Version 1.6.4 - Minor usability changes, re bar visibility when targeting or not targeting.
Version 1.6.3 - Some bug fixes for patch 4.2. Also added mana-bar-only mode for mages.
Light Meter is a healing estimation addon. It supports priests, shamans, druids, and paladins. Priest support is the most extensive.
Since v1.6.3, also shows only the mana bar, with Evocation and Mana Gem marks, for mages. When in mage mode, the mana bar doesn't adjust its maximum for intellect procs like Volcano card. This makes it easier for arcane mages to know when they would waste mana, when the proc ends.
Light Meter accomplishes SIX (6) things.
(1) Show predicted healing against target's health.
(2) Show your own mana in the same place.
(3) Track Power Word: Shield and Divine Aegis absorption, using a length of shield at the end of the health bar. As your target is hit, the shield grows shorter, until it is gone.
(4) Indicate incoming heals on your target, using a blue bar at the end of your own estimated healing.
(5) It also tracks your mana just below the health bar. It places tick marks on your mana bar for the expected mana gains from different abilities and a mana potion. Large gains and loss of mana are highlighted on your mana bar.
(6) Light Meter will finally track statistics on your heals and display these, estimating efficiency and throughput from your empirical data, in spell tooltips.
Note that I made this addon for my own use. It doesn't have a fancy customization interface, and it probably never will.
Type "/lm" or "/lightmeter" for options.
v1.6.1 - Added experimental support for incoming heals. They will appear as the blue segment at the end of the healing prediction bar. Some minor bug fixes for rare errors.
v1.5.0 - updated for 4.0.1 patch. No longer calculating expected heal sizes, but rather learning them from your actual casts. So cast each spell a few times, in order to get the calculations in tooltips working. Most of the shield tracking stuff hasn't been updated. Still bugs for classes other than priest.
v1.3.1 - Updated to patch 3.3. Has accumulated various fixes and more class support (partial) along the way, but I haven't been uploading intermediate versions, so I've lost track of all the changes. I still use it daily, though, so its core functionality for priests is still good.
v1.2 - Updated for patch 3.2. Also added minimal druid support, for those with druid alts.
v1.1.1 - Added '/lm showbars' command to toggle always hiding the bars, in case you just want to tooltip statistics.
v1.1.0 - Updated for Patch 3.1 talents and spells.