SEGFAULT in paintEvent() and drawImage() [SOLVED]

hipersayan_x

Hi, i have created a widget that inherits from QWidget and reimplements paintEvent. The only purpose of this widget is to show a QImage as faster as possible. This is the code;

@
void ImageDisplay::paintEvent(QPaintEvent *event)
{
QWidget::paintEvent(event);

QImage image = this->m_image; 

QSize size = image.size();
size.scale(this->size(), Qt::KeepAspectRatio);
QRect rect(QPoint(), size);
rect.moveCenter(this->rect().center());

QPainter painter(this);

painter.drawImage(rect,
                  image,
                  image.rect());

}

void ImageDisplay::setImage(const QImage &image)
{
this->m_image = image;

this->update();

}
@

But, it seams to cause a SEGFAULT when calling setImage in certain cases, specially when calling from inside a slot .
When i debugg it with GDB, it give me the error in this line:

@
painter.drawImage(rect,
image,
image.rect());
@

But all parameters in rect and image are correct.
When I change the line from:

@ QImage image = this->m_image; @

to (for example):

@ QImage image = QImage("whatever.jpg"); @

or when i comment the line:

@ this->m_image = image; @

It doesn't crashes.
If i replace:

@ this->update(); @

with:

@ this->repaint(); @

In certain conditions it crashes, and in other works.

So, I'm very confused, and no idea on how to solve this, ¿any ideas please?

hipersayan_x

Ok, based in "this":https://qt-project.org/doc/qt-4.8/qimage.html#QImage-6:

bq. The buffer must remain valid throughout the life of the QImage. The image does not delete the buffer at destruction.

I has been deleting the QImage pixel buffer before rendering it with drawImage().
A quick solution could be (not the best way), change the line:

@
void ImageDisplay::setImage(const QImage &image)
{
this->m_image = image;

this->update();

}
@

to:

@
void ImageDisplay::setImage(const QImage &image)
{
this->m_image = image.copy();

this->update();

}
@