Add basic support for ANSI terminal escape sequences

[deweerdt]

• when printing the cells of the view, we look for escape codes, and
  update the attributes of the cell accordingly. This is done via the
  escapeIntepreter struct and methods
• add a colors.go example

The code currently only supports the 8 basic colors, and bold,
underscore and reverse.

[deweerdt]

Updated the branch with a fix so that attributes carry over the new line

[jroimartin]

First of all, sorry for the late response. Thanks for the contribution!

I'll review it to see if it fits with the internals refactoring I have in progress. Basically, I want to use some kind of cell struct (containing color info) instead of rune :) So it will be easier to implement edition, buffer reading, etc.

[deweerdt]

No worries. I see that there are conflicts now, let me know when you're closer to a review, and I'll update the PR.

Thanks!

[jroimartin]

Hi @deweerdt ,

I just pushed a commit that adds support for colored text (b342d3a).

Basically, now contents are stored as cells (rune + fgcolor + bgcolor) and ESC sequences are processed when the data is written to the View via View.Write(). This way:

1. The color information is in the cell struct, which makes much easier to implement Edition modes (displacements, conversion between visual a internal buffer coordinates, etc).
2. When reading from the View, it is possible to read only the contents (without colors); or the data + colors and then output it in a given format.
3. Of course, users can use any external ansi-color package in combination with gocui to add colored text to the view. Of course, it is also possible to write just raw data directly.

For ESC sequences, I used your escapeInterpreter, but did some style changes. Could you review those changes?

On the other hand, looks like you know quite well how ANSI colors work, would it be possible for you to create some tests for escapeInterpreter?

Please, check if everything works as expected. I also added a little example under _examples/colors.go :)

Thanks a lot for your great contribution! :)

[jroimartin]

I forgot the mandatory screenshot :)

BTW note that everything is in the branch colors.

[deweerdt]

That sounds good, I'll take a look at b342d3a this week-end. Thanks!

[jroimartin]

Cool! Bear in mind that I pushed more commits to the branch colors (https://github.com/jroimartin/gocui/commits/colors).

[deweerdt]

The changes in b342d3a look good to me, thanks!

[deweerdt]

Closing this #PR in favor of b342d3a

[jroimartin]

Merged in master! Thanks! :D