Only compose image vector frame when the replay group has changed

src/ol/renderer/canvas/imagelayer.js

@@ -127,8 +127,9 @@ ol.renderer.canvas.ImageLayer.prototype.prepareFrame = function(frameState, laye
         projection = sourceProjection;
       }
     }
-    if (this.vectorRenderer_) {
+    var vectorRenderer = this.vectorRenderer_;
-      var context = this.vectorRenderer_.context;
+    if (vectorRenderer) {
+      var context = vectorRenderer.context;
       var imageFrameState = /** @type {olx.FrameState} */ (ol.obj.assign({}, frameState, {
         size: [
           ol.extent.getWidth(renderedExtent) / viewResolution,
@@ -138,12 +139,12 @@ ol.renderer.canvas.ImageLayer.prototype.prepareFrame = function(frameState, laye
           rotation: 0
         }))
       }));
-      if (this.vectorRenderer_.prepareFrame(imageFrameState, layerState)) {
+      if (vectorRenderer.prepareFrame(imageFrameState, layerState) && vectorRenderer.replayGroupChanged) {
         context.canvas.width = imageFrameState.size[0] * pixelRatio;
         context.canvas.height = imageFrameState.size[1] * pixelRatio;
-        this.vectorRenderer_.composeFrame(imageFrameState, layerState, context);
+        vectorRenderer.composeFrame(imageFrameState, layerState, context);
+        this.image_ = new ol.ImageCanvas(renderedExtent, viewResolution, pixelRatio, context.canvas);
       }
-      this.image_ = new ol.ImageCanvas(renderedExtent, viewResolution, pixelRatio, context.canvas);
     } else {
       image = imageSource.getImage(
           renderedExtent, viewResolution, pixelRatio, projection);

src/ol/renderer/canvas/vectorlayer.js

@@ -69,6 +69,12 @@ ol.renderer.canvas.VectorLayer = function(vectorLayer) {
    */
   this.replayGroup_ = null;
 
+  /**
+   * A new replay group had to be created by `prepareFrame()`
+   * @type {boolean}
+   */
+  this.replayGroupChanged = true;
+
   /**
    * @type {CanvasRenderingContext2D}
    */
@@ -343,6 +349,7 @@ ol.renderer.canvas.VectorLayer.prototype.prepareFrame = function(frameState, lay
       this.renderedRevision_ == vectorLayerRevision &&
       this.renderedRenderOrder_ == vectorLayerRenderOrder &&
       ol.extent.containsExtent(this.renderedExtent_, extent)) {
+    this.replayGroupChanged = false;
     return true;
   }
 
@@ -400,6 +407,7 @@ ol.renderer.canvas.VectorLayer.prototype.prepareFrame = function(frameState, lay
   this.renderedExtent_ = extent;
   this.replayGroup_ = replayGroup;
 
+  this.replayGroupChanged = true;
   return true;
 };
 

test/spec/ol/renderer/canvas/vectorlayer.test.js

@@ -290,6 +290,14 @@ describe('ol.renderer.canvas.VectorLayer', function() {
       ], buffer));
     });
 
+    it('sets replayGroupChanged correctly', function() {
+      frameState.extent = [-10000, -10000, 10000, 10000];
+      renderer.prepareFrame(frameState, {});
+      expect(renderer.replayGroupChanged).to.be(true);
+      renderer.prepareFrame(frameState, {});
+      expect(renderer.replayGroupChanged).to.be(false);
+    });
+
   });
 
 });