[Qt-qml] Applying common behaviour to a group of elements

[alan.westbrook at nokia.com]

I'm not sure if there is an easy declarative way to do that.

You could probably write a javascript function that would take care of some of the typing, something like:

Component.onCompleted: {
	for(var i = 0; i < target_id_list.count(); ++i)
	{
		var obj = numberAnimationComponent.create(animations)
		obj.target = target_id_list[i]
		var pause = pauseAnimationComponent.create(animation)
	}           

	animations.start()
}

Probably best not to cut and paste that, my javascript skillz are lacking.

You could probably write a C++ class that iterates over all it's child items and does the same thing when it becomes visible, or some other method is called though.

HTH!
Alan


On Aug 4, 2010, at 11:42 AM, ext Alex wrote:

> Hi Alan,
> 
> Sorry for not being more clear.
> 
> I have a large number of pages, with each page containing several
> elements.  The "fading in" behaviour applies to the elements on a
> given page.
> 
> The large number of pages is my motivation for encapsulating this
> behaviour, so I don't have to re-implement it on every page.
> 
> For example, I currently have a page that has 4 elements, and I fade
> them in as follows:
> 
>    SequentialAnimation {
>        id: animations
>        NumberAnimation { target: e1; property: "opacity"; from: 0;
> to: 1; duration: 600 }
>        PauseAnimation { duration: 1000 }
>        NumberAnimation { target: e2; property: "opacity"; from: 0;
> to: 1; duration: 600 }
>        PauseAnimation { duration: 1000 }
>        NumberAnimation { target: e3; property: "opacity"; from: 0;
> to: 1; duration: 600 }
>        PauseAnimation { duration: 1000 }
>        NumberAnimation { target: e4; property: "opacity"; from: 0;
> to: 1; duration: 600 }
>    }
> 
> For this to work, I also set opacity to 0 in the definitions of e1,
> e2, e3, and e4.
> 
> If I were using an imperative language, I would do something like:
> 
> Fader fader;
> fader.setFadeDuration(600)
> fader.setPauseDuration(1000)
> fader.addElement(e1)
> fader.addElement(e2)
> etc
> fader.start()
> 
> Is there an idiomatic way to do something similar in QML?
> 
> Cheers,
> Alex
> 
> 
> 
> On Wed, Aug 4, 2010 at 11:24 AM,  <alan.westbrook at nokia.com> wrote:
>> So it's a slideshow and each element is a page, and you have hundreds of pages?
>> 
>> Or do you have a few pages each with a bunch of elements?
>> 
>> Or do you have hundreds of elements which pop in and out on a single page?
>> 
>> Depending on what you mean, you could try putting your elements in a model and iterating over them setting opacity. You can also use a Behavior on opacity to enable fade in and out in the element definition.
>> 
>> Or you can fade each page in and out, all child elements will follow the opacity of it's parent page.
>> 
>> Alan
>> 
>> On Aug 4, 2010, at 11:14 AM, ext Alex wrote:
>> 
>>> Hi all,
>>> 
>>> I am building an application that has a PowerPoint-like informational
>>> component. To this end, I have a bunch of QML files that display
>>> content progressively, with items fading in one at a time.
>>> 
>>> In my current implementation, I give each object an id and set opacity
>>> to 0. I then have a SequentialAnimation block that uses a
>>> PropertyAnimation, individually referencing each id, to bring the
>>> opacity to 1.
>>> 
>>> This approach works but it is suboptimal (from a development point of
>>> view), considering that I will have hundreds of these QML files. Is
>>> there a better way to abstract/automate this behaviour?
>>> 
>>> Thanks,
>>> Alex
>>> _______________________________________________
>>> Qt-qml mailing list
>>> Qt-qml at trolltech.com
>>> http://lists.trolltech.com/mailman/listinfo/qt-qml
>> 
>>