QPrinter prints different font size and region on different computers (printing PDF)

**MisterIKS** · 19th December 2012, 23:03

Hey everyone,

I'm trying and searching all the forums I know for days now, but I just can't find the problem with this one:

Qt Code:

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QWebView *view = new QWebView();
QString htmlPage = "<html>   .....   </html>";
view->setHtml(htmlPage);
 
QPrinter printer;
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName(fileName);
printer.setFullPage(true);
printer.setOrientation(QPrinter::Portrait);
printer.setPaperSize(QPrinter::A4);
view->print(&printer);    
QDesktopServices::openUrl(QUrl("file:///" + fileName, QUrl::TolerantMode));

QWebView *view = new QWebView();
QString htmlPage = "<html>   .....   </html>";
view->setHtml(htmlPage);

QPrinter printer;
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName(fileName);
printer.setFullPage(true);
printer.setOrientation(QPrinter::Portrait);
printer.setPaperSize(QPrinter::A4);
view->print(&printer);    
QDesktopServices::openUrl(QUrl("file:///" + fileName, QUrl::TolerantMode));

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I'm simply trying to print an HTML-File to PDF that I previously parsed in a QWebView. The HTML should fill the whole page, which it does on the machine I'm developing on.
But on some computers I tried my application, in the PDF either fonts appear printed a lot larger or the HTML is printed in an area much smaller than the actual page.
My client is starting to get mad, cause on his computer the content only fills the uppler left quarter of the page and is too small to read...

Am I doing something wrong here? Is there some kind of relative size setting that I missed? (setResolution doesn't show an effect) How can i specify the area in which the WebView should print to?

Thank you so much for your advice, MisterIKS

**ChrisW67** · 20th December 2012, 01:23

QTBUG-5363 might explain a small offset on Windows but not the scaling issue unless the user's default margins on the page are really broken.

Have you tried explicitly setting QPrinter's margins to 0?

**MisterIKS** · 20th December 2012, 07:49

Thanks for your reply, I would be fine with a small offset, but not with the content filling only half the page...
Actually I just found out that the windows setting "Control Panel -> Appearance and Personalization -> Display -> Make text an other items larger of smaller" causes this problem when set to something different from 100%.

There must be a way to force QPrinter not to care about windows settings and print the size I want?

**wysota** · 20th December 2012, 21:30

Does it change anything if you pass QPrinter::HighResolution to the constructor of the printer object?

What about setting an explicit resolution with QPrinter::setResolution()?

**ChrisW67** · 20th December 2012, 22:01

Changing the Windows display scaling to 125% or 150% does not affect printing the Google front page for me. The test code I used is below.

What is the HTML you are loading? Is it well formed? Does it use styles with fixed widths? External CSS? Javascript?

Qt Code:

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#include <QApplication>
#include <QWebView>
#include <QPrinter>
#include <QDebug>
 
class MyWebView: public QWebView
{
    Q_OBJECT
public:
    MyWebView(QWidget *p = 0): QWebView(p) {
        connect(this, SIGNAL(loadFinished(bool)), SLOT(doPrint(bool)));
    }
public slots:
    void doPrint(bool ok) {
        qDebug() << "doPrint" << ok;
        QPrinter printer;
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setOutputFileName("zz.pdf");
        printer.setFullPage(true);
        printer.setOrientation(QPrinter::Portrait);
        printer.setPaperSize(QPrinter::A4);
        print(&printer);    
        qDebug() << "doPrint done";
    }
};
 
 
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    MyWebView web;
    web.setUrl(QUrl("http://www.google.com.au"));
    web.show();
    return app.exec();
}
#include "main.moc"

#include <QApplication>
#include <QWebView>
#include <QPrinter>
#include <QDebug>

class MyWebView: public QWebView
{
    Q_OBJECT
public:
    MyWebView(QWidget *p = 0): QWebView(p) {
        connect(this, SIGNAL(loadFinished(bool)), SLOT(doPrint(bool)));
    }
public slots:
    void doPrint(bool ok) {
        qDebug() << "doPrint" << ok;
        QPrinter printer;
        printer.setOutputFormat(QPrinter::PdfFormat);
        printer.setOutputFileName("zz.pdf");
        printer.setFullPage(true);
        printer.setOrientation(QPrinter::Portrait);
        printer.setPaperSize(QPrinter::A4);
        print(&printer);    
        qDebug() << "doPrint done";
    }
};


int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    MyWebView web;
    web.setUrl(QUrl("http://www.google.com.au"));
    web.show();
    return app.exec();
}
#include "main.moc"

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**MisterIKS** · 20th December 2012, 23:55

Thanks for your replies!

Explicitly setting a resolution via constructor or setResolution() unfortunately doesn't change anything for me.

I actually use fixed widths to 800px in my document for the body-tag. I did this as the printed size of my document otherwise depended on the actual content I'm adding dynamically to the HTML. I probably got something wrong here concerning the way Qt transforms the WebView into printed Document, but without fixed width and with the text getting longer in my document the printed fontsize got smaller to have the text fit in one line instead of doing line breaks, which I could only prevent by setting the width in CSS.

However at some other point in my application I'm also printing PDFs directly with QPrinter and QPainter and without QWebView, which also results in larger fontsize when set to 125% (the layout stays intact here because I'm using fixed pixel values for positioning the text) ... does anybody experience this too? Thats why I still thing that this has more something to do with QPrinter but the HTML.

Let me know if you need more information. I really hope to get this working until christmas

**d_stranz** · 21st December 2012, 00:16

This may or may not be related, but on some of my printers web pages are printed very small also. The problem seems to be related to a printer setting, something like "scale to fit page". The default setting was to print without scaling, and that caused the microscopic output. Once the driver was set to "scale to fit", things were fine.

I don't know if you can do that programmatically from Qt, but your client might be willing to change a few printer settings.

**ChrisW67** · 21st December 2012, 02:32

Are you able to post a sample HTML file, and supporting images etc., that displays the problem?

Further to d_stranz suggestion you may also like to check if the affected user has a default printer set at all, and if selecting a different printer as the default changes the behaviour.

**MisterIKS** · 21st December 2012, 18:48

I thought that printing to PDF would be a Qt internal thing, does changing default printer and it's settings really change something? Anyway I'm currently testing on my PC an notebook which both run on Windows 7, both have the same one and only printer installed, the only difference is, that my notebook is set to 125% in windows scaling options because of the small screen.

I now tried the following code on both notebook and pc which resulted in these two files:
notebook_result.pdf pc_result.pdf

Qt Code:

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<html><head><style type=\"text/css\">body{margin-top:0px; margin-left:20px; padding:0px 80px; font-family:Arial; font-size:16px;}</style></head><body>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.</body></html>

<html><head><style type=\"text/css\">body{margin-top:0px; margin-left:20px; padding:0px 80px; font-family:Arial; font-size:16px;}</style></head><body>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.</body></html>

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I feel like it can't be a problem in my html, any other ideas?

**ChrisW67** · 21st December 2012, 20:59

Originally Posted by MisterIKS

I thought that printing to PDF would be a Qt internal thing, does changing default printer and it's settings really change something?

It is, but when you create a default QPrinter it configures itself for the system default printer and then you change it to PDF and fiddle with the margins etc. I reasoned that if there is no default printer perhaps you get odd results.

Your example HTML is missing <p> tags but browsers are tolerant of these things.

I can reproduce the issue here using a longer form of the lorem ipsum, your style, 32-bit Win 7 and the MS document writer as the only printer. The text gets smaller as the display scaling value increases. Changing to font size specified as 16pt did not help.

Try rendering some 16px Arial text on the QPrinter using a QPainter directly. If that also scales with the display scaling then the problem is outside QWebView... might help searching for (or reporting) a Qt bug.

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