How to visualize model data in different ways in QTableView?

I have a model containing in one column floats (ex: 22.7). Now, I want that in QTableView, it will be visualized together with the unit (MB): 22.7 MB. The reason I am doing so is because I want that sorting is based on floats, but the visualization is as I said with units.

I created a Model, a Filter and a View. But it does not work. Here is a piece of my code:

QStandardItemModel* model = new QStandardItemModel(this);
QSortFilterProxyModel *filterModel = new QSortFilterProxyModel(0);
filterModel->setSourceModel(model);

QStandardItem* vSItem6 = new QStandardItem();
vSItem6->setData(22.7, Qt::DisplayRole); 
model->setItem(1, 7, vSItem6);
QModelIndex index = model->index(1, 7, QModelIndex());
QString itext = model->data(index, Qt::DisplayRole).toS开发者_高级运维tring(); 
filterModel->setData(index, itext + " MB", Qt::DisplayRole);


mUi.tableView->setModel(filterModel);
mUi.tableView->setSortingEnabled(true);
mUi.tableView->show();

Everything seems to be fine, but in QTableView, only the float number is visualized (without the unit MB). Can anybody please help me? Thanks

Have a look at setItemDelegate or setItemDelegateForColumn. You can derive your delegate class from QStyledItemDelegate, and in the overridden paint method you can paint your numbers including the units.

I'm a newbie in Qt development, but can't you derive from class QAbstactTableModel, and implement the data method so that it returns the float value plus "MB" (in a QString object), when role is DisplayRole?

If you just want to take the value of the model and modify it's string representation you can do so easily by inheriting from QStyledItemDelegate and just overriding a single method namely displayText(), which returns a QString. I just did that to have the values (representing the amount of memory consumed by a process) displayed in the most appropriate unit (byte, kbyte, megabyte and so on). So it's a usecase that is more or less similar to the problem described above and it works like a charme. You can see the code below (but ignore the application specific parts).

Header file:

#pragma once 

#include <QStyledItemDelegate>

class UnitAwareItemDelegate : public QStyledItemDelegate {
    Q_OBJECT
public:
    explicit UnitAwareItemDelegate(QObject* parent = 0);
    virtual QString displayText(const QVariant & value, const QLocale & locale) const;
};

Implementation file:

#include "UnitAwareItemDelegate.hpp"
#include "UnitUtils.hpp"

#include <QPainter>
#include <QStyleOptionViewItem>
#include <QModelIndex>

UnitAwareItemDelegate::UnitAwareItemDelegate(QObject* parent): QStyledItemDelegate(parent)
{
}

QString UnitAwareItemDelegate::displayText(const QVariant& value, const QLocale& locale) const
{
    if (value == 0)
    return QString();

    // value supplied by libproc is in kb so we mul by 1024 to get the byte value
    uint64_t oldValue = value.toULongLong() * 1024;
    const UnitUtils::ValueUnit unit = UnitUtils::findSuitableUnit(oldValue);
    const uint64_t newValue = oldValue / UnitUtils::value(unit);

    return QString("%1 %2")
    .arg(QString::number(newValue))
    .arg(QString(UnitUtils::name(unit).at(0)).toUpper());
}

I know your question was about QTableView, but it might be easier if it is the only thing you want to display (I don't know your objectives) to use a QTableWidget with a QDoubleSpinBox since it has a method that allows you to set a suffix to the value that is displayed.

In your case, it would be:

QDoubleSpinBox* spin = new QDoubleSpinBox();
spin->setSuffix("MB");

Note that the range is set by default from 0.0 to 99.99 so if you want to set other values you should change the range before.

Hope this helps.