optimize line dash recalculation

mapbox · Mar 4, 2016 · 61ca1c8 · 61ca1c8
1 parent c369202
commit 61ca1c8
Showing 1 changed file with 11 additions and 12 deletions.
diff --git a/js/style/style_layer/line_style_layer.js b/js/style/style_layer/line_style_layer.js
@@ -12,22 +12,21 @@ module.exports = LineStyleLayer;
 LineStyleLayer.prototype = util.inherit(StyleLayer, {
 
     getPaintValue: function(name, zoom, zoomHistory) {
-        var output = StyleLayer.prototype.getPaintValue.call(this, name, zoom, zoomHistory);
+        var value = StyleLayer.prototype.getPaintValue.call(this, name, zoom, zoomHistory);
 
         // If the line is dashed, scale the dash lengths by the line
         // width at the previous round zoom level.
-        if (output && name === 'line-dasharray') {
-            var lineWidth = this.getPaintValue('line-width', Math.floor(zoom), Infinity);
-            output.fromScale *= lineWidth;
-            output.toScale *= lineWidth;
+        if (value && name === 'line-dasharray') {
+            var flooredZoom = Math.floor(zoom);
+            if (this._flooredZoom !== flooredZoom) {
+                this._flooredZoom = flooredZoom;
+                this._flooredLineWidth = this.getPaintValue('line-width', flooredZoom, Infinity);
+            }
+
+            value.fromScale *= this._flooredLineWidth;
+            value.toScale *= this._flooredLineWidth;
         }
 
-        return output;
-    },
-
-    recalculate: function(zoom, zoomHistory) {
-        StyleLayer.prototype.recalculate.call(this, zoom, zoomHistory);
-        var key = 'line-dasharray';
-        if (this._paintTransitions[key]) this.paint[key] = this.getPaintValue(key, zoom, zoomHistory);
+        return value;
     }
 });