Hi,

I am developing with QT4.6, and deploying onto a Nokia N8
I am a bit stuck getting my listview with internal drag and drop working correctly.
I am trying to create functionality that will allow the reordering of items in the list.
However I have an edge case whereby *sometimes* items just disapear from the list, when attempting to move them.

I understand that this is controlled from MyModel::flags but I am at a loss on how to fix it.

I can only seem to reproduce this on the actual device.


would anyone be able to propose a solution?

I have included my source code below (minus my drawing delegate)

thanks in advance

Guus Davidson


Qt Code: 
  1. #ifndef WIDGETSETTINGS_H
  2. #define WIDGETSETTINGS_H
  3.  
  4. #include <QWidget>
  5. #include <QLabel>
  6. #include <QListView>
  7. #include <QListWidget>
  8. #include <QList>
  9. #include <QIcon>
  10. #include <QStandardItemModel>
  11. #include <QStyledItemDelegate>
  12. #include <QVBoxLayout>
  13.  
  14. #include "src/ui/delegates/settingswidgetdelgate.h"
  15.  
  16. class MyModel : public QStandardItemModel
  17. {
  18. public:
  19.         MyModel(QObject *parent = 0 );
  20.         Qt::ItemFlags flags(const QModelIndex&index) const;
  21.         Qt::DropActions supportedDropActions() const;
  22. };
  23.  
  24. class WidgetSettings : public QWidget
  25. {
  26.     Q_OBJECT
  27. public:
  28.     explicit WidgetSettings(QStyledItemDelegate* listviewDelegate= 0,QWidget *parent = 0);
  29.     virtual void resizeEvent(QResizeEvent *);
  30.  
  31. signals:
  32.  
  33. public slots:
  34.  
  35. private:
  36.     QListView* iListView;
  37.     QStyledItemDelegate* iListViewDelegate;
  38.     QVBoxLayout *iMainLayout;
  39. };
  40.  
  41. #endif // WIDGETSETTINGS_H
To copy to clipboard, switch view to plain text mode 



Qt Code: 
  1. #include "widgetsettings.h"
  2.  
  3.  
  4. MyModel::MyModel(QObject *parent) : QStandardItemModel(parent)
  5. {
  6.  
  7. }
  8.  
  9. Qt::ItemFlags MyModel::flags(const QModelIndex& index) const
  10. {
  11.     Qt::ItemFlags flags;
  12.  
  13.     if (index.isValid())
  14.     {
  15.         flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsEnabled;
  16.         qDebug() << "MyModel::flags index is valid";
  17.     }
  18.     else
  19.     {
  20.         flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled  | Qt::ItemIsEnabled;
  21.         qDebug() << "MyModel::flags index is invalid";
  22.     }
  23.     return flags;
  24. }
  25.  
  26.  
  27.  
  28.  
  29. Qt::DropActions MyModel::supportedDropActions() const
  30. {
  31.     return Qt::CopyAction | Qt::MoveAction;
  32. }
  33.  
  34. void WidgetSettings::resizeEvent(QResizeEvent *event)
  35. {
  36.    QWidget::resizeEvent (event);
  37.  
  38.    QRect screensizerect = QApplication::desktop()->screenGeometry();
  39.  
  40.    if(iListView)
  41.    {
  42.       iListView->setGridSize(QSize(screensizerect.width() - 20,Constants::SETTINGS_ICON_HEIGHT + (2 * 10)));
  43.    }
  44.  }
  45.  
  46. WidgetSettings::WidgetSettings(QStyledItemDelegate* listviewDelegate,QWidget *parent) :
  47.     QWidget(parent),
  48.     iListViewDelegate(listviewDelegate)
  49. {
  50.     iMainLayout  = new QVBoxLayout;
  51.     iMainLayout->setContentsMargins(0,0,0,0);
  52.     iMainLayout->setSpacing(0);
  53.  
  54.     iListView = new QListView();
  55.     iListView->setFocusPolicy(Qt::NoFocus);
  56.     iListView->setUniformItemSizes (true);
  57.     iListView->setVerticalScrollMode (QAbstractItemView::ScrollPerPixel);
  58.     iListView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  59.     iListView->setItemDelegate(iListViewDelegate);
  60.  
  61.     iListView->setViewMode(QListView::ListMode);
  62.     iListView->setMovement(QListView::Snap);
  63.     iListView->setSelectionMode(QAbstractItemView::ExtendedSelection);
  64.     iListView->setDragDropMode(QAbstractItemView::InternalMove);
  65.     iListView->setDragDropOverwriteMode(false);
  66.  
  67.     MyModel* model = new MyModel;
  68.  
  69.     QSize size(Constants::SETTINGS_ICON_WIDTH ,Constants::SETTINGS_ICON_HEIGHT);
  70.  
  71.     QImageReader imageread(":/menuicons/icon_app_menu");
  72.     imageread.setScaledSize(size);
  73.     QImage image;
  74.     imageread.read(&image);
  75.     QPixmap itemImage = QPixmap::fromImage(image);
  76.  
  77.     QPixmap checkboxImageOn = QPixmap(":/general/btn_checkbox_on");
  78.     QPixmap checkboxImageOff = QPixmap(":/general/btn_checkbox_off");
  79.  
  80.  
  81.   QString text = "item ";
  82.   for(int i = 0; i < 12 ; i++)
  83.   {
  85.  
  86.       item->setData(QString("App Name %1").arg(QString::number(i)),SettingsWidgetDelgate::TitleTextRole);
  87.  
  88.       item->setData(itemImage,SettingsWidgetDelgate::IconRole);
  89.       item->setData(checkboxImageOn,SettingsWidgetDelgate::SelectionOnIconRole);
  90.       item->setData(checkboxImageOff,SettingsWidgetDelgate::SelectionOffIconRole);
  91.  
  92.       model->appendRow(item);
  93.   }
  94.  
  95.     iListView->setModel(model);
  96.  
  97.     iMainLayout ->addWidget(iListView);
  98.     setLayout(iMainLayout);
  99. }
To copy to clipboard, switch view to plain text mode