Some FL regression fixes after #4901 (#4921)

* Make hasNaturalLight* caps safe to call without a device check. (fix #4919)
Make it clear that it's expecting the NTX implementation, though.
* Don't turn the FL on on resume if it was off on suspend
* Make sure turnOn/turnOff actually updates hw_intensity in the process where it matters, instead of just in a short lived fork ;). (fix #4923)

frontend/apps/reader/modules/readerfooter.lua

@@ -747,7 +747,7 @@ end
 
 function ReaderFooter:onFrontlightStateChanged()
     if self.settings.frontlight then
-        self:updateFooter()
+        self:updateFooter(true)
     end
 end
 

frontend/device/generic/device.lua

@@ -27,6 +27,8 @@ local Device = {
     hasWifiManager = no,
     isTouchDevice = no,
     hasFrontlight = no,
+    hasNaturalLight = no, -- FL warmth implementation specific to NTX boards (Kobo, Cervantes)
+    hasNaturalLightMixer = no, -- Same, but only found on newer boards
     needsTouchScreenProbe = no,
     hasClipboard = yes, -- generic internal clipboard on all devices
     hasEinkScreen = yes,

frontend/device/kobo/powerd.lua

@@ -21,6 +21,7 @@ local KoboPowerD = BasePowerD:new{
     fl_warmth = nil,
     auto_warmth = false,
     max_warmth_hour = 23,
+    fl_was_on = nil,
 }
 
 -- TODO: Remove KOBO_LIGHT_ON_START
@@ -148,8 +149,9 @@ function KoboPowerD:init()
             -- Use setIntensity to ensure it sets fl_intensity, and because we don't want the ramping behavior of turnOn
             self:setIntensity(self:frontlightIntensityHW())
         else
-            -- Use setIntensityHW so as *NOT* to set fl_intensity, so toggle will still work.
-            self:setIntensityHW(0)
+            -- Use _setIntensity for setIntensityHW so as *NOT* to set fl_intensity, so toggle will still work,
+            -- plus the FrontlightStateChanged event.
+            self:_setIntensity(0)
         end
     end
 end
@@ -293,7 +295,7 @@ function KoboPowerD:isChargingHW()
 end
 
 function KoboPowerD:turnOffFrontlightHW()
-    if self:isFrontlightOff() then
+    if not self:isFrontlightOnHW() then
         return
     end
     local util = require("ffi/util")
@@ -308,9 +310,20 @@ function KoboPowerD:turnOffFrontlightHW()
             end
         end
     end, false, true)
+    -- NOTE: This is essentially what _setIntensity does, except we don't actually touch the FL,
+    --       we only sync the state of the main process with the final state of what we're doing in the forks.
+    -- And update hw_intensity in our actual process ;).
+    self.hw_intensity = self.fl_min
+    self:_decideFrontlightState()
+    -- And let the footer know of the change
+    if package.loaded["ui/uimanager"] ~= nil then
+        local Event = require("ui/event")
+        local UIManager = require("ui/uimanager")
+        UIManager:broadcastEvent(Event:new("FrontlightStateChanged"))
+    end
 end
 function KoboPowerD:turnOnFrontlightHW()
-    if self:isFrontlightOn() then
+    if self:isFrontlightOnHW() then
         return
     end
     local util = require("ffi/util")
@@ -324,11 +337,24 @@ function KoboPowerD:turnOnFrontlightHW()
             end
         end
     end, false, true)
+    -- NOTE: This is essentially what _setIntensity does, except we don't actually touch the FL,
+    --       we only sync the state of the main process with the final state of what we're doing in the forks.
+    -- And update hw_intensity in our actual process ;).
+    self.hw_intensity = self.fl_intensity
+    self:_decideFrontlightState()
+    -- And let the footer know of the change
+    if package.loaded["ui/uimanager"] ~= nil then
+        local Event = require("ui/event")
+        local UIManager = require("ui/uimanager")
+        UIManager:broadcastEvent(Event:new("FrontlightStateChanged"))
+    end
 end
 
 -- Turn off front light before suspend.
 function KoboPowerD:beforeSuspend()
     if self.fl == nil then return end
+    -- Remember the current frontlight state
+    self.fl_was_on = self:isFrontlightOnHW()
     -- Turn off the frontlight
     self:turnOffFrontlight()
 end
@@ -336,6 +362,8 @@ end
 -- Restore front light state after resume.
 function KoboPowerD:afterResume()
     if self.fl == nil then return end
+    -- Don't bother if the light was already off on suspend
+    if not self.fl_was_on then return end
     -- Update AutoWarmth state
     if self.fl_warmth ~= nil and self.auto_warmth then
         self:calculateAutoWarmth()

plugins/kobolight.koplugin/main.lua

@@ -1,7 +1,7 @@
 local Device = require("device")
 
 local with_frontlight = (Device:isCervantes() or Device:isKindle() or Device:isKobo()) and Device:hasFrontlight()
-local with_natural_light = (Device:isCervantes() or Device:isKobo()) and Device:hasNaturalLight()
+local with_natural_light = Device:hasNaturalLight()
 if not (with_frontlight or Device:isSDL()) then
     return { disabled = true, }
 end