Why i can't change color of QString?

[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

[Engelard]

@VRonin oKay. In what files that stuff which i should to replace? I only can assume that such stuff MODELUTILITIES_EXPORT is macro, so it must be in some .h files, right?

[VRonin]

Actually, it probably just easier to replace the entire modelutilities_global.h with

#ifndef modelutilities_global_h__
#define modelutilities_global_h__
#define MODELUTILITIES_EXPORT
#endif // modelutilities_global_h__