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Qt 5.0.2 & 5.1.0 Drag and Drop crash

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  • S Offline
    S Offline
    SoulSharer
    wrote on last edited by
    #2

    Added additional information, spent a day debugging, still out of luck. :(

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    • S Offline
      S Offline
      SoulSharer
      wrote on last edited by
      #3

      -Finally managed to temporary fix this issue with-
      @setAttribute(Qt::WA_DontCreateNativeAncestors, true); @
      -Just in case someone will run into the same problem.-

      Was wrong, still the same thing..

      P.s. I updated to 5.0.2 and it didn't help

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      • B Offline
        B Offline
        bodzio131
        wrote on last edited by
        #4

        Hi,
        Could you load *.pdb files for Qt binaries and then provide callstack?
        As far as I can see you use visual leak detector (vld_x86.dll). Do you encounter your problems without it?
        Could you try to build your program on linux and use valgrind?

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        • raven-worxR Offline
          raven-worxR Offline
          raven-worx
          Moderators
          wrote on last edited by
          #5

          can you show some lines of code ... or even share your project for inspection?

          --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
          If you have a question please use the forum so others can benefit from the solution in the future

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          • S Offline
            S Offline
            SoulSharer
            wrote on last edited by
            #6

            Thanks for replies guys, I did try to turn off visual leak detector (and it is off by default in release) - same situation and I don't have a chance to build it on Linux I'm afraid. (mostly because I depend on Microsofts stuff, like DirectX for example)

            Not sure where would I get .pdb files for binaries, other than by compiling myself which is a pain for Qt 5 with this new libraries (icu, angle) as far as I see.

            [quote author="raven-worx" date="1365878204"]can you show some lines of code ... or even share your project for inspection?[/quote]
            There is a lot of code and a lot of unrelated to the issue (also it is a closed project so I can't open the whole thing to the public, even if I want to), so I can only provide small snippets from it I guess, not sure what is need though. So I will post what I'm doing with drag and drop.

            Starting with (SpriteDBList : QListWidget):
            @void SpriteDBList::mousePressEvent( QMouseEvent *event )
            {
            QListWidget::mousePressEvent(event);

            if (this->selectedItems().count() == 0) return;

            if (event->button() == Qt::LeftButton)
            dragStartPosition = event->pos();
            }

            void SpriteDBList::mouseMoveEvent( QMouseEvent *event )
            {
            if (selectedItems().count() == 0 || !(event->buttons() & Qt::LeftButton) || (event->pos() - dragStartPosition).manhattanLength()
            < QApplication::startDragDistance())
            {
            QListWidget::mouseMoveEvent(event);
            return;
            }

            if (!currentItem()) {
            return;
            }

            seString spriteFrameName = currentItem()->text().toStdString();
            seString spriteFrameFullPath = m_dbWidget->GetCurrentDir() + "\" + spriteFrameName;

            QDrag *drag = new QDrag(this);
            QMimeData *mimeData = new QMimeData();
            QByteArray data(spriteFrameFullPath.c_str());
            mimeData->setData("joi/spriteframe_path", data);
            drag->setMimeData(mimeData);
            drag->setPixmap(currentItem()->icon().pixmap(80, 80)); //icon with which we will move
            drag->setHotSpot(QPoint(drag->pixmap().width()/2,
            drag->pixmap().height()/2)); //where our cursor will be relative to topleft of pixmap

            Qt::DropAction dropAction = drag->exec(Qt::CopyAction, Qt::CopyAction);
            }
            @
            and ending in (AnimationFrameTable : QTableWidget):
            @
            void AnimationFrameTable::dragEnterEvent(QDragEnterEvent *event) {
            Qt::DropAction action = event->proposedAction();

            if (action == Qt::IgnoreAction) {
            event->ignore();
            return;
            }

            QObject* source = event->source();

            if (event->mimeData() == NULL) {
            event->ignore();
            return;
            } else {
            const QMimeData* mime = event->mimeData();

            if (mime->hasFormat("joi/spriteframe_path")) {
            event->accept(); //looks like crash happens after this line
            } else {
            event->ignore();
            }
            }
            }

            void AnimationFrameTable::dragMoveEvent(QDragMoveEvent *e) {
            Qt::DropAction action = e->proposedAction();
            if (action == Qt::IgnoreAction) {
            e->ignore();
            return;
            }

            QObject* source = e->source();
            const QMimeData* mime = e->mimeData();
            if (mime == NULL) {
            e->ignore();
            } else if (mime->hasFormat("joi/spriteframe_path")) {
            e->accept();
            } else {
            e->ignore();
            }
            }

            void AnimationFrameTable::dropEvent(QDropEvent *event) {
            Qt::DropAction action = event->proposedAction();
            if (action == Qt::IgnoreAction) {
            event->ignore();
            return;
            }

            if (event->mimeData() == NULL || !event->mimeData()->hasFormat("joi/spriteframe_path")) {
            event->ignore();
            return;
            }

            QByteArray data = event->mimeData()->data("joi/spriteframe_path");
            QString fullpath = data;
            m_animWindow->AddSpriteFrame(fullpath.toStdString());

            event->accept();
            }@

            There are a lot of checks just because I wanted to nail down the issue, still didn't help at all.
            I checked everything in what I've posted. For example I commented strings just to see whether it is a heap corruption and passed mimeData with empty QByteArray, didn't help either.

            And it crashes before it gets to dropEvent() function as I've mentioned before

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            • S Offline
              S Offline
              SoulSharer
              wrote on last edited by
              #7

              Ok, I've managed to load in .pdb and here is a callstack, now it looks useful:

              Updated callstacks:
              http://i.imgur.com/BAoL8mC.png
              http://i.imgur.com/XIEbyvp.png

              and where it stopped
              http://i.imgur.com/BJdc8SP.png

              • looks like scoped pointer was destroyed or something
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              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #8

                Hi,

                Hope you don't mind me asking that, but would aren't you reinventing the wheel ? Drag and Drop support are already supported in QTableWidget and QListWidget.

                You might better go overloading "QTableWidget::dropMimeData":http://qt-project.org/doc/qt-4.8/qtablewidget.html#dropMimeData and "QListWidget::mimeData":http://qt-project.org/doc/qt-4.8/qlistwidget.html#mimeData

                You would then only have to care about your data.

                Hope it helps

                Interested in AI ? www.idiap.ch
                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                • S Offline
                  S Offline
                  SoulSharer
                  wrote on last edited by
                  #9

                  [quote author="SGaist" date="1365890494"]Hi,

                  Hope you don't mind me asking that, but would aren't you reinventing the wheel ? Drag and Drop support are already supported in QTableWidget and QListWidget.

                  You might better go overloading "QTableWidget::dropMimeData":http://qt-project.org/doc/qt-4.8/qtablewidget.html#dropMimeData and "QListWidget::mimeData":http://qt-project.org/doc/qt-4.8/qlistwidget.html#mimeData

                  You would then only have to care about your data.

                  Hope it helps[/quote]

                  Didn't know about that, thanks. I might use it for most of the stuff, but I still want to find out what's wrong with current code if possible.

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                  • raven-worxR Offline
                    raven-worxR Offline
                    raven-worx
                    Moderators
                    wrote on last edited by
                    #10

                    This code looks good so far ... the problem must be somewhere else.

                    --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                    If you have a question please use the forum so others can benefit from the solution in the future

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                    • B Offline
                      B Offline
                      bodzio131
                      wrote on last edited by
                      #11

                      Do you manage QObject descendants by yourself? Maybe you delete such objects directly (instead of deleteLater) or you use smart pointers with such objects. It could be a real problem if you interfere with Qt objects management model.

                      I think you need to narrow your project by cutting whatever you can step by step, or try to use the same drag-drop logic in simpler app. However, I suppose the problem can be far away from part which shows crash :(

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                      • S Offline
                        S Offline
                        SoulSharer
                        wrote on last edited by
                        #12

                        Thanks for the help.

                        [quote author="Bogdan" date="1365933102"]Do you manage QObject descendants by yourself? Maybe you delete such objects directly (instead of deleteLater) or you use smart pointers with such objects. It could be a real problem if you interfere with Qt objects management model.

                        I think you need to narrow your project by cutting whatever you can step by step, or try to use the same drag-drop logic in simpler app. However, I suppose the problem can be far away from part which shows crash :([/quote]

                        No I don't manage anything related to QObject myself and don't use smart pointers at all. The maximum I do is subclassing existing widgets to reimplement drag and drop actions.

                        And yeah I will try to cut it into something testable.

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                        • S Offline
                          S Offline
                          SoulSharer
                          wrote on last edited by
                          #13

                          For some reason in notifyInternal() receiver is NULL (0) after dropping, which causes all of this. Still trying to recreate this issue.

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                          • raven-worxR Offline
                            raven-worxR Offline
                            raven-worx
                            Moderators
                            wrote on last edited by
                            #14

                            this means that you probably deleting objects before the drag has finished.
                            Or creating them on the wrong storage location (e.g. stack).

                            --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                            If you have a question please use the forum so others can benefit from the solution in the future

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                            • S Offline
                              S Offline
                              SoulSharer
                              wrote on last edited by
                              #15

                              Thing is I don't allocate on stack or delete them at all, my windows are allocated on heap and are not deleted until main window closes.
                              -Checked it once more, everything alright

                              Could it be because of some broken relationship between QMainWindows or QWidgets?

                              And Dropping does work if I don't do it fast, if I do it fast it gets reciever that is null and so it crashes.

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                              • raven-worxR Offline
                                raven-worxR Offline
                                raven-worx
                                Moderators
                                wrote on last edited by
                                #16

                                Hard to tell if you can't show more code...

                                --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                                If you have a question please use the forum so others can benefit from the solution in the future

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                                • S Offline
                                  S Offline
                                  SoulSharer
                                  wrote on last edited by
                                  #17

                                  Never mind, thanks for help anyway.

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                                  • W Offline
                                    W Offline
                                    wizzhard
                                    wrote on last edited by
                                    #18

                                    Hello,

                                    I also experience a crash during drag n drop with the very same callstack after the crash.

                                    In my case the crash occurs in a qtreeview when i drag n drop item internally.

                                    In fact everything works fine until I double click an item of the view to rename it.

                                    1 - I fill the item delegate with the new name
                                    2 - Press enter to validate
                                    3 - setData of the model is called (but does nothing).
                                    4 - I try to drag & drop an item
                                    5 - dragEnterEvent is called once.
                                    6 - dragMoveEvent is called once
                                    7 - program crash in QScopedPointer line134

                                    @0 QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >::data qscopedpointer.h 134 0x651f1d4a
                                    1 qGetPtrHelper<QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> > > qglobal.h 991 0x651df58b
                                    2 QObject::d_func qobject.h 119 0x651f0323
                                    3 QCoreApplication::notifyInternal qcoreapplication.cpp 764 0x65468230
                                    4 QCoreApplication::sendSpontaneousEvent qcoreapplication.h 206 0x65577098
                                    5 QWidgetWindow::handleDropEvent qwidgetwindow.cpp 566 0x65d3e759
                                    6 QWidgetWindow::event qwidgetwindow.cpp 195 0x65d3d30c
                                    7 QApplicationPrivate::notify_helper qapplication.cpp 3398 0x65cc291e
                                    8 QApplication::notify qapplication.cpp 2829 0x65cc035a
                                    9 QCoreApplication::notifyInternal qcoreapplication.cpp 767 0x65468264
                                    10 QCoreApplication::sendEvent qcoreapplication.h 203 0x6546d5e9
                                    11 QGuiApplicationPrivate::processDrop qguiapplication.cpp 2228 0x66673045
                                    12 QWindowSystemInterface::handleDrop qwindowsysteminterface.cpp 556 0x6665860c
                                    13 QWindowsOleDropTarget::Drop qwindowsdrag.cpp 683 0x64eef4dd
                                    14 CPrivDragDrop::PrivDragDrop getif.cxx 960 0x770f2b79
                                    15 PrivDragDrop getif.cxx 1099 0x770f2d78
                                    16 CDropTarget::Drop drag.cpp 2492 0x770ca04d
                                    17 CDragOperation::CompleteDrop drag.cpp 1601 0x770c9ede
                                    18 DoDragDrop drag.cpp 1964 0x770ca8dd
                                    19 QWindowsDrag::drag qwindowsdrag.cpp 802 0x64eef9fa
                                    20 QDragManager::drag qdnd.cpp 143 0x666831c8
                                    21 QDrag::exec qdrag.cpp 282 0x66681daa
                                    22 QAbstractItemView::startDrag qabstractitemview.cpp 3581 0x65faf1a5
                                    23 QAbstractItemView::mouseMoveEvent qabstractitemview.cpp 1761 0x65fa9d9b
                                    24 QTreeView::mouseMoveEvent qtreeview.cpp 1924 0x65ff6a8b
                                    25 QWidget::event qwidget.cpp 7842 0x65d0a0ed
                                    26 QFrame::event qframe.cpp 534 0x65e67772
                                    27 QAbstractScrollArea::viewportEvent qabstractscrollarea.cpp 1163 0x65f089c4
                                    28 QAbstractItemView::viewportEvent qabstractitemview.cpp 1680 0x65fa971b
                                    29 QTreeView::viewportEvent qtreeview.cpp 1260 0x65ff3ece
                                    30 QAbstractScrollAreaPrivate::viewportEvent qabstractscrollarea_p.h 105 0x65caaf28
                                    31 QAbstractScrollAreaFilter::eventFilter qabstractscrollarea_p.h 121 0x65f0a919
                                    32 QCoreApplicationPrivate::sendThroughObjectEventFilters qcoreapplication.cpp 863 0x654684f3
                                    33 QApplicationPrivate::notify_helper qapplication.cpp 3394 0x65cc2902
                                    34 QApplication::notify qapplication.cpp 2962 0x65cc098c
                                    35 QCoreApplication::notifyInternal qcoreapplication.cpp 767 0x65468264
                                    36 QCoreApplication::sendSpontaneousEvent qcoreapplication.h 206 0x65577098
                                    37 QApplicationPrivate::sendMouseEvent qapplication.cpp 2469 0x65cbfab5
                                    38 QWidgetWindow::handleMouseEvent qwidgetwindow.cpp 403 0x65d3dd00
                                    39 QWidgetWindow::event qwidgetwindow.cpp 155 0x65d3d274
                                    40 QApplicationPrivate::notify_helper qapplication.cpp 3398 0x65cc291e
                                    41 QApplication::notify qapplication.cpp 2829 0x65cc035a
                                    42 QCoreApplication::notifyInternal qcoreapplication.cpp 767 0x65468264
                                    43 QCoreApplication::sendSpontaneousEvent qcoreapplication.h 206 0x65577098
                                    44 QGuiApplicationPrivate::processMouseEvent qguiapplication.cpp 1417 0x6666ffe4
                                    45 QGuiApplicationPrivate::processWindowSystemEvent qguiapplication.cpp 1249 0x6666f852
                                    46 QWindowSystemInterface::sendWindowSystemEventsImplementation qwindowsysteminterface.cpp 536 0x66658561
                                    47 QWindowSystemInterface::sendWindowSystemEvents qwindowsysteminterface.cpp 516 0x666584e9
                                    48 QWindowsGuiEventDispatcher::sendPostedEvents qwindowsguieventdispatcher.cpp 86 0x64ecc014
                                    49 qt_internal_proc qeventdispatcher_win.cpp 423 0x654f08d7
                                    50 InternalCallWinProc USER32 0x766662fa
                                    51 UserCallWinProcCheckWow USER32 0x76666d3a
                                    52 DispatchMessageWorker USER32 0x766677c4
                                    53 DispatchMessageW USER32 0x7666788a
                                    54 QEventDispatcherWin32::processEvents qeventdispatcher_win.cpp 744 0x654f19c3
                                    55 QWindowsGuiEventDispatcher::processEvents qwindowsguieventdispatcher.cpp 78 0x64ecbf7e
                                    56 QEventLoop::processEvents qeventloop.cpp 137 0x65464ea1
                                    57 QEventLoop::exec qeventloop.cpp 212 0x65464ffe
                                    58 QCoreApplication::exec qcoreapplication.cpp 1020 0x6546879d
                                    59 QGuiApplication::exec qguiapplication.cpp 1184 0x6666f5e8
                                    60 QApplication::exec qapplication.cpp 2674 0x65cc0009
                                    61 main main.cpp 20 0xbaf6fe
                                    62 WinMain qtmain_win.cpp 131 0xc5f5ea
                                    63 __tmainCRTStartup crtexe.c 547 0xc5d440
                                    64 WinMainCRTStartup crtexe.c 371 0xc5d1cf
                                    65 BaseThreadInitThunk kernel32 0x775f33aa
                                    66 __RtlUserThreadStart ntdll32 0x77bd9f72
                                    67 _RtlUserThreadStart ntdll32 0x77bd9f45 @

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                                    • W Offline
                                      W Offline
                                      wizzhard
                                      wrote on last edited by
                                      #19

                                      I just found something that seems to fix the issue here.

                                      http://stackoverflow.com/questions/17373591/qt5-custom-lineedit-widget-qlineedit-subclass-private-variable-crashes-applica

                                      I have unchecked acceptDrop on the qtreeview that own the items and it doesn't crash anymore.

                                      EDIT : it doesn't works finally, it was the interruption of the debugger that prevented the problem to occur by interrupting the item delegate validation.

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                                      • S Offline
                                        S Offline
                                        SoulSharer
                                        wrote on last edited by
                                        #20

                                        Well, I've updated to 5.1.0, it still crashes. But now it also outputs this:

                                        bq. QAccessibleTree::indexFromLogical: invalid index: 1 0 for QTreeWidget(0x4b06408)
                                        Cannot creat accessible child interface for object: QTreeWidget(0x4b06408) index: 1
                                        QAccessibleTree::indexFromLogical: invalid index: 2 0 for LayersTreeWidget(0x4a69668, name = "treeWidget")
                                        Cannot creat accessible child interface for object: LayersTreeWidget(0x4a69668, name = "treeWidget") index: 2
                                        QAccessibleTree::indexFromLogical: invalid index: 2 0 for LayersTreeWidget(0x4a69668, name = "treeWidget")
                                        Cannot creat accessible child interface for object: LayersTreeWidget(0x4a69668, name = "treeWidget") index: 2
                                        First-chance exception at 0x74c2c41f in JOI_Editor.exe: 0x80010001: Вызов был отклонен.
                                        QAccessibleTree::indexFromLogical: invalid index: 3 0 for LayersTreeWidget(0x4a69668, name = "treeWidget")
                                        Cannot creat accessible child interface for object: LayersTreeWidget(0x4a69668, name = "treeWidget") index: 3
                                        First-chance exception at 0x6631232a in JOI_Editor.exe: 0xC0000005: Access violation reading location 0x00000004.
                                        Unhandled exception at 0x770815de in JOI_Editor.exe: 0xC0000005: Access violation reading location 0x00000004.
                                        The program '[7544] JOI_Editor.exe: Native' has exited with code -1073741819 (0xc0000005).

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                                        • W Offline
                                          W Offline
                                          wizzhard
                                          wrote on last edited by
                                          #21

                                          I have debugged a little in qt's code and there is something weird.

                                          Before I rename an item everything works fine and the function QWindowsOleDropTarget::Drop qwindowsdrag.cpp 683 is called only when I release the mouse button over the item I want to do the drop on.
                                          After I have renamed an item I start a drag, the dragEnterEvent occurs one time, then dragMoveEvent occurs one time too and the program crashes under QWindowsOleDropTarget::Drop qwindowsdrag.cpp 683 but I never released the button so this drop should not have occured.
                                          If , after I renamed an item (so the app should crash the next time I drag an item in the treeview), I open an explorer windows, start to drag an item in it and press escape to cancel the drag then come back to my application and start a drag I don't crash and everything works fine.

                                          I am on Windows 7 x64 with Qt 5.1.0 (vs2010)

                                          QtCreator designer has a very similar problem, I can't drag widget from the toolbox until I canceled a drag with ESC in an explorer window. If I delete a widget in the designer the pb reappear and I must cancel a drag again in an explorer window.

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