Why i can't change color of QString?

[mrjj]

@Engelard
Well if you insert the items from code, then you can first change the color after you insert item into
combobox.
If you made it with Designer, the item is already there.

Try make clean new project. add combo to form , right click it and select "edit Items."
Add some items and then add the color code and see if its still not working.

Ah, if you change model, you will have to Color that index also.

[Engelard]

@mrjj said in Why i can't change color of QString?:

Ah, if you change model, you will have to Color that index also.

Tried that just after you post your example with setItemData.

Now i try to figure out how use this not to comboBox, but to the model. But setItemData from model is much more complex( i can't get how 2nd argument should looks like).

[mrjj]

@Engelard
You have you own std. item models you use with it ?

Anyway, this also seems to work
auto model = ui->comboBox->model();
model->setData( model->index(4, 0), QColor(255, 0, 0), Qt::TextColorRole );

[Engelard]

@mrjj I did'nt quite understand your question, here is how whole code looks like:

QComboBox *tempBx = ui->comboBox1;

tempBx->setModel(new QStringListModel(someList));
tempBx->setCurrentIndex(indx);
tempBx->setItemData(indx, QColor(Qt::red), Qt::TextColorRole);

Everything is working as it should, but not that part which should change colors..

@mrjj said in Why i can't change color of QString?:

model->setData( model->index(4, 0), QColor(255, 0, 0), Qt::TextColorRole );

Ah it is setData, not item data. But also, no effect....

[mrjj]

Hi
Tested with QStringListModel and you are right. It does not color it.
Same code with inserted items from Designer works.
So its seems it wont work with QStringListModel.

[raven-worx]

@Engelard
QStringListModel only supports DisplayRole and EditRole.

You can however quickly implement a simple QAbstractListModel and add support for multiple other roles (btw you should use Qt::ForegroundRole)

[mrjj]

Hi
As @raven-worx says, a QAbstractListModel would be the cleanest solution.

You could also cheat and do.

  QStringList StrList{"test" , "test2" , "test3" };

    QStandardItemModel *model = new QStandardItemModel (StrList.size(), 1);
    for (int row = 0; row < StrList.size(); ++row) {
        QStandardItem *item = new QStandardItem(QString("row %0").arg(row));
        model->setItem(row, 0, item);
    }

    ui->comboBox->setModel(model);

    model->setData( model->index(0, 0), QColor(255, 0, 0), Qt::TextColorRole );
    model->setData( model->index(1, 0), QColor(0, 255, 0), Qt::TextColorRole );

[Engelard]

Thanks @raven-worx && @mrjj for help. It is like 8-times more code now, i can't rly understand why it don't work with simple QStringListModel, but it is at least some success today.

It change color in list of ComboBox, but not in actual CB, in @mrjj screenshot such thing also present:

P.S. in my initial priority was to display colored in mainWidget of ComboBox rather then in opened list.

[mrjj]

Hi

• i can't rly understand why it don't work with simple QStringListModel

Well @raven-worx was kind enough to show the source
so we can see how QStringListModel works

QVariant QStringListModel::data(const QModelIndex &index, int role) const
{
    if (index.row() < 0 || index.row() >= lst.size())
        return QVariant();

    if (role == Qt::DisplayRole || role == Qt::EditRole)
        return lst.at(index.row());

    return QVariant();
}

The data function of a model IS the place where it returns the data for the roles so we can see
it only really uses (role == Qt::DisplayRole || role == Qt::EditRole) and
we want it to also use Qt::ForegroundRole.

[VRonin]

I made a proxy model to support roles in models that don't https://github.com/VSRonin/QtModelUtilities the class is called RoleMaskProxyModel. Here is an example that uses it to colour QStringListModel: https://github.com/VSRonin/QtModelUtilities/blob/1.0.0/examples/exam_RoleMaskProxyModel/exam_rolemaskhighlight.cpp

Hopefully I'll eventually find the time to complete adding that class to Qt: https://codereview.qt-project.org/#/c/245572/

[Engelard]

@VRonin Looks very interesting.
I downloaded your rolemaskproxymodel and classes related to it(whole src directory), but when i tried to Run i got such strange stuff:

Oh and don't look at first two errors, they unrelated completelly, it appears when i swap compiler to Release mode, did'nt figure out what it is yet.

[VRonin]

If you just copy-paste the code you have to add DEFINES += MODELUTILITIES_STATIC to your .pro file

[Engelard]

@VRonin ye, first time tried to use someone elses code :D
Now i downloaded whole stuff like a normal person. Look at my post with screenshot above.

[VRonin]

Exact same answer.
There's a section in the readme that explains how to use the library: https://vsronin.github.io/QtModelUtilities/md__i_n_s_t_a_l_l.html

[Engelard]

@VRonin I added that macro to .pro file and nothing changed, same 4 errors.

[VRonin]

You have to manually click on build-> rerun qmake every time you change something in the .pro file

[Engelard]

@VRonin of course i did that. Still same 4 errors

[VRonin]

let's do it manually then: remove all the MODELUTILITIES_EXPORT

[Engelard]

@VRonin said in Why i can't change color of QString?:

MODELUTILITIES_EXPORT

How? you mean edit your src files?

[VRonin]

yep!
All DEFINES += MODELUTILITIES_STATIC does is transforming MODELUTILITIES_EXPORT into an empty string. if that doesn't work then just manually do a find and replace