With a bunch of experimentation, J'ai réussi à more or less work out the format of that Registry value and wrote a PowerShell script to set it.
Tested on 21H2
And possibly appropriate for versions as early as the 2019 updates.
Function Set-BlueLightReductionSettings {
[CmdletBinding()]
Param (
[Parameter(Mandatory=$true)] [ValidateRange(0, 23)] [int]$StartHour,
[Parameter(Mandatory=$true)] [ValidateSet(0, 15, 30, 45)] [int]$StartMinutes,
[Parameter(Mandatory=$true)] [ValidateRange(0, 23)] [int]$EndHour,
[Parameter(Mandatory=$true)] [ValidateSet(0, 15, 30, 45)] [int]$EndMinutes,
[Parameter(Mandatory=$true)] [bool]$Enabled,
[Parameter(Mandatory=$true)] [ValidateRange(1200, 6500)] [int]$NightColorTemperature
)
$data = (0x43, 0x42, 0x01, 0x00, 0x0A, 0x02, 0x01, 0x00, 0x2A, 0x06)
$epochTime = [System.DateTimeOffset]::new((date)).ToUnixTimeSeconds()
$data += $epochTime -band 0x7F -bor 0x80
$data += ($epochTime -shr 7) -band 0x7F -bor 0x80
$data += ($epochTime -shr 14) -band 0x7F -bor 0x80
$data += ($epochTime -shr 21) -band 0x7F -bor 0x80
$data += $epochTime -shr 28
$data += (0x2A, 0x2B, 0x0E, 0x1D, 0x43, 0x42, 0x01, 0x00)
If ($Enabled) {$data += (0x02, 0x01)}
$data += (0xCA, 0x14, 0x0E)
$data += $StartHour
$data += 0x2E
$data += $StartMinutes
$data += (0x00, 0xCA, 0x1E, 0x0E)
$data += $EndHour
$data += 0x2E
$data += $EndMinutes
$data += (0x00, 0xCF, 0x28)
$data += ($NightColorTemperature -band 0x3F) * 2 + 0x80
$data += ($NightColorTemperature -shr 6)
$data += (0xCA, 0x32, 0x00, 0xCA, 0x3C, 0x00, 0x00, 0x00, 0x00, 0x00)
Set-ItemProperty -Path 'HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\CloudStore\Store\DefaultAccount\Current\default$windows.data.bluelightreduction.settings\windows.data.bluelightreduction.settings' -Name 'Data' -Value ([byte[]]$data) -Type Binary
}
The format (or more properly a working format, since the Settings app can create multiple slightly different layouts):
10 constant bytes
The last-modified Unix timestamp in seconds, mangled and spread across 5 bytes in what is probably a variable-length encoding:
One byte whose bits 0-6 are the timestamp's bits 0-6 but whose top bit 7 is always set
One byte whose bits 0-6 are the timestamps' 7-13 but whose top bit is always set
Likewise for two more sets of 7 bits
One final byte for timestamp bits 28-31, top bit not set
8 constant bytes
Only if the schedule is enabled: constant bytes 0x02, 0x01
3 constant bytes
The start hour
The constant byte 0x2E (presumably a field delimiter or type)
The start minute
4 constant bytes
The end hour
The constant byte 0x2E again
3 constant bytes
The night color temperature in Kelvin, two mangled bytes:
One byte whose low bit 0 is always unset, bits 1-6 are the temperature's bits 0-5, and top bit 7 is always set
One byte for the temperature's bit 6 and above, top bit not set
10 constant bytes
Tested on 1703/1709
And possibly working as late as the 2018 updates.
Function Set-BlueLightReductionSettings {
[CmdletBinding()]
Param (
[Parameter(Mandatory=$true)] [ValidateRange(0, 23)] [int]$StartHour,
[Parameter(Mandatory=$true)] [ValidateSet(0, 15, 30, 45)] [int]$StartMinutes,
[Parameter(Mandatory=$true)] [ValidateRange(0, 23)] [int]$EndHour,
[Parameter(Mandatory=$true)] [ValidateSet(0, 15, 30, 45)] [int]$EndMinutes,
[Parameter(Mandatory=$true)] [bool]$Enabled,
[Parameter(Mandatory=$true)] [ValidateRange(1200, 6500)] [int]$NightColorTemperature
)
$data = (2, 0, 0, 0)
$data += [BitConverter]::GetBytes((Get-Date).ToFileTime())
$data += (0, 0, 0, 0, 0x43, 0x42, 1, 0)
If ($Enabled) {$data += (2, 1)}
$data += (0xC2, 0x0A, 0x00) # Some users have reported this line necessary on 1709, was not needed originally
$data += (0xCA, 0x14, 0x0E)
$data += $StartHour
$data += 0x2E
$data += $StartMinutes
$data += (0, 0xCA, 0x1E, 0x0E)
$data += $EndHour
$data += 0x2E
$data += $EndMinutes
$data += (0, 0xCF, 0x28)
$tempHi = [Math]::Floor($NightColorTemperature / 64)
$tempLo = (($NightColorTemperature - ($tempHi * 64)) * 2) + 128
# Alternate proposed version (see edit history), possibly version-specific?: $tempLo = ($NightColorTemperature - ($tempHi * 64)) * 4
$data += ($tempLo, $tempHi)
$data += (0xCA, 0x32, 0, 0xCA, 0x3C, 0, 0)
Set-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\CloudStore\Store\Cache\DefaultAccount\$$windows.data.bluelightreduction.settings\Current' -Name 'Data' -Value ([byte[]]$data) -Type Binary
}
Using it
Save the script as a .ps1 file and follow the instructions in the Enabling Scripts section of the PowerShell tag wiki. Vous pouvez then import the script's contents by dot-sourcing:
. ./bluelightmanagement.ps1
And then use the cmdlet-like function that it supplies:
Set-BlueLightReductionSettings -StartHour 7 -StartMinutes 0 -EndHour 21 -EndMinutes 15 -Enabled $true -NightColorTemperature 6000
The Settings app even updates everything (except the strength/color slider) immediately si vous avez the blue light reduction page open when you run the command. For the slider to see the changes, vous devrez reouvrez le Settings app.
