QTreeWidget + drag&drop : How to set pixmap as Icon+Text

[pl01]

Hi,

During a drag&drop I would like to display the icon and the text of the tree-item in the drag element. How can I do this ?

If I set the pixmap, it only display the icon... but not the text !

Thanks

---

Added after 28 minutes:

I have a partial solution, like this

void QShaderNavigator::mousePressEvent(QMouseEvent *event)
{
	//---- Search for the selected definition
	_dragTreeViewItem =	itemAt(event->pos());
	if (_dragTreeViewItem)
	{
		QVariant data = _dragTreeViewItem->data(0, 1);	
		if (data.isNull())
			_dragTreeViewItem = 0;
		else
		{
			const QPixmap image = iconShader.pixmap(QSize(16,16));
			_dragPainter->drawPixmap(0, 0, 16, 16, image);
			_dragPainter->drawText(QRect(20, 0, 170, 20), _dragTreeViewItem->text(0) );
		}
	}
 
	QTreeWidget::mousePressEvent(event);
}

void QShaderNavigator::mousePressEvent(QMouseEvent *event)
{
	//---- Search for the selected definition
	_dragTreeViewItem =	itemAt(event->pos());
	if (_dragTreeViewItem)
	{
		QVariant data = _dragTreeViewItem->data(0, 1);	
		if (data.isNull())
			_dragTreeViewItem = 0;
		else
		{
			const QPixmap image = iconShader.pixmap(QSize(16,16));
			_dragPainter->drawPixmap(0, 0, 16, 16, image);
			_dragPainter->drawText(QRect(20, 0, 170, 20), _dragTreeViewItem->text(0) );
		}
	}
	
	QTreeWidget::mousePressEvent(event);
}

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void QShaderNavigator::mouseMoveEvent(QMouseEvent * event)
{
...
drag->setPixmap( *_dragPixmap );
...
}

void QShaderNavigator::mouseMoveEvent(QMouseEvent * event)
{
...
drag->setPixmap( *_dragPixmap );
...
}

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But the problem is that I have a big gray background in the Drag item !!!

[goldnrod]

This post is pretty old, but I'll write this up anyway.

You were on the right track, you just need to paint a transparent rectangle and then use the SourceOver compostion mode of the painter to draw your icon and text over top of the transparent background. The following code differs slightly from yours, but I think you will understand what I'm doing:

///
///
///
void SourceTreeWidget::mousePressEvent(QMouseEvent *event)
{
    if ( event->button() == Qt::LeftButton )
    {
        QTreeWidgetItem * item = itemAt(event->pos());
        if ( item && item->childCount() == 0 ) {
            startPos = event->pos();
        }
        else {
            startPos.setX(0); startPos.setY(0);
        }
    }
 
    QTreeWidget::mousePressEvent(event);
}

///
///
///
void SourceTreeWidget::mousePressEvent(QMouseEvent *event)
{
    if ( event->button() == Qt::LeftButton )
    {
        QTreeWidgetItem * item = itemAt(event->pos());
        if ( item && item->childCount() == 0 ) {
            startPos = event->pos();
        }
        else {
            startPos.setX(0); startPos.setY(0);
        }
    }

    QTreeWidget::mousePressEvent(event);
}

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///
///
///
void SourceTreeWidget::mouseMoveEvent(QMouseEvent *event)
{
    if ( (event->buttons() & Qt::LeftButton) && !startPos.isNull() )
    {
        int distance = (event->pos() - startPos).manhattanLength();
        if (distance >= QApplication::startDragDistance())
        {
            QTreeWidgetItem * dragTreeViewItem = itemAt(startPos);
 
            //
            // Paint an image composed of a transparent background and an icon and some text
            //
            QImage icon(QString(":/images/bean.ico"));
            QSize dragImageSize(186, 20);
            QImage dragImage(dragImageSize, QImage::Format_ARGB32_Premultiplied);
 
            QPainter dragPainter(&dragImage);
 
            dragPainter.setCompositionMode(QPainter::CompositionMode_Source);
            dragPainter.fillRect(dragImage.rect(), Qt::transparent);
 
            dragPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
            dragPainter.drawPixmap(0, 0, 16, 16, QPixmap::fromImage(icon));
            dragPainter.drawText(QRect(20, 0, 170, 20), dragTreeViewItem->text(0) );
 
            dragPainter.end();
 
            QDrag *drag = new QDrag(this);
            drag->setPixmap( QPixmap::fromImage(dragImage) );
 
 
            QMimeData *mimeData = new QMimeData;
            mimeData->setText(dragTreeViewItem->text(0));
            drag->setMimeData(mimeData);
            drag->exec(Qt::MoveAction);
        }
    }
 
    QTreeWidget::mouseMoveEvent(event);
}

///
///
///
void SourceTreeWidget::mouseMoveEvent(QMouseEvent *event)
{
    if ( (event->buttons() & Qt::LeftButton) && !startPos.isNull() )
    {
        int distance = (event->pos() - startPos).manhattanLength();
        if (distance >= QApplication::startDragDistance())
        {
            QTreeWidgetItem * dragTreeViewItem = itemAt(startPos);

            //
            // Paint an image composed of a transparent background and an icon and some text
            //
            QImage icon(QString(":/images/bean.ico"));
            QSize dragImageSize(186, 20);
            QImage dragImage(dragImageSize, QImage::Format_ARGB32_Premultiplied);

            QPainter dragPainter(&dragImage);

            dragPainter.setCompositionMode(QPainter::CompositionMode_Source);
            dragPainter.fillRect(dragImage.rect(), Qt::transparent);

            dragPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
            dragPainter.drawPixmap(0, 0, 16, 16, QPixmap::fromImage(icon));
            dragPainter.drawText(QRect(20, 0, 170, 20), dragTreeViewItem->text(0) );

            dragPainter.end();

            QDrag *drag = new QDrag(this);
            drag->setPixmap( QPixmap::fromImage(dragImage) );


            QMimeData *mimeData = new QMimeData;
            mimeData->setText(dragTreeViewItem->text(0));
            drag->setMimeData(mimeData);
            drag->exec(Qt::MoveAction);
        }
    }

    QTreeWidget::mouseMoveEvent(event);
}

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I had to do the same thing for a project, but with multi-select. I'm attaching a project (treeMultiDrag.zip) that shows how to do the same thing with more elaborate multi-select.