mirror of
https://github.com/koreader/koreader
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122 lines
3.6 KiB
Lua
122 lines
3.6 KiB
Lua
-- Generic frontlight SysFS interface.
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-- This also supports the natural light, which consists of additional
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-- red and green light LEDs.
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local logger = require("logger")
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local dbg = require("dbg")
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local SysfsLight = {
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frontlight_white = nil,
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frontlight_red = nil,
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frontlight_green = nil,
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current_brightness = 0,
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current_warmth = 0,
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white_gain = 25,
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red_gain = 24,
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green_gain = 24,
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white_offset = -25,
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red_offset = 0,
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green_offset = -65,
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exponent = 0.25,
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}
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function SysfsLight:new(o)
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o = o or {}
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setmetatable(o, self)
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self.__index = self
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if o.init then o:init() end
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return o
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end
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function SysfsLight:setBrightness(brightness)
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self:setNaturalBrightness(brightness, self.current_warmth)
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end
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dbg:guard(SysfsLight, 'setBrightness',
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function(self, brightness)
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assert(brightness >= 0 and brightness <= 100,
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"Wrong brightness value given!")
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end)
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function SysfsLight:setWarmth(warmth)
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self:setNaturalBrightness(self.current_brightness, warmth)
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end
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dbg:guard(SysfsLight, 'setWarmth',
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function(self, warmth)
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assert(warmth >= 0 and warmth <= 100,
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"Wrong warmth value given!")
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end)
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function SysfsLight:setNaturalBrightness(brightness, warmth)
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if not brightness then
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brightness = self.current_brightness
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end
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if not warmth then
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warmth = self.current_warmth
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end
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local red = 0
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local green = 0
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local white = 0
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if brightness > 0 then
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-- On Nickel, the values for white/red/green are roughly linearly dependent
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-- on the 4th root of brightness and warmth.
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white = math.min(self.white_gain * math.pow(brightness, self.exponent) *
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math.pow(100 - warmth, self.exponent) + self.white_offset, 255)
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end
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if warmth > 0 then
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red = math.min(self.red_gain * math.pow(brightness, self.exponent) *
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math.pow(warmth, self.exponent) + self.red_offset, 255)
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green = math.min(self.green_gain * math.pow(brightness, self.exponent) *
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math.pow(warmth, self.exponent) + self.green_offset, 255)
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end
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white = math.max(white, 0)
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red = math.max(red, 0)
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green = math.max(green, 0)
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self:_set_light_value(self.frontlight_white, math.floor(white))
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self:_set_light_value(self.frontlight_green, math.floor(green))
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self:_set_light_value(self.frontlight_red, math.floor(red))
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self.current_brightness = brightness
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self.current_warmth = warmth
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end
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dbg:guard(SysfsLight, 'setNaturalBrightness',
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function(self, brightness, warmth)
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assert(brightness >= 0 and brightness <= 100,
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"Wrong brightness value given!")
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assert(warmth >= 0 and warmth <= 100,
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"Wrong warmth value given!")
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end)
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function SysfsLight:_set_light_value(sysfs_directory, value)
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if not sysfs_directory then return end
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-- bl_power is '31' when the light is turned on, '0' otherwise.
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if (value > 0) then
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self:_write_value(sysfs_directory .. "/bl_power", 31)
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else
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self:_write_value(sysfs_directory .. "/bl_power", 0)
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end
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self:_write_value(sysfs_directory .. "/brightness", value)
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end
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function SysfsLight:_write_value(file, value)
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local f = io.open(file, "w")
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if not f then
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logger.err("Could not open file: ", file)
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return false
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end
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local ret, err_msg, err_code = f:write(value)
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io.close(f)
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if not ret then
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logger.err("Write error: ", err_msg, err_code)
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return false
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end
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return true
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end
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return SysfsLight
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