From dde9fb5bc42c6a5e9fd3e97dbfbd1b91f77456de Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Thu, 7 Sep 2017 20:32:12 +0200
Subject: [PATCH] Fix abort handling of tileload events

---
 src/ol/source/tileeventtype.js        |  3 +-
 src/ol/source/urltile.js              | 35 ++++++++-------
 test/spec/ol/source/tileimage.test.js | 64 +++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 16 deletions(-)

diff --git a/src/ol/source/tileeventtype.js b/src/ol/source/tileeventtype.js
index 273fe96dd0..c62ea14bc1 100644
--- a/src/ol/source/tileeventtype.js
+++ b/src/ol/source/tileeventtype.js
@@ -13,7 +13,8 @@ ol.source.TileEventType = {
   TILELOADSTART: 'tileloadstart',
 
   /**
-   * Triggered when a tile finishes loading.
+   * Triggered when a tile finishes loading, either when its data is loaded,
+   * or when loading was aborted because the tile is no longer needed.
    * @event ol.source.Tile.Event#tileloadend
    * @api
    */
diff --git a/src/ol/source/urltile.js b/src/ol/source/urltile.js
index bb1d73c7aa..c66d78d515 100644
--- a/src/ol/source/urltile.js
+++ b/src/ol/source/urltile.js
@@ -61,6 +61,12 @@ ol.source.UrlTile = function(options) {
     this.setTileUrlFunction(options.tileUrlFunction);
   }
 
+  /**
+   * @private
+   * @type {Object.<number, boolean>}
+   */
+  this.tileLoadingKeys_ = {};
+
 };
 ol.inherits(ol.source.UrlTile, ol.source.Tile);
 
@@ -110,21 +116,20 @@ ol.source.UrlTile.prototype.getUrls = function() {
  */
 ol.source.UrlTile.prototype.handleTileChange = function(event) {
   var tile = /** @type {ol.Tile} */ (event.target);
-  switch (tile.getState()) {
-    case ol.TileState.LOADING:
-      this.dispatchEvent(
-          new ol.source.Tile.Event(ol.source.TileEventType.TILELOADSTART, tile));
-      break;
-    case ol.TileState.LOADED:
-      this.dispatchEvent(
-          new ol.source.Tile.Event(ol.source.TileEventType.TILELOADEND, tile));
-      break;
-    case ol.TileState.ERROR:
-      this.dispatchEvent(
-          new ol.source.Tile.Event(ol.source.TileEventType.TILELOADERROR, tile));
-      break;
-    default:
-      // pass
+  var uid = ol.getUid(tile);
+  var tileState = tile.getState();
+  var type;
+  if (tileState == ol.TileState.LOADING) {
+    this.tileLoadingKeys_[uid] = true;
+    type = ol.source.TileEventType.TILELOADSTART;
+  } else if (uid in this.tileLoadingKeys_) {
+    delete this.tileLoadingKeys_[uid];
+    type = tileState == ol.TileState.ERROR ? ol.source.TileEventType.TILELOADERROR :
+      (tileState == ol.TileState.LOADED || tileState == ol.TileState.ABORT) ?
+        ol.source.TileEventType.TILELOADEND : undefined;
+  }
+  if (type != undefined) {
+    this.dispatchEvent(new ol.source.Tile.Event(type, tile));
   }
 };
 
diff --git a/test/spec/ol/source/tileimage.test.js b/test/spec/ol/source/tileimage.test.js
index 878bb61899..4f4c549417 100644
--- a/test/spec/ol/source/tileimage.test.js
+++ b/test/spec/ol/source/tileimage.test.js
@@ -1,6 +1,7 @@
 
 
 goog.require('ol.ImageTile');
+goog.require('ol.TileState');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.events');
 goog.require('ol.proj');
@@ -172,4 +173,67 @@ describe('ol.source.TileImage', function() {
       tile.load();
     });
   });
+
+  describe('tile load events', function() {
+
+    var source;
+
+    beforeEach(function() {
+      source = new ol.source.TileImage({
+        url: '{z}/{x}/{y}'
+      });
+    });
+
+    it('dispatches tileloadstart and tileloadend events', function() {
+      source.setTileLoadFunction(function(tile) {
+        tile.setState(ol.TileState.LOADED);
+      });
+      var startSpy = sinon.spy();
+      source.on('tileloadstart', startSpy);
+      var endSpy = sinon.spy();
+      source.on('tileloadend', endSpy);
+      var tile = source.getTile(0, 0, -1, 1, ol.proj.get('EPSG:3857'));
+      tile.load();
+      expect(startSpy.callCount).to.be(1);
+      expect(endSpy.callCount).to.be(1);
+    });
+
+    it('works for loading-error-loading-loaded sequences', function(done) {
+      source.setTileLoadFunction(function(tile) {
+        tile.setState(
+            tile.state == ol.TileState.ERROR ? ol.TileState.LOADED : ol.TileState.ERROR);
+      });
+      var startSpy = sinon.spy();
+      source.on('tileloadstart', startSpy);
+      var errorSpy = sinon.spy();
+      source.on('tileloaderror', function(e) {
+        setTimeout(function() {
+          e.tile.setState(ol.TileState.LOADING);
+          e.tile.setState(ol.TileState.LOADED);
+        }, 0);
+        errorSpy();
+      });
+      source.on('tileloadend', function() {
+        expect(startSpy.callCount).to.be(2);
+        expect(errorSpy.callCount).to.be(1);
+        done();
+      });
+      var tile = source.getTile(0, 0, -1, 1, ol.proj.get('EPSG:3857'));
+      tile.load();
+    });
+
+    it('dispatches tileloadend events for aborted tiles', function() {
+      source.setTileLoadFunction(function() {});
+      var startSpy = sinon.spy();
+      source.on('tileloadstart', startSpy);
+      var endSpy = sinon.spy();
+      source.on('tileloadend', endSpy);
+      var tile = source.getTile(0, 0, -1, 1, ol.proj.get('EPSG:3857'));
+      tile.load();
+      tile.dispose();
+      expect(startSpy.callCount).to.be(1);
+      expect(endSpy.callCount).to.be(1);
+    });
+  });
+
 });