Method to reduce polygon literals

src/ol/style/style.js

@@ -4,6 +4,7 @@ goog.require('ol.Feature');
 goog.require('ol.geom.GeometryType');
 goog.require('ol.style.Rule');
 goog.require('ol.style.Literal');
+goog.require('ol.style.PolygonLiteral');
 
 
 
@@ -68,3 +69,56 @@ ol.style.Style.applyDefaultStyle = function(feature) {
   }
   return symbolizerLiterals;
 };
+
+
+/**
+ * Collapse partial polygon symbolizers.
+ * @param {Array.<ol.style.Literal>} literals Input literals.
+ * @return {Array.<ol.style.Literal>} Reduced literals.
+ */
+ol.style.Style.reduceLiterals = function(literals) {
+  var reduced = [];
+  var literal, stroke, fill, key, value;
+  for (var i = 0, ii = literals.length; i < ii; ++i) {
+    literal = literals[i];
+    if (literal instanceof ol.style.PolygonLiteral) {
+      if (goog.isDef(literal.strokeColor) &&
+          !goog.isDef(literal.fillColor)) {
+        // stroke only, check for previous fill only
+        if (fill) {
+          for (key in literal) {
+            value = literal[key];
+            if (goog.isDef(value)) {
+              fill[key] = value;
+            }
+          }
+          fill = null;
+        } else {
+          stroke = literal;
+          reduced.push(stroke);
+        }
+      } else if (goog.isDef(literal.fillColor)
+          && !goog.isDef(literal.strokeColor)) {
+        // fill only, check for previous stroke only
+        if (stroke) {
+          for (key in literal) {
+            value = literal[key];
+            if (goog.isDef(value)) {
+              stroke[key] = value;
+            }
+          }
+          stroke = null;
+        } else {
+          fill = literal;
+          reduced.push(fill);
+        }
+      } else {
+        // both stroke and fill, proceed
+        reduced.push(literal);
+      }
+    } else {
+      reduced.push(literal);
+    }
+  }
+  return reduced;
+};

test/spec/ol/style/style.test.js

@@ -58,13 +58,116 @@ describe('ol.style.Style', function() {
 
   });
 
+  describe('#reduceLiterals', function() {
+
+    it('collapses stroke or fill only literals where possible', function() {
+      var literals = [
+        new ol.style.PolygonLiteral({
+          fillColor: '#ff0000',
+          fillOpacity: 0.5
+        }),
+        new ol.style.PolygonLiteral({
+          strokeColor: '#00ff00',
+          strokeOpacity: 0.6,
+          strokeWidth: 3
+        })
+      ];
+
+      var reduced = ol.style.Style.reduceLiterals(literals);
+      expect(reduced).to.have.length(1);
+
+      var poly = reduced[0];
+      expect(poly.fillColor).to.be('#ff0000');
+      expect(poly.fillOpacity).to.be(0.5);
+      expect(poly.strokeColor).to.be('#00ff00');
+      expect(poly.strokeOpacity).to.be(0.6);
+      expect(poly.strokeWidth).to.be(3);
+    });
+
+    it('leaves complete polygon literals alone', function() {
+      var literals = [
+        new ol.style.PolygonLiteral({
+          fillColor: '#ff0000',
+          fillOpacity: 0.5,
+          strokeColor: '#00ff00',
+          strokeOpacity: 0.6,
+          strokeWidth: 3
+        }),
+        new ol.style.PolygonLiteral({
+          strokeColor: '#0000ff',
+          strokeOpacity: 0.7,
+          strokeWidth: 1
+        })
+      ];
+
+      var reduced = ol.style.Style.reduceLiterals(literals);
+      expect(reduced).to.have.length(2);
+
+      var first = reduced[0];
+      expect(first.fillColor).to.be('#ff0000');
+      expect(first.fillOpacity).to.be(0.5);
+      expect(first.strokeColor).to.be('#00ff00');
+      expect(first.strokeOpacity).to.be(0.6);
+      expect(first.strokeWidth).to.be(3);
+
+      var second = reduced[1];
+      expect(second.fillColor).to.be(undefined);
+      expect(second.fillOpacity).to.be(undefined);
+      expect(second.strokeColor).to.be('#0000ff');
+      expect(second.strokeOpacity).to.be(0.7);
+      expect(second.strokeWidth).to.be(1);
+    });
+
+    it('leaves other literals alone', function() {
+      var literals = [
+        new ol.style.PolygonLiteral({
+          strokeColor: '#00ff00',
+          strokeOpacity: 0.6,
+          strokeWidth: 3
+        }),
+        new ol.style.PolygonLiteral({
+          fillColor: '#ff0000',
+          fillOpacity: 0.5
+        }),
+        new ol.style.TextLiteral({
+          color: '#ffffff',
+          fontFamily: 'Arial',
+          fontSize: 11,
+          text: 'Test',
+          opacity: 0.5
+        })
+      ];
+
+      var reduced = ol.style.Style.reduceLiterals(literals);
+      expect(reduced).to.have.length(2);
+
+      var first = reduced[0];
+      expect(first.fillColor).to.be('#ff0000');
+      expect(first.fillOpacity).to.be(0.5);
+      expect(first.strokeColor).to.be('#00ff00');
+      expect(first.strokeOpacity).to.be(0.6);
+      expect(first.strokeWidth).to.be(3);
+
+      var second = reduced[1];
+      expect(second.color).to.be('#ffffff');
+      expect(second.fontFamily).to.be('Arial');
+      expect(second.fontSize).to.be(11);
+      expect(second.text).to.be('Test');
+      expect(second.opacity).to.be(0.5);
+    });
+
+
+  })
+
 });
 
 goog.require('ol.Feature');
 goog.require('ol.geom.LineString');
 goog.require('ol.geom.Point');
 goog.require('ol.geom.Polygon');
+goog.require('ol.style.PolygonLiteral');
 goog.require('ol.style.Rule');
 goog.require('ol.style.Shape');
 goog.require('ol.style.ShapeLiteral');
 goog.require('ol.style.Style');
+goog.require('ol.style.TextLiteral');