Hi, when I switched to xterm-direct for running Emacs, I noticed that it does not work correctly under trunk of screen with "truecolor on", with all the colors being shifted like blue instead of green and so on, if I set TERM to xterm-direct inside screen.
Reason for that is, official ANSI Escape sequence for truecolor have extra parameter after 38;2, so full sequence looks like this: esc;38;2;colorspace:r:g:b There is a very detailed explanation on how this came to be in https://github.com/ThomasDickey/xterm-snapshots/blob/master/charproc.c#L1976 The xterm-direct terminal description that Emacs uses (tbh I don't know where this comes from , ncurses or terminfo?) has the foreground/background color change sequences defined with this extra colorspace parameter, so Emacs sends extra parameter as 0 when changing colors with TERM=xterm-direct. So under screen, the sequence is interpreted as r,g,b being 0,r,g with b ignored, thus the shifted colors. Below patch implements the same fix as XTerm uses for screen, that is to skip the colorspace parameter if its specified. With this patch Emacs inside screen with xterm-direct produces correct color for me diff --git a/src/ansi.c b/src/ansi.c index 9ee4ffa..4913243 100644 --- a/src/ansi.c +++ b/src/ansi.c @@ -1734,16 +1734,17 @@ static void SelectRendition(Window *win) if ((j == 38 || j == 48) && i + 4 < win->w_NumArgs && win->w_args[i + 1] == 2) { uint8_t r, g, b; - r = win->w_args[i + 2]; - g = win->w_args[i + 3]; - b = win->w_args[i + 4]; + int have_colorspace = (i + 5 < win->w_NumArgs); + r = win->w_args[i + 2 + have_colorspace]; + g = win->w_args[i + 3 + have_colorspace]; + b = win->w_args[i + 4 + have_colorspace]; if (j == 38) { colorfg = 0x04000000 | (r << 16) | (g << 8) | b; } else { colorbg = 0x04000000 | (r << 16) | (g << 8) | b; } - i += 4; + i += 4 + have_colorspace; continue; } if (j >= 90 && j <= 97)
