[Qt-interest] cannot grab gesture with qgraphicsobject

[Sean Hayes]

Wathek,

I would assume that this is a Qt bug then. I recommend creating a bug report
at http://bugreports.qt.nokia.com. I wish I could have been more help.

Sean

On Mon, Mar 14, 2011 at 5:21 AM, Wathek LOUED <wathek at gmail.com> wrote:

> Sean,
>
> Unfortunatly even using Qt 4.7.2 under GNU/Linux 64bits doesn't change
> anything. I still cannot grab gesture in QGraphicsObject.
>
> Using the example you sent to me I still getting the message
> QGestureManager::deliverEvent: could not find the target for gesture.
>
> Sincerely
> W.L
>
>
> On Fri, Mar 11, 2011 at 4:17 PM, Wathek LOUED <wathek at gmail.com> wrote:
>
>> 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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