Merge pull request #6890 from ahocevar/movestart

Add a movestart event

src/ol/map.js

@@ -210,7 +210,7 @@ ol.Map = function(options) {
    * @private
    * @type {ol.Extent}
    */
-  this.previousExtent_ = ol.extent.createEmpty();
+  this.previousExtent_ = null;
 
   /**
    * @private
@@ -1200,6 +1200,7 @@ ol.Map.prototype.renderFrame_ = function(time) {
   var size = this.getSize();
   var view = this.getView();
   var extent = ol.extent.createEmpty();
+  var previousFrameState = this.frameState_;
   /** @type {?olx.FrameState} */
   var frameState = null;
   if (size !== undefined && ol.size.hasArea(size) && view && view.isDef()) {
@@ -1249,7 +1250,19 @@ ol.Map.prototype.renderFrame_ = function(time) {
     Array.prototype.push.apply(
         this.postRenderFunctions_, frameState.postRenderFunctions);
 
-    var idle = !frameState.viewHints[ol.ViewHint.ANIMATING] &&
+    if (previousFrameState) {
+      var moveStart = !this.previousExtent_ ||
+          (!ol.extent.isEmpty(this.previousExtent_) &&
+          !ol.extent.equals(frameState.extent, this.previousExtent_));
+      if (moveStart) {
+        this.dispatchEvent(
+            new ol.MapEvent(ol.MapEventType.MOVESTART, this, previousFrameState));
+        this.previousExtent_ = ol.extent.createOrUpdateEmpty(this.previousExtent_);
+      }
+    }
+
+    var idle = this.previousExtent_ &&
+        !frameState.viewHints[ol.ViewHint.ANIMATING] &&
         !frameState.viewHints[ol.ViewHint.INTERACTING] &&
         !ol.extent.equals(frameState.extent, this.previousExtent_);
 

src/ol/mapeventtype.js

@@ -12,6 +12,13 @@ ol.MapEventType = {
    */
   POSTRENDER: 'postrender',
 
+  /**
+   * Triggered when the map starts moving.
+   * @event ol.MapEvent#movestart
+   * @api
+   */
+  MOVESTART: 'movestart',
+
   /**
    * Triggered after the map is moved.
    * @event ol.MapEvent#moveend

test/spec/ol/map.test.js

@@ -99,7 +99,7 @@ describe('ol.Map', function() {
     });
   });
 
-  describe('moveend event', function() {
+  describe('movestart/moveend event', function() {
 
     var target, view, map;
 
@@ -135,13 +135,18 @@ describe('ol.Map', function() {
       document.body.removeChild(target);
     });
 
-    it('is fired only once after view changes', function(done) {
+    it('are fired only once after view changes', function(done) {
       var center = [10, 20];
       var zoom = 3;
-      var calls = 0;
+      var startCalls = 0;
+      var endCalls = 0;
+      map.on('movestart', function() {
+        ++startCalls;
+        expect(startCalls).to.be(1);
+      });
       map.on('moveend', function() {
-        ++calls;
-        expect(calls).to.be(1);
+        ++endCalls;
+        expect(endCalls).to.be(1);
         expect(view.getCenter()).to.eql(center);
         expect(view.getZoom()).to.be(zoom);
         window.setTimeout(done, 1000);
@@ -151,6 +156,31 @@ describe('ol.Map', function() {
       view.setZoom(zoom);
     });
 
+    it('are fired in sequence', function(done) {
+      view.setCenter([0, 0]);
+      view.setResolution(0.703125);
+      map.renderSync();
+      var center = [10, 20];
+      var zoom = 3;
+      var calls = [];
+      map.on('movestart', function(e) {
+        calls.push('start');
+        expect(calls).to.eql(['start']);
+        expect(e.frameState.viewState.center).to.eql([0, 0]);
+        expect(e.frameState.viewState.resolution).to.be(0.703125);
+      });
+      map.on('moveend', function() {
+        calls.push('end');
+        expect(calls).to.eql(['start', 'end']);
+        expect(view.getCenter()).to.eql(center);
+        expect(view.getZoom()).to.be(zoom);
+        done();
+      });
+
+      view.setCenter(center);
+      view.setZoom(zoom);
+    });
+
   });
 
   describe('#forEachLayerAtPixel()', function()  {