Combine Multiple Images Into a Single PDF

[mrjj]

@geor
well a screen is 72/96 DPI
and a printer is 600/1200/2400 DPI
so images do get really small.

As far as I remember, QPdfWriter have some setting for pdf resolution.
maybe it can produce better output.

[geor]

@mrjj yeah I saw that but unfortunately I am using qt 5.2.1

[mrjj]

@geor
maybe you could try to scale it before
drawing it to pdf.
the scale function can be adjusted to aim for quality
http://doc.qt.io/qt-5/qpixmap.html#scaled
with Qt::SmoothTransformation

note. it returns the scaled pixmap not modify the original.
so something like
mypixmap = mypixmap.scaled(xx)

[geor]

@mrjj It is abit better but still low quality

[mrjj]

@geor
well it was worth a shot.
I assume you play around with different scales?
Have you tried huge image like 1920x1080 and scale it down?
You are using http://doc.qt.io/qt-5/qpaintdevice.html#logicalDpiX
to calc how much to scale it?

I dont remember quality being so bad but i was using a fairly
large resolution so the widget was not that small.

[geor]

@mrjj yes I am using it the quality is not so good however if I save it into an image its gives me a good quality so it seems taking an image instead of a pixmap a lot better.
just like this
ui->myWidget->grab().save("image.png");
but this make me save 5 usless Images and I could not find a way to just use it temporarly..

[mrjj]

@geor
Im not sure what grab() is.
Does it return QImage?
Im wondering if u could just draw this directly?
No reason to save first.

[geor]

@mrjj it returns a pixmap

[mrjj]

@geor
have you tried to convert to qimage and draw it?
http://doc.qt.io/qt-4.8/qpixmap.html#toImage
Not sure why saving as png makes any difference.

[drich]

This post is deleted!

[JonB]

@MarieBurgan
Thanks for the plug. I'm sure @geor will thank you for this tip, if he visits here now two years after he last posted... ;-)