Combine Multiple Images Into a Single PDF

[mrjj]

@geor
I think its just a path thing

void writePdf()
{
    const QString fileName("e:/mydoc.pdf");
       QPdfWriter pdfWriter(fileName);
    pdfWriter.setPageSize(QPageSize(QPageSize::A4));
    QPainter painter(&pdfWriter);

    for (int i=0; i<3; ++i) {
        painter.drawPixmap(QRect(0,0,pdfWriter.logicalDpiX()*8.3,pdfWriter.logicalDpiY()*11.7), QPixmap("e:/truck.png"));
        pdfWriter.newPage();
    }
}

works here. makes PDF on e:

[mrjj]

@geor
hi
You will / might need to scale the picture or its really small.

[geor]

@mrjj

yeh it worked after scaling thank you.

[geor]

@mrjj one more question lol

the size of my widget is too big to fit well on a A4 paper without looking deformed. So I want to break the layout of it's parent, resize my widget it and then take it's pixmap to put it in an A4 so it is not deformed (with the grab function) but the problem is I can't break the layout of the parent i can only delete (in code) and when I delete it it deletes everything in it any tips?

[mrjj]

@geor
Hi you can use the takeAt method to get your widget back from a layout.
But maybe you can just ask the widget to render directly?
it has a render function that can draw itself to anything you like.
http://doc.qt.io/qt-5/qwidget.html#render

[geor]

@mrjj

it doesn't seem to chnage much unless I am using it wrong? here is my code 1870 and 994 is the size of my widget.making the pixmap the same as the size of my widget gives me excatly the same ouput as before so i made it smaller it's better but cuts most of the widget out

                   ui->page1->setBackgroundRole(QPalette::BrightText);

             QPixmap pixMap1(600,900);
           ui->page1->render(&pixMap1,QPoint(),QRegion(0,0,1870,994));




    const QString fileName("D:/mydoc2.pdf");
       QPdfWriter pdfWriter(fileName);
    pdfWriter.setPageSize(QPagedPaintDevice::A4);
    QPainter painter(&pdfWriter);

   
        painter.drawPixmap(QRect(0,0,pdfWriter.logicalDpiX()*8.3,pdfWriter.logicalDpiY()*11.7), pixMap1);
        pdfWriter.newPage();

[mrjj]

@geor
hi
Sorry, didn't read the right docs.
The rect is for clipping not resize the widget.
So render will not help you to render it smaller.

so yes, i guess to render it in different size, you must take widget out , call resize +render and put it back it.
Not sure how well it will work if there is other stuff in the layout.
If sole widget, it should work ok.

[geor]

@mrjj Yeah I tried this method and It works but it's not perfect even if I resize the widget to the size of an A4 and then take it's pixmap fore some reason in the pdf it loses some quality (it looks a lot better in the user interface then in the pdf )even tho they are both the same size.I tried different functions from the painter class to draw the pixamp but the all seam the same not so good .If I draw the pixmap withouth any scaling it is very small in the pdf .. any ideas?

[mrjj]

@geor
hi , have you tried to render it really large and then
scale down to fit A4?

[geor]

@mrjj yep no matter how large the pixmap awlays appears very small on the 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]

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