From 71d12072010adba6deb9e1befa4222f02b10f27a Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Thu, 4 Apr 2013 23:33:18 +0200
Subject: [PATCH 1/2] Start a maximum of two new tile downloads per frame

---
 src/ol/map.js       | 8 +++++++-
 src/ol/tilequeue.js | 9 ++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/ol/map.js b/src/ol/map.js
index c616c64669..ca1d36b2e3 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -77,6 +77,12 @@ ol.ENABLE_DOM = true;
 ol.ENABLE_WEBGL = true;
 
 
+/**
+ * @define {number} Maximum new tile loads per frame.
+ */
+ol.MAXIMUM_NEW_TILE_LOADS_PER_FRAME = 2;
+
+
 /**
  * @enum {string}
  */
@@ -556,7 +562,7 @@ ol.Map.prototype.handleMapBrowserEvent = function(mapBrowserEvent) {
  */
 ol.Map.prototype.handlePostRender = function() {
   this.tileQueue_.reprioritize(); // FIXME only call if needed
-  this.tileQueue_.loadMoreTiles();
+  this.tileQueue_.loadMoreTiles(ol.MAXIMUM_NEW_TILE_LOADS_PER_FRAME);
 
   var postRenderFunctions = this.postRenderFunctions_;
   var i;
diff --git a/src/ol/tilequeue.js b/src/ol/tilequeue.js
index 4d21f2ef44..43c25f85cb 100644
--- a/src/ol/tilequeue.js
+++ b/src/ol/tilequeue.js
@@ -74,15 +74,18 @@ ol.TileQueue.prototype.handleTileChange = function() {
 
 
 /**
- *  FIXME empty description for jsdoc
+ * @param {number} limit Maximum number of new tiles to load.
  */
-ol.TileQueue.prototype.loadMoreTiles = function() {
+ol.TileQueue.prototype.loadMoreTiles = function(limit) {
   var tile;
-  while (!this.isEmpty() && this.tilesLoading_ < this.maxTilesLoading_) {
+  while (limit > 0 &&
+         !this.isEmpty() &&
+         this.tilesLoading_ < this.maxTilesLoading_) {
     tile = /** @type {ol.Tile} */ (this.dequeue()[0]);
     goog.events.listenOnce(tile, goog.events.EventType.CHANGE,
         this.handleTileChange, false, this);
     tile.load();
     ++this.tilesLoading_;
+    --limit;
   }
 };

From 0e12d16c37965620bd2f3d03899d2ffe1ab8b0af Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Thu, 4 Apr 2013 23:49:21 +0200
Subject: [PATCH 2/2] Move configuration of maximum tiles loading into map.js

---
 src/ol/map.js       | 10 +++++++++-
 src/ol/tilequeue.js |  7 +++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/ol/map.js b/src/ol/map.js
index ca1d36b2e3..9508938a21 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -77,6 +77,12 @@ ol.ENABLE_DOM = true;
 ol.ENABLE_WEBGL = true;
 
 
+/**
+ * @define {number} Maximum number of simultaneously loading tiles.
+ */
+ol.MAXIMUM_TILES_LOADING = 8;
+
+
 /**
  * @define {number} Maximum new tile loads per frame.
  */
@@ -279,7 +285,9 @@ ol.Map = function(mapOptions) {
    * @private
    * @type {ol.TileQueue}
    */
-  this.tileQueue_ = new ol.TileQueue(goog.bind(this.getTilePriority, this),
+  this.tileQueue_ = new ol.TileQueue(
+      ol.MAXIMUM_TILES_LOADING,
+      goog.bind(this.getTilePriority, this),
       goog.bind(this.handleTileChange_, this));
 
   goog.events.listen(this, ol.Object.getChangedEventType(ol.MapProperty.VIEW),
diff --git a/src/ol/tilequeue.js b/src/ol/tilequeue.js
index 43c25f85cb..94274ca6d7 100644
--- a/src/ol/tilequeue.js
+++ b/src/ol/tilequeue.js
@@ -18,12 +18,15 @@ ol.TilePriorityFunction;
 /**
  * @constructor
  * @extends {ol.structs.PriorityQueue}
+ * @param {number} maxTilesLoading Maximum number of simultaneously loading
+ *     tiles.
  * @param {ol.TilePriorityFunction} tilePriorityFunction
  *     Tile priority function.
  * @param {Function} tileChangeCallback
  *     Function called on each tile change event.
  */
-ol.TileQueue = function(tilePriorityFunction, tileChangeCallback) {
+ol.TileQueue =
+    function(maxTilesLoading, tilePriorityFunction, tileChangeCallback) {
 
   goog.base(
       this,
@@ -52,7 +55,7 @@ ol.TileQueue = function(tilePriorityFunction, tileChangeCallback) {
    * @private
    * @type {number}
    */
-  this.maxTilesLoading_ = 8;
+  this.maxTilesLoading_ = maxTilesLoading;
 
   /**
    * @private