How to draw and correctly animate progress bar in QTableView?

[mrjj]

@hamov

Just to be sure. By animation, you mean that the green part cover more/moves. as when moving the mouse over.

Since it can draw , (when mouse move/over) it somehow must be the signal that get lost ?

you did also try direct repaint ?

void MainWin::on_toolButton_clicked()
{
m_table->repaint();
}

If that dont work then your Qt install must be funky somehow.

[hamov]

@mrjj
Yes, that's right.
Here is my code with timer and button:
*.hpp

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
private slots:
    void buttonPressed();
private:
    void createList();
    void startTimer();
private:
    QListView* m_list;
    QStandardItemModel* m_model;
    QPushButton* m_button;
    QTimer* m_timer;
};

*.cpp

class TestDelegate : public QStyledItemDelegate
{
public:
    TestDelegate(QObject* parent = 0);

public:
    virtual void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;
};

TestDelegate::
TestDelegate(QObject* parent)
    : QStyledItemDelegate(parent)
{

}

void TestDelegate::
paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    static int cc = 0;
    cc++;

    QStyledItemDelegate::paint ( painter, option, index );

    QStyleOptionProgressBar progressBarOption;
    progressBarOption.rect = option.rect;

    int progress = cc;

    progressBarOption.minimum = 0;
    progressBarOption.maximum = 100;
    progressBarOption.textAlignment = Qt::AlignCenter;
    progressBarOption.progress = progress;
    progressBarOption.text = QString ( "%1%" ).arg ( progress );
    progressBarOption.textVisible = true;
    QApplication::style()->drawControl ( QStyle::CE_ProgressBar, &progressBarOption, painter );
}

MainWindow::
MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    createList();
    startTimer();
}

void MainWindow::
createList()
{
    m_model = new QStandardItemModel();
    m_model->setRowCount(1);
    m_model->setColumnCount(1);

    TestDelegate* delegate = new TestDelegate(this);

    m_list = new QListView(this);
    m_list->setModel(m_model);
    m_list->setItemDelegate(delegate);

    m_button = new QPushButton("Paint!", this);
    bool c = connect(m_button, SIGNAL(released()), this, SLOT(buttonPressed()));
    assert(c);

    QVBoxLayout* wLayout = new QVBoxLayout();
    wLayout->addWidget(m_list);
    wLayout->addWidget(m_button);

    QWidget* cWidget = new QWidget(this);
    cWidget->setLayout(wLayout);

    setCentralWidget(cWidget);
}

void MainWindow::
startTimer()
{
    m_timer = new QTimer(this);
    bool c = connect(m_timer, SIGNAL(timeout()), m_list, SLOT(update()));
    assert(c);

    m_timer->start(2000);
}

void MainWindow::
buttonPressed()
{
    m_list->repaint();
}

I also build the code using Qt 4.8.0 + VS2010, but result is same...no animation until move/resize. Don't know what to think...

[mrjj]

well, that does not work for me either.
And im on mingw compiler :)

So thats good news :)

its 2 in night so will first have good look tomorrow.

[mrjj]

Hi
Funny/strange thing was I got a project where it did work in.

I then try to recreate it (new project) and that DID not work.
Nearly drove me nuts so after
3 hours of comparing/removing, i found out the following:

if I set set a stylesheet

MainWindow::MainWindow ( QWidget *parent )
    : QMainWindow ( parent )
{
  createList();
  startTimer();
  setStyleSheet(QLatin1String("QFrame { border: 1px solid gray;margin-top 0px padding-top 0px}"));
}

for main window,
It does work. (your code)

If I do not, it does not. Same result as you. no repaint on demand/timer.

So it seems to work if mainwin has a stylesheet ?!?

Im a bit excited to see if it works the same for you.

[hamov]

@mrjj
Wow!...unbelievable...but setting stylesheet for main window works for me too... :-))) I would never have thought of it. :-)) Thanks a lot for helping, this can be a workaround. :-))
The only remaining question is how setting style sheet refers to repaint process??!... :-))

[mrjj]

@hamov

Yeah blew my mind too. Glad it at least worked for you.

The strange thing is that the stylesheet do not even alter QListView

I have no idea why setting a stylesheet on mainwindow makes it respond to ->repaint()

Looking at the source
https://github.com/Vitallium/qt5/blob/master/qtbase/src/widgets/itemviews/qlistview.cpp

There is nothing that (that i see) which could explain it.

Update:
After digging around more. I think the reason for ignoring update/repaint
is that we do not change the model.
so the view thinks it is fully updated.
So one has to emit datachanged() somehow.
Or actually change the data in the model.

[hamov]

@mrjj
You are absolutely right. I'm created a simple model class with function updateData() which calls beginResetData() and endResetData(). Also I've changed the timer, now it is QObject::startTimer() call and QObject::timerEvent() handler. In example I didn't call update()/repaint() at all. Delegate class can be taken from previous example.
*.hpp

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
private:
    void createList();
protected:
    virtual void timerEvent(QTimerEvent * event);
private:
    QListView* m_list;
    TestModel* m_model;
    int m_timerId;
};

*.cpp

class TestModel : public QStandardItemModel
{
public:
    TestModel(QObject* parent = 0);
public:
    void updateData();
};

TestModel::
TestModel( QObject* parent)
    : QStandardItemModel(parent)
{
}

void TestModel::
updateData()
{
    beginResetModel();
    endResetModel();
}


MainWindow::
MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    createList();
    m_timerId = startTimer(2000);
}

void MainWindow::
createList()
{
    m_model = new TestModel();
    m_model->setRowCount(1);
    m_model->setColumnCount(1);

    TestDelegate* delegate = new TestDelegate(this);

    m_list = new QListView(this);
    m_list->setModel(m_model);
    m_list->setItemDelegate(delegate);

    setCentralWidget(m_list);
}

void MainWindow::
timerEvent( QTimerEvent * event )
{
    m_model->updateData();
}

And all works fine! I'm tested with Qt 4.8.0 but I'm sure this will work also for 5.4.2. The example works also for QTableView and QTreeView. But this isn't match my logic a bit. I think model data update and direct repaint should be independent since:

1. There are no data in my model which need to be updated.
2. update()/repaint() have no sense. It is enough to emit dataChanged() for repaint.

So the conclusion of all turns:

1. If you want to repaint view, you should update model data even if there are no data(or 'default' data).
2. QWidget's update()/repaint() functions doesn't make sense for any View.

Am I right?

[mrjj]

@hamov said:

Also found out the same effect can happen by simply call
m_model->reset() from main window.
But that is bad for a tree since it resets all open states etc.

I think one is to use the

void	dataChanged(const QModelIndex & topLeft, const QModelIndex & bottomRight, const QVector<int> & roles = QVector<int> ())

From (inside?) the model for optimized redrawing.

I agree with you.
Repaint should still repaint even if model is not dirty. Also it redraws on mousemove even
model is not changed so a bit odd that it then ignores direct repaints .

You are right.
I guess we can add to the conclusion
that if you have no data/very static , the Item-based ListWidget might work better (?)

update:
ListWidget suffer the same. update/repaint does nothing.
So not sure how one would go about asking it to redraw.

[hamov]

@mrjj
I have tested that signal for treeview and all works fine. :-)
Seems update()/repaint() didn't work for any widget/view. Is it a Qt bug?...or such behavior of redraw was planned by developers?!

[mrjj]

@hamov

well digging around, I also found
m_list->viewport()->repaint();

which works for WidgetList. Did not test with model/view yet.

I think it is by design as it does redraw when data changes but we are not alone finding
it strange working if one google it