Support for `-1` as a color

[geolessel]

It looks like use -1 as a color number is supported to display no color. I'd like to be able to modify the code to allow that as a color pair value but it looks like it is only expecting unsigned integers. I don't have enough experience in Crystal to know how to fix this issue or I would have included it in #5.

An example of where this matters is when setting NCurses.use_default_colors. Since I'm forced to use a defined background color, it overwrites my default terminal background color. Is there a good way to fix this?

Without NCurses.use_default_colors

With NCurses.use_default_colors

[geolessel]

@agatan any input on this one?

[agatan]

Sorry, I missed this issue.

I think your purpose is to run the following code in Crystal, right?

#include <ncurses.h>
#include <string.h>

int main()
{
 initscr();
 use_default_colors();
 printw("default color\n");
 start_color();
 init_pair(1, COLOR_RED, -1); // This cannot be done in NCurses.cr now.
 attrset(COLOR_PAIR(1));
 printw("fg: red, bg: default (no color)");
 getch();
 endwin();
 return 0;
}

Yes, the signature of ColorPair#init is wrong so far...
I'll try to fix it by adding an overloaded method to set default colors or making Color be union type of unsigned and signed integer.

[agatan]

hmm... I just tried to pass -1 to init_pair now, but it doesn't work well.
Would you try #8 ?