dark mode makes picture in book negative (inverted)

[ghost]

• KOReader version: 2024.03.1 Latest
• Device: PocketBook 633

I turn on the dark mode and starting reading the book, the first page is with the cover of the book.
The picture inside the book became negative (inverted) anyway (see photos)

It seems that in the settings I turn on invert images - it’s still a negative image, then I turn off the function - it’s still a negative image, not a real color one!

PHOTOS DESCRIBES PROBLEM

Help me fix it please.
Please fix it in the new version.

[Frenzie]

I don't think MuPDF (easily) offers that through its API, but if it does it's still something that should probably be off by default (e.g., the whole document might consist of images, the images might count on transparency so you get black on black, etc.).

Interested parties could start investigating around fz_invert_pixmap and fz_gamma_pixmap.

[poire-z]

I think this is not related to MuPDF: the bottom menu is the one we get with CRE.
And I guess, from the russian UI, that this is a FB2 document - and for FB2 document, the cover is something special drawn via a dedicated codepath (unlike other images in the FB2, or all image including the cover in EPUBs) where we don't do that inversion (because we just didn't think about it :/).
Not sure yet if it's easy to fix, I'll look at it, no promise.

[poire-z]

OK, the fix looks easy, will push that in the coming days.

--- a/crengine/src/lvdocview.cpp
+++ b/crengine/src/lvdocview.cpp
@@ -1161,6 +1161,7 @@ void LVDocView::drawCoverTo(LVDrawBuf * drawBuf, lvRect & rc) {
                        dst_dy = imgrc.height();
                //CRLog::trace("drawCoverTo() - drawing image");
         LVColorDrawBuf buf2(src_dx, src_dy, 32);
+        buf2.setInvertImages(drawBuf->getInvertImages());
         buf2.Draw(imgsrc, 0, 0, src_dx, src_dy, true);
         drawBuf->DrawRescaled(&buf2, imgrc.left + (imgrc.width() - dst_dx) / 2,
                 imgrc.top + (imgrc.height() - dst_dy) / 2, dst_dx, dst_dy, 0);