I have custom model inherited from QAbstractItemModel and custom view inherited from QAbstractItemView. Model is a wrap on data organized as a tree. When model is changed it emits neccessary signals to notify view about changes. View has default item delegate.
And now I want to craete a custom widget for every item in a view and set it with QAbstractItemView::setIndexWidget(). How can I catch and handle every item creation in the view to make that?
you are better off using an itemdelegate.
class MyItemDelegate: public QAbstractItemDelegate
{
Q_OBJECT
QWidget *widget;
public:
MyItemDelegate(QObject *p):QAbstractItemDelegate(p)
{
//create widget
}
void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
{
//initialize painting widget
widget->render(painter);
}
}
Related
I am using a custom delegate to render rich text in a QComboBox. It is used to allow users to select a color to plot a variable on a graph. It works for items in the drop down menu, but not the selected item. Any help would be appreciated.
Here is the code for the delegate I am using:
class CustomDelegate : public QStyledItemDelegate
{
public:
CustomDelegate();
protected:
void paint ( QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index ) const;
QSize sizeHint ( const QStyleOptionViewItem & option, const QModelIndex & index ) const;
};
void CustomDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const{
QStyleOptionViewItemV4 optionV4 = option;
initStyleOption(&optionV4, index);
QStyle *style = optionV4.widget? optionV4.widget->style() : QApplication::style();
QTextDocument doc;
doc.setHtml(optionV4.text);
/// Painting item without text
optionV4.text = QString();
style->drawControl(QStyle::CE_ItemViewItem, &optionV4, painter);
QAbstractTextDocumentLayout::PaintContext ctx;
// Highlighting text if item is selected
if (optionV4.state & QStyle::State_Selected)
ctx.palette.setColor(QPalette::Text, optionV4.palette.color(QPalette::Active, QPalette::HighlightedText));
QRect textRect = style->subElementRect(QStyle::SE_ItemViewItemText, &optionV4);
painter->save();
painter->translate(textRect.topLeft());
painter->setClipRect(textRect.translated(-textRect.topLeft()));
doc.documentLayout()->draw(painter, ctx);
painter->restore();
}
QSize CustomDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const{
QStyleOptionViewItemV4 optionV4 = option;
initStyleOption(&optionV4, index);
QTextDocument doc;
doc.setHtml(optionV4.text);
doc.setTextWidth(optionV4.rect.width());
return QSize(doc.idealWidth(), doc.size().height());
}
I set the options and delegate for the combo box using code similar, I removed some of the options to reduce the size of the code:
ui->SelectColor->clear();
ui->SelectColor->addItem("Select Color");
ui->SelectColor->addItem("<font color='blue'>Blue</font>");
ui->SelectColor->addItem("<font color='darkBlue'>Dark Blue</font>");
ui->SelectColor->addItem("<font color='red'>Red</font>");
ui->SelectColor->addItem("Dark Yellow");
ui->SelectColor->addItem("<font color='magenta'>Dark Magenta</font>");
ui->SelectColor->addItem("White");
ui->SelectColor->setItemDelegate(new CustomDelegate);
Some of the options are just the names because they don't look good when rendered.
Your custom styled item delegate is applied to items that are part of QComboBox (i.e. ones in QComboBox popup), not for the current item which is represented. The easiest way to achieve what you want would be to introduce your custom class inheriting QComboBox, and then override void QWidget::paintEvent(QPaintEvent *event) method by applying changes you would like to introduce, e.g. set some colored text. Another way (in case you can not introduce another class inheriting QComboBox for some reason) would be to introduce an event filter that does something just after the QPaintEvent. However, usage of event filters might be tricky, and I would advise you to just introduce some another class, and then override paint event.
Now, in case you want to show current item in the same way as an option in the combo box list popup, you could do the following (code is not complete, and you should apply it to your needs yourself):
virtual void paintEvent(QPaintEvent* e) override
{
// QComboBox::paintEvent(e); - this will leave just a rectangle in which you can perform your custom drawings.
// Will make your option colored at least.
QPainter p(this);
QTextDocument doc;
doc.setHtml(this->currentText());
doc.drawContents(&p, rect());
}
Finally, it is worth to mention that QComboBox painting is pretty complex, and you might still need to rewrite pretty everything that Qt already has done for you, so it would be possible to apply other styles you might want not to lose. In order to do that, you should take a look into the source code of this class. You can do this in the Code Browser by Woboq for C & C++ (QComboBox). Hopefully, this clarifies the problem for you more, and now you know what to do in order to achieve your goal.
I have implemented an OSGQt based model viewer. I am currently attempting to reposition submodels by changing their properties in a child QFrame to the main MainWindow based viewer frame. The child frame is non-modal and the key events are being passed to the OSG Viewer based handler in the MainWindow instead of the child window.
What would be the appropriate attributes for the child window to keep the keyboard focus there and allow typing new values in the QLineEdit based modifier for the QTreeWidgetItem column.
I have implemented a working solution by using a custom ItemDelegate as follows.
class DoublePositionEditDelegate: public QStyledItemDelegate {
public:
DoublePositionEditDelegate(QObject* parent=0): QStyledItemDelegate(parent) {}
virtual QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const {
QDoubleSpinBox* dspinbox = new QDoubleSpinBox(parent);
dspinbox->setMaximum(1000000.0);
dspinbox->setMinimum(-1000000.0);
dspinbox->grabKeyboard();
return dspinbox;
}
};
A more elegant/better solution is still welcome.
I have a QTableView which has some QString based items in its model. I implemented setData in my table model, so editing is working (I can change the data in the cell, setData is called to update the model, and the table is properly updated).
Currently setData is only called when the user is done with editing, e.g. after they hit Enter or click out of the text entry box to finalize the text entry. I want to update other other parts of the table while the user is typing/editing into the text edit control instead of after they're done and the edited contents are finalized.
A simple example of what I want to have is for the next table cell to display a count of how many characters have been entered into the cell being edited, but to do this as the user is typing/editing the cell contents, not just after the edit is finalized and setData is called.
Any pointers to what I should be looking for? Thanks!
You can subclass QStyledItemDelegate and commit the data whenever something changes, and then set that delegate for the view with QAbstractItemView::setItemDelegate.
class MyDelegate : public QStyledItemDelegate {
QSignalMapper *mapper;
public:
MyDelegate(QObject*parent = 0)
: QStyledItemDelegate(parent)
, mapper(new QSignalMapper(this))
{
connect(mapper, SIGNAL(mapped(QWidget*)), SIGNAL(commitData(QWidget*)));
}
QWidget * createEditor(QWidget * parent, const QStyleOptionViewItem & option,
const QModelIndex & index ) const
{
QWidget *editor = QStyledItemDelegate::createEditor(parent, option, index);
if(qobject_cast<QLineEdit*>(editor)) {
connect(editor, SIGNAL(textChanged(QString)), mapper, SLOT(map()));
mapper->setMapping(editor, editor);
}
return editor;
}
};
The answer offered by #alexisdm did not work for me when I needed a persistent
editor enabled by QAbstractTableModel::setPersistentEditor(QModelIndex()).
The following solves this problem:
class Delegate : public QStyledItemDelegate
{
Q_OBJECT
public:
// ... omitted for brevity
QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,
const QModelIndex &index) const override
{
auto *editor = static_cast<QLineEdit*>(
QStyledItemDelegate::createEditor(parent, option, index));
if (editor) {
connect(editor,
&QLineEdit::textChanged,
[=] (const QString &)
{
const_cast<Delegate*>(this)->commitData(editor);
});
}
return editor;
}
// ... omitted for brevity
};
We simply cast the constness from this and make it commit data for the editor.
Note that in the lambda we capture the editor variable by value [=] because otherwise, capturing with reference would make the value of editor undefined when the function runs out of scope.
When I set flags of QAbstractItemModel selectable but not enabled, I can't select items by mouse click. However internally select() function selects objects.
Is this qt bug, or I do something wrong?
From what I understood, you want to "Disable" the item, but at the same time, be able to select it. it's fairly easy to fake that on the model.
if ( role == Qt::BackgroundRole ){
return QVariant(QApplication::palette()->color(QPalette::Inactive, QPalette::Window );
}
This will paint your item as grayed out, and you will still be able to select it.
You're doing something wrong. If you disable a widget it is greyed out and it doesn't receive user mouse clicks and keyboard input.
I just had similar problem (I need to copy disabled items). Here is solution that sets correct style for disabled items (without ignoring any style sheets).
Create custom item delegate for your model.
/// Returns false only if item needs to be rendered as disabled.
bool isIndexEnabled(const QModelIndex &index)
{
// Implement this function.
}
class ItemDelegate : public QStyledItemDelegate {
public:
explicit ItemDelegate(QObject *parent = nullptr)
: QStyledItemDelegate(parent) {}
protected:
void initStyleOption(
QStyleOptionItemView *option, const QModelIndex &index) const override
{
QStyledItemDelegate::initStyleOption(option, index);
if (!isIndexEnabled(index))
option->state &= ~QStyle::State_Enabled;
}
};
Set the new item delegate to your model.
auto itemDelegate = new ItemDelegate(model)
model->setItemDelegate(itemDelegate);
Is there any way to determine if a QTableView has an open editor in the current cell? I need to handle the following situation:
A user double-clicks a cell and edits the data, but leaves the cell in the "edit" state.
On another part of the UI, an action is taken that changes the selected row of the underlying model.
Back on my view, I want to determine if the newly selected row is the same as the open row. If not, I need to take an action. (Prompt the user? Commit automatically? Revert?)
I see how to get the current item, and can get the delegate on that item, but I don't see any isEditMode() property I was hoping to find.
Can someone point me in the right direction?
Just check whether the return value of
State QAbstractItemView::state () const
is
QTableView::EditingState
Connect to underlying model dataChanged signal
void QAbstractItemModel::dataChanged ( const QModelIndex & topLeft, const QModelIndex & bottomRight )
You can check if the cell where data has changed is the same than the currentIndex
QModelIndex QAbstractItemView::currentIndex () const
You cannot know if the current cell had an open editor straight, but can check if the view is in QAbstractItemView::EditingState
State QAbstractItemView::state () const
It should be enough to do what you want.
You can subclass QTableView in order to be able to access the state() function, which is unfortunately protected. However, I did not try that.
If you already have an QStyledItemDelegate subclass, you can use it to track whether an editor is currently open. However, you can't just use setEditorData/setModelData, because setModelData won't be called, when the user cancels editing. Instead, you can track the creation and destruction of the editor itself.
class MyItemDelegate : public QStyledItemDelegate
{
Q_OBJECT
public:
MyItemDelegate( QObject* parent = nullptr );
~MyItemDelegate();
QWidget* createEditor( QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index ) const;
void setEditorData( QWidget* editor, const QModelIndex& index ) const;
void setModelData( QWidget* editor, QAbstractItemModel* model, const QModelIndex& index ) const;
bool isEditorOpen() const { return *m_editorCount > 0; }
protected:
int* m_editorCount;
protected slots:
void onEditorDestroyed( QObject* obj );
};
Implementation:
MyItemDelegate::MyItemDelegate( QObject* parent ) :
QStyledItemDelegate( parent )
{
m_editorCount = new int;
*m_editorCount = 0;
}
MyItemDelegate::~MyItemDelegate()
{
delete m_editorCount;
}
QWidget* MyItemDelegate::createEditor( QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index ) const
{
// create an editor, can be changed as needed
QWidget* editor = QStyledItemDelegate::createEditor( parent, option, index );
connect( editor, SIGNAL(destroyed(QObject*)), SLOT(onEditorDestroyed(QObject*)));
printf( "editor %p created\n", (void*) editor );
(*m_editorCount)++;
return editor;
}
void MyItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
...
}
void MyItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
...
}
void MyItemDelegate::onEditorDestroyed( QObject* obj )
{
printf( "editor %p destroyed\n", (void*) obj );
(*m_editorCount)--;
}
On some occasions, e.g. when moving to the next item in the tree using the cursor keys, Qt will create the new editor first and then destroy the old one. Hence, m_editorCount must be an integer instead of a bool.
Unfortunately, createEditor() is a const function. Therefore, you cannot create an int-member. Instead, create a pointer to an int and use that.
Subclass your delegate so that it includes an accessor that tells you when it's editing:
void MyDelegate::setEditorData ( QWidget * editor, const QModelIndex & index ) const {
// _isEditing will have to be mutable because this method is const
_isEditing = true;
QStyledItemDelegate::setEditorData(editor, index);
}
void MyDelegate::setModelData ( QWidget * editor, QAbstractItemModel * model, const QModelIndex & index ) const {
QStyledItemDelegate::setModelData(editor, model, index);
_isEditing = false;
}
bool MyDelegate::isEditing() const { return _isEditing; }
Then you can just check the delegate to see what's going on. Alternatively and/or if you don't like the mutable, you can emit signals so you know what state the delegate is in.
If you know the index of the item being edited, you can call indexWidget() and attempt to cast it. If it's valid, you not only know you're editing, but you also have your editor widget handy.
EditWidget *editWidget = qobject_cast<EditWidget*>(tableView->indexWidget(tableView->currentIndex()));
if(editWidget)
{
//yep, ur editing bro
}
Here is an idea, its even helpful to get the edit/combo widget before the edit begins...
just emit a signal and consume it in the mainwindow... this is what I used one to get combo box in QTableWidget before editing...
first create a signal in ComoBoxItemDelegate...
signals:
void OnComboEdit(QComboBox* pCombo) const;
then emit the signal in the createEditor method...
QWidget* ComboBoxItemDelegate::createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
// Create the combobox and populate it
QComboBox* cb = new QComboBox(parent);
emit OnComboEdit(cb);
return cb;
}
and in the MainWindow declare a function to receive the singal...
void MainWindow::OnComboEidt(QComboBox *pCB) const
{
qDebug() << "Combo Eidt Singal Received";
}
Then finally in the constructor of MainWindow connect it...
ComboBoxItemDelegate* cbid = new ComboBoxItemDelegate(ui->tableWidget);
connect(cbid, &ComboBoxItemDelegate::OnComboEdit, this, &MainWindow::OnComboEidt);
ui->tableWidget->setItemDelegateForColumn(0, cbid);