Ignoring global cooldown

[Benalish]

Greetings,
I've created an icon that lights up when a spell is ready to use. Sometimes though, the icon blinks (disappears for a moment): I think it's a problem due to the global cooldown. I tried to work around this problem like this:

local usable, _ = IsUsableSpell(spellName)
local start, duration = GetSpellCooldown(spellName)
local ignore, gcd = GetSpellCooldown(61304)
if (usable) then
     if (duration == 0 and (start < ignore)) or (duration <= gcd) then --ignore global cooldown
          --show icon
     end
else --hide icon
end

Is there a better method?

[Benalish]

I'll try to explain better with an example:
- Immolate is active on the target

usable == true

- The conflagrate is ready

duration == 0

- I cast Incinerate, and the icon is displayed
- But if I try to cast Incinerate while another Incinerate is in progress, the icon disappears
I wish this last step didn't happen

Can you help me?

[Fizzlemizz]

Maybe something along the lines of:

local usable, _ = IsUsableSpell(spellName)
local start, duration = GetSpellCooldown(spellName)
local ignore, gcd = GetSpellCooldown(61304)
if (usable) then
     if (duration == 0 and (start < ignore)) or (duration <= gcd) then --ignore global cooldown
          --show icon
          Frame.endTime = start + duration
     end
else
      if not Frame.endTime or Frame.endTime <= GetTime() then
          Frame:Hide() -- only if it's not still ticking
      end
end

[Benalish]

Perfect!
There's a better method to ignore global cooldown than this?

if (duration == 0 and (start < ignore)) or (duration <= gcd)

[Fizzlemizz]

There is no built in IsOnGCD(...) test so you have to "roll-your-own".