added labelXOffset and labelYOffset symbolizer properties. Thanks madair for the original patch, and thanks jlacroix for turning it into symbolizer properties so nicely. p=jlacroix, r=me (fixes #2312)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9755 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

examples/vector-features-with-text.html

@@ -33,7 +33,9 @@
                     fontSize: "12px",
                     fontFamily: "Courier New, monospace",
                     fontWeight: "bold",
-                    labelAlign: "${align}"
+                    labelAlign: "${align}",
+                    labelXOffset: "${xOffset}",
+                    labelYOffset: "${yOffset}"
                 }}),
                 renderers: renderer
             });
@@ -83,6 +85,22 @@
                     favColor: 'black',
                     align: 'rt'
                 });
+
+            // Create a point feature to show the label offset options
+            var labelOffsetPoint = new OpenLayers.Geometry.Point(-101.04, 35.68);
+            var labelOffsetFeature = new OpenLayers.Feature.Vector(labelOffsetPoint);
+            labelOffsetFeature.attributes = {
+                name: "offset",
+                age: 22,
+                favColor: 'blue',
+                align: "cm",
+                // positive value moves the label to the right
+                xOffset: 50,
+                // negative value moves the label down
+                yOffset: -15
+            };
+
+
             var nullFeature = new OpenLayers.Feature.Vector(null);
             nullFeature.attributes = {
                 name: "toto is some text about the world",
@@ -94,7 +112,7 @@
             map.addLayer(vectorLayer);
             vectorLayer.drawFeature(multiFeature);
             map.setCenter(new OpenLayers.LonLat(point.x, point.y), 3);
-            vectorLayer.addFeatures([pointFeature, polygonFeature, multiFeature, nullFeature ]);
+            vectorLayer.addFeatures([pointFeature, polygonFeature, multiFeature, labelOffsetFeature, nullFeature ]);
         }
     </script>
   </head>

lib/OpenLayers/Feature/Vector.js

@@ -356,6 +356,8 @@ OpenLayers.Feature.Vector = OpenLayers.Class(OpenLayers.Feature, {
  *     alignment. Valid values for horizontal alignment: "l"=left, "c"=center, "r"=right. Valid values for vertical
  *     alignment: "t"=top, "m"=middle, "b"=bottom. Example values: "lt", "cm", "rb". The canvas renderer does not
  *     support vertical alignment, it will always use "b".
+ * labelXOffset - {Number} Pixel offset along the positive x axis for displacing the label.
+ * labelYOffset - {Number} Pixel offset along the positive y axis for displacing the label.
  * labelSelect - {Boolean} If set to true, labels will be selectable using SelectFeature or similar controls.
  *     Default is false.
  * fontColor - {String} The font color for the label, to be provided like CSS.

lib/OpenLayers/Renderer.js

@@ -178,7 +178,14 @@ OpenLayers.Renderer = OpenLayers.Class({
                 }
                 var rendered = this.drawGeometry(feature.geometry, style, feature.id);
                 if(style.display != "none" && style.label && rendered !== false) {
-                    this.drawText(feature.id, style, feature.geometry.getCentroid());
+                    var location = feature.geometry.getCentroid(); 
+                    if(style.labelXOffset || style.labelYOffset) {
+                        xOffset = isNaN(style.labelXOffset) ? 0 : style.labelXOffset;
+                        yOffset = isNaN(style.labelYOffset) ? 0 : style.labelYOffset;
+                        var res = this.getResolution();
+                        location.move(xOffset*res, yOffset*res);
+                    }
+                    this.drawText(feature.id, style, location);
                 } else {
                     this.removeText(feature.id);
                 }