Proper elide and peridically set background color of QTableView cell and possible for user to edit value - qt

Question

To summarize:
I need a solution for QTableView cells which fulfills
Proper elide
Possible to set background color by emitting dataChanged() from the model in a method called by a timer at ~50ms
Possible for user to edit value as normal.
QTBUG for the elide: https://bugreports.qt.io/browse/QTBUG-87178
Solution which fulfills req 1 but not 2 and 3: How to prevent too aggressive text elide in QTableview?
Sample program which demonstrates the issue:https://udokaelectronics.com/files/untitled.zip
Comment out
ui->tableView->setItemDelegate(elideDelegate);
to see behavior with and without elide delegate.
Anyone with ideas?

Answer 1

This is what I've come up with.
A delegate for keeping track of when an edit is in progress. Then use the state of the delegate in the table models to avoid emitting dataChanged()
#pragma once
#include <QStyledItemDelegate>
class EditInProgressDelegate : public QStyledItemDelegate
{
public:
EditInProgressDelegate(QObject* parent = nullptr) : QStyledItemDelegate(parent), editInProgress_(false){};
QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const override;
void destroyEditor(QWidget* editor, const QModelIndex& index) const override;
bool editInProgress() const { return editInProgress_; }
int editInProgressRow() const { return editInProgressRow_; }
int editInProgressColumn() const { return editInProgressColumn_; }
protected:
mutable bool editInProgress_;
mutable int editInProgressRow_;
mutable int editInProgressColumn_;
};
#include "EditInProgressDelegate.h"
QWidget* EditInProgressDelegate::createEditor(QWidget* parent,
const QStyleOptionViewItem& option,
const QModelIndex& index) const
{
editInProgress_ = true;
editInProgressColumn_ = index.column();
editInProgressRow_ = index.row();
return QStyledItemDelegate::createEditor(parent, option, index);
};
void EditInProgressDelegate::destroyEditor(QWidget* editor, const QModelIndex& index) const
{
editInProgress_ = false;
QStyledItemDelegate::destroyEditor(editor, index);
}
A second delegate with a magic 10 to handle elide
#pragma once
#include "EditInProgressDelegate.h"
// This entire class is a plaster because QTableWidgetItem or
// QStyledItemDelegate malfunctions, see
// https://stackoverflow.com/questions/64198197/how-to-prevent-too-aggressive-text-elide-in-qtableview
// and
// https://bugreports.qt.io/browse/QTBUG-87178
class ElideDelegate : public EditInProgressDelegate
{
public:
ElideDelegate(QObject* parent = nullptr) : EditInProgressDelegate(parent){};
void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const override;
};
#include "ElideDelegate.h"
#include <QApplication>
#include <QPainter>
void ElideDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
if (!index.isValid())
{
return;
}
QStyleOptionViewItem opt = option;
initStyleOption(&opt, index);
opt.text = opt.fontMetrics.elidedText(opt.text,
Qt::ElideRight,
opt.rect.width() - 10); // 10 was determined by experimentation
opt.textElideMode = Qt::ElideNone;
QApplication::style()->drawControl(QStyle::CE_ItemViewItem, &opt, painter);
}