Add onFrontlightStateChanged event (#2966)

So we do not need the hacky solution in KoboLight plugin anymore. PageFooter can receive and process the event itself.

frontend/apps/reader/modules/readerfooter.lua

@@ -668,4 +668,10 @@ function ReaderFooter:onSuspend()
     end
 end
 
+function ReaderFooter:onFrontlightStateChanged()
+    if self.settings.frontlight then
+        self:updateFooter()
+    end
+end
+
 return ReaderFooter

frontend/device/generic/powerd.lua

@@ -35,8 +35,8 @@ function BasePowerD:setIntensityHW(intensity) end
 function BasePowerD:getCapacityHW() return 0 end
 function BasePowerD:isChargingHW() return false end
 function BasePowerD:frontlightIntensityHW() return 0 end
-function BasePowerD:turnOffFrontlightHW() self:setIntensityHW(self.fl_min) end
-function BasePowerD:turnOnFrontlightHW() self:setIntensityHW(self.fl_intensity) end
+function BasePowerD:turnOffFrontlightHW() self:_setIntensity(self.fl_min) end
+function BasePowerD:turnOnFrontlightHW() self:_setIntensity(self.fl_intensity) end
 -- Anything needs to be done before do a real hardware suspend. Such as turn off
 -- front light.
 function BasePowerD:beforeSuspend() end
@@ -80,8 +80,8 @@ function BasePowerD:turnOffFrontlight()
     assert(self ~= nil)
     if not self.device.hasFrontlight() then return end
     if self:isFrontlightOff() then return false end
-    self:turnOffFrontlightHW()
     self.is_fl_on = false
+    self:turnOffFrontlightHW()
     return true
 end
 
@@ -90,8 +90,8 @@ function BasePowerD:turnOnFrontlight()
     if not self.device.hasFrontlight() then return end
     if self:isFrontlightOn() then return false end
     if self.fl_intensity == self.fl_min then return false end
-    self:turnOnFrontlightHW()
     self.is_fl_on = true
+    self:turnOnFrontlightHW()
     return true
 end
 
@@ -128,7 +128,7 @@ function BasePowerD:setIntensity(intensity)
     self.fl_intensity = self:normalizeIntensity(intensity)
     self:_decideFrontlightState()
     logger.dbg("set light intensity", self.fl_intensity)
-    self:setIntensityHW(self.fl_intensity)
+    self:_setIntensity(self.fl_intensity)
     return true
 end
 
@@ -144,4 +144,15 @@ function BasePowerD:isCharging()
     return self:isChargingHW()
 end
 
+function BasePowerD:_setIntensity(intensity)
+    self:setIntensityHW(intensity)
+    -- BasePowerD is loaded before UIManager. So we cannot broadcast events before UIManager has
+    -- been loaded.
+    if package.loaded["ui/uimanager"] ~= nil then
+        local Event = require("ui/event")
+        local UIManager = require("ui/uimanager")
+        UIManager:broadcastEvent(Event:new("FrontlightStateChanged"))
+    end
+end
+
 return BasePowerD

plugins/kobolight.koplugin/main.lua

@@ -122,9 +122,6 @@ end
 function KoboLight:onTap()
     Device:getPowerDevice():toggleFrontlight()
     self:onShowOnOff()
-    if self.view.footer_visible and self.view.footer.settings.frontlight then
-        self.view.footer:updateFooter()
-    end
     return true
 end
 
@@ -153,9 +150,6 @@ function KoboLight:onSwipe(_, ges)
         powerd:setIntensity(new_intensity)
         self:onShowIntensity()
     end
-    if self.view.footer_visible and self.view.footer.settings.frontlight then
-        self.view.footer:updateFooter()
-    end
     return true
 end