Merge pull request #13491 from ahocevar/map-loadstart-loadend

Add loadstart and loadend map events

examples/image-load-events.html

@@ -3,11 +3,13 @@ layout: example.html
 title: Image Load Events
 shortdesc: Example using image load events.
 docs: >
-  <p>Image sources fire events related to image loading.  You can
+  Image sources fire events related to image loading.  You can
   listen for <code>imageloadstart</code>, <code>imageloadend</code>,
   and <code>imageloaderror</code> type events to monitor image loading
   progress.  This example registers listeners for these events and
-  renders an image loading progress bar at the bottom of the map.</p>
+  renders an image loading progress bar at the bottom of the map. The
+  progress bar is shown and hidden according to the map's <code>loadstart</code>
+  and <code>loadend</code> events.
 tags: "image, events, loading"
 ---
 <div class="wrapper">

examples/image-load-events.js

@@ -18,9 +18,6 @@ function Progress(el) {
  * Increment the count of loading tiles.
  */
 Progress.prototype.addLoading = function () {
-  if (this.loading === 0) {
-    this.show();
-  }
   ++this.loading;
   this.update();
 };
@@ -29,11 +26,8 @@ Progress.prototype.addLoading = function () {
  * Increment the count of loaded tiles.
  */
 Progress.prototype.addLoaded = function () {
-  const this_ = this;
+  ++this.loaded;
-  setTimeout(function () {
+  this.update();
-    ++this_.loaded;
-    this_.update();
-  }, 100);
 };
 
 /**
@@ -42,14 +36,6 @@ Progress.prototype.addLoaded = function () {
 Progress.prototype.update = function () {
   const width = ((this.loaded / this.loading) * 100).toFixed(1) + '%';
   this.el.style.width = width;
-  if (this.loading === this.loaded) {
-    this.loading = 0;
-    this.loaded = 0;
-    const this_ = this;
-    setTimeout(function () {
-      this_.hide();
-    }, 500);
-  }
 };
 
 /**
@@ -63,10 +49,11 @@ Progress.prototype.show = function () {
  * Hide the progress bar.
  */
 Progress.prototype.hide = function () {
-  if (this.loading === this.loaded) {
+  const style = this.el.style;
-    this.el.style.visibility = 'hidden';
+  setTimeout(function () {
-    this.el.style.width = 0;
+    style.visibility = 'hidden';
-  }
+    style.width = 0;
+  }, 250);
 };
 
 const progress = new Progress(document.getElementById('progress'));
@@ -80,11 +67,7 @@ const source = new ImageWMS({
 source.on('imageloadstart', function () {
   progress.addLoading();
 });
-
+source.on(['imageloadend', 'imageloaderror'], function () {
-source.on('imageloadend', function () {
-  progress.addLoaded();
-});
-source.on('imageloaderror', function () {
   progress.addLoaded();
 });
 
@@ -96,3 +79,10 @@ const map = new Map({
     zoom: 4,
   }),
 });
+
+map.on('loadstart', function () {
+  progress.show();
+});
+map.on('loadend', function () {
+  progress.hide();
+});

examples/load-events.css

@@ -0,0 +1,30 @@
+.map {
+  background: #85ccf9;
+  position: relative;
+}
+#map {
+  height: 400px;
+  position: relative;
+}
+
+@keyframes spinner {
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.spinner:after {
+  content: "";
+  box-sizing: border-box;
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  width: 40px;
+  height: 40px;
+  margin-top: -20px;
+  margin-left: -20px;
+  border-radius: 50%;
+  border: 5px solid rgba(180, 180, 180, 0.6);
+  border-top-color: rgba(0, 0, 0, 0.6);
+  animation: spinner 0.6s linear infinite;
+}

examples/load-events.html

@@ -0,0 +1,13 @@
+---
+layout: example.html
+title: Loading Spinner
+shortdesc: Example using load events to show a loading spinner.
+docs: >
+  You can listen for the map's <code>loadstart</code> and <code>loadend</code> events
+  to show a loading spinner on top of the map.
+tags: "events, loading, spinner"
+cloak:
+  - key: pk.eyJ1IjoiYWhvY2V2YXIiLCJhIjoiY2t0cGdwMHVnMGdlbzMxbDhwazBic2xrNSJ9.WbcTL9uj8JPAsnT9mgb7oQ
+    value: Your Mapbox access token from https://mapbox.com/ here
+---
+<div id="map" class="map"></div>

examples/load-events.js

@@ -0,0 +1,31 @@
+import Map from '../src/ol/Map.js';
+import TileLayer from '../src/ol/layer/Tile.js';
+import View from '../src/ol/View.js';
+import XYZ from '../src/ol/source/XYZ.js';
+
+const key = 'get_your_own_D6rA4zTHduk6KOKTXzGB';
+const attributions =
+  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
+  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';
+
+const source = new XYZ({
+  attributions: attributions,
+  url: 'https://api.maptiler.com/maps/streets/{z}/{x}/{y}.png?key=' + key,
+  tileSize: 512,
+});
+
+const map = new Map({
+  layers: [new TileLayer({source: source})],
+  target: 'map',
+  view: new View({
+    center: [0, 0],
+    zoom: 2,
+  }),
+});
+
+map.on('loadstart', function () {
+  map.getTargetElement().classList.add('spinner');
+});
+map.on('loadend', function () {
+  map.getTargetElement().classList.remove('spinner');
+});

examples/tile-load-events.html

@@ -7,7 +7,9 @@ docs: >
   listen for <code>tileloadstart</code>, <code>tileloadend</code>,
   and <code>tileloaderror</code> type events to monitor tile loading
   progress.  This example registers listeners for these events and
-  renders a tile loading progress bar at the bottom of the map.</p>
+  renders a tile loading progress bar at the bottom of the map. The
+  progress bar is shown and hidden according to the map's <code>loadstart</code>
+  and <code>loadend</code> events.
 tags: "tile, events, loading"
 cloak:
   - key: pk.eyJ1IjoiYWhvY2V2YXIiLCJhIjoiY2t0cGdwMHVnMGdlbzMxbDhwazBic2xrNSJ9.WbcTL9uj8JPAsnT9mgb7oQ

examples/tile-load-events.js

@@ -18,9 +18,6 @@ function Progress(el) {
  * Increment the count of loading tiles.
  */
 Progress.prototype.addLoading = function () {
-  if (this.loading === 0) {
-    this.show();
-  }
   ++this.loading;
   this.update();
 };
@@ -29,11 +26,8 @@ Progress.prototype.addLoading = function () {
  * Increment the count of loaded tiles.
  */
 Progress.prototype.addLoaded = function () {
-  const this_ = this;
+  ++this.loaded;
-  setTimeout(function () {
+  this.update();
-    ++this_.loaded;
-    this_.update();
-  }, 100);
 };
 
 /**
@@ -42,14 +36,6 @@ Progress.prototype.addLoaded = function () {
 Progress.prototype.update = function () {
   const width = ((this.loaded / this.loading) * 100).toFixed(1) + '%';
   this.el.style.width = width;
-  if (this.loading === this.loaded) {
-    this.loading = 0;
-    this.loaded = 0;
-    const this_ = this;
-    setTimeout(function () {
-      this_.hide();
-    }, 500);
-  }
 };
 
 /**
@@ -63,10 +49,11 @@ Progress.prototype.show = function () {
  * Hide the progress bar.
  */
 Progress.prototype.hide = function () {
-  if (this.loading === this.loaded) {
+  const style = this.el.style;
-    this.el.style.visibility = 'hidden';
+  setTimeout(function () {
-    this.el.style.width = 0;
+    style.visibility = 'hidden';
-  }
+    style.width = 0;
+  }, 250);
 };
 
 const progress = new Progress(document.getElementById('progress'));
@@ -85,11 +72,7 @@ const source = new XYZ({
 source.on('tileloadstart', function () {
   progress.addLoading();
 });
-
+source.on(['tileloadend', 'tileloaderror'], function () {
-source.on('tileloadend', function () {
-  progress.addLoaded();
-});
-source.on('tileloaderror', function () {
   progress.addLoaded();
 });
 
@@ -101,3 +84,10 @@ const map = new Map({
     zoom: 2,
   }),
 });
+
+map.on('loadstart', function () {
+  progress.show();
+});
+map.on('loadend', function () {
+  progress.hide();
+});

src/ol/MapEventType.js

@@ -26,8 +26,22 @@ export default {
    * @api
    */
   MOVEEND: 'moveend',
+
+  /**
+   * Triggered when loading of additional map data (tiles, images, features) starts.
+   * @event module:ol/render/Event~RenderEvent#loadstart
+   * @api
+   */
+  LOADSTART: 'loadstart',
+
+  /**
+   * Triggered when loading of additional map data has completed.
+   * @event module:ol/render/Event~RenderEvent#loadend
+   * @api
+   */
+  LOADEND: 'loadend',
 };
 
 /***
- * @typedef {'postrender'|'movestart'|'moveend'} Types
+ * @typedef {'postrender'|'movestart'|'moveend'|'loadstart'|'loadend'} Types
  */

src/ol/PluggableMap.js

@@ -211,10 +211,16 @@ class PluggableMap extends BaseObject {
 
     /**
      * @private
-     * @type {boolean}
+     * @type {boolean|undefined}
      */
     this.renderComplete_;
 
+    /**
+     * @private
+     * @type {boolean}
+     */
+    this.loaded_ = true;
+
     /** @private */
     this.boundHandleBrowserEvent_ = this.handleBrowserEvent.bind(this);
 
@@ -1187,17 +1193,26 @@ class PluggableMap extends BaseObject {
       }
     }
 
-    if (
+    if (frameState && this.renderer_ && !frameState.animate) {
-      frameState &&
+      if (this.renderComplete_ === true) {
-      this.renderer_ &&
+        if (this.hasListener(RenderEventType.RENDERCOMPLETE)) {
-      this.hasListener(RenderEventType.RENDERCOMPLETE) &&
+          this.renderer_.dispatchRenderEvent(
-      !frameState.animate &&
+            RenderEventType.RENDERCOMPLETE,
-      this.renderComplete_
+            frameState
-    ) {
+          );
-      this.renderer_.dispatchRenderEvent(
+        }
-        RenderEventType.RENDERCOMPLETE,
+        if (this.loaded_ === false) {
-        frameState
+          this.loaded_ = true;
-      );
+          this.dispatchEvent(
+            new MapEvent(MapEventType.LOADEND, this, frameState)
+          );
+        }
+      } else if (this.loaded_ === true) {
+        this.loaded_ = false;
+        this.dispatchEvent(
+          new MapEvent(MapEventType.LOADSTART, this, frameState)
+        );
+      }
     }
 
     const postRenderFunctions = this.postRenderFunctions_;
@@ -1573,9 +1588,13 @@ class PluggableMap extends BaseObject {
     this.dispatchEvent(new MapEvent(MapEventType.POSTRENDER, this, frameState));
 
     this.renderComplete_ =
-      !this.tileQueue_.getTilesLoading() &&
+      this.hasListener(MapEventType.LOADSTART) ||
-      !this.tileQueue_.getCount() &&
+      this.hasListener(MapEventType.LOADEND) ||
-      !this.getLoadingOrNotReady();
+      this.hasListener(RenderEventType.RENDERCOMPLETE)
+        ? !this.tileQueue_.getTilesLoading() &&
+          !this.tileQueue_.getCount() &&
+          !this.getLoadingOrNotReady()
+        : undefined;
 
     if (!this.postRenderTimeoutHandle_) {
       this.postRenderTimeoutHandle_ = setTimeout(() => {

test/browser/spec/ol/Map.test.js

@@ -505,6 +505,97 @@ describe('ol/Map', function () {
     });
   });
 
+  describe('loadstart/loadend event sequence', function () {
+    let map;
+    beforeEach(function () {
+      const target = document.createElement('div');
+      target.style.width = '100px';
+      target.style.height = '100px';
+      document.body.appendChild(target);
+      map = new Map({
+        target: target,
+        layers: [
+          new TileLayer({
+            opacity: 0.5,
+            source: new XYZ({
+              url: 'spec/ol/data/osm-{z}-{x}-{y}.png',
+            }),
+          }),
+          new ImageLayer({
+            source: new ImageStatic({
+              url: 'spec/ol/data/osm-0-0-0.png',
+              imageExtent: getProjection('EPSG:3857').getExtent(),
+              projection: 'EPSG:3857',
+            }),
+          }),
+          new VectorLayer({
+            source: new VectorSource({
+              url: 'spec/ol/data/point.json',
+              format: new GeoJSON(),
+            }),
+          }),
+          new VectorLayer({
+            source: new VectorSource({
+              url: 'spec/ol/data/point.json',
+              format: new GeoJSON(),
+              strategy: tileStrategy(createXYZ()),
+            }),
+          }),
+          new VectorLayer({
+            source: new VectorSource({
+              features: [new Feature(new Point([0, 0]))],
+            }),
+          }),
+          new VectorLayer({
+            source: new VectorSource({
+              loader: function (extent, resolution, projection) {
+                this.addFeature(new Feature(new Point([0, 0])));
+              },
+            }),
+          }),
+          new WebGLPointsLayer({
+            source: new VectorSource({
+              features: [new Feature(new Point([0, 0]))],
+            }),
+            style: {
+              symbol: {
+                color: 'red',
+                symbolType: 'circle',
+              },
+            },
+          }),
+        ],
+      });
+    });
+
+    afterEach(function () {
+      document.body.removeChild(map.getTargetElement());
+      map.setTarget(null);
+      map.dispose();
+      map.getLayers().forEach((layer) => layer.dispose());
+    });
+
+    it('is a reliable start-end sequence', function (done) {
+      const layers = map.getLayers().getArray();
+      expect(layers[6].getRenderer().ready).to.be(false);
+      let loading = 0;
+      map.on('loadstart', () => {
+        map.getView().setZoom(0.1);
+        loading++;
+      });
+      map.on('loadend', () => {
+        expect(loading).to.be(1);
+        done();
+      });
+      map.setView(
+        new View({
+          center: [0, 0],
+          zoom: 0,
+        })
+      );
+    });
+  });
+
   describe('#getFeaturesAtPixel', function () {
     let target, map, layer;
     beforeEach(function () {