Why i can't change color of QString?

Engelard

I did it in other programs before many times, but this time it is not working, i can't understand why. tempBx is pointer to some ComboBox:

tempBx->setItemText(indx, "<font color=\"green\">"+tempBx->itemText(indx));

It does change text, but don't convert that HTML code:

jsulm

This post is deleted!

Engelard

P.S. if i'd do same thing at stage of creation QStringList like:

QStringList list << "<font color=\"green\">some text";

and then apply it to the model, it will be the same;

P.P.S if i'll then try to print it in something like QTextBrowser, it do it right(text is green):

ui->textBrowser1->append(tempBx->itemText(indx));

mrjj

@Engelard
Hi
QComboBox does not draw html/rich text. ( like QTextBrowser )

You can set text color with
ui->comboBox->setItemData(0, QBrush(Qt::red), Qt::TextColorRole);
alt text

KroMignon

This post is deleted!

Engelard

@mrjj Looks nice, but not working...(

tempBx->setItemData(indx, QBrush(Qt::red), Qt::TextColorRole);

mrjj

@Engelard
Maybe you have applied StyleSheet to it ?
Also, item should be inserted first before you call setItemData.

Engelard

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

Maybe you have applied StyleSheet to it ?

No, but i apply and reapply different models to it during runtime.

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

Also, item should be inserted first before you call setItemData.

I did'nt get this one. What do you mean?

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 );

alt text

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 );

alt text

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