Merge pull request #509 from twpayne/use-high-resolution-tiles

Use high resolution tiles

examples/rotation.js

@@ -8,7 +8,6 @@ goog.require('ol.source.OpenStreetMap');
 var map = new ol.Map({
   layers: [
     new ol.layer.TileLayer({
-      preload: 4,
       source: new ol.source.OpenStreetMap()
     })
   ],

examples/stamen.js

@@ -9,7 +9,6 @@ goog.require('ol.source.Stamen');
 var map = new ol.Map({
   layers: [
     new ol.layer.TileLayer({
-      preload: 4,
       source: new ol.source.Stamen({
         layer: 'watercolor'
       })

src/ol/renderer/canvas/canvastilelayerrenderer.js

@@ -201,7 +201,7 @@ ol.renderer.canvas.TileLayer.prototype.renderFrame =
       tilesToDrawByZ, getTileIfLoaded);
 
   var allTilesLoaded = true;
-  var tile, tileState, x, y;
+  var childTileRange, fullyLoaded, tile, tileState, x, y;
   for (x = tileRange.minX; x <= tileRange.maxX; ++x) {
     for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
 
@@ -215,7 +215,14 @@ ol.renderer.canvas.TileLayer.prototype.renderFrame =
       }
 
       allTilesLoaded = false;
-      tileGrid.forEachTileCoordParentTileRange(tile.tileCoord, findLoadedTiles);
+      fullyLoaded = tileGrid.forEachTileCoordParentTileRange(
+          tile.tileCoord, findLoadedTiles);
+      if (!fullyLoaded) {
+        childTileRange = tileGrid.getTileCoordChildTileRange(tile.tileCoord);
+        if (!goog.isNull(childTileRange)) {
+          findLoadedTiles(z + 1, childTileRange);
+        }
+      }
 
     }
   }

src/ol/renderer/dom/domtilelayerrenderer.js

@@ -115,7 +115,7 @@ ol.renderer.dom.TileLayer.prototype.renderFrame =
       tilesToDrawByZ, getTileIfLoaded);
 
   var allTilesLoaded = true;
-  var tile, tileState, x, y;
+  var childTileRange, fullyLoaded, tile, tileState, x, y;
   for (x = tileRange.minX; x <= tileRange.maxX; ++x) {
     for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
 
@@ -130,7 +130,14 @@ ol.renderer.dom.TileLayer.prototype.renderFrame =
       }
 
       allTilesLoaded = false;
-      tileGrid.forEachTileCoordParentTileRange(tile.tileCoord, findLoadedTiles);
+      fullyLoaded = tileGrid.forEachTileCoordParentTileRange(
+          tile.tileCoord, findLoadedTiles);
+      if (!fullyLoaded) {
+        childTileRange = tileGrid.getTileCoordChildTileRange(tile.tileCoord);
+        if (!goog.isNull(childTileRange)) {
+          findLoadedTiles(z + 1, childTileRange);
+        }
+      }
 
     }
 

src/ol/renderer/webgl/webgltilelayerrenderer.js

@@ -199,7 +199,7 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
         tilesToDrawByZ, getTileIfLoaded);
 
     var allTilesLoaded = true;
-    var tile, tileState, x, y;
+    var childTileRange, fullyLoaded, tile, tileState, x, y;
     for (x = tileRange.minX; x <= tileRange.maxX; ++x) {
       for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
 
@@ -216,8 +216,14 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
         }
 
         allTilesLoaded = false;
-        tileGrid.forEachTileCoordParentTileRange(
+        fullyLoaded = tileGrid.forEachTileCoordParentTileRange(
             tile.tileCoord, findLoadedTiles);
+        if (!fullyLoaded) {
+          childTileRange = tileGrid.getTileCoordChildTileRange(tile.tileCoord);
+          if (!goog.isNull(childTileRange)) {
+            findLoadedTiles(z + 1, childTileRange);
+          }
+        }
 
       }
 

src/ol/tilegrid/tilegrid.js

@@ -96,6 +96,7 @@ ol.tilegrid.TileGrid = function(options) {
  * @param {ol.TileCoord} tileCoord Tile coordinate.
  * @param {function(this: T, number, ol.TileRange): boolean} callback Callback.
  * @param {T=} opt_obj Object.
+ * @return {boolean} Callback succeeded.
  * @template T
  */
 ol.tilegrid.TileGrid.prototype.forEachTileCoordParentTileRange =
@@ -105,10 +106,11 @@ ol.tilegrid.TileGrid.prototype.forEachTileCoordParentTileRange =
   while (z >= 0) {
     if (callback.call(
         opt_obj, z, this.getTileRangeForExtentAndZ(tileCoordExtent, z))) {
-      return;
+      return true;
     }
     --z;
   }
+  return false;
 };
 
 
@@ -164,6 +166,21 @@ ol.tilegrid.TileGrid.prototype.getResolutions = function() {
 };
 
 
+/**
+ * @param {ol.TileCoord} tileCoord Tile coordinate.
+ * @return {ol.TileRange} Tile range.
+ */
+ol.tilegrid.TileGrid.prototype.getTileCoordChildTileRange =
+    function(tileCoord) {
+  if (tileCoord.z < this.resolutions_.length) {
+    var tileCoordExtent = this.getTileCoordExtent(tileCoord);
+    return this.getTileRangeForExtentAndZ(tileCoordExtent, tileCoord.z + 1);
+  } else {
+    return null;
+  }
+};
+
+
 /**
  * @param {number} z Z.
  * @param {ol.TileRange} tileRange Tile range.

src/ol/tilegrid/xyztilegrid.js

@@ -15,10 +15,16 @@ goog.require('ol.tilegrid.TileGrid');
  */
 ol.tilegrid.XYZ = function(options) {
 
-  var resolutions = new Array(options.maxZoom + 1);
+  /**
+   * @private
+   * @type {number}
+   */
+  this.maxZoom_ = options.maxZoom;
+
+  var resolutions = new Array(this.maxZoom_ + 1);
   var z;
   var size = 2 * ol.projection.EPSG3857.HALF_SIZE / ol.DEFAULT_TILE_SIZE;
-  for (z = 0; z <= options.maxZoom; ++z) {
+  for (z = 0; z <= this.maxZoom_; ++z) {
     resolutions[z] = size / Math.pow(2, z);
   }
 
@@ -33,6 +39,20 @@ ol.tilegrid.XYZ = function(options) {
 goog.inherits(ol.tilegrid.XYZ, ol.tilegrid.TileGrid);
 
 
+/**
+ * @inheritDoc
+ */
+ol.tilegrid.XYZ.prototype.getTileCoordChildTileRange = function(tileCoord) {
+  if (tileCoord.z < this.maxZoom_) {
+    return new ol.TileRange(
+        tileCoord.x << 1, tileCoord.y << 1,
+        tileCoord.x + 1 << 1, tileCoord.y + 1 << 1);
+  } else {
+    return null;
+  }
+};
+
+
 /**
  * @inheritDoc
  */
@@ -44,7 +64,8 @@ ol.tilegrid.XYZ.prototype.forEachTileCoordParentTileRange =
     tileRange.minX = tileRange.maxX >>= 1;
     tileRange.minY = tileRange.maxY >>= 1;
     if (callback.call(opt_obj, z, tileRange)) {
-      break;
+      return true;
     }
   }
+  return false;
 };