getFeature() for VectorTile layer

examples/vector-tile-selection.js

@@ -45,26 +45,27 @@ const map = new Map({
 const selectElement = document.getElementById('type');
 
 map.on('click', function(event) {
-  const features = map.getFeaturesAtPixel(event.pixel);
-  if (!features) {
-    selection = {};
+  vtLayer.getFeatures(event.pixel).then(function(features) {
+    if (!features.length) {
+      selection = {};
+      // force redraw of layer style
+      vtLayer.setStyle(vtLayer.getStyle());
+      return;
+    }
+    const feature = features[0];
+    if (!feature) {
+      return;
+    }
+    const fid = feature.get(idProp);
+
+    if (selectElement.value === 'singleselect') {
+      selection = {};
+    }
+    // add selected feature to lookup
+    selection[fid] = feature;
+
     // force redraw of layer style
     vtLayer.setStyle(vtLayer.getStyle());
-    return;
-  }
-  const feature = features[0];
-  if (!feature) {
-    return;
-  }
+  });
 
-  const fid = feature.get(idProp);
-
-  if (selectElement.value === 'singleselect') {
-    selection = {};
-  }
-  // add selected feature to lookup
-  selection[fid] = feature;
-
-  // force redraw of layer style
-  vtLayer.setStyle(vtLayer.getStyle());
 });

src/ol/Tile.js

@@ -87,6 +87,11 @@ class Tile extends EventTarget {
 
     const options = opt_options ? opt_options : {};
 
+    /**
+     * @type {ImageData}
+     */
+    this.hitDetectionImageData = null;
+
     /**
      * @type {import("./tilecoord.js").TileCoord}
      */

src/ol/layer/VectorTile.js

@@ -116,6 +116,24 @@ class VectorTileLayer extends BaseVectorLayer {
     return new CanvasVectorTileLayerRenderer(this);
   }
 
+  /**
+   * Get the topmost feature that intersects the given pixel on the viewport. Returns a promise
+   * that resolves with an array of features. The array will either contain the topmost feature
+   * when a hit was detected, or it will be empty.
+   *
+   * The hit detection algorithm used for this method is optimized for performance, but is less
+   * accurate than the one used in {@link import("../PluggableMap.js").default#getFeaturesAtPixel}: Text
+   * is not considered, and icons are only represented by their bounding box instead of the exact
+   * image.
+   *
+   * @param {import("../pixel.js").Pixel} pixel Pixel.
+   * @return {Promise<Array<import("../Feature").default>>} Promise that resolves with an array of features.
+   * @api
+   */
+  getFeatures(pixel) {
+    return super.getFeatures(pixel);
+  }
+
   /**
    * @return {VectorTileRenderType} The render mode.
    */

src/ol/render/canvas/Immediate.js

@@ -980,8 +980,8 @@ export default CanvasImmediateRenderer;
  * @param {Array<import("../../transform.js").Transform>} transforms Transforms
  * for rendering features to all worlds of the viewport, from coordinates to css
  * pixels.
- * @param {Array<import("../../Feature.js").default>} features Features to consider.
- * for hit detection.
+ * @param {Array<import("../../Feature.js").FeatureLike>} features
+ * Features to consider for hit detection.
  * @param {import("../../style/Style.js").StyleFunction|undefined} styleFunction
  * Layer style function.
  * @param {import("../../extent.js").Extent} extent Extent.
@@ -1085,11 +1085,11 @@ export function createHitDetectionImageData(size, transforms, features, styleFun
 /**
  * @param {import("../../pixel").Pixel} pixel Pixel coordinate on the hit
  * detection canvas in css pixels.
- * @param {Array<import("../../Feature").default>} features Features. Has to
+ * @param {Array<import("../../Feature").FeatureLike>} features Features. Has to
  * match the `features` array that was passed to `createHitDetectionImageData()`.
  * @param {ImageData} imageData Hit detection image data generated by
  * `createHitDetectionImageData()`.
- * @return {Array<import("../../Feature").default>} features Features.
+ * @return {Array<import("../../Feature").FeatureLike>} features Features.
  */
 export function hitDetect(pixel, features, imageData) {
   const resultFeatures = [];

src/ol/renderer/canvas/TileLayer.js

@@ -35,6 +35,18 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
      */
     this.renderedExtent_ = null;
 
+    /**
+     * @protected
+     * @type {number}
+     */
+    this.renderedPixelRatio;
+
+    /**
+     * @protected
+     * @type {import("../../proj/Projection.js").default}
+     */
+    this.renderedProjection = null;
+
     /**
      * @protected
      * @type {number}
@@ -342,6 +354,8 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
     this.renderedResolution = tileResolution;
     this.extentChanged = !this.renderedExtent_ || !equals(this.renderedExtent_, canvasExtent);
     this.renderedExtent_ = canvasExtent;
+    this.renderedPixelRatio = pixelRatio;
+    this.renderedProjection = projection;
 
     this.manageTilePyramid(frameState, tileSource, tileGrid, pixelRatio,
       projection, extent, z, tileLayer.getPreload());

src/ol/renderer/canvas/VectorTileLayer.js

@@ -7,11 +7,12 @@ import TileState from '../../TileState.js';
 import ViewHint from '../../ViewHint.js';
 import {listen, unlistenByKey} from '../../events.js';
 import EventType from '../../events/EventType.js';
-import {buffer, containsCoordinate, equals, getIntersection, intersects} from '../../extent.js';
+import {buffer, containsCoordinate, equals, getIntersection, intersects, containsExtent, getWidth, getTopLeft} from '../../extent.js';
 import VectorTileRenderType from '../../layer/VectorTileRenderType.js';
 import ReplayType from '../../render/canvas/BuilderType.js';
 import CanvasBuilderGroup from '../../render/canvas/BuilderGroup.js';
 import CanvasTileLayerRenderer from './TileLayer.js';
+import {toSize} from '../../size.js';
 import {getSquaredTolerance as getSquaredRenderTolerance, renderFeature} from '../vector.js';
 import {
   apply as applyTransform,
@@ -25,6 +26,7 @@ import {
 } from '../../transform.js';
 import CanvasExecutorGroup, {replayDeclutter} from '../../render/canvas/ExecutorGroup.js';
 import {clear} from '../../obj.js';
+import {createHitDetectionImageData, hitDetect} from '../../render/canvas/Immediate.js';
 
 
 /**
@@ -99,6 +101,18 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
      */
     this.renderedLayerRevision_;
 
+    /**
+     * @private
+     * @type {import("../../transform").Transform}
+     */
+    this.renderedPixelToCoordinateTransform_ = null;
+
+    /**
+     * @private
+     * @type {number}
+     */
+    this.renderedRotation_;
+
     /**
      * @private
      * @type {!Object<string, import("../../VectorRenderTile.js").default>}
@@ -303,6 +317,7 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
       if (renderOrder && renderOrder !== builderState.renderedRenderOrder) {
         features.sort(renderOrder);
       }
+      sourceTile.hitDetectionImageData = null;
       for (let i = 0, ii = features.length; i < ii; ++i) {
         const feature = features[i];
         if (!bufferedExtent || intersects(bufferedExtent, feature.getGeometry().getExtent())) {
@@ -379,6 +394,69 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
     return found;
   }
 
+  /**
+   * @inheritDoc
+   */
+  getFeatures(pixel) {
+    return new Promise(function(resolve, reject) {
+      const layer = /** @type {import("../../layer/VectorTile.js").default} */ (this.getLayer());
+      const source = layer.getSource();
+      const projection = this.renderedProjection;
+      const projectionExtent = projection.getExtent();
+      const resolution = this.renderedResolution;
+      const pixelRatio = this.renderedPixelRatio;
+      const tileGrid = source.getTileGridForProjection(projection);
+      const sourceTileGrid = source.getTileGrid();
+      const coordinate = applyTransform(this.renderedPixelToCoordinateTransform_, pixel.slice());
+      const tileCoord = tileGrid.getTileCoordForCoordAndResolution(coordinate, resolution);
+      let sourceTile;
+      for (let i = 0, ii = this.renderedTiles.length; i < ii; ++i) {
+        if (tileCoord.toString() === this.renderedTiles[i].tileCoord.toString()) {
+          const tile = this.renderedTiles[i];
+          if (tile.getState() === TileState.LOADED && tile.hifi) {
+            const extent = tileGrid.getTileCoordExtent(tileCoord);
+            if (source.getWrapX() && projection.canWrapX() && !containsExtent(projectionExtent, extent)) {
+              const worldWidth = getWidth(projectionExtent);
+              const worldsAway = Math.floor((coordinate[0] - projectionExtent[0]) / worldWidth);
+              coordinate[0] -= (worldsAway * worldWidth);
+            }
+            const sourceTiles = source.getSourceTiles(pixelRatio, projection, tile);
+            const sourceTileCoord = sourceTileGrid.getTileCoordForCoordAndResolution(coordinate, resolution);
+            for (let j = 0, jj = sourceTiles.length; j < jj; ++j) {
+              if (sourceTileCoord.toString() === sourceTiles[j].tileCoord.toString()) {
+                sourceTile = sourceTiles[j];
+                break;
+              }
+            }
+          }
+          break;
+        }
+      }
+      const corner = getTopLeft(tileGrid.getTileCoordExtent(sourceTile.tileCoord));
+      const tilePixel = [
+        (coordinate[0] - corner[0]) / resolution,
+        (corner[1] - coordinate[1]) / resolution
+      ];
+      if (!sourceTile.hitDetectionImageData) {
+        const tileSize = toSize(sourceTileGrid.getTileSize(sourceTileGrid.getZForResolution(resolution)));
+        const size = [tileSize[0] / 2, tileSize[1] / 2];
+        const rotation = this.renderedRotation_;
+        const transforms = [
+          this.getRenderTransform(tileGrid.getTileCoordCenter(sourceTile.tileCoord),
+            resolution, 0, 0.5, size[0], size[1], 0)
+        ];
+        requestAnimationFrame(function() {
+          sourceTile.hitDetectionImageData = createHitDetectionImageData(tileSize, transforms,
+            sourceTile.getFeatures(), layer.getStyleFunction(),
+            tileGrid.getTileCoordExtent(sourceTile.tileCoord), resolution, rotation);
+          resolve(hitDetect(tilePixel, sourceTile.getFeatures(), sourceTile.hitDetectionImageData));
+        });
+      } else {
+        resolve(hitDetect(tilePixel, sourceTile.getFeatures(), sourceTile.hitDetectionImageData));
+      }
+    }.bind(this));
+  }
+
   /**
    * @inheritDoc
    */
@@ -408,6 +486,9 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
     this.renderQueuedTileImages_(hifi, frameState);
 
     super.renderFrame(frameState, target);
+    this.renderedPixelToCoordinateTransform_ = frameState.pixelToCoordinateTransform.slice();
+    this.renderedRotation_ = frameState.viewState.rotation;
+
 
     const layer = /** @type {import("../../layer/VectorTile.js").default} */ (this.getLayer());
     const renderMode = layer.getRenderMode();