Re: unable to set black text color for cdk

[Thomas Dickey]

On Wed, Apr 01, 2015 at 10:50:26AM +0200, daggs wrote:
> 
> 
> > Sent: Wednesday, April 01, 2015 at 3:54 AM
> > From: "Thomas Dickey" <address@hidden>
> > To: daggs <address@hidden>
> > Cc: address@hidden
> > Subject: Re: unable to set black text color for cdk
> >
> > On Mon, Mar 30, 2015 at 12:31:33PM +0200, daggs wrote:
> > > Greetings,
> > > 
> > > I'm trying to setup a text in black color and it ends up in gray, looping
> > > over the first 49 colors (with and without bold) didn't returned any label
> > > with black text color, is it possible that there is no black color text in
> > > cdk?
> > 
> > hmm - it's more complicated than that - partly Cdk and partly (n)curses.
> > 
> > The initCDKColor function is probably what you're looking at, since
> > it is the only place that calls init_pair().  It's a little odd (I think)
> > because it maps the colors 0-7 in this order:
> > 
> >       COLOR_WHITE, COLOR_RED, COLOR_GREEN,
> >       COLOR_YELLOW, COLOR_BLUE, COLOR_MAGENTA,
> >       COLOR_CYAN, COLOR_BLACK
> > 
> > If the terminal supports more than 8, cdk uses only 8.  You can always
> > override that by calling init_pair() in your application.
> > 
> > Normally in curses, black is zero.  That raises a point, i.e., that color
> > pair 0 is special in curses (no colors as such).  So cdk does not use that.
> > 
> > In any case, since black is last, you would see black text on pairs 57-64,
> > due to the way the loops are ordered.
> 
> Greeting Thomas,
> 
> my issue in fact is with the (0,0) pair, e.g. black text over black 
> background.
> you might ask why one need such option, well using black background color 
> ober a background image gives me a transparency affect.
> for example, I want to create a background image that has a white square in 
> it and write inside it text.

I see.  I think the issue is that Cdk is putting black-on-black in the last
color pair which it requests -- the 65th slot.  However, for an 8-color
terminal, the description would say the terminal supports only 64 = 8*8
color pairs.
 
> as I see that all the other same combinations works ((n,n) for n:=1->7) and
> it works when using special esc chars I can only assume that it is a either
> ncurses or cdk limitation.

It's more cdk than ncurses in this case -- cdk's design tries to allocate
more color pairs than the terminal supports.  Going past the maximum color
pairs value doesn't work...

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

signature.asc
Description: Digital signature