How to save the widget containing pixmap which keep changing at certain time interval, as an image file.

NIXIN

I am having a QWidget which conatins a QLabel. I have set a pixmap on this QLabel using setPixmap(). The pixmap is changing every 500 msec.

Now I want to print this widget as well as save it as an image file.

In order to do so I am using grab() and passing it to printer something like this....

QPrinter *printer;
QPainter painter(printer);

QPixmap pixmap = widget->grab(QRect(QPoint(10,10, ), QSize( widgetMaxWidth, widgetMaxHeight) ));
painter.drawPixmap(0, 0, pixmap);

This works fine for me because I am able to see the drawing inside QPrintPreviewDialog.

Whereas, when I try to save it as an image by the same way;

QPixmap pixmap = widget->grab(QRect(QPoint(0, 0, ), QSize( widgetMaxWidth, widgetMaxHeight) ));

QFile image(myfile.png);

pixmap.save(&image, "PNG");

I dont get the image file.

I would like to know how to achieve it??

And Also, when I am getting the grabbed widget painted on printer, then why not as an image file, when I save the same grabbed widget.

J.Hilk

hi,

first glance I would say, you're missing a line here:

image.open(QIODevice::WriteOnly);

NIXIN

tried, still not working...

jsulm

@NIXIN "still not working" - is not really helpful. Your code does not contain ANY error handling!
Did you check whether the file was opened? QFile::open returns a boolean signalling whether the file was opened or not. Use http://doc.qt.io/qt-5/qiodevice.html#errorString to print the error in case it returns false.
Same for QPixmap::save returns a boolean, did you check it?
What is the path to the image file?

VRonin

QPixmap pixmap = widget->grab(QRect(QPoint(0, 0), QSize( widgetMaxWidth, widgetMaxHeight) ));
if(!pixmap.toImage().save("myfile.png"))
qCritical("Save Failed!");

NIXIN

Checked

Qfile::open() returns true, and also

QPixmap::save() returns true.

still the I am not getting the image file....

J.Hilk

@NIXIN
if file.open() returns true, you should at least have the file (with size 0) created in your destination.

Can you comfirm that?

If not, try to give it a specific path, not only the name+ ending, so you can at least be sure where to look for the file :)

NIXIN

Yes, a file with size 0 kb is being created