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Premptively load low resolution tiles

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This commit is contained in:
Tom Payne
2013-03-12 18:04:28 +01:00
parent e3abe376f1
commit 80df629319
6 changed files with 86 additions and 46 deletions
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11
src/ol/map.js
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@@ -484,9 +484,13 @@ ol.Map.prototype.getOverlayContainer = function() {
* @param {ol.Tile} tile Tile.
* @param {string} tileSourceKey Tile source key.
* @param {ol.Coordinate} tileCenter Tile center.
* @param {number} tileResolution Tile resolution.
* @return {number} Tile priority.
*/
ol.Map.prototype.getTilePriority = function(tile, tileSourceKey, tileCenter) {
ol.Map.prototype.getTilePriority =
function(tile, tileSourceKey, tileCenter, tileResolution) {
// Filter out tiles at higher zoom levels than the current zoom level, or that
// are outside the visible extent.
var frameState = this.frameState_;
if (goog.isNull(frameState) || !(tileSourceKey in frameState.wantedTiles)) {
return ol.TileQueue.DROP;
@@ -495,11 +499,14 @@ ol.Map.prototype.getTilePriority = function(tile, tileSourceKey, tileCenter) {
if (!frameState.wantedTiles[tileSourceKey][coordKey]) {
return ol.TileQueue.DROP;
}
// Prioritize tiles closest to the focus or center. The + 1 helps to
// prioritize tiles at higher zoom levels over tiles at lower zoom levels,
// even if the tile's center is close to the focus.
var focus = goog.isNull(this.focus_) ?
frameState.view2DState.center : this.focus_;
var deltaX = tileCenter.x - focus.x;
var deltaY = tileCenter.y - focus.y;
return deltaX * deltaX + deltaY * deltaY;
return tileResolution * (deltaX * deltaX + deltaY * deltaY + 1);
};