From 14f580fe30417c3b2bb47aee142c6316327a603a Mon Sep 17 00:00:00 2001
From: Olivier Guyot <olivier.guyot@camptocamp.com>
Date: Mon, 13 May 2019 16:08:24 +0200
Subject: [PATCH] Layer / accepts a custom render function

---
 src/ol/layer/Layer.js            | 11 +++++++++++
 test/spec/ol/layer/layer.test.js | 10 ++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/ol/layer/Layer.js b/src/ol/layer/Layer.js
index 1c9f916c47..443daf3e6b 100644
--- a/src/ol/layer/Layer.js
+++ b/src/ol/layer/Layer.js
@@ -10,6 +10,10 @@ import {assign} from '../obj.js';
 import RenderEventType from '../render/EventType.js';
 import SourceState from '../source/State.js';
 
+/**
+ * @typedef {function(import("../PluggableMap.js").FrameState):HTMLElement} RenderFunction
+ */
+
 
 /**
  * @typedef {Object} Options
@@ -29,6 +33,8 @@ import SourceState from '../source/State.js';
  * the source can be set by calling {@link module:ol/layer/Layer#setSource layer.setSource(source)} after
  * construction.
  * @property {import("../PluggableMap.js").default} [map] Map.
+ * @property {RenderFunction} [render] Render function. Takes the frame state as input and is expected to return an
+ * HTML element. Will overwrite the default rendering for the layer.
  */
 
 
@@ -100,6 +106,11 @@ class Layer extends BaseLayer {
      */
     this.renderer_ = null;
 
+    // Overwrite default render method with a custom one
+    if (options.render) {
+      this.render = options.render;
+    }
+
     if (options.map) {
       this.setMap(options.map);
     }
diff --git a/test/spec/ol/layer/layer.test.js b/test/spec/ol/layer/layer.test.js
index dba518a47a..010a289687 100644
--- a/test/spec/ol/layer/layer.test.js
+++ b/test/spec/ol/layer/layer.test.js
@@ -94,6 +94,16 @@ describe('ol.layer.Layer', function() {
       layer.dispose();
     });
 
+    it('accepts a custom render function', function() {
+      let called = false;
+      const layer = new Layer({
+        render: function() {
+          called = true;
+        }
+      });
+      layer.render();
+      expect(called).to.eql(true);
+    });
   });
 
   describe('visibleAtResolution', function() {