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ScreenNavigator, StackScreenNavigator: added an experimental workarou…
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…nd for the issue where the first few frames of a transition can be skipped. the full animation is now visible even on slow mobile devices.
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@joshtynjala
joshtynjala committed Dec 18, 2014
1 parent 9c26e3c commit b37b803
Showing 1 changed file with 50 additions and 2 deletions.
52 changes: 50 additions & 2 deletions source/feathers/controls/supportClasses/BaseScreenNavigator.as
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Original file line number Diff line number Diff line change
Expand Up @@ -309,6 +309,16 @@ package feathers.controls.supportClasses
this.invalidate(INVALIDATION_FLAG_SIZE);
}

/**
* @private
*/
protected var _waitingTransition:Function;

/**
* @private
*/
private var _waitingForTransitionFrameCount:int = 1;

/**
* @private
*/
Expand Down Expand Up @@ -602,7 +612,14 @@ package feathers.controls.supportClasses
}
if(transition != null)
{
transition(this._previousScreenInTransition, this._activeScreen, transitionComplete);
//temporarily make the active screen invisible because the
//transition doesn't start right away.
this._activeScreen.visible = false;
this._waitingForTransitionFrameCount = 0;
this._waitingTransition = transition;
//this is a workaround for an issue with transition performance.
//see the comment in the listener for details.
this.addEventListener(Event.ENTER_FRAME, waitingForTransition_enterFrameHandler);
}
else
{
Expand Down Expand Up @@ -646,7 +663,12 @@ package feathers.controls.supportClasses
{
this.dispatchEventWith(FeathersEventType.TRANSITION_START);
this._previousScreenInTransition.dispatchEventWith(FeathersEventType.TRANSITION_OUT_START);
transition(this._previousScreenInTransition, null, transitionComplete);

this._waitingForTransitionFrameCount = 0;
this._waitingTransition = transition;
//this is a workaround for an issue with transition performance.
//see the comment in the listener for details.
this.addEventListener(Event.ENTER_FRAME, waitingForTransition_enterFrameHandler);
}
this.invalidate(INVALIDATION_FLAG_SELECTED);
}
Expand Down Expand Up @@ -764,5 +786,31 @@ package feathers.controls.supportClasses
{
this.invalidate(INVALIDATION_FLAG_SIZE);
}

/**
* @private
*/
private function waitingForTransition_enterFrameHandler(event:Event):void
{
//we need to wait a couple of frames before we can start the
//transition to make it as smooth as possible. this feels a little
//hacky, to be honest, but I can't figure out why waiting only one
//frame won't do the trick. the delay is so small though that it's
//virtually impossible to notice.
if(this._waitingForTransitionFrameCount < 2)
{
this._waitingForTransitionFrameCount++;
return;
}
this.removeEventListener(Event.ENTER_FRAME, waitingForTransition_enterFrameHandler);
if(this._activeScreen)
{
this._activeScreen.visible = true;
}

var transition:Function = this._waitingTransition;
this._waitingTransition = null;
transition(this._previousScreenInTransition, this._activeScreen, transitionComplete);
}
}
}

7 comments on commit b37b803

@harry248
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Makes a big difference. Thanks!

@harry248
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But now sometimes an exception is thrown because item equals null in line 734 of BaseScreenNavigator.

@joshtynjala
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I don't know how to reproduce that issue. Are you removing a screen? If so, when?

@apellerano-kong
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This commit causes my very first frame of stage3d drawing to be invisible. I was doing the trick where you draw a flash.display.Bitmap to the flash stage and then listen for Starling's Event.ROOT_CREATED to convert it into a starling.textures.Texture. The effect is a seamless transition from preloader image to the game's background image. With this commit there is exactly 1 frame of white flash while it waits for the ENTER_FRAME, which ruins the effect.

I could try and avoid the visibility toggle if I could set myScreenNavigator.transition = null, but if you try to set transition to null in ScreenNavigator it detects the null and assigns it defaultTransition() instead (which does nothing).

So there's not really a workaround for this right now other than to rollback to a previous commit.

@joshtynjala
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Thanks. I'll see what I can do.

@joshtynjala
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Okay, I just pushed some changes that should clear this up. If the transition is null, the ScreenNavigator won't wait for Event.ENTER_FRAME. There is no animation to optimize in that case, so it just shows the new screen instantly. That should once again allow for a preloader image while Starling initializes.

@apellerano-kong
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Works perfectly

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