How to stretch the child nodes of QTreeView

mpergand

Is the treeview inside a layout ?

deleted385

@mpergand, It's inside a QSplitter and that splitter is inside a QVBoxLayout. The QWidget that contains the QTreeView is inside a QStackedWidget and that StackedWidget is the centralWidget of the QMainWindow.

mpergand

I think you have to add a layout to the widget containing the treeview for this one to expand.

To visualize the actual size of the treeview, you can do:
tree->setFrameShape(QFrame::Box);

To verify if your interface is correct, you can try to reproduce it in the Designer and see if it works as you expected.

deleted385

@mpergand, I've put these 3 segments in a QWidget named QueryWidget. On the left where the TreeView is, called ObjectView and on the right the CodeEditor and in bottom a textbox, and for now everything is in its constructor:

QueryWidget::QueryWidget(QWidget *parent) : QWidget(parent)
{
    objects = new ObjectsView(this);
    codeEditor = new CodeEditor(this);
    auto textBox = new QTextEdit(this);
    auto split1 = new QSplitter(Qt::Horizontal, this);
    auto split2 = new QSplitter(Qt::Vertical, this);

    split1->addWidget(objects);
    split1->addWidget(codeEditor);
    QSizePolicy obj(QSizePolicy::Preferred, QSizePolicy::Preferred);
    QSizePolicy cod(QSizePolicy::Preferred, QSizePolicy::Preferred);
    obj.setHorizontalStretch(1);
    cod.setHorizontalStretch(3);
    objects->setSizePolicy(obj);
    codeEditor->setSizePolicy(cod);

    split2->addWidget(split1);
    split2->addWidget(textBox);
    QSizePolicy sp1(QSizePolicy::Preferred, QSizePolicy::Preferred);
    QSizePolicy txt(QSizePolicy::Preferred, QSizePolicy::Preferred);
    sp1.setVerticalStretch(2);
    txt.setVerticalStretch(1);
    split1->setSizePolicy(sp1);
    textBox->setSizePolicy(txt);

    auto vLay = new QVBoxLayout(this);
    vLay->addWidget(split2);
}

in the ObjectView's constructor I've a toolBar and treeview in QVBoxlayout:

ObjectsView::ObjectsView(QWidget *parent) : QWidget(parent)
{
    auto toolBar = new QToolBar(this);
    tree = new QTreeView(this);
    tree->setHeaderHidden(true);

    auto attach = new QAction(QIcon(":/database-plus.svg"), "attach database", this);
    toolBar->addAction(attach);
    connect(attach, &QAction::triggered, this, &ObjectsView::openFileDialog);

    auto layout = new QVBoxLayout(this);
    layout->setContentsMargins(0,0,0,0);
    layout->addWidget(toolBar);
    layout->addWidget(tree);
    setLayout(layout);
}

and in the MainWindow's constructor I've put the QueryWidget in the StackWidget like this:

Window::Window(QWidget *parent) : QMainWindow(parent)
{
    stack = new QStackedWidget(this);
    queryWidget = new QueryWidget(stack);
    tableWidget = new TableWidget(stack);
    stack->addWidget(queryWidget);
    stack->addWidget(tableWidget);
    setCentralWidget(stack);
    ....
}

I've tried the tree->setFrameShape(QFrame::Box) BUT there's no apparent difference in the Window.

mpergand

I've tried the tree->setFrameShape(QFrame::Box) BUT there's no apparent difference in the Window.

It doesn't change anything, it draws a box around the treeview.

Look at this splitter

The frame on the left doesn't expand because the parent widget has no layout.

[EDIT]

auto layout = new QVBoxLayout(this);
    layout->setContentsMargins(0,0,0,0);
    layout->addWidget(toolBar);
    layout->addWidget(tree);
    setLayout(layout);

Your code seems correct.
If you don't add the toolbar, what happens ?
Do you see the frame box around the tree ?

deleted385

@mpergand, it shows the border around the treeview without setFrameShape. See, it takes up the remainder of the QVboxLayout and shows black/grey border around white space allocated for the QTreeView:

mpergand

You may set a minimum width for the first column or save/restore the state of the header,
see QHeaderView :

QByteArray QHeaderView::saveState() const
Saves the current state of this header view.
To restore the saved state, pass the return value to restoreState().
This function was introduced in Qt 4.3.
See also restoreState().

deleted385

@mpergand, I don't want to show the headers with splitter on top and without that I can't change the state manually. like I did in the GIF example above.

mpergand

Look at the doc about QHeaderView::ResizeMode
and this methods:
setMinimumSectionSize(int size)
setDefaultSectionSize(int size)
and others ...

kshegunov

@Emon-Haque said in How to stretch the child nodes of QTreeView:

@mpergand, I don't want to show the headers with splitter on top and without that I can't change the state manually. like I did in the GIF example above.

Did you mean this?

tree->header()->setSectionResizeMode(0, QHeaderView::Stretch);

deleted385

@kshegunov, exactly. Now with header hidden, columns stretches automatically as I move the splitter.
Thanks