From b3f14f09c484a4cb6745f9ad203532a4f0e1fcd7 Mon Sep 17 00:00:00 2001
From: rattai <rattai@ccri.com>
Date: Tue, 4 Aug 2015 17:25:47 -0400
Subject: [PATCH] Compute new image extent for comparison to existing image
 extent

---
 src/ol/source/imagewmssource.js            | 36 +++++++++++-----------
 test/spec/ol/source/imagewmssource.test.js |  8 +++++
 2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/src/ol/source/imagewmssource.js b/src/ol/source/imagewmssource.js
index 0df69e3c19..e098af2960 100644
--- a/src/ol/source/imagewmssource.js
+++ b/src/ol/source/imagewmssource.js
@@ -198,24 +198,6 @@ ol.source.ImageWMS.prototype.getImage =
     pixelRatio = 1;
   }
 
-  var image = this.image_;
-  if (!goog.isNull(image) &&
-      this.renderedRevision_ == this.getRevision() &&
-      image.getResolution() == resolution &&
-      image.getPixelRatio() == pixelRatio &&
-      ol.extent.containsExtent(image.getExtent(), extent)) {
-    return image;
-  }
-
-  var params = {
-    'SERVICE': 'WMS',
-    'VERSION': ol.DEFAULT_WMS_VERSION,
-    'REQUEST': 'GetMap',
-    'FORMAT': 'image/png',
-    'TRANSPARENT': true
-  };
-  goog.object.extend(params, this.params_);
-
   extent = extent.slice();
   var centerX = (extent[0] + extent[2]) / 2;
   var centerY = (extent[1] + extent[3]) / 2;
@@ -240,6 +222,24 @@ ol.source.ImageWMS.prototype.getImage =
   extent[1] = centerY - imageResolution * height / 2;
   extent[3] = centerY + imageResolution * height / 2;
 
+  var image = this.image_;
+  if (!goog.isNull(image) &&
+      this.renderedRevision_ == this.getRevision() &&
+      image.getResolution() == resolution &&
+      image.getPixelRatio() == pixelRatio &&
+      ol.extent.containsExtent(image.getExtent(), extent)) {
+    return image;
+  }
+
+  var params = {
+    'SERVICE': 'WMS',
+    'VERSION': ol.DEFAULT_WMS_VERSION,
+    'REQUEST': 'GetMap',
+    'FORMAT': 'image/png',
+    'TRANSPARENT': true
+  };
+  goog.object.extend(params, this.params_);
+
   this.imageSize_[0] = width;
   this.imageSize_[1] = height;
 
diff --git a/test/spec/ol/source/imagewmssource.test.js b/test/spec/ol/source/imagewmssource.test.js
index 0230edd9ea..7e697e9d4e 100644
--- a/test/spec/ol/source/imagewmssource.test.js
+++ b/test/spec/ol/source/imagewmssource.test.js
@@ -155,6 +155,14 @@ describe('ol.source.ImageWMS', function() {
       expect(imageLoadFunction.calledWith(image, image.src_)).to.be(true);
     });
 
+    it('returns the same image for consecutive calls with the same args', function() {
+      var extent = [10.01, 20, 30.01, 40];
+      var source = new ol.source.ImageWMS(options);
+      var image1 = source.getImage(extent, resolution, pixelRatio, projection);
+      var image2 = source.getImage(extent, resolution, pixelRatio, projection);
+      expect(image1).to.equal(image2);
+    });
+
   });
 
   describe('#getGetFeatureInfo', function() {