Reading a CSS file using Qt C++

Question

I'm trying to load in a CSS file for formatting across my entire Qt application. Currently I have my "stylesheet.css" file in the same folder as my built exe (both debug and release). However, upon running the program it produces no errors and simply outputs "test: ", so it's clearly not finding the file or perhaps I'm not reading it properly?

Forgive me if it's a dumb mistake - I'm fairly new to both Qt and C++.

#include "mainwindow.h"
#include "qfile.h"
#include "qtextstream.h"
#include <QApplication>
#include <iostream>

int main(int argc, char *argv[])
{
    QApplication program(argc, argv);

    QFile styleFile("stylesheet.css");
    styleFile.open(QIODevice::ReadOnly);
    QTextStream textStream(&styleFile);
    QString styleSheet = textStream.readAll();
    styleFile.close();
    program.setStyleSheet(styleSheet);

    std::cout << "test: " << styleSheet.toStdString() << std::endl;

    MainWindow w;
    w.showMaximized();

    return program.exec();
}

Copy the CSS file beside your source code while you're running the program via Qt. — masoud
– masoud, Commented Sep 5, 2013 at 7:27
QFile::open() returns true if successful. You should always check if the file was opened successfully before trying to do anything with it. You can also check the error that occurred with QFile::errorString(). — thuga
– thuga, Commented Sep 5, 2013 at 7:28
Thanks guys - though, after a bit more research it turns out that the problem was simpler than I thought. Also, I'll definitely remember to do that, thanks for the tip thuga. After digging a bit deeper, it turns out I was lacking a QRC file (which I wasn't even aware existed). So I created a resource (QRC) file, added the prefix "/style", and then added my stylesheet to that prefix. It now works flawlessly. Also, at one point I changed the .css to a .qss (thought I should mention it, although I doubt it made any difference). — Geoffrey Tucker
– Geoffrey Tucker, Commented Sep 5, 2013 at 7:45
@GeoffreyTucker You should post your solution as an answer and accept it when you can. — thuga
– thuga, Commented Sep 5, 2013 at 7:51
I actually tried doing that first - though, it says I have to wait 8 hours for having less than 10 reputation. I'll be sure to post it some time tomorrow — Geoffrey Tucker
– Geoffrey Tucker, Commented Sep 5, 2013 at 7:53

Geoffrey Tucker · Accepted Answer · 2013-09-05 16:42:05Z

4

After digging a bit deeper, it turns out I was lacking a QRC file (which I wasn't even aware existed). So I created a resource (QRC) file, added the prefix "/style", and then added my stylesheet to that prefix. It now works flawlessly. Also, at one point I changed the .css to a .qss (thought I should mention it, although I doubt it made any difference).

Here's the final code:

#include "mainwindow.h"
#include "qfile.h"
#include "qtextstream.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication program(argc, argv);

    QFile styleFile(":/style/stylesheet.qss");
    if(styleFile.open(QIODevice::ReadOnly))
    {
        QTextStream textStream(&styleFile);
        QString styleSheet = textStream.readAll();
        styleFile.close();
        program.setStyleSheet(styleSheet);
    }

    MainWindow w;
    w.showMaximized();

    return program.exec();
}

answered Sep 5, 2013 at 16:42

Geoffrey Tucker

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1 Comment

Marino Šimić Over a year ago

that is not why it was not working before. here you load the stylesheet from the resource. before you were trying to load the stylesheet from a relative path, and the current directory when doing so was not the one where the stylesheet was. the current directory is not necessarily the one where the exe file is.

sashoalm · Accepted Answer · 2013-09-05 07:40:28Z

0

Change

QFile styleFile("stylesheet.css");

to

QFile styleFile("C:/path/to/stylesheet.css");

You need to pass the full file path for your program to find the file. If you just give its name but not the directory it's in, the program will search for it in the current directory only (which is not necessarily the directory of your exe file), and if it's not there, it won't find it.

answered Sep 5, 2013 at 7:40

sashoalm

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2 Comments

thuga Over a year ago

Or rather, use QApplication::applicationDirPath() to find the path that contains the executable.

sashoalm Over a year ago

Yes, of course, he should construct the full file path instead of hard-coding it. But that goes beyond the scope of his immediate problem, which is he doesn't understand relative vs absolute paths.

Jan Kundrát · Accepted Answer · 2013-09-05 13:26:29Z

0

If you want to deploy this CSS file with your application, you are looking for the Qt resource file support.

answered Sep 5, 2013 at 13:26

Jan Kundrát

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1 Comment

Geoffrey Tucker Over a year ago

Thanks! I definitely would have chosen your answer as best answer had I not figured it out myself last night (as seen in the comments to my original post).

reena · Accepted Answer · 2017-10-12 11:13:43Z

0

its coz u shoud uncheck " shadow build " under projects. and check the path of the project . and make sure that .css file is inside the project folder

answered Oct 12, 2017 at 11:13

reena

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