How can I check if QPdfWriter object can write to the specified file? - qt

Question

I am creating the PDF documents in Qt using command:
QPdfWriter *pdf;
pdf = new QPdfWriter(filename);
Sometimes the object is not created due to a wrong filename or document exists and is open in other application...
How can I check if object was created (if the pdf pointer points to the valid object)?
EDIT: My mistake was, that object is not created. It is not true. The QPdfWriter object is created, but there is no exception or error generated.
I can set some properties.
The problem will occur later when I am trying to write something to the document - see comments of the last 3 commands:
pdf->setParent(this);
pdf->setPageSize(QPdfWriter::A4);
pdf->setPageOrientation(QPageLayout::Orientation::Landscape);
QPainter *p = new QPainter(pdf); //got message: QPainter::begin(): Returned false
ui->chartView->render(p); // no error
p->end(); // got message: QPainter::end: Painter not active, aborted
I read the documentation of QpdfWriter and parent classes QPagedPaintDevice and QPaintDevice. I cannot find any property/method to check if I can write to the document...
So question - how to check if I can write to the document?

Answer 1

Ive just stumpled over the same issue, the hint with bool QFileInfo::isWritable() const didn't do the trick for me. Though you basically gave the answer yourself with the comment on the third last command, with the return value of QPainter::begin() you can check if the QPdfWriter can generate the pdf.
QPainter *p = new QPainter;
if (p->begin(pdf)) {
ui->chartView->render(p);
p->end();
} else {
// error message...
}