Move tile specific methods to the tile layer renderer

src/ol/renderer/canvas/TileLayer.js

@@ -385,6 +385,47 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
     return /** @type {import("../../ImageTile.js").default} */ (tile).getImage();
   }
 
+  /**
+   * @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
+   * @param {import("../../source/Tile.js").default} tileSource Tile source.
+   * @protected
+   */
+  scheduleExpireCache(frameState, tileSource) {
+    if (tileSource.canExpireCache()) {
+      /**
+       * @param {import("../../source/Tile.js").default} tileSource Tile source.
+       * @param {import("../../PluggableMap.js").default} map Map.
+       * @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
+       */
+      const postRenderFunction = function(tileSource, map, frameState) {
+        const tileSourceKey = getUid(tileSource);
+        if (tileSourceKey in frameState.usedTiles) {
+          tileSource.expireCache(frameState.viewState.projection,
+            frameState.usedTiles[tileSourceKey]);
+        }
+      }.bind(null, tileSource);
+
+      frameState.postRenderFunctions.push(
+        /** @type {import("../../PluggableMap.js").PostRenderFunction} */ (postRenderFunction)
+      );
+    }
+  }
+
+  /**
+   * @param {!Object<string, !Object<string, boolean>>} usedTiles Used tiles.
+   * @param {import("../../source/Tile.js").default} tileSource Tile source.
+   * @param {import('../../Tile.js').default} tile Tile.
+   * @protected
+   */
+  updateUsedTiles(usedTiles, tileSource, tile) {
+    // FIXME should we use tilesToDrawByZ instead?
+    const tileSourceKey = getUid(tileSource);
+    if (!(tileSourceKey in usedTiles)) {
+      usedTiles[tileSourceKey] = {};
+    }
+    usedTiles[tileSourceKey][tile.getKey()] = true;
+  }
+
   /**
    * Check if the cache is big enough, and increase its size if necessary.
    * @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
@@ -405,6 +446,67 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
   }
 
   /**
+   * Manage tile pyramid.
+   * This function performs a number of functions related to the tiles at the
+   * current zoom and lower zoom levels:
+   * - registers idle tiles in frameState.wantedTiles so that they are not
+   *   discarded by the tile queue
+   * - enqueues missing tiles
+   * @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
+   * @param {import("../../source/Tile.js").default} tileSource Tile source.
+   * @param {import("../../tilegrid/TileGrid.js").default} tileGrid Tile grid.
+   * @param {number} pixelRatio Pixel ratio.
+   * @param {import("../../proj/Projection.js").default} projection Projection.
+   * @param {import("../../extent.js").Extent} extent Extent.
+   * @param {number} currentZ Current Z.
+   * @param {number} preload Load low resolution tiles up to 'preload' levels.
+   * @param {function(import("../../Tile.js").default)=} opt_tileCallback Tile callback.
+   * @protected
+   */
+  manageTilePyramid(
+    frameState,
+    tileSource,
+    tileGrid,
+    pixelRatio,
+    projection,
+    extent,
+    currentZ,
+    preload,
+    opt_tileCallback
+  ) {
+    const tileSourceKey = getUid(tileSource);
+    if (!(tileSourceKey in frameState.wantedTiles)) {
+      frameState.wantedTiles[tileSourceKey] = {};
+    }
+    const wantedTiles = frameState.wantedTiles[tileSourceKey];
+    const tileQueue = frameState.tileQueue;
+    const minZoom = tileGrid.getMinZoom();
+    let tile, tileRange, tileResolution, x, y, z;
+    for (z = minZoom; z <= currentZ; ++z) {
+      tileRange = tileGrid.getTileRangeForExtentAndZ(extent, z, tileRange);
+      tileResolution = tileGrid.getResolution(z);
+      for (x = tileRange.minX; x <= tileRange.maxX; ++x) {
+        for (y = tileRange.minY; y <= tileRange.maxY; ++y) {
+          if (currentZ - z <= preload) {
+            tile = tileSource.getTile(z, x, y, pixelRatio, projection);
+            if (tile.getState() == TileState.IDLE) {
+              wantedTiles[tile.getKey()] = true;
+              if (!tileQueue.isKeyQueued(tile.getKey())) {
+                tileQueue.enqueue([tile, tileSourceKey,
+                  tileGrid.getTileCoordCenter(tile.tileCoord), tileResolution]);
+              }
+            }
+            if (opt_tileCallback !== undefined) {
+              opt_tileCallback(tile);
+            }
+          } else {
+            tileSource.useTile(z, x, y, projection);
+          }
+        }
+      }
+    }
+  }
+
 }