[Qt-interest] QTouchEvent/QGestureEvent propagation

[Wathek LOUED]

Sean there's a method of QObject : bool QObject::inherits ( const char
* className ) const that tells you if it inherits such class or not.

In my recognize() method it depends on the Gesture but if it's one finger
gesture I get all the touchpoints in a QList and if there are more than one
touchpoint I cancel that gesture.

For gestures with more than one finger I've always to check the number of
touchpoints that are on one Item. And for my TouchUpdate/TouchEnd I always
work with the saved touchpoints.

On Mon, Apr 11, 2011 at 4:02 PM, Sean Hayes <sean.t.hayes at vanderbilt.edu>wrote:

> That is an interesting idea. I have no experience using the QObject
> parameter in QGestreRecognizer::recognize(). How are you type checking to
> insure the object inherits QGraphicsObject? I would suggest using
> qobject_cast <http://doc.qt.nokia.com/latest/qobject.html#qobject_cast>instead of static_cast. What do you do differently within the recognize()
> method if the item is not a QGraphicsObject?
>
> On Mon, Apr 11, 2011 at 8:49 AM, Wathek LOUED <wathek at gmail.com> wrote:
>
>> I see Sean thank you so much I had found an other way but it doesn't work
>> very well. I thought that since I'm using QGraphicsView/QGrahicsScene and
>> QGraphicsObject I could try to cast the "object" in
>> QGestreRecognizer::recognize(QGesture *state, QObject *object, QEvent
>> *event)
>>
>> I try to do a static_cast<QGraphicsObject *>(object) and see if the item
>> inherits QGraphicsObject if so I get its scene and then I call the
>> QGraphicsScene::itemAt function with the QTouchPoint position and I check if
>> it's the same item as the casted object or not.
>>
>> And If the object doesn't inherits QGraphicsObject that means that it's
>> probably the scene or the view.
>>
>> But it seems that there's some fix to do cause it doesn't really work
>> well.
>>
>>
>> On Mon, Apr 11, 2011 at 3:47 AM, Sean Hayes <sean.t.hayes at vanderbilt.edu>wrote:
>>
>>> I agree, the order the events are received in within the QGraphicsView is
>>> counter intuitive.
>>>
>>> I had a problem similar to this a while ago and I think I solved it by
>>> adding a custom property to all my QGraphicsObjects (something link
>>> receiveNextGesture). Then within the items I only handled the gesture if
>>> that property was true. The property was set through my implementation of
>>> QGraphicsView::sceneEvent(). The pseudocode for the sceneEvent() function
>>> is:
>>>
>>> if the event is a QGestureEvent
>>>
>>> if the gesture has a hotspot
>>>
>>>  itemList = list of all items at the hotspot (see
>>> http://doc.qt.nokia.com/latest/qgraphicsview.html#items-2)
>>> if itemList.size() >= 1
>>>
>>>  itemList[0]->receiveNextGesture = true
>>>
>>> for all the rest of the items in the list
>>>
>>>  itemList[iter]->receiveNextGesture = false
>>>
>>>
>>> On Sun, Apr 10, 2011 at 3:33 PM, Wathek LOUED <wathek at gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I've noticed that the Events in Qt using the
>>>> QGraphicsView/QGraphicsScene/QGraphicsItem are spread from the QGraphicsView
>>>> then to the QGraphicsScene and the to the item that got the lowest Z-Index
>>>> to the most top item.
>>>>
>>>> I think that that's a bit weird cause generally when using QTouchEvent
>>>> and QGesture we look at the most top element so imagine that you programmed
>>>> a gesture and that that gesture occured at position (x, y) and in that
>>>> position there's 4 items that are grabbing the same gesture, so it'll be
>>>> grabbed by all the item and not the top element won't it ?
>>>>
>>>> I'm trying to find a way to make it grabbed by only the most top element
>>>> at the position (x, y) any one could help me for that please ?
>>>>
>>>> Thank you so much
>>>>
>>>> Sincerely
>>>> W.L
>>>>
>>>> _______________________________________________
>>>> Qt-interest mailing list
>>>> Qt-interest at qt.nokia.com
>>>> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
>>>>
>>>>
>>>
>>
>
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