void QPdfView::paintEvent(QPaintEvent *event)
{
Q_D(QPdfView);
QPainter painter(viewport());
painter.fillRect(event->rect(), palette().brush(QPalette::Dark));
painter.translate(-d->m_viewport.x(), -d->m_viewport.y());
for (auto it = d->m_documentLayout.pageGeometryAndScale.cbegin();
it != d->m_documentLayout.pageGeometryAndScale.cend(); ++it) {
const QRect pageGeometry = it.value().first;
if (pageGeometry.intersects(d->m_viewport)) { // page needs to be
painted
painter.fillRect(pageGeometry, Qt::white);
So the answer for now is no. You can write up a suggestion on bugreports.qt.io
if you want. Perhaps the page background should use a palette color. But
then, dark mode would be problematic, wouldn't it? If the page background is
dark, and the PDF also has dark text, we’d get a bug report right away, now
that dark mode is popular.
I also hate trying to read bright-white PDFs in dark rooms when I’m trying to
have most of the onscreen content be dark. It can make my eyes go into a weird
mode where I see jagged-edged round-ish rainbows for a while, and can’t read
anything for a few minutes. (Does anybody know what that’s called?) But PDF
is a simulation of paper.. and paper is usually white, so the content usually
has dark text. In another PDF viewer, I once tried to solve that problem with
a shader. (That’s also tricky: you want to only replace the background color
itself, and the main text color, which is likely black but perhaps not. So the
fragment shader can invert any color that is a shade of grey, but leave the
rest as they are. And often it will work well enough, but not always.) It’s
just that if we shipped such a feature, there would probably be more bug
reports, I suppose.
It’s easier in Qt Quick though. Image { source: “file.pdf”; currentFrame: 5 }
will give you page 5 (starting from 0, so probably page 6) with no background
at all (unless the PDF does its own background fill): whatever is behind it
will show through. (Window is white by default though.) The packaged viewer
components are much more complex than that, of course. You can experiment by
forking one of those QML files (depending whether you want to scroll through
all the pages, or just one page at a time).
https://code.qt.io/cgit/qt/qtwebengine.git/tree/src/pdfquick
On Dec 5, 2024, at 00:58, Joshua Grauman <jnf...@grauman.com> wrote:
Hello,
I generate pdfs by using QPainter to paint onto a QPrinter. My understanding is
that the generated pdf has a transparent background, even though most viewers
view the pdf with a white background. I am able to view the pdf with a
different color background with Okular for example. I'm wondering if there is
any way to change the background color of QPdfView (to black)? I tried changing
the palette of QPdfView or change it's style sheet but those didn't do it. Does
anyone know if there is any way to display the pdf with a different background
color using QPdfView?
Josh
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