Inaccurate MouseEvent position over a Scaled Pixmap

[jpn]

First of all, there is no need to allocate QPixmaps on the heap. It's an implicitly shared class:

// QPixmap* originalPx;
// QPixmap* newPx;
QPixmap originalPx;
QPixmap newPx;
 
originalPx = QPixmap::fromImage(img);
newPx = QPixmap(width(), height());

// QPixmap* originalPx;
// QPixmap* newPx;
QPixmap originalPx;
QPixmap newPx;

originalPx = QPixmap::fromImage(img);
newPx = QPixmap(width(), height());

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Notice that QPixmap::scaled() RETURNS the scaled pixmap and you might want to always scale the original pixmap not to lose information over time:

newPx = originalPx.scaled(size, Qt::IgnoreAspectRatio, Qt::FastTransformation);

newPx = originalPx.scaled(size, Qt::IgnoreAspectRatio, Qt::FastTransformation);

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Because you ignore aspect ratio and the pixmap size always matches widget size, you can just draw the pixmap in the upper left corner (0,0):

painter.drawPixmap(0, 0, newPx);

painter.drawPixmap(0, 0, newPx);

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If you later decide to keep aspect ratio, then you can use this handy method in QStyle to draw the pixmap as aligned:

style()->drawItemPixmap(&painter, rect(), Qt::AlignCenter, newPx);

style()->drawItemPixmap(&painter, rect(), Qt::AlignCenter, newPx);

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[ramstormrage]

Hi jpn,

Thank you for the clarifications.
I did some modifications and I placed the codes from the resizeEvent to loadPixmap() because I wanted to be able to change the Pixmap whenever necessary.

void simplePixmapWidget::loadPixmap(QImage &img)
{
	origPx = QPixmap::fromImage(img);
	newPx = QPixmap(width(), height());
	QSize size(width(), height());
        newPx = origPx.scaled(size, Qt::IgnoreAspectRatio, Qt::FastTransformation); 
        QImag0 = newPx.toImage();
	update();
}

void simplePixmapWidget::loadPixmap(QImage &img)
{
	origPx = QPixmap::fromImage(img);
	newPx = QPixmap(width(), height());
	QSize size(width(), height());
        newPx = origPx.scaled(size, Qt::IgnoreAspectRatio, Qt::FastTransformation); 
        QImag0 = newPx.toImage();
	update();
}

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Thank you very much.

[jpn]

Call QWidget::update() to schedule a paint event.