[Qt-interest] cannot grab gesture with qgraphicsobject

[Wathek LOUED]

Sean,

I just tried your code and with Qt 4.6.3 and Debian 6.0 I'm
getting QGestureManager::deliverEvent: could not find the target for gesture
when I tap on the button but outside the button (on QGraphicsView) it works.
But not with the QGraphicsObject.

I'm downloading the sources of Qt 4.7.2 I'd like to try with that.

Thank you

On Fri, Mar 11, 2011 at 4:06 PM, Wathek LOUED <wathek at gmail.com> wrote:

> Sean,
>
> I'm giving your code a try. I'm using Debian Squeeze with Qt 4.6.3.
>
>
> On Fri, Mar 11, 2011 at 3:50 PM, Sean Hayes <sean.t.hayes at vanderbilt.edu>wrote:
>
>> Wathek,
>>
>> When I try the code I am getting gesture events in the
>> QGraphicsObject/PushButtonItem. The state of these gesture events are
>> Qt::GestureStarted. Also, I am no longer getting the "QGestureManager::deliverEvent:
>> could not find the target for gesture" error.
>>
>> I am using Windows 7 and Qt 4.7.2. What is your setup? Attached is my
>> example program based on your code. Let me know if that example works on
>> your system.
>>
>> Sean
>>
>>
>> On Fri, Mar 11, 2011 at 5:11 AM, Wathek LOUED <wathek at gmail.com> wrote:
>>
>>> Sean,
>>>
>>> I'm sorry but your changes doesn't make any difference. But there's one
>>> thing that I don't understand why do the QGesture::state() doesn't change ?
>>> it's always the same equal to 0 which mean NoGesture.
>>>
>>>
>>> On Thu, Mar 10, 2011 at 6:22 PM, Wathek LOUED <wathek at gmail.com> wrote:
>>>
>>>> Hi Sean,
>>>>
>>>> Thank you for your reponse I'm trying that and I'll tell you if it's Ok.
>>>>
>>>> Thank you so much.
>>>>
>>>> Sincerely
>>>> Wathek
>>>>
>>>>
>>>> On Thu, Mar 10, 2011 at 5:17 PM, Sean Hayes <
>>>> sean.t.hayes at vanderbilt.edu> wrote:
>>>>
>>>>> The problem is that in your TabGestureRecognizer you are setting the
>>>>> result to canceled for gestures that have not been triggered (e.g.,
>>>>> non-touch events). Note the changes I made to your recognize() function
>>>>> below. Also, note that you do not need the mouse event code there.
>>>>>
>>>>> QGestureRecognizer::Result TapGestureRecognizer::recognize(QGesture
>>>>> *state, QObject *, QEvent *event)
>>>>> {
>>>>>  TapGesture *q = static_cast<TapGesture *>(state);
>>>>> const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);
>>>>>  QGestureRecognizer::Result result = *QGestureRecognizer::Ignore*;
>>>>>
>>>>> switch (event->type()) {
>>>>>  case QEvent::TouchBegin: {
>>>>> q->setPosition(ev->touchPoints().at(0).pos());
>>>>>  q->setHotSpot(ev->touchPoints().at(0).screenPos());
>>>>> q->start();
>>>>>  result = QGestureRecognizer::MayBeGesture;
>>>>> break;
>>>>>  }
>>>>> case QEvent::TouchUpdate:
>>>>>  case QEvent::TouchEnd: {
>>>>> if (ev->touchPoints().size() == 1) {
>>>>>  QTouchEvent::TouchPoint p = ev->touchPoints().at(0);
>>>>> QPoint delta = p.pos().toPoint() - p.startPos().toPoint();
>>>>>  if (delta.manhattanLength() <= Delta && q->elapsed() <= TimerInterval
>>>>> && event->type() == QEvent::TouchEnd)
>>>>>  result = QGestureRecognizer::TriggerGesture;
>>>>> else* if(q->state() == Qt::GestureUpdated || q->state() ==
>>>>> Qt::GestureStarted)*
>>>>>  result = QGestureRecognizer::CancelGesture;
>>>>> }
>>>>>  break;
>>>>> }
>>>>>  }
>>>>> return result;
>>>>>  }
>>>>>
>>>>> On Wed, Mar 9, 2011 at 10:34 AM, Wathek LOUED <wathek at gmail.com>wrote:
>>>>>
>>>>>> Hi Till,
>>>>>>
>>>>>> Thank you for your response I've already seen your bug post but
>>>>>> unfortunatly that doesn't help. Here are some part of my code :
>>>>>>
>>>>>> *gesturerecognizer class :*
>>>>>> *
>>>>>> *
>>>>>> #ifndef GESTURERECOGNIZER_H
>>>>>> #define GESTURERECOGNIZER_H
>>>>>>
>>>>>> #include "tapgesture.h"
>>>>>> #include "tapandholdgesture.h"
>>>>>>
>>>>>> #include <QGestureRecognizer>
>>>>>> #include <QGesture>
>>>>>> #include <QEvent>
>>>>>> #include <QObject>
>>>>>> #include <QHash>
>>>>>>
>>>>>> class TapGestureRecognizer: public QGestureRecognizer
>>>>>> {
>>>>>> public:
>>>>>> TapGestureRecognizer();
>>>>>>  QGesture *create(QObject *target);
>>>>>> QGestureRecognizer::Result recognize(QGesture *state, QObject
>>>>>> *watched, QEvent *event);
>>>>>>  void reset(QGesture *state);
>>>>>> private:
>>>>>> enum { TimerInterval = 400  };
>>>>>> enum { Delta = 20 };
>>>>>>  QHash<long, TapGesture *> touchPoints;
>>>>>> };
>>>>>> #endif
>>>>>>
>>>>>> #include "gesturerecognizer.h"
>>>>>>
>>>>>> #include <QWidget>
>>>>>> #include <QTouchEvent>
>>>>>> #include <QDebug>
>>>>>> /*******************************************************
>>>>>>  * TapGesture Recognizer
>>>>>>  *******************************************************/
>>>>>> TapGestureRecognizer::TapGestureRecognizer()
>>>>>> {}
>>>>>>
>>>>>> QGesture *TapGestureRecognizer::create(QObject *target)
>>>>>> {
>>>>>> if (target && target->isWidgetType())
>>>>>>  static_cast<QWidget
>>>>>> *>(target)->setAttribute(Qt::WA_AcceptTouchEvents);
>>>>>> return new TapGesture;
>>>>>> }
>>>>>>
>>>>>> QGestureRecognizer::Result TapGestureRecognizer::recognize(QGesture
>>>>>> *state, QObject *, QEvent *event)
>>>>>> {
>>>>>> TapGesture *q = static_cast<TapGesture *>(state);
>>>>>>  const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);
>>>>>> QGestureRecognizer::Result result = QGestureRecognizer::CancelGesture;
>>>>>>
>>>>>> switch (event->type()) {
>>>>>> case QEvent::TouchBegin: {
>>>>>> q->setPosition(ev->touchPoints().at(0).pos());
>>>>>>  q->setHotSpot(ev->touchPoints().at(0).screenPos());
>>>>>> q->start();
>>>>>> result = QGestureRecognizer::MayBeGesture;
>>>>>>  break;
>>>>>> }
>>>>>> case QEvent::TouchUpdate:
>>>>>> case QEvent::TouchEnd: {
>>>>>>  if (ev->touchPoints().size() == 1) {
>>>>>> QTouchEvent::TouchPoint p = ev->touchPoints().at(0);
>>>>>> QPoint delta = p.pos().toPoint() - p.startPos().toPoint();
>>>>>>  if (delta.manhattanLength() <= Delta && q->elapsed() <=
>>>>>> TimerInterval && event->type() == QEvent::TouchEnd)
>>>>>> result = QGestureRecognizer::TriggerGesture;
>>>>>>  else
>>>>>> result = QGestureRecognizer::CancelGesture;
>>>>>> }
>>>>>>  break;
>>>>>> }
>>>>>> case QEvent::MouseButtonPress:
>>>>>> case QEvent::MouseMove:
>>>>>>  case QEvent::MouseButtonRelease: {
>>>>>> result = QGestureRecognizer::Ignore;
>>>>>> break;
>>>>>>  }
>>>>>> default: {
>>>>>> result = QGestureRecognizer::Ignore;
>>>>>>  break;
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> return result;
>>>>>> }
>>>>>>
>>>>>> void TapGestureRecognizer::reset(QGesture *state)
>>>>>> {
>>>>>> TapGesture *q = static_cast<TapGesture *>(state);
>>>>>> q->setPosition(QPointF());
>>>>>>  QGestureRecognizer::reset(state);
>>>>>> }
>>>>>>
>>>>>>
>>>>>> *My QGraphicsView class :*
>>>>>> *
>>>>>> *
>>>>>> #ifndef FRMACCUEIL_H
>>>>>> #define FRMACCUEIL_H
>>>>>>
>>>>>> #include "gesture/gesturerecognizer.h"
>>>>>>
>>>>>> #include <QGraphicsView>
>>>>>> #include <QGraphicsScene>
>>>>>> #include <QGestureEvent>
>>>>>> #include <QEvent>
>>>>>> #include <QTouchEvent>
>>>>>> #include <QHash>
>>>>>>
>>>>>> class FrmAccueil: public QGraphicsView
>>>>>> {
>>>>>> Q_OBJECT
>>>>>> public:
>>>>>> FrmAccueil(QGraphicsScene *scene=0, QWidget *parent=0);
>>>>>> bool viewportEvent(QEvent *event);
>>>>>>
>>>>>> private:
>>>>>> void gestureEvent(QGestureEvent *event);
>>>>>> Qt::GestureType tapGesture;
>>>>>>  TapGestureRecognizer *tapGestureRecognizer;
>>>>>> };
>>>>>>
>>>>>> #endif
>>>>>>
>>>>>> #include "frmaccueil.h"
>>>>>>
>>>>>> #include <QDebug>
>>>>>> #include <QGestureRecognizer>
>>>>>>
>>>>>> FrmAccueil::FrmAccueil(QGraphicsScene *scene, QWidget *parent)
>>>>>>    :QGraphicsView(scene, parent)
>>>>>>  {
>>>>>> tapGestureRecognizer = new TapGestureRecognizer();
>>>>>>
>>>>>> tapGesture =
>>>>>> QGestureRecognizer::registerRecognizer(tapGestureRecognizer);
>>>>>>
>>>>>>         viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
>>>>>> viewport()->grabGesture(tapGesture);
>>>>>> }
>>>>>>
>>>>>>  bool FrmAccueil::viewportEvent(QEvent *event)
>>>>>> {
>>>>>> if (event->type() == QEvent::Gesture)
>>>>>> gestureEvent(static_cast<QGestureEvent*>(event));
>>>>>>
>>>>>> return QGraphicsView::viewportEvent(event);
>>>>>> }
>>>>>>
>>>>>> void FrmAccueil::gestureEvent(QGestureEvent *event)
>>>>>> {
>>>>>>  if (event->gesture(tapGesture))
>>>>>> qDebug("TAP GESTURE");
>>>>>> }
>>>>>>
>>>>>> *My QGraphicsScene class:*
>>>>>>
>>>>>> #ifndef PUSHBUTTONITEM_H
>>>>>> #define PUSHBUTTONITEM_H
>>>>>>
>>>>>> #include "gesture/gesturerecognizer.h"
>>>>>>
>>>>>> #include <QGraphicsObject>
>>>>>> #include <QEvent>
>>>>>> #include <QGestureEvent>
>>>>>> #include <QPixmap>
>>>>>> #include <QPainter>
>>>>>>
>>>>>> class PushButtonItem:public QGraphicsObject
>>>>>> {
>>>>>> Q_OBJECT
>>>>>> public:
>>>>>> enum ShapeMode {
>>>>>> MaskShape,
>>>>>> BoundingRectShape,
>>>>>>  HeuristicMaskShape
>>>>>> };
>>>>>>
>>>>>> PushButtonItem(QGraphicsItem *parent=0);
>>>>>>  QPainterPath shape() const;
>>>>>>
>>>>>> /* QGraphicsPixmapItem */
>>>>>> QPixmap pixmap() const;
>>>>>>  void setPixmap(const QPixmap &pixmap);
>>>>>>
>>>>>> Qt::TransformationMode transformationMode() const;
>>>>>>  void setTransformationMode(Qt::TransformationMode transformation);
>>>>>>
>>>>>> QRectF boundingRect() const;
>>>>>>  void paint(QPainter *painter, const QStyleOptionGraphicsItem
>>>>>> *option, QWidget *widget=0);
>>>>>>
>>>>>> protected:
>>>>>> bool sceneEvent(QEvent *event);
>>>>>>
>>>>>> private:
>>>>>> void gestureEvent(QGestureEvent *event);
>>>>>>
>>>>>> ButtonType type;
>>>>>>
>>>>>> QList<GraphicsLineItem *> edgeList;
>>>>>>  TapGestureRecognizer *tapGestureRecognizer;
>>>>>> Qt::GestureType tapGesture;
>>>>>>
>>>>>> // QGraphicsPixmapItem
>>>>>> QPixmap pix;
>>>>>> bool hasShape;
>>>>>>  Qt::TransformationMode transfMode;
>>>>>> };
>>>>>>
>>>>>> #endif
>>>>>>
>>>>>> #include "pushbuttonitem.h"
>>>>>>
>>>>>> #include <QPixmap>
>>>>>>
>>>>>> #include <QDebug>
>>>>>> #include <QTouchEvent>
>>>>>> #include <QGestureRecognizer>
>>>>>>
>>>>>> PushButtonItem::PushButtonItem(QGraphicsItem *parent)
>>>>>>        :QGraphicsObject(parent)
>>>>>> {
>>>>>> setFlags(QGraphicsItem::ItemIsMovable |
>>>>>> QGraphicsItem::ItemSendsGeometryChanges);
>>>>>>
>>>>>> setTransformationMode(Qt::SmoothTransformation);
>>>>>>   setAcceptTouchEvents(true);
>>>>>>
>>>>>> tapGestureRecognizer = new TapGestureRecognizer();
>>>>>>  tapGesture =
>>>>>> QGestureRecognizer::registerRecognizer(tapGestureRecognizer);
>>>>>>
>>>>>> grabGesture(tapGesture);
>>>>>> }
>>>>>>
>>>>>> QPainterPath PushButtonItem::shape() const
>>>>>> { return QGraphicsItem::shape();     }
>>>>>>
>>>>>> bool PushButtonItem::sceneEvent(QEvent *event)
>>>>>> {
>>>>>> qDebug("Event received");
>>>>>> if (event->type() == QEvent::Gesture)
>>>>>>  gestureEvent(static_cast<QGestureEvent *>(event));
>>>>>> return true;
>>>>>>
>>>>>> }
>>>>>>
>>>>>> void PushButtonItem::gestureEvent(QGestureEvent *event)
>>>>>> {
>>>>>> if (event->gesture(tapGesture))
>>>>>> qDebug("button Tapped");
>>>>>> }
>>>>>>
>>>>>> /***************************************************************
>>>>>>  * QGraphicsPixmapItem Reimplementation
>>>>>>  ***************************************************************/
>>>>>>
>>>>>>
>>>>>> I cannot really see where's the problem the QGraphicsView receive the
>>>>>> gestureEvent but not the QGraphicsObject.
>>>>>>
>>>>>>
>>>>>> Thank you so much
>>>>>>
>>>>>> Sincerely
>>>>>> W.L
>>>>>>
>>>>>> On Mon, Mar 7, 2011 at 11:02 PM, Till Oliver Knoll <
>>>>>> till.oliver.knoll at gmail.com> wrote:
>>>>>>
>>>>>>> Am 07.03.11 19:31, schrieb Wathek LOUED:
>>>>>>>  > Hi,
>>>>>>>  >
>>>>>>>  > I got a problem with QGraphicsObject, I cannot grab gesture and
>>>>>>> I'm
>>>>>>>  > getting this message : QGestureManager::deliverEvent: could not
>>>>>>> find the
>>>>>>>  > target for gesture.
>>>>>>>
>>>>>>> My experience up to Qt 4.7.1 is that QGestures are not as "mature" as
>>>>>>> one would wish, especially on Mac.
>>>>>>>
>>>>>>> I had a somewhat similar issue that Pan gesture would not get through
>>>>>>> to
>>>>>>> QGraphicsObjects in a QGraphicsScene. It turned out that this is a
>>>>>>> "design issue" (how Gestures are implemented respective how items in
>>>>>>> a
>>>>>>> scene deal with events) and won't be fixed:
>>>>>>>
>>>>>>>   http://bugreports.qt.nokia.com/browse/QTBUG-16618
>>>>>>>
>>>>>>> There is an example attached which shows how gestures SHOULD work
>>>>>>> with
>>>>>>> QGraphicsObjects. Note that up to Qt 4.6.x also the QGraphicsView
>>>>>>> (the
>>>>>>> view widget thereof!) had to grab the same gestures as the item
>>>>>>> itself.
>>>>>>> This should not be necessary anymore with Qt 4.7.x.
>>>>>>>
>>>>>>> So in my case the QGraphicsObject did not receive Pan gesture events
>>>>>>> (only the "start" event, but never the "update" or "end" events).
>>>>>>> Never
>>>>>>> tried "Tab" events, but I got "pinch" (zoom/rotate) to work.
>>>>>>>
>>>>>>> But just now I am investigating another issue: it seems that the
>>>>>>> value of
>>>>>>>
>>>>>>>  http://doc.trolltech.com/4.7/qpinchgesture.html#scaleFactor-prop
>>>>>>>
>>>>>>> returns different signed values on Mac and Windows 7. I developped my
>>>>>>> app on Mac and implemented my "zoom" in such a way that when moving
>>>>>>> the
>>>>>>> fingers apart the object would get bigger.
>>>>>>>
>>>>>>> A quick test on some netbook and laptop running Windows 7 revealed
>>>>>>> that
>>>>>>> the "zoom" would work the other way (the object was scaled down
>>>>>>> instead
>>>>>>> of scaled up). So I assume it is the sign which is different on Mac
>>>>>>> and
>>>>>>> Windows 7 (= bug). But again, I did not have the opportunity yet to
>>>>>>> reproduce this behaviour with debugging possibilities.
>>>>>>>
>>>>>>>
>>>>>>> Hope that gives you some pointers,
>>>>>>>   Oliver
>>>>>>> _______________________________________________
>>>>>>> Qt-interest mailing list
>>>>>>> Qt-interest at qt.nokia.com
>>>>>>> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
>>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Qt-interest mailing list
>>>>>> Qt-interest at qt.nokia.com
>>>>>> http://lists.qt.nokia.com/mailman/listinfo/qt-interest
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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