Re: [Qt-qml] Error with PropertyAction/SequentialAnimation/Timer

2010-12-08 Thread Mark Tucker 
Thanks,

That works!

The behaviour does seem slightly strange though - I would expect the JS 
function to complete and THEN have everything else updated, but as long as I 
know that this is the current behaviour I can create code accordingly.

Thanks again

Mark

-Original Message-
From: Adriano Rezende [mailto:adriano.reze...@openbossa.org] 
Sent: 07 December 2010 19:16
To: Mark Tucker
Cc: qt-qml@trolltech.com
Subject: Re: [Qt-qml] Error with PropertyAction/SequentialAnimation/Timer

On Tue, Dec 7, 2010 at 12:59 PM, Mark Tucker mark.tuc...@airborne.aero wrote:
        Timer {
                id: textTimer
                interval: 5000
                repeat: true
                running: true
                triggeredOnStart: true
                onTriggered: {
                        listIndex++;
                        if (listIndex = model.count) {
                                listIndex = 0;
                        }
                        //console.log(listIndex:  + listIndex + 
 count:  + model.count)
                        textAnimation.start();
                }
        }
 }
 For some reason the PropertyAction is being called when listIndex is 3
 and hence causes an error due to an undefined value. I'm failing to see
 how it should ever be the case that listIndex should be 3 when the
 PropertyAction does its thing though.

I believe QML will reevaluate a JS statement each time you change a
bindable property contained in that statement. So, even if the
animation is not running, model.get(listIndex).dataString will be
reevaluated when listIndex changes.
So, in order to solve this problem you can change the code below:

 listIndex++;
 if (listIndex = model.count) {
 listIndex = 0;
 }

for the following:

listIndex = (listIndex + 1) % model.count;

Br,
Adriano

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[Qt-qml] Error with PropertyAction/SequentialAnimation/Timer

2010-12-07 Thread Mark Tucker 
Hello,

I am trying to animate changing a string, by fading it out, changing it,
then fading it back in, but I'm having an issue with the way I am
populating the string, and I have no idea why. The following is an
example as simplified as I can get it that exhibits this error:

//ListIndexError.qml
import Qt 4.7
Rectangle {
width: 200
height: 200
property int listIndex: 0
ListModel {
id: model
ListElement{ dataString: String 1 }
ListElement{ dataString: String 2 }
ListElement{ dataString: String 3 }
}
Text {
id: textArea
anchors.centerIn: parent
}
SequentialAnimation {
id: textAnimation
//alwaysRunToEnd: true
NumberAnimation { target: textArea; property: opacity;
to: 0; duration: 250 }
PropertyAction { target: textArea; property: text;
value: { /*console.log(In PropertyAction  + listIndex:  + listIndex
+  count:  + model.count);*/ model.get(listIndex).dataString } }
NumberAnimation { target: textArea; property: opacity;
to: 1; duration: 250 }
}
Timer {
id: textTimer
interval: 5000
repeat: true
running: true
triggeredOnStart: true
onTriggered: {
listIndex++;
if (listIndex = model.count) {
listIndex = 0;
}
//console.log(listIndex:  + listIndex + 
count:  + model.count)
textAnimation.start();
}
}
}

I've commented out the two console.log entries above, which I am using
to try and figure out what is going on. Note that the behaviour observed
is the same with Qt 4.7.0 or 4.7.1.

The Timer fires every 5 seconds and in doing so increments the listIndex
property. It then checks to make sure that it is still valid by checking
it against model.count, if it's equal to or greater then that then it
resets it to 0. After that, still in the onTriggered handler, it then
starts the animation.

For some reason the PropertyAction is being called when listIndex is 3
and hence causes an error due to an undefined value. I'm failing to see
how it should ever be the case that listIndex should be 3 when the
PropertyAction does its thing though.

Am I missing something blatantly obvious here or is there a but in Qt
somewhere here?

Thanks


Mark Tucker




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Re: [Qt-qml] Error with PropertyAction/SequentialAnimation/Timer

2010-12-07 Thread Adriano Rezende 
On Tue, Dec 7, 2010 at 12:59 PM, Mark Tucker mark.tuc...@airborne.aero wrote:
        Timer {
                id: textTimer
                interval: 5000
                repeat: true
                running: true
                triggeredOnStart: true
                onTriggered: {
                        listIndex++;
                        if (listIndex = model.count) {
                                listIndex = 0;
                        }
                        //console.log(listIndex:  + listIndex + 
 count:  + model.count)
                        textAnimation.start();
                }
        }
 }
 For some reason the PropertyAction is being called when listIndex is 3
 and hence causes an error due to an undefined value. I'm failing to see
 how it should ever be the case that listIndex should be 3 when the
 PropertyAction does its thing though.

I believe QML will reevaluate a JS statement each time you change a
bindable property contained in that statement. So, even if the
animation is not running, model.get(listIndex).dataString will be
reevaluated when listIndex changes.
So, in order to solve this problem you can change the code below:

 listIndex++;
 if (listIndex = model.count) {
 listIndex = 0;
 }

for the following:

listIndex = (listIndex + 1) % model.count;

Br,
Adriano

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