom/pan/drag interactions:', function() {
             return Plotly.relayout(gd, 'geo.showocean', false);
         })
         .then(function() {
-                [-124.4, 0], [-124.4, 29.5], 1.3
             _assert('after some relayout call that causes a replot', [
+                [-151.2, 0], [-151.2, 29.5], 1.3
             ], [
                 // converts translate (px) to center (lonlat)
                 [151.2, 0], [350, 260], [0, 29.5], 134.4
