Images + QTableview + Delegates

[NoRulez]

Hey @all,

can anybody help me or can give me an example on how to draw an image into a cell without white spaces on each side using a delegates?

Kind Regards
NoRulez

[faldzip]

Here is the mainwindow.cpp fragment (from constructor):

ui->tableView->setShowGrid(false);
	ui->tableView->horizontalHeader()->hide();
	ui->tableView->verticalHeader()->hide();
	ui->tableView->horizontalHeader()->setMinimumSectionSize(1);
	ui->tableView->verticalHeader()->setMinimumSectionSize(1);
	ui->tableView->setModel(new ImageModel(this));
	ui->tableView->setItemDelegate(new ImageDelegate(this));
	ui->tableView->resizeColumnsToContents();
	ui->tableView->resizeRowsToContents();

ui->tableView->setShowGrid(false);
	ui->tableView->horizontalHeader()->hide();
	ui->tableView->verticalHeader()->hide();
	ui->tableView->horizontalHeader()->setMinimumSectionSize(1);
	ui->tableView->verticalHeader()->setMinimumSectionSize(1);
	ui->tableView->setModel(new ImageModel(this));
	ui->tableView->setItemDelegate(new ImageDelegate(this));
	ui->tableView->resizeColumnsToContents();
	ui->tableView->resizeRowsToContents();

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ImageModel is returning 0, 1, 2 as data() depending od row and col. It's derived from QAbstractTableModel and has headerData():

QVariant ImageModel::headerData(int /* section */, Qt::Orientation /* orientation */, int role) const
{
	if (role == Qt::SizeHintRole)
		return QSize(1, 1);
	return QVariant();
}

QVariant ImageModel::headerData(int /* section */, Qt::Orientation /* orientation */, int role) const
{
	if (role == Qt::SizeHintRole)
		return QSize(1, 1);
	return QVariant();
}

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And the delegate looks like that (header file):

#ifndef IMAGEDELEGATE_H
#define IMAGEDELEGATE_H
 
#include <QAbstractItemDelegate>
#include <QSize>
#include <QPixmap>
#include <QPainter>
 
class ImageDelegate : public QAbstractItemDelegate
{
public:
	ImageDelegate(QObject * parent = 0);
 
	void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const;
	QSize sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const;
};
 
#endif // IMAGEDELEGATE_H

#ifndef IMAGEDELEGATE_H
#define IMAGEDELEGATE_H

#include <QAbstractItemDelegate>
#include <QSize>
#include <QPixmap>
#include <QPainter>

class ImageDelegate : public QAbstractItemDelegate
{
public:
	ImageDelegate(QObject * parent = 0);

	void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const;
	QSize sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const;
};

#endif // IMAGEDELEGATE_H

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and cpp file:

#include "imagedelegate.h"
 
ImageDelegate::ImageDelegate(QObject * parent)
		: QAbstractItemDelegate(parent)
{
}
 
QSize ImageDelegate::sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const
{
	return QSize(32,32);
}
 
void ImageDelegate::paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
{
	int data = index.data(Qt::DisplayRole).toInt();
 
	switch (data)
	{
	case 0:
		{
			QPixmap pm(":/img/red");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	case 1:
		{
			QPixmap pm(":/img/green");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	case 2:
		{
			QPixmap pm(":/img/blue");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	}
}

#include "imagedelegate.h"

ImageDelegate::ImageDelegate(QObject * parent)
		: QAbstractItemDelegate(parent)
{
}

QSize ImageDelegate::sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const
{
	return QSize(32,32);
}

void ImageDelegate::paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
{
	int data = index.data(Qt::DisplayRole).toInt();

	switch (data)
	{
	case 0:
		{
			QPixmap pm(":/img/red");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	case 1:
		{
			QPixmap pm(":/img/green");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	case 2:
		{
			QPixmap pm(":/img/blue");
			painter->drawPixmap(option.rect, pm);
			return;
		}
	}
}

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the result you can see in attachment. Also take closer look to Pixelator example in Qt Examples & Demos.

[NoRulez]

Thank you very much, but if I had vertical and horizontal headers, the image on (for example) the vertical header is tiny, how can i made to have a background image on the header?
QHeaderView doesn't have an addPixmap or something similar function. I read that QHeaderView can't be modified with Delegates is it?

Kind Regards
NoRulez

[faldzip]

Setting delegate for QHeaderView has no effect, so:
1. You can use Qt::BackgroundRole for setting brush used for background painting
2. Or, I'm afraid, you have to subclass QHeaderView and reimplement paintEvent(), as it stands in docs.

[NoRulez]

And the paintEvent() must be the same as in your paint() example for example? Is this correct?

LG NoRulez