Feature: add in custom bar character and delimiters

[TRex22]

What does this PR do?

• Implements the ability to change the progress bar characters

[paul]

Can you also add a test that it allows multibyte UTF characters? Like ║.

[paul]

Oh, there is kind of a test for multibyte characters I guess. Why are there two separate spec files?

[TRex22]

I wasnt certain the arguments_spec really covered the use case. I was more of an interface positive negative check. I wanted a test that specifically checked the feature and its output

[TRex22]

@paul Is this PR fine to merge? Or is there more you would like me to change to get it mergeable?

[TRex22]

I had to remove the character limit because lots of new emojis are multi-sequence characters. This isn't supported everywhere but in modern terminals it is. I dont see a reason to limit this functionality and its up to the developer using this Gem to make sure the character doesnt mess up for their use case if they select a multi-character sequence

[TRex22]

So totally ridiculous but Ive made a Nyan cat loading bar. A colleague of mine joked that it'd be funny if I got something like that to work

@bar = ProgressBar.new(bar: "🏳️‍🌈")
100.times do |idex|
  @bar.increment!
  print "\r"
  str = @bar.to_s
  str = str.sub(/(.*)🏳️‍🌈/, '\1🏳️‍🌈‍😺‍')
  print str
  sleep 0.1
end

I had to do some outside overriding but it's pretty funny that this is possible. It does use a few zero width joiners which may hurt if this code is copy-pasted

[paul]

Hah, I love the nyancat bar. I was thinking along similar lines from our themeing discussion the other day, it would be useful if the theme values were permitted to be strings or functions. Then when the bar prints, it would yield to the function for each one with info about the current progress.

So your nyancat could just be:

# count - current progress bar increment
# max - initialized maximum
# bar_pos - function is `yield`ed for each character in the bar, this is what character that is
nyan = -> (count, max, bar_pos) {
  if bar_pos == (count / max)
    😼
  else
    🏳️‍🌈 
  end
end

bar = ProgressBar.new(100, theme: {bar_character: nyan})

100.times { bar.increment! }

I'd need to play with it some more, i'm not sure what values should be yielded to the function.

[TRex22]

Yeah Ive been thinking about that as well. Ideally the interface should be permissive to things like #51 the prefix and suffix stuff but also more advanced lambdas.

Since I think a lambda to change the colour seems too complicated but "Nyan" cat or more complex stylings and animations would require something more complex to achieve.

Unless only one new interface parameter is added which accepts a lambda and returns some kind of hash / function which overwrites the default character sets, and/or output string (prefix / suffix).

bar = ProgressBar.new(100, func: some_lambda)

And that function gets a uniform interface of things like terminal_width, the bar_width, set default values, position, max, count, time etc ... and can modify values which would include adding conditional logic to the bar character for instance

[paul]

@TRex22 I've been tinkering:

require "paint"

require_relative "../lib/progress_bar"

CAT = "🐱"
# RAINBOW = "🏳️‍🌈"
RAINBOW = "🌈"

def self.rainbow(ratio)
  blue  = Math.sin(ratio + 0) * 127 + 128
  red   = Math.sin(ratio + 2 * Math::PI / 3) * 127 + 128
  green = Math.sin(ratio + 4 * Math::PI / 3) * 127 + 128
  "#%02X%02X%02X" % [red, green, blue]
end

theme = ProgressBar::Theme.new(
  line_prefix: ->(bar, **) {
    color = rainbow(bar.ratio * 6)
    Paint.color(color)
  },
  bar_element: ->(bar, pos:, width:) {
    if pos + bar.display_width(CAT) >= width
      CAT
    else
      RAINBOW
    end
  }
)

bar = ProgressBar.new(100, theme: theme)

100.times do
  bar.increment!
  sleep 0.1
end

[TRex22]

I like that approach. Its very clean. Means only one parameter is needed and its up to the dev to decide to add in helper gems or not.

In the documentation there could also be example themes like the one above

[TRex22]

Hey @paul sorry I let this slip. Just had some life issues, studies, and work get in the way. Ill work on getting a solution out when I can and cleaning up my PRs