About background colors

[yozhic]

There’s currently some confusion regarding background colors in pre-release 18291. But before submitting a bug report, I’d like to make sure I’ve understood everything correctly.

Yesterday I created issue #5521, and it seems I didn’t express myself clearly, which only made things more confusing (my apologies—my English is machine-translated 🤦‍♂️). In light of this, I’d like to suggest an idea: how we could avoid confusion in the future.

So, right now we have several settings responsible for the background color (as indicated by the names of these settings in the INI file):

1. MainWindowBackground
2. FixedPageUI → BackgroundColor
3. EBookUI → BackgroundColor
4. ComicBookUI → BackgroundColor
5. ImageUI → BackgroundColor
6. Themes → <Custom Theme> → BackgroundColor

All of these settings are called “background.” But what do they actually control? Which “background” are we talking about in each case?

The most intuitive logic, imho, is this:

Right?

But, currently, FixedPageUI > BackgroundColor setting controls the canvas, Themes > BackgroundColor settings are ignored, the paper (page) color cannot be adjusted, and MainWindowBackground setting has no effect at all.

To clarify the situation, we could follow the approach used in the famous Unix Okular viewer. The color of the window (canvas) is called Background:

Whereas the color of the page is called Paper:

Based on this logic, we could rename the settings as follows:

1. Themes → <Custom Theme> → BackgroundColor
2. FixedPageUI → PaperColor
3. EBookUI → PaperColor
4. ComicBookUI → PaperColor
5. ImageUI → BackgroundColor (or CanvasColor like in Adobe Apps: Photoshop, Illustrator):

6. MainWindowBackground — I’m not entirely sure about this one yet, because when using custom themes, this setting has no effect.

What do you think about this?

I’m ready to create a relevant issue report, but first I need to make sure I understand everything correctly and haven’t missed anything.

[GitHubRulesOK]

Main was primarily for dialog or start screen !

Entirely up to @kjk but IMHO For images it really is no need to be different to the one used for other formats but understand all can benefit from separate choices. The canvas/background/canvas colour is the same effect as others. HOWEVER which is which in this case

Ideally the pdf and image checkered background may allow over lay with transparent image/pages which I was hoping for but unsure if MuPDF allows for that as PDF specification says the background should be white (ish) then Adobe allows for user alteration.

PDF 32000-1:2008

The backdrop is nominally white, although varying according to the
actual properties of the medium. However, some conforming readers may choose to provide a different
backdrop, such as a checker board or grid to aid in visualizing the effects of transparency in the artwork.
A “page” of a PDF file may be treated as a graphics object to be used as an element of a page of some
other document.
EXAMPLE
This case arises, for example, when placing a PDF file containing a piece of artwork produced by a
drawing program into a page layout produced by a layout program. In this situation, the PDF “page” is not
composited with the media colour; instead, it is treated as an ordinary transparency group, which can be
either isolated or non-isolated and is composited with its backdrop in the normal way.

[yozhic]

Main was primarily for dialog or start screen

Yes, I remember that used to be the case. But now, when Themes > BackgroundColor is enabled, it takes precedence over that setting.

HOWEVER which is which in this case

One thing I'm absolutely sure of: it's not “Paper” 😄

As for choosing between “Background” and “Canvas” in images, I don't think there's much of a difference between them. It's just that Adobe applications have a wide range of users, and that affects which terminology is more widely used. But I’ve made the correction in the post above—thanks.

Yes, I understand that nothing in this world is flawless, and any solution will have its shortcomings. I only started thinking about renaming the settings after the confusion in #5521: when the different backgrounds swapped places.

[kjk]

Yes, I need to make some changes and be more explicit

[kjk]

should be fixed in latest pre-release

[yozhic]

Yes, 3.7.18299 and the new WindowBgCol setting—everything is much clearer now, thank you very much!

The color change now works correctly for both the window background and the page background.

I’m seeing some unexpected behavior when calling the “Change Background Color” dialog, but that’s a small detail, so I’ll better move it to the Issues section.