high contrast accessibility application guidelines?

[Caolán McNamara]

On Tue, 2022-10-11 at 15:20 +0000, Michael Weghorn wrote:
> On 10/10/2022 22.02, Caolán McNamara wrote:
> 
> > As far as I can see in impress/draw/shapes we ignore/force-
> > highcontrast text color, line color and fill colors, and there's a
> > certain logic to that.

> > On the other hand in writer we do show the real text color and fill
> > color in the normal document content, but do the opposite for
> > shapes and for the content of frames.
> 
> Is that with any explicit high-contrast settings either in the
> desktop environment or OS (like a specific theme) or LibreOffice
> explicitly applied?

Yeah, this is with High Contrast applied. In GNOME from the desktop
High Contrast selected from the a11y dropdown (which for me is black
text on white background). Windows is similar.

In impress, we seem to at least be attempting something like the
reference Stuart mentioned:
https://learn.microsoft.com/en-us/windows/win32/winauto/high-contrast-parameter

"applications should do the following:

    Map all colors to a single pair of foreground and background
colors. Use the GetSysColor function to determine the appropriate
foreground and background colors, using either a combination of
COLOR_WINDOWTEXT and COLOR_WINDOW or a combination of COLOR_BTNTEXT and
COLOR_BTNFACE....
    Omit any bitmapped images that would typically be displayed behind
text. Such images are visually distracting to a user who needs high
contrast.
    Images that would typically be drawn in multiple colors should be
drawn using the foreground and background colors selected for text."

If I assume that impress is basically on the right track, then this
does reasonably describe what happens in impress in High Contrast, 
while things seem a bit more chaotic in writer (and calc) so I could
assume that they're currently incorrect in showing text colors and
custom bg colors.

On the other hand, in Word (2013) table bg colors are shown even in
High Contrast mode, but maybe that's a bug of its own. Unless there is
some logic to excluding tables from the mono-color scheme.

> In a quick test on Windows 10 (with an older LO master as of  commit 
> 349e3af0c5dd5ed495ed61aab526f63c16f0e215), enabling "Use high
> contrast" in the Windows settings results in unreadable text in
> Impress in a new presentation (both, font and background use the same
> dark color).

That's with "High Contrast Black", will be fixed by
https://gerrit.libreoffice.org/c/core/+/141247
things look a little more reasonable with "High Contrast White"