Get simplified transformed geometry and load features in user projection

examples/geographic.js

@@ -1,22 +1,33 @@
 import {useGeographic} from '../src/ol/proj.js';
-import Map from '../src/ol/Map.js';
-import View from '../src/ol/View.js';
-import TileLayer from '../src/ol/layer/Tile.js';
-import OSM from '../src/ol/source/OSM.js';
+import {Map, View, Feature} from '../src/ol/index.js';
+import {Point} from '../src/ol/geom.js';
+import {Vector as VectorLayer, Tile as TileLayer} from '../src/ol/layer.js';
+import {OSM, Vector as VectorSource} from '../src/ol/source.js';
 
 useGeographic();
 
+const place = [-110, 45];
+
+const point = new Point(place);
+
 const map = new Map({
+  target: 'map',
+  view: new View({
+    center: place,
+    zoom: 8
+  }),
   layers: [
     new TileLayer({
       source: new OSM()
+    }),
+    new VectorLayer({
+      source: new VectorSource({
+        features: [
+          new Feature(point)
+        ]
+      })
     })
-  ],
-  target: 'map',
-  view: new View({
-    center: [-110, 45],
-    zoom: 8
-  })
+  ]
 });
 
 const info = document.getElementById('info');

rendering/cases/geometry-geographic/main.js

@@ -0,0 +1,43 @@
+import {Map, View, Feature} from '../../../src/ol/index.js';
+import {Point} from '../../../src/ol/geom.js';
+import {Tile as TileLayer, Vector as VectorLayer} from '../../../src/ol/layer.js';
+import {useGeographic} from '../../../src/ol/proj.js';
+import {XYZ, Vector as VectorSource} from '../../../src/ol/source.js';
+import {Style, Circle, Fill} from '../../../src/ol/style.js';
+
+useGeographic();
+
+const center = [8.6, 50.1];
+
+const point = new Point(center);
+
+new Map({
+  layers: [
+    new TileLayer({
+      source: new XYZ({
+        url: '/data/tiles/satellite/{z}/{x}/{y}.jpg',
+        transition: 0
+      })
+    }),
+    new VectorLayer({
+      source: new VectorSource({
+        features: [
+          new Feature(point)
+        ]
+      }),
+      style: new Style({
+        image: new Circle({
+          radius: 5,
+          fill: new Fill({color: 'red'})
+        })
+      })
+    })
+  ],
+  target: 'map',
+  view: new View({
+    center: center,
+    zoom: 3
+  })
+});
+
+render();

src/ol/functions.js

@@ -2,6 +2,8 @@
  * @module ol/functions
  */
 
+import {equals as arrayEquals} from './array.js';
+
 /**
  * Always returns true.
  * @returns {boolean} true.
@@ -24,3 +26,36 @@ export function FALSE() {
  * @return {void} Nothing.
  */
 export function VOID() {}
+
+/**
+ * Wrap a function in another function that remembers the last return.  If the
+ * returned function is called twice in a row with the same arguments and the same
+ * this object, it will return the value from the first call in the second call.
+ *
+ * @template ReturnType
+ * @template ThisType
+ * @param {function(this:ThisType, ...any):ReturnType} fn The function to memoize.
+ * @return {function(this:ThisType, ...any):ReturnType} The memoized function.
+ */
+export function memoizeOne(fn) {
+  let called = false;
+
+  /** @type ReturnType */
+  let lastResult;
+
+  /** @type Array<any> */
+  let lastArgs;
+
+  let lastThis;
+
+  return function() {
+    const nextArgs = Array.prototype.slice.call(arguments);
+    if (!called || this !== lastThis || !arrayEquals(nextArgs, lastArgs)) {
+      called = true;
+      lastThis = this;
+      lastArgs = nextArgs;
+      lastResult = fn.apply(this, arguments);
+    }
+    return lastResult;
+  };
+}

src/ol/geom/Geometry.js

@@ -5,10 +5,10 @@ import {abstract} from '../util.js';
 import BaseObject from '../Object.js';
 import {createEmpty, getHeight, returnOrUpdate} from '../extent.js';
 import {transform2D} from './flat/transform.js';
-import {get as getProjection, getTransform} from '../proj.js';
+import {get as getProjection, getTransform, getTransformFromProjections} from '../proj.js';
 import Units from '../proj/Units.js';
 import {create as createTransform, compose as composeTransform} from '../transform.js';
-
+import {memoizeOne} from '../functions.js';
 
 /**
  * @type {import("../transform.js").Transform}
@@ -63,6 +63,24 @@ class Geometry extends BaseObject {
      */
     this.simplifiedGeometryRevision = 0;
 
+    /**
+     * Get a transformed and simplified version of the geometry.
+     * @abstract
+     * @param {number} squaredTolerance Squared tolerance.
+     * @param {import("../proj/Projection.js").default} sourceProjection The source projection.
+     * @param {import("../proj/Projection.js").default} destProjection The destination projection.
+     * @return {Geometry} Simplified geometry.
+     */
+    this.simplifyTransformed = memoizeOne(function(squaredTolerance, sourceProjection, destProjection) {
+      if (!sourceProjection || !destProjection) {
+        return this.getSimplifiedGeometry(squaredTolerance);
+      }
+      const transform = getTransformFromProjections(sourceProjection, destProjection);
+      const clone = this.clone();
+      clone.applyTransform(transform);
+      return clone.getSimplifiedGeometry(squaredTolerance);
+    });
+
   }
 
   /**

src/ol/render/Feature.js

@@ -200,6 +200,18 @@ class RenderFeature {
     return this;
   }
 
+  /**
+   * Get a transformed and simplified version of the geometry.
+   * @abstract
+   * @param {number} squaredTolerance Squared tolerance.
+   * @param {import("../proj/Projection.js").default} sourceProjection The source projection.
+   * @param {import("../proj/Projection.js").default} destProjection The destination projection.
+   * @return {RenderFeature} Simplified geometry.
+   */
+  simplifyTransformed(squaredTolerance, sourceProjection, destProjection) {
+    return this;
+  }
+
   /**
    * Get the feature properties.
    * @return {Object<string, *>} Feature properties.

src/ol/renderer/canvas/VectorLayer.js

@@ -4,7 +4,7 @@
 import {getUid} from '../../util.js';
 import ViewHint from '../../ViewHint.js';
 import {buffer, createEmpty, containsExtent, getWidth, intersects as intersectsExtent} from '../../extent.js';
-import {fromUserExtent} from '../../proj.js';
+import {fromUserExtent, toUserExtent, getUserProjection} from '../../proj.js';
 import CanvasBuilderGroup from '../../render/canvas/BuilderGroup.js';
 import ExecutorGroup, {replayDeclutter} from '../../render/canvas/ExecutorGroup.js';
 import CanvasLayerRenderer from './Layer.js';
@@ -304,7 +304,12 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
       getRenderTolerance(resolution, pixelRatio), extent, resolution,
       pixelRatio, vectorLayer.getDeclutter());
 
-    vectorSource.loadFeatures(extent, resolution, projection);
+    const userProjection = getUserProjection();
+    if (userProjection) {
+      vectorSource.loadFeatures(toUserExtent(extent, projection), resolution, userProjection);
+    } else {
+      vectorSource.loadFeatures(extent, resolution, projection);
+    }
 
     const squaredTolerance = getSquaredRenderTolerance(resolution, pixelRatio);
 
@@ -319,15 +324,16 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
         styles = styleFunction(feature, resolution);
       }
       if (styles) {
-        const dirty = this.renderFeature(feature, squaredTolerance, styles, replayGroup);
+        const dirty = this.renderFeature(feature, squaredTolerance, styles, replayGroup, projection);
         this.dirty_ = this.dirty_ || dirty;
       }
     }.bind(this);
 
+    const userExtent = toUserExtent(extent, projection);
     if (vectorLayerRenderOrder) {
       /** @type {Array<import("../../Feature.js").default>} */
       const features = [];
-      vectorSource.forEachFeatureInExtent(extent,
+      vectorSource.forEachFeatureInExtent(userExtent,
         /**
          * @param {import("../../Feature.js").default} feature Feature.
          */
@@ -339,7 +345,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
         render(features[i]);
       }
     } else {
-      vectorSource.forEachFeatureInExtent(extent, render);
+      vectorSource.forEachFeatureInExtent(userExtent, render);
     }
 
     const replayGroupInstructions = replayGroup.finish();
@@ -362,9 +368,10 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
    * @param {number} squaredTolerance Squared render tolerance.
    * @param {import("../../style/Style.js").default|Array<import("../../style/Style.js").default>} styles The style or array of styles.
    * @param {import("../../render/canvas/BuilderGroup.js").default} builderGroup Builder group.
+   * @param {import("../../proj/Projection.js").default} projection The view projection.
    * @return {boolean} `true` if an image is loading.
    */
-  renderFeature(feature, squaredTolerance, styles, builderGroup) {
+  renderFeature(feature, squaredTolerance, styles, builderGroup, projection) {
     if (!styles) {
       return false;
     }
@@ -373,12 +380,12 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
       for (let i = 0, ii = styles.length; i < ii; ++i) {
         loading = renderFeature(
           builderGroup, feature, styles[i], squaredTolerance,
-          this.boundHandleStyleImageChange_) || loading;
+          this.boundHandleStyleImageChange_, projection) || loading;
       }
     } else {
       loading = renderFeature(
         builderGroup, feature, styles, squaredTolerance,
-        this.boundHandleStyleImageChange_);
+        this.boundHandleStyleImageChange_, projection);
     }
     return loading;
   }

src/ol/renderer/vector.js

@@ -5,6 +5,7 @@ import {getUid} from '../util.js';
 import ImageState from '../ImageState.js';
 import GeometryType from '../geom/GeometryType.js';
 import BuilderType from '../render/canvas/BuilderType.js';
+import {getUserProjection} from '../proj.js';
 
 
 /**
@@ -92,10 +93,11 @@ function renderCircleGeometry(builderGroup, geometry, style, feature) {
  * @param {import("../style/Style.js").default} style Style.
  * @param {number} squaredTolerance Squared tolerance.
  * @param {function(import("../events/Event.js").default): void} listener Listener function.
+ * @param {import("../proj/Projection.js").default} projection The view projection.
  * @return {boolean} `true` if style is loading.
  * @template T
  */
-export function renderFeature(replayGroup, feature, style, squaredTolerance, listener) {
+export function renderFeature(replayGroup, feature, style, squaredTolerance, listener, projection) {
   let loading = false;
   const imageStyle = style.getImage();
   if (imageStyle) {
@@ -111,7 +113,7 @@ export function renderFeature(replayGroup, feature, style, squaredTolerance, lis
       loading = true;
     }
   }
-  renderFeatureInternal(replayGroup, feature, style, squaredTolerance);
+  renderFeatureInternal(replayGroup, feature, style, squaredTolerance, projection);
 
   return loading;
 }
@@ -122,13 +124,14 @@ export function renderFeature(replayGroup, feature, style, squaredTolerance, lis
  * @param {import("../Feature.js").FeatureLike} feature Feature.
  * @param {import("../style/Style.js").default} style Style.
  * @param {number} squaredTolerance Squared tolerance.
+ * @param {import("../proj/Projection.js").default} projection The view projection.
  */
-function renderFeatureInternal(replayGroup, feature, style, squaredTolerance) {
+function renderFeatureInternal(replayGroup, feature, style, squaredTolerance, projection) {
   const geometry = style.getGeometryFunction()(feature);
   if (!geometry) {
     return;
   }
-  const simplifiedGeometry = geometry.getSimplifiedGeometry(squaredTolerance);
+  const simplifiedGeometry = geometry.simplifyTransformed(squaredTolerance, getUserProjection(), projection);
   const renderer = style.getRenderer();
   if (renderer) {
     renderGeometry(replayGroup, simplifiedGeometry, style, feature);

test/spec/ol/functions.test.js

@@ -0,0 +1,61 @@
+import {memoizeOne} from '../../../src/ol/functions.js';
+
+
+describe('ol/functions', function() {
+
+  describe('memoizeOne()', function() {
+    it('returns the result from the first call when called a second time with the same args', function() {
+      const arg1 = {};
+      const arg2 = {};
+      const arg3 = {};
+      function call(a1, a2, a3) {
+        return {};
+      }
+      const memoized = memoizeOne(call);
+      const result = memoized(arg1, arg2, arg3);
+      expect(memoized(arg1, arg2, arg3)).to.be(result);
+    });
+
+    it('returns the result from the first call when called a second time with the same this object', function() {
+      const arg1 = {};
+      const arg2 = {};
+      const arg3 = {};
+      function call(a1, a2, a3) {
+        return {};
+      }
+      const memoized = memoizeOne(call);
+
+      const thisObj = {};
+
+      const result = memoized.call(thisObj, arg1, arg2, arg3);
+      expect(memoized.call(thisObj, arg1, arg2, arg3)).to.be(result);
+    });
+
+    it('returns a different result when called a second time with the different args', function() {
+      const arg1 = {};
+      const arg2 = {};
+      const arg3 = {};
+      function call(a1, a2, a3) {
+        return {};
+      }
+      const memoized = memoizeOne(call);
+      const result = memoized(arg1, arg2, arg3);
+      expect(memoized(arg3, arg2, arg1)).not.to.be(result);
+    });
+
+    it('returns a different result when called a second time with a different this object', function() {
+      const arg1 = {};
+      const arg2 = {};
+      const arg3 = {};
+      function call(a1, a2, a3) {
+        return {};
+      }
+      const firstThis = {};
+      const secondThis = {};
+      const memoized = memoizeOne(call);
+      const result = memoized.call(firstThis, arg1, arg2, arg3);
+      expect(memoized.call(secondThis, arg1, arg2, arg3)).not.to.be(result);
+    });
+  });
+
+});