Emit more useful data on plotly_animatingframe

Author: rreusser

src/plot_api/plot_api.js

@@ -2274,7 +2274,14 @@ Plotly.animate = function(gd, frameOrGroupNameOrFrameList, animationOpts) {
             var newFrame = trans._currentFrame = trans._frameQueue.shift();
 
             if(newFrame) {
-                gd.emit('plotly_animatingframe', newFrame.name);
+                gd.emit('plotly_animatingframe', {
+                    name: newFrame.name,
+                    frame: newFrame.frame,
+                    animation: {
+                        frame: newFrame.frameOpts,
+                        transition: newFrame.transitionOpts,
+                    }
+                });
 
                 trans._lastFrameAt = Date.now();
                 trans._timeToNext = newFrame.frameOpts.duration;

test/jasmine/tests/animate_test.js

@@ -409,8 +409,11 @@ describe('Test animate API', function() {
     describe('frame events', function() {
         it('emits an event when a frame is transitioned to', function(done) {
             var frames = [];
-            gd.on('plotly_animatingframe', function(name) {
-                frames.push(name);
+            gd.on('plotly_animatingframe', function(data) {
+                frames.push(data.name);
+                expect(data.frame).not.toBe(undefined);
+                expect(data.animation.frame).not.toBe(undefined);
+                expect(data.animation.transition).not.toBe(undefined);
             });
 
             Plotly.animate(gd, ['frame0', 'frame1', {name: 'test'}, {data: []}], {