CODEWITHSUNDEEP
windowsqtfiledialog
GrueMaster
GrueMaster

Reputation: 101

How to create a generic file selection dialog in QT4 for Windows

I have been searching for clues on this issue for some time now, with no results. So, here goes...

I have an application that I want to have a simple button to open a file dialog window. There are other buttons on the main window that will read or create/write the file (after doing the appropriate checks for the function selected). I used to use the QFileDialog::getSaveFileName() function without issues, but with Windows 7, this fails if the file exists AND is read-only. I switched to the getOpenFileName() to get around this issue, but now the file dialog fails if the user tries to select a non-existent file (irrelevant on a save operation).

Is there a way to add a "Create New File" icon to the file dialog, or add it to the right-click menu within the file dialog window? I would really hate to have to rewrite the app just because of (yet another) Windows behavior change.

Upvotes: 2

Views: 740

Answers (2)

GrueMaster
GrueMaster

Reputation: 101

Ok, since this was never really answered here, and I have since figured out a solution, I thought I would update this with the code snippet I am using.

void MainWindow::on_tbBrowse_clicked()
{
    // Use the location of already entered file
    QString fileLocation = leFile->text();
    QFileInfo fileinfo(fileLocation);

    // See if there is a user-defined file extension.
    QString fileType = qgetenv("DiskImagerFiles");
    if (fileType.length() && !fileType.endsWith(";;"))
    {
        fileType.append(";;");
    }
    fileType.append(tr("Disk Images (*.img *.IMG);;*.*"));
    // create a generic FileDialog
    QFileDialog dialog(this, tr("Select a disk image"));
    dialog.setNameFilter(fileType);
    dialog.setFileMode(QFileDialog::AnyFile);
    dialog.setViewMode(QFileDialog::Detail);
    dialog.setConfirmOverwrite(false);
    if (fileinfo.exists())
    {
        dialog.selectFile(fileLocation);
    }
    else
    {
        dialog.setDirectory(myHomeDir);
    }

    if (dialog.exec())
    {
        // selectedFiles returns a QStringList - we just want 1 filename,
        //      so use the zero'th element from that list as the filename
        fileLocation = (dialog.selectedFiles())[0];

        if (!fileLocation.isNull())
        {
            leFile->setText(fileLocation);
            QFileInfo newFileInfo(fileLocation);
            myHomeDir = newFileInfo.absolutePath();
        }
        setReadWriteButtonState();
        updateHashControls();
    }
}

setReadWriteButtonState() will enable the buttons according to the file state:

  • if file is read-only, only Read button is enabled
  • if file doesn't exist, only Write button is enabled

The entire code is available for others to review at https://sourceforge.net/projects/win32diskimager/. I hope this helps the next person that is looking for a solution to this. Just please include attribution if you use our code.

Upvotes: 0

RobbieE
RobbieE

Reputation: 4360

QFileDialog::getOpenFileName() should only be used for opening existing files. If you type in a name of a file that doesn't exist and the system complains, this is proper behaviour. It's correctly telling you that you can't open a file that doesn't exist.

If you want to write to an existing file or create a new file, you should be using QFileDialog::getSaveFileName()

If you're trying to write to an existing file that is marked as Read-Only in the operating system and you get an error saying that the file is Read-Only, then the error is correct. You should not be allowed to write to a read-only file, that's just what Read-Only means.

From what you've explained, there are no errors here. Everything's happening as it should be. If you're trying to force the system to do something different, don't. You should rather try and think of doing things a different way.

Upvotes: 1

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