[Solved] Difference between Qt4.8 and Qt5.0 when print pdf

SergioDanielG

Hi, I had a little code in Qt4.8 used to make a pdf file with barcodes and to print in cards (like credit cards).
When my pc died, I installed Qt5.0, adding printsupport and other few modification not related with QPrinter o QPainter.
No problem to compile or run in Qt5, but the file output it's diferent, (see the picture), making an invalid barcode.

Well, can somebody tell me why the output differ between Qt4.8 and Qt5?
Thanks in advance.

The code:
@mm = 11.8;
QPrinter printer;
QStringList path = QStandardPaths::standardLocations(QStandardPaths::DocumentsLocation);
QString home = QFileInfo(path.at(0)).absoluteFilePath();

QDateTime fecha;
QString tarjFile = tr("tarjetas_%1.pdf").arg(fecha.currentMSecsSinceEpoch());
QString outputPdf = tr("%1/%2").arg(home).arg(tarjFile);

printer.setOutputFileName(outputPdf);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setPaperSize(QSize(85.6, 54), QPrinter::Millimeter);
printer.setResolution(300);
printer.setColorMode(QPrinter::Color);
printer.setPageMargins(0.0, 0.0, 0.0, 0.0, QPrinter::Millimeter);
printer.setFontEmbeddingEnabled(true);

QPainter painter;
painter.begin(&printer);
QFont fontC("3 of 9 Barcode", 16);

tarjeta = ("1234567890123456");
painter.drawText(QRect(0, 5mm, 85.6mm, 5*mm), Qt::AlignHCenter, tarjeta);
painter.end();
@

The picture:
!https://imageshack.us/scaled/medium/854/13050023.png(barcode3of9)!

ChrisW67

This font: http://www.dafont.com/3of9-barcode.font
This code:
@
#include <QApplication>
#include <QFontDatabase>
#include <QPrinter>
#include <QPainter>

int main(int argc, char **argv)
{
QApplication app(argc, argv);

QFontDatabase::addApplicationFont("3OF9_NEW.TTF");

const int mm = 11.8;
QPrinter printer;
 
printer.setOutputFileName("test.pdf");
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setPaperSize(QSize(85.6, 54), QPrinter::Millimeter);
printer.setResolution(300);
printer.setColorMode(QPrinter::Color);
printer.setPageMargins(0.0, 0.0, 0.0, 0.0, QPrinter::Millimeter);
printer.setFontEmbeddingEnabled(true);
 
QPainter painter;
painter.begin(&printer);
QFont fontC("3 of 9 Barcode", 16);
painter.setFont(fontC);
 
painter.drawText(QRect(0,  5*mm, 85.6*mm, 5*mm), Qt::AlignHCenter, "0123456789012345");
painter.end();

return 0;

}
@
This result with Qt 4.8.4 (top) and Qt 5.0.1 (bottom) on Linux:
!http://img547.imageshack.us/img547/9773/7nsaj.png(Barcodes)!

Differences are fairly subtle.

SergioDanielG

Thanks for reply.
I can't see your picture, but I tried with several fonts, using directly from windows's (xp) fonts and adding with QFontDatabase::addApplicationFont(). Same result.
Recently, I try print barcode using LibreOffice on windows and it works (when I say "it works", is: the bardcode reader can read it and decode)
This is the barcode on LibreOffice
!https://imageshack.us/a/img199/7908/3of9libreoffice.png(barcode on LibreOffice)!
Well, like the problem it's at pdf generation in Qt, but why? or where?
Thanks again.

tobias.hunger

Have you tried to "file a bug report":https://bugreports.qt-project.org/ ? Adding a minimum working example like the one you gave here helps a lot:)

Bugreports do end up at the desk of the people that work on the relevant sub-system. They have to stumble over the issue by accident here in the forums.

SergioDanielG

Hi Tobias. Thanks for your reply.
Well, not really, before send a bug report I try always deplete all option to find a solution. (I'm not acquainted with bug report too) But, I'll try to report this as a bug.
Thanks again.

ChrisW67

I've uploaded the original image to another host. Maybe you can see it now.

Here is a Windows XP version of the same (4.8.0 top, 5.0.1 bottom):
!http://img401.imageshack.us/img401/761/testpages.png(On Win XP)!

So the problem is Windows (or XP) specific.

SergioDanielG

Yes, I can see it now, and effectively, it's like a problem in windows and Qt5. Lines in the barcode are wider than in Qt4.8.
As Tobias recommended, I did a bug report, now let's wait..
Thanks.

ChrisW67

I did wonder it if is some curious text anti-aliasing glitch

SergioDanielG

Hi all.
The problem was fixed with: "https://codereview.qt-project.org/#change,60448":https://codereview.qt-project.org/#change,60448.
Tested with Qt 5.1.1 MinGW 32bit.
Regards.