How to create in QT main chat windows like this?

qwe3

Hello,

I would like to create GUI for chat with other person.

I would like something like that:

I have a problem with the main Window ( there are text messages: "Hi!" , "How are you?" ).

I think I have to use QLabel with setStyleSheet and set background-color to yellow. But how Can I add QLabel to QWidget like QTableView?

mrjj

Hi
While it is possible to insert say a QLabel on top of a cell in a Table/ListView, it
becomes heavy quite fast if you got many "chats"

The better solution is to use a Delegate.
https://doc.qt.io/qt-5/model-view-programming.html
(Delegate Classes)

Here is some samples
https://stackoverflow.com/questions/1956542/how-to-make-item-view-render-rich-html-text-in-qt
https://gist.github.com/niklasf/6124645

You can also have a look at a real chat app ( written in Qt)
https://github.com/telegramdesktop/tdesktop

For the network part/sending text etc. i would use
https://wiki.qt.io/WIP-How_to_create_a_simple_chat_application

qwe3

@mrjj Thank you.

I check Delegate and I think this isn't what I want. Of course I can add QLabel to QTableView, but when I click on QLabel I see the QTableView's cell. I setShowGrid to false but this isn't what I need.

I check this chat app tdesktop. This application is WOW, but at this moment it's too hard and too big for me to understand and find where is QLabel with text's messages ( or something what do the same ).

EDIT:

I try with delegate and it may works.

mrjj

@qwe3
Telegram uses a delegate.
Delegate is for custom drawing.
But it also controls the editing via CreateEditor function.
So you can program it to work as you wish.

of course I can add QLabel to QTableView
Did you expect to type into the QLabel ?
but when I click on QLabel I see the QTableView's cell.

Im not sure i follow?
QLabel is non editable normally so that is expected.
You cannot directly type to it.

qwe3

@mrjj I wrote "I can add QLabel to QTableView". This is wrong. Now my code is very strange - I try do something good.

My class delegate:

delegate::delegate()
{

}

QWidget *delegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
        QLabel *label = new QLabel( parent);
        label->setStyleSheet("QLabel {background-color:red}");
        return label;
}

void delegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
        QLabel *label = static_cast<QLabel *>(editor);
        label->setText(index.data().toString());
}

void delegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QLabel *label = static_cast<QLabel *>(editor);
    label->setText("abcde");
    model->setData(index, index.data());
}

void delegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    editor->setGeometry(option.rect);
}

void delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{

}

I find in youtube movie about Qt Delegate and rewrite the code and try change it to my needs.

My mainApp:

    table = new QTableView(this);
    deleg = new delegate;
    table->setGeometry(0,0,500,500);
    model = new QStandardItemModel(10,2, this);
    item = new QStandardItem("somethingABC");
    model->setItem(0,0,item);

    table->setModel(model);
    for(int i=0;i<100;i++)
        model->appendRow(QList<QStandardItem *>());

    table->setItemDelegate(deleg);
    table->setShowGrid(false);
    table->verticalHeader()->hide();
    table->horizontalHeader()->hide();
    table->setColumnWidth(0,250);
    table->setColumnWidth(1,250);

When I double click on first cel ( 0,0 ) I get red rectangle with text "somethingABC". I would like to have this text when I execute the app ( no when I double click in QTableView ).

EDIT:

I would like something like:
After 5 sec ( I can use QTimer and timeout()) I would like to add to my QTableView new QLabel in color red with text ( for example "Hello!" ) and this QLabel I would like to be rounded ( I know I can use setStyleSheet ).

I would like to create GUI like in first post.

mrjj

Hi
2 things that caught my eye.

1:

void delegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QLabel *label = static_cast<QLabel *>(editor);
    label->setText("abcde");
    model->setData(index, index.data());
}
This function writes back the data to the model. You write back the same data
so not sure what you do with label :)

2:
You are not painting anything. (no code)

void delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
call base class paint here or simply delete it if you have no need for extra paitning
}

Hi
Did you read about Delegates ?
The Editor is only active when editing, rest of the time its not shown.
Then its paint job to show the data.

qwe3

@mrjj Yes, I read about editor. But my problem is: I don't know what can I write in paint. I have 3 args: painter, option and index. I don't access to QLabel which I create in createEditor() function.

mrjj

@qwe3
Ok. its important to read the docs as the Delegate follow a system so
one has to understand how it acts.

In paint you have access to the model which has the data.
So you can use QPainter and drawText to draw it. Also make it red if needed etc.
The QLabel you use is for Editing and not display.

qwe3

@mrjj Okay. But Can I create text in red background which is in rounded background by QPainter. I never do something like that :)

mrjj

@qwe3
Yes all StyleSheet and Widgets use QPainter internally.
So you can make look like anything you like.

https://stackoverflow.com/questions/29196610/qt-drawing-a-filled-rounded-rectangle-with-border

QPainter p(this);
p.setRenderHint(QPainter::Antialiasing);
QPainterPath path;
path.addRoundedRect(QRectF(10, 10, 100, 50), 10, 10);  
QPen pen(Qt::black, 10);
p.setPen(pen);
p.fillPath(path, Qt::red);
p.drawPath(path);

Do note the cell area is in option.rect
so you have to use its values to draw the right place. else you draw somewhere else on the view :)

qwe3

@mrjj Now I add to paint() function:

    QPen pen(Qt::black, 1);
    painter->setPen(pen);
    painter->drawText(0,0,100,100,0,index.data().toString());

and it works!

But I see next 2 problems:

I have to write 100,100 in drawText() function. Is there any way to get size which my index.data().toString() needs?
When I add this lines to my paint() function I only see this text in first cell (0,0).

I have:

    item = new QStandardItem("somethingABC");
    item2 = new QStandardItem("somethingABC");
    item3 = new QStandardItem("somethingABC");
    model->setItem(0,0,item);
    model->setItem(1,0,item2);
    model->setItem(2,0,item3);

So I think I have to get 3 texts "somethingABC" in my QTableView. Right?

mrjj

@qwe3 said in How to create in QT main chat windows like this?:

1
The cell area is in option.rect. (one of the parameters to paint)
2:
i think its related to 1 as all cells then paint its text in 100,100 :)

painter->drawText(option.rect, index.data().toString());

qwe3

@mrjj One line and 2 problems aren't now problems :D Perfect!

mrjj

@qwe3
Super.
Delegates are a bit complicated to begin with but later you love them as you can do anything you like.
and then have good performance too \o/

qwe3

@mrjj I create rounded rectangle and it works :)

But I don't know how can I do the last thing:

The message text can be longer than one line. I think I have to change row's height. This is not a problem: table->setRowHeight(1,240);

But when I have to do that? In delegate functions()?

mrjj

@qwe3
Hi
Nope, its not the delegates job
if its for all rows then

QHeaderView *verticalHeader = myTableView->verticalHeader();
verticalHeader->setSectionResizeMode(QHeaderView::Fixed);
verticalHeader->setDefaultSectionSize(24);

qwe3

@mrjj Thank you! I have to change your code to:

verticalHeader->setSectionResizeMode(QHeaderView::ResizeToContents);

But you helped me next time! :)

Thank you

mrjj

@qwe3
Hi
Super.
Congratulation on your first Delegate.

qwe3

@mrjj Only in 50%.

I need one more:

QWidget *delegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    return nullptr;
}

void delegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    editor->setGeometry(option.rect);
}

void delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if(index.row()%2==0 && index.column()!=1)
    {
        QPen pen2(Qt::yellow, 1);
        painter->setPen(pen2);
    
        QPainterPath path;
        path.addRoundedRect(QRectF(option.rect), 10, 10);
        painter->fillPath(path, Qt::yellow);
        painter->drawPath(path);
        QPen pen(Qt::black, 1);
        painter->setPen(pen);
        painter->drawText(option.rect,Qt::AlignCenter, index.data().toString());
    }
}

I would like to select text message, click on it right mouse button, get the list, where is "copy" and other possibilities. How can I do this?

Now I can't select text and click right mouse button

mrjj

Hi
For right click menu you can use a context menu

https://forum.qt.io/topic/31233/how-to-create-a-custom-context-menu-for-qtableview/8