$animator and ngShow: Initial state after route change

[olostan]

There was in issue #2309 about animations that are run on a elements that are hidden during initial load. And it was fixed in case if page is opened straight away.

But in case if some view is loaded with ngView after route change all animations that initially shouldn't be run are run...

Here is example: http://plnkr.co/edit/lOu6Np?p=preview

May be disable animations during route change?

[blob42]

+1

[olostan]

Updated to 1.2 RC ( http://plnkr.co/edit/lOu6Np?p=preview ).... seems much better.

The only problem that stays is a text that should be initially hidden is shown after route change and then quickly disappear (but without animation).

So this issue could be probably closed...

[matsko]

@olostan can you please try 1.2rc2. Some flicker-related fixes were merged in.

[olostan]

wow.... unfortunately it becomes even worse: http://plnkr.co/edit/lOu6Np?p=preview

in rc1 text that should initially hidden just flicked, but now it is animated... so looks like hiding animation was fired to the elements that were initially hidden... :(

[dfaivre]

Same behavior with ui-router.

[matsko]

Working on a fix for pre 1.2.

[matsko]

@olostan does this fix your problem fully? http://plnkr.co/edit/nBlXzb?p=preview. This one fixes ngShow.

Avoiding ng-hide animation during page load can only work if you apply an animation to the ngView element.

[olostan]

@matsko I see fading-out animation after route was changed.

The issue is that if initially (in controller or ng-init) the ngShow expression is false we shouldn't apply ng-show-remove etc classes so no animation should happen at all.

I've tried some solutions but didn't found ideal one: if to turn off animation during route change, then some nice features like animated highlighting current page in breadcrumb is gone. Other solution - to track is it initial value in ngShow's $watch (check for undefined of second paramter - old value) works good but looks like not so generic (actually I did a pull request with this solution). But now, as for me, it could be quite good workaround until there is another way to figure out is it initial state of expression or not.

[kevin-smets]

👍

[matsko]

@olostan thinking about animations for the first ngShow/ngHide digest change makes me believe there is no point in animating them. Only when they change. This typically doesn't follow the function of other directives, but if you think about it then you don't see ngInclude or ngRepeat "leaving" itself when the directive boots up. I'll update the plunkr shortly.

[olostan]

@matsko absolutely agree - there is no point of doing any initial animation: even if initial value of ngShow expression is true and it is inside some partial view, loaded by ngView/ngInclude, appearing animation should be responsibility of ngView/ngInclude.

So that is why my idea was in https://github.com/angular/angular.js/blob/master/src/ng/directive/ngShowHide.js#L148 to do something like

    scope.$watch(attr.ngShow, function ngShowWatchAction(value, oldValue){
      if (oldValue === undefined)
         // this is probably our first digest, so we shouldn't animate it
         element[toBoolean(value) ? 'removeClass' : 'addClass']('ng-hide');
      else
         $animate[toBoolean(value) ? 'removeClass' : 'addClass'](element, 'ng-hide');
    });

But I am not sure that we can trust this test of is it first digest or not. Or it is better to:

    var watcher = scope.$watch(attr.ngShow, function ngShowWatchFirstDigestAction(value){
         // Its our first digest, so we directly add class without animation
         element[toBoolean(value) ? 'removeClass' : 'addClass']('ng-hide');
         watcher(); // unregister
         scope.$watch(attr.ngShow, function ngShowWatchAction(value){
              $animate[toBoolean(value) ? 'removeClass' : 'addClass'](element, 'ng-hide');
         }); 
    });

[matsko]

Thanks @olostan for the code. This actually effects all inner animation directives (ngRepeat/ngInclude/ngSwitch/ngIf/ngShow/ngClass) so the solution is to automatically shim the ngView animation so that no other animations are rendered per view change (even if ngView doesn't have an animation). This means that only ngView and ngInclude need to be changed and not only ngShow.

I talked with @mhevery and we're working on the fix.

[olostan]

But as for ngView there could be quite usefull to have initial animation. For example on one of my projects ( http://gamme.co/ I use initial animation on ngView when you just open web site.

[matsko]

ngView will have it (but only when the route first changes not on bootstrap). This basically means that any top-level structural directive will (like ngInclude/ngSwitch/ngIf/ngView and ngRepeat) will stop child the animations temporarily whenever it does its thing (anything inside of those directives will be disabled until the compilation and digest loop are done).

Here's a grand demo (no animation present on ngView):
http://plnkr.co/edit/nBlXzb?p=preview

Here's a grand demo (animation is present on ngView):
http://plnkr.co/edit/YGmknb?p=preview