[RaidFrames] animated clock border and cast countdown timer for targeted spell icons

[maxzaleski]

This PR introduces animated clock border and cast countdown timer for targeted spell icons. The former is a feature I enjoyed when Cell was still around (somewhat inspired), and the latter is a nice usability addition.

Both features are showcased here.

Note

While I have been tinkering with these features for a few days now, the landscape of targeted spells remains experimental. I would recommend spending a bit of time independently testing either feature to be somewhat confident with their stability. I have not encountered major downsides as of yet (degradation in performance, Lua errors, etc).

If a more informed maintainer could look at my API utilisation that would be helpful for future development. I have a couple more PRs to submit; I hope to be able to finish them in the coming days.

Summary Changes

Clock Border

A CooldownFrameTemplate frame is placed 3 px outside the icon edges. The spell texture, rendered at a higher frame level, masks the interior such that only the outer ring is visible. The ring depletes clockwise as the cast drains, giving an immediate visual read on urgency without obscuring the icon.

• The default pie-sweep texture ignores SetSwipeColor, so WHITE8X8 is used as the swipe texture and tinted to the user's chosen colour. Colour must also be re-applied after every SetCooldownFromDurationObject call, as that resets both the texture and colour.
• The black background for the elapsed arc lives on a separate sibling Frame (frame level +2) rather than on the
  CooldownFrame itself. WoW seems to draws the cooldown swipe before standard textures on the same frame, so a BACKGROUND texture directly on the CooldownFrame renders above the sweep and obscures it.

Important

Please note that when ShowClockBorder is enabled, the static pixel-perfect border (_borderFrame) is hidden to avoid visual conflict with the ring.

UI Widgets

Toggle, colour swatch, and border size slider (1–10 px, default 3) per section (raid / party).

Cast Countdown Timer

A second CooldownFrameTemplate is placed over the icon with the swipe disabled and the built-in countdown numbers enabled. It shows the remaining cast time as a ticking number.

• The obvious approach of reading UnitCastingInfo timestamps and doing the arithmetic in Lua is not viable as these are now secret values. I managed to circumvent this by using SetCooldownFromDurationObject instead (a bit hacky but works nonetheless).

• Font size and colour are user-configurable. The internal FontString inside the CooldownFrame is not exposed via a named method, so it is discovered once at creation time via GetRegions() and stored as _timerCdFS for later use in StyleIcon.

UI Widgets

Toggle and colour swatch inline, with a cog popup for text size and X/Y offset. Clock Border and Timer controls share two rows in the options panel to keep the section compact.

Backwards Compatibility

I will include this section in all future PRs as it might save a comment or two.

Both features are fully opt-in with existing profiles are unaffected on upgrade. All new settings (ShowClockBorder, ClockBorderSize, ClockBorderColor, ShowTimer, TimerSize, TimerColor, TimerOffsetX, TimerOffsetY) are absent from existing profiles; it is my understanding that the Setting() helper returns the declared default when a key is nil, so no migration logic is needed.

Screenshots

Settings

Stills from demo video

[maxzaleski]

From reviewing the footage, I'm realising now that the new border bleeds onto the "personal space" of sibling icons. I will push a new commit tomorrow aiming to allow the spacing between icons to be customised.