[Qt-qml] Timer without animation ?

[michael.brasser at nokia.com]

Hi,

Only one default property is currently supported. Item works around this by having a single default property (data), that also assigns its values to either children or resources based on their type (e.g. when a Timer gets appended to the data property of Item, Item checks the type, and also appends to resources).

Regards,
Michael

On 11/01/2011, at 3:21 AM, ext mathias.malmqvist at nokia.com wrote:

> A related question; can you define several default properties for different types? 
> 
> The Item seems to have e.g. a list<Item> children and a list<Object> resources
> that are both default, no? But when I try to define more than one default property
> I get an error. 
> 
> Maybe this is another aspect of http://bugreports.qt.nokia.com/browse/QTBUG-15127
> or maybe it's just something you can't do in pure QML?
> 
> 
> Cheers
> Mathias
> 
> 
> ________________________________________
> From: qt-qml-bounces+mathias.malmqvist=nokia.com at qt.nokia.com [qt-qml-bounces+mathias.malmqvist=nokia.com at qt.nokia.com] on behalf of ext Gregory Schlomoff [gregory.schlomoff at gmail.com]
> Sent: Monday, January 10, 2011 10:46 AM
> To: Attila Csipa
> Cc: qt-qml at trolltech.com
> Subject: Re: [Qt-qml] Timer without animation ?
> 
> Hello,
> 
> The answer is yes.
> 
> One thing that QML developpers tend to forget easily is that nesting
> elements inside others is not a "native" feature of the language.
> Instead, it works through the default property mechanism.
> 
> Let's consider an example. When you write:
> 
> Rectangle {
>  Timer {...}
> }
> The QML engine actually interprets that as:
> Rectangle {
>  data: [
>   Timer {...}
>  ]
> }
> 
> But because "data" has been declared as the default property, you
> don't need to specify it. You just write your objects one inside the
> other.
> 
> "data" is a property of Item [1], and since all visual items inherit
> from Item, now you know why you can put a Timer inside any visual
> item. QtObject, on the other hand, has only one property: QString
> objectName. This is why you cannot put the timer inside it.
> 
> Now, if you want to put a Timer inside a QtObject, you at least two options :
> 
> === Option 1 : inside a dedicated property ===
> QtObject {
>  property Timer myTimer: Timer { ... }
> }
> 
> === Option 2 : inside a generic property ===
> QtObject {
>  property list<QtObject> data
>  data: [
>    Timer { id: myTimer; ... }
>  ]
> }
> 
> Etc...
> 
> The best solution would be to use the second case and to declare
> "data" as the default property, so that you actually get the same
> syntaxt as with visual items, but for some reason it's not working. I
> guess if you create your own QObject wrapper in C++ and declare the
> default property there, it will be ok.
> 
> Cheers,
> 
> Greg
> 
> [1] see: http://doc.qt.nokia.com/main-snapshot/qml-item.html
> On Mon, Jan 10, 2011 at 5:05 PM, Attila Csipa <qt at csipa.in.rs> wrote:
>> 
>> Is it possible to have a Timer without having a visual item that brings in the animation timer ? Think
>> 
>> QtObject {
>>    Component.onCompleted: console.log("hello world");
>>    Timer {
>>             interval: 500; running: true; repeat: true;
>>             onTriggered: console.log("tick");
>>    }
>> }
>> 
>> This gives somewhat cryptic Component is not ready error, but does work if I replace QtObject with Item. Now, you will be asking well, why don't you just use Item, and the answer is that it feels a bit weird - I'm experimenting with GUIless QML (think custom structured QtObject creation, textual UIs, etc).
>> 
>> Best regards,
>> Attila
>> 
>> _______________________________________________
>> Qt-qml mailing list
>> Qt-qml at qt.nokia.com
>> http://lists.qt.nokia.com/mailman/listinfo/qt-qml
>> 
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