Add render order function support

gwt-ol3-client/src/main/java/ol/layer/BaseVectorLayerOptions.java

@@ -20,6 +20,8 @@
 
 import jsinterop.annotations.JsType;
 import ol.PluggableMap;
+import ol.style.OrderFunction;
+import ol.style.OrderFunctionRender;
 import ol.style.Style;
 import ol.style.StyleFunction;
 
@@ -67,6 +69,26 @@ public class BaseVectorLayerOptions extends LayerOptions {
     @JsProperty
     public native void setRenderBuffer(double renderBuffer);
 
+    /**
+     * Render order. Function to be used when sorting features before rendering.
+     * By default features are drawn in the order that they are created. Use null
+     * to avoid the sort, but get an undefined draw order.
+     *
+     * @param orderFunction order function
+     */
+    @JsProperty
+    public native void setRenderOrder(OrderFunction orderFunction);
+
+    /**
+     * Render order. Function to be used when sorting features before rendering.
+     * By default features are drawn in the order that they are created. Use null
+     * to avoid the sort, but get an undefined draw order.
+     *
+     * @param orderFunction order function
+     */
+    @JsProperty
+    public native void setRenderOrder(OrderFunctionRender orderFunction);
+
     @JsProperty
     public native void setStyle(Style style);
 

gwt-ol3-client/src/main/java/ol/style/OrderFunction.java

@@ -0,0 +1,33 @@
+/*******************************************************************************
+ * Copyright 2014, 2021 gwt-ol
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *******************************************************************************/
+package ol.style;
+
+import jsinterop.annotations.JsFunction;
+import ol.Feature;
+
+/**
+ * A function to be used when sorting features before rendering.
+ *
+ * @author TDesjardins
+ *
+ */
+@FunctionalInterface
+@JsFunction
+public interface OrderFunction {
+
+    double sort(Feature feature1, Feature feature2);
+
+}

gwt-ol3-client/src/main/java/ol/style/OrderFunctionRender.java

@@ -0,0 +1,33 @@
+/*******************************************************************************
+ * Copyright 2014, 2021 gwt-ol
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *******************************************************************************/
+package ol.style;
+
+import jsinterop.annotations.JsFunction;
+import ol.render.Feature;
+
+/**
+ * A function to be used when sorting features before rendering.
+ *
+ * @author TDesjardins
+ *
+ */
+@FunctionalInterface
+@JsFunction
+public interface OrderFunctionRender {
+
+    double sort(Feature feature1, Feature feature2);
+
+}