Greedify the queue loading strategy

src/ol/tilequeue.js

@@ -89,16 +89,17 @@ ol.TileQueue.prototype.handleTileChange = function(event) {
  * @param {number} maxNewLoads Maximum number of new tiles to load.
  */
 ol.TileQueue.prototype.loadMoreTiles = function(maxTotalLoading, maxNewLoads) {
-  var newLoads = Math.min(
+  var newLoads = 0;
-      maxTotalLoading - this.getTilesLoading(), maxNewLoads, this.getCount());
+  var tile;
-  var i, tile;
+  while (this.tilesLoading_ < maxTotalLoading && newLoads < maxNewLoads &&
-  for (i = 0; i < newLoads; ++i) {
+         this.getCount() > 0) {
     tile = /** @type {ol.Tile} */ (this.dequeue()[0]);
     if (tile.getState() === ol.TileState.IDLE) {
       goog.events.listen(tile, goog.events.EventType.CHANGE,
           this.handleTileChange, false, this);
       tile.load();
       ++this.tilesLoading_;
+      ++newLoads;
     }
   }
 };

test/spec/ol/tilequeue.test.js

@@ -45,6 +45,7 @@ describe('ol.TileQueue', function() {
 
       var maxLoading = numTiles / 2;
 
+      // and nothing is loading
       expect(q1.getTilesLoading()).to.equal(0);
       expect(q2.getTilesLoading()).to.equal(0);
 
@@ -52,32 +53,20 @@ describe('ol.TileQueue', function() {
       q1.loadMoreTiles(maxLoading, maxLoading);
       q2.loadMoreTiles(maxLoading, maxLoading);
 
-      // since tiles can only load once, we expect one queue to load them
+      // both tiles will be loading the max
-      expect(q1.getTilesLoading()).to.equal(maxLoading);
-      expect(q2.getTilesLoading()).to.equal(0);
-
-      // however, both queues will be reduced
-      expect(q1.getCount()).to.equal(numTiles - maxLoading);
-      expect(q2.getCount()).to.equal(numTiles - maxLoading);
-
-      // ask both to load more
-      q1.loadMoreTiles(maxLoading, maxLoading);
-      q2.loadMoreTiles(maxLoading, maxLoading);
-
-      // now the second queue will be empty
-      expect(q1.getCount()).to.equal(numTiles - maxLoading);
-      expect(q2.getCount()).to.equal(0);
-
-      // after the first is saturated, the second should start loading
       expect(q1.getTilesLoading()).to.equal(maxLoading);
       expect(q2.getTilesLoading()).to.equal(maxLoading);
 
+      // the second queue will be empty now
+      expect(q1.getCount()).to.equal(numTiles - maxLoading);
+      expect(q2.getCount()).to.equal(0);
+
       // let all tiles load
       setTimeout(function() {
         expect(q1.getTilesLoading()).to.equal(0);
         expect(q2.getTilesLoading()).to.equal(0);
 
-        // load again, which will clear the first queue
+        // ask both to load, this should clear q1
         q1.loadMoreTiles(maxLoading, maxLoading);
         q2.loadMoreTiles(maxLoading, maxLoading);