Internal Drag and Drop in list view , sometimes deletes items on nokia device

[GuusDavidson]

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

#ifndef WIDGETSETTINGS_H
#define WIDGETSETTINGS_H
 
#include <QWidget>
#include <QLabel>
#include <QListView>
#include <QListWidget>
#include <QList>
#include <QIcon>
#include <QStandardItemModel>
#include <QStyledItemDelegate>
#include <QVBoxLayout>
 
#include "src/ui/delegates/settingswidgetdelgate.h"
 
class MyModel : public QStandardItemModel
{
public:
        MyModel(QObject *parent = 0 );
        Qt::ItemFlags flags(const QModelIndex&index) const;
        Qt::DropActions supportedDropActions() const;
};
 
class WidgetSettings : public QWidget
{
    Q_OBJECT
public:
    explicit WidgetSettings(QStyledItemDelegate* listviewDelegate= 0,QWidget *parent = 0);
    virtual void resizeEvent(QResizeEvent *);
 
signals:
 
public slots:
 
private:
    QListView* iListView;
    QStyledItemDelegate* iListViewDelegate;
    QVBoxLayout *iMainLayout;
};
 
#endif // WIDGETSETTINGS_H

#ifndef WIDGETSETTINGS_H
#define WIDGETSETTINGS_H

#include <QWidget>
#include <QLabel>
#include <QListView>
#include <QListWidget>
#include <QList>
#include <QIcon>
#include <QStandardItemModel>
#include <QStyledItemDelegate>
#include <QVBoxLayout>

#include "src/ui/delegates/settingswidgetdelgate.h"

class MyModel : public QStandardItemModel
{
public:
        MyModel(QObject *parent = 0 );
        Qt::ItemFlags flags(const QModelIndex&index) const;
        Qt::DropActions supportedDropActions() const;
};

class WidgetSettings : public QWidget
{
    Q_OBJECT
public:
    explicit WidgetSettings(QStyledItemDelegate* listviewDelegate= 0,QWidget *parent = 0);
    virtual void resizeEvent(QResizeEvent *);

signals:

public slots:

private:
    QListView* iListView;
    QStyledItemDelegate* iListViewDelegate;
    QVBoxLayout *iMainLayout;
};

#endif // WIDGETSETTINGS_H

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#include "widgetsettings.h"
 
 
MyModel::MyModel(QObject *parent) : QStandardItemModel(parent)
{
 
}
 
Qt::ItemFlags MyModel::flags(const QModelIndex& index) const
{
    Qt::ItemFlags flags;
 
    if (index.isValid())
    {
        flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsEnabled;
        qDebug() << "MyModel::flags index is valid";
    }
    else
    {
        flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled  | Qt::ItemIsEnabled;
        qDebug() << "MyModel::flags index is invalid";
    }
    return flags;
}
 
 
 
 
Qt::DropActions MyModel::supportedDropActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}
 
void WidgetSettings::resizeEvent(QResizeEvent *event)
{
   QWidget::resizeEvent (event);
 
   QRect screensizerect = QApplication::desktop()->screenGeometry();
 
   if(iListView)
   {
      iListView->setGridSize(QSize(screensizerect.width() - 20,Constants::SETTINGS_ICON_HEIGHT + (2 * 10)));
   }
 }
 
WidgetSettings::WidgetSettings(QStyledItemDelegate* listviewDelegate,QWidget *parent) :
    QWidget(parent),
    iListViewDelegate(listviewDelegate)
{
    iMainLayout  = new QVBoxLayout;
    iMainLayout->setContentsMargins(0,0,0,0);
    iMainLayout->setSpacing(0);
 
    iListView = new QListView();
    iListView->setFocusPolicy(Qt::NoFocus);
    iListView->setUniformItemSizes (true);
    iListView->setVerticalScrollMode (QAbstractItemView::ScrollPerPixel);
    iListView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    iListView->setItemDelegate(iListViewDelegate);
 
    iListView->setViewMode(QListView::ListMode);
    iListView->setMovement(QListView::Snap);
    iListView->setSelectionMode(QAbstractItemView::ExtendedSelection);
    iListView->setDragDropMode(QAbstractItemView::InternalMove);
    iListView->setDragDropOverwriteMode(false);
 
    MyModel* model = new MyModel;
 
    QSize size(Constants::SETTINGS_ICON_WIDTH ,Constants::SETTINGS_ICON_HEIGHT);
 
    QImageReader imageread(":/menuicons/icon_app_menu");
    imageread.setScaledSize(size);
    QImage image;
    imageread.read(&image);
    QPixmap itemImage = QPixmap::fromImage(image);
 
    QPixmap checkboxImageOn = QPixmap(":/general/btn_checkbox_on");
    QPixmap checkboxImageOff = QPixmap(":/general/btn_checkbox_off");
 
 
  QString text = "item ";
  for(int i = 0; i < 12 ; i++)
  {
      QStandardItem* item = new QStandardItem();
 
      item->setData(QString("App Name %1").arg(QString::number(i)),SettingsWidgetDelgate::TitleTextRole);
 
      item->setData(itemImage,SettingsWidgetDelgate::IconRole);
      item->setData(checkboxImageOn,SettingsWidgetDelgate::SelectionOnIconRole);
      item->setData(checkboxImageOff,SettingsWidgetDelgate::SelectionOffIconRole);
 
      model->appendRow(item);
  }
 
    iListView->setModel(model);
 
    iMainLayout ->addWidget(iListView);
    setLayout(iMainLayout);
}

#include "widgetsettings.h"


MyModel::MyModel(QObject *parent) : QStandardItemModel(parent)
{

}

Qt::ItemFlags MyModel::flags(const QModelIndex& index) const
{
    Qt::ItemFlags flags;

    if (index.isValid())
    {
        flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsEnabled;
        qDebug() << "MyModel::flags index is valid";
    }
    else
    {
        flags =  Qt::ItemIsSelectable | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled  | Qt::ItemIsEnabled;
        qDebug() << "MyModel::flags index is invalid";
    }
    return flags;
}




Qt::DropActions MyModel::supportedDropActions() const
{
    return Qt::CopyAction | Qt::MoveAction;
}

void WidgetSettings::resizeEvent(QResizeEvent *event)
{
   QWidget::resizeEvent (event);

   QRect screensizerect = QApplication::desktop()->screenGeometry();

   if(iListView)
   {
      iListView->setGridSize(QSize(screensizerect.width() - 20,Constants::SETTINGS_ICON_HEIGHT + (2 * 10)));
   }
 }

WidgetSettings::WidgetSettings(QStyledItemDelegate* listviewDelegate,QWidget *parent) :
    QWidget(parent),
    iListViewDelegate(listviewDelegate)
{
    iMainLayout  = new QVBoxLayout;
    iMainLayout->setContentsMargins(0,0,0,0);
    iMainLayout->setSpacing(0);

    iListView = new QListView();
    iListView->setFocusPolicy(Qt::NoFocus);
    iListView->setUniformItemSizes (true);
    iListView->setVerticalScrollMode (QAbstractItemView::ScrollPerPixel);
    iListView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    iListView->setItemDelegate(iListViewDelegate);

    iListView->setViewMode(QListView::ListMode);
    iListView->setMovement(QListView::Snap);
    iListView->setSelectionMode(QAbstractItemView::ExtendedSelection);
    iListView->setDragDropMode(QAbstractItemView::InternalMove);
    iListView->setDragDropOverwriteMode(false);

    MyModel* model = new MyModel;

    QSize size(Constants::SETTINGS_ICON_WIDTH ,Constants::SETTINGS_ICON_HEIGHT);

    QImageReader imageread(":/menuicons/icon_app_menu");
    imageread.setScaledSize(size);
    QImage image;
    imageread.read(&image);
    QPixmap itemImage = QPixmap::fromImage(image);

    QPixmap checkboxImageOn = QPixmap(":/general/btn_checkbox_on");
    QPixmap checkboxImageOff = QPixmap(":/general/btn_checkbox_off");


  QString text = "item ";
  for(int i = 0; i < 12 ; i++)
  {
      QStandardItem* item = new QStandardItem();

      item->setData(QString("App Name %1").arg(QString::number(i)),SettingsWidgetDelgate::TitleTextRole);

      item->setData(itemImage,SettingsWidgetDelgate::IconRole);
      item->setData(checkboxImageOn,SettingsWidgetDelgate::SelectionOnIconRole);
      item->setData(checkboxImageOff,SettingsWidgetDelgate::SelectionOffIconRole);

      model->appendRow(item);
  }

    iListView->setModel(model);

    iMainLayout ->addWidget(iListView);
    setLayout(iMainLayout);
}

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[GuusDavidson]

I should add that I can now reproduce this on the emulator.
Guus .