Re: [Nano-devel] [PATCH] index/RGB colors and italic/reverse/underline attributes

[Benno Schulenberg]

Op 20-02-18 om 02:09 schreef Brand Huntsman:
> On Mon, 19 Feb 2018 14:07:39 +0100
> Benno Schulenberg <address@hidden> wrote:
>>> +           unsigned char g_shades[4] = {0, 68, 176, 255};
>>> +                   /* black - 13% / 35% / 36% / 16% - white */
>>> +
>>> +           unsigned char c_shades[5] = {0, 51, 127, 204, 255};
>>> +                   /* dark - 10% / 25% / 30% / 25% / 10% -
>>> bright */  
>>
>> I don't understand these comments.  How do the percentages relate to
>> the numbers?
> 
> They represent what percentage of 0-255 channel values get mapped to
> 0-4, which then get looked up in the low color cube array.

I still don't see how the percentages relate to the numbers: 13% -> 0,
35% -> 68...?  Are these comments in the right place?

> We will need to pass a second flag to color_to_short() that is set for fg but 
> not for bg. If 8-color terminal it must either fail for 8-15 or clamp them to 
> 0-7 without setting bright flag. So 15,9 and 15,1 always use a dark red 
> background on 8-color terminals. Clamping would cause issues if fg color has 
> low or no contrast with the clamped bg color. And not passing fg/bg flag to 
> color_to_short() would cause 8-15 bg indices to fail on every terminal type. 
> What should we do?

If the user uses color indexes, they have a specific terminal in mind.  If
they then use the syntax on a different terminal, they get to live with any
resulting unreadability -- they should have used RGB values instead.  So I
would say: clamp.

Benno

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