add albersUsa-only logic for geo.center

etpinard · etpinard · commit 9c9264fdda22 · 2017-09-19T17:46:56.000-04:00
- as albersUsa projection does not expose `center()` method
diff --git a/src/plots/geo/geo2.js b/src/plots/geo/geo2.js
@@ -215,8 +215,17 @@ proto.updateProjection = function(fullLayout, geoLayout) {
         .translate([t[0] + (midPt[0] - t[0]), t[1] + (midPt[1] - t[1])])
         .clipExtent(b);
 
-    // TODO we'll need to special algo for albersUsa projection
-    // as this particular projection does not support `.center`
+    // the 'albers usa' projection does not expose a 'center' method
+    // so here's this hack to make it respond to 'geoLayout.center'
+    if(geoLayout._isAlbersUsa) {
+        var centerPx = projection([center.lon, center.lat]);
+        var tt = projection.translate();
+
+        projection.translate([
+            tt[0] - (centerPx[0] - tt[0]),
+            tt[1] - (centerPx[1] - tt[1])
+        ]);
+    }
 };
 
 proto.updateBaseLayers = function(fullLayout, geoLayout) {
diff --git a/src/plots/geo/layout/defaults.js b/src/plots/geo/layout/defaults.js
@@ -98,8 +98,22 @@ function handleGeoDefaults(geoLayoutIn, geoLayoutOut, coerce) {
         if(show) coerce('oceancolor');
     }
 
-    coerce('center.lon', isScoped ? centerLon : projLon);
-    coerce('center.lat', latRange[0] + (latRange[1] - latRange[0]) / 2);
+    var centerLonDflt;
+    var centerLatDflt;
+
+    if(isAlbersUsa) {
+        // 'albers usa' does not have a 'center',
+        // these values were found using via:
+        //   projection.invert([geoLayout.center.lon, geoLayoutIn.center.lat])
+        centerLonDflt = -96.6;
+        centerLatDflt = 38.7;
+    } else {
+        centerLonDflt = isScoped ? centerLon : projLon;
+        centerLatDflt = latRange[0] + (latRange[1] - latRange[0]) / 2;
+    }
+
+    coerce('center.lon', centerLonDflt);
+    coerce('center.lat', centerLatDflt);
 
     if(isConic) {
         var dfltProjParallels = scopeParams.projParallels || [0, 60];
