修改显示器 EDID 强制开启 HIDPI

准备

复制以下内容到编辑器并另存为patch-edid.rb

#!/usr/bin/ruby

require 'base64'

data=`ioreg -l -w0 -d0 -r -c AppleDisplay`

edid_hex=data.match(/IODisplayEDID.*?<([a-z0-9]+)>/i)[1]  
vendorid=data.match(/DisplayVendorID.*?([0-9]+)/i)[1].to_i  
productid=data.match(/DisplayProductID.*?([0-9]+)/i)[1].to_i

puts "found display: vendorid #{vendorid}, productid #{productid}, EDID:\n#{edid_hex}"

bytes=edid_hex.scan(/../).map{|x|Integer("0x#{x}")}.flatten

puts "Setting color support to RGB 4:4:4 only"  
bytes[24] &= ~(0b11000)

puts "Number of extension blocks: #{bytes[126]}"  
puts "removing extension block"  
bytes = bytes[0..127]  
bytes[126] = 0

bytes[127] = (0x100-(bytes[0..126].reduce(:+) % 256)) % 256  
puts  
puts "Recalculated checksum: 0x%x" % bytes[127]  
puts "new EDID:\n#{bytes.map{|b|"%02X"%b}.join}"

Dir.mkdir("DisplayVendorID-%x" % vendorid) rescue nil  
f = File.open("DisplayVendorID-%x/DisplayProductID-%x" % [vendorid, productid], 'w')  
f.write '<?xml version="1.0" encoding="UTF-8"?>  
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">  
<plist version="1.0">'  
f.write "  
<dict>  
  <key>DisplayProductName</key>
  <string>Display with forced RGB mode (EDID override)</string>
  <key>IODisplayEDID</key>
  <data>#{Base64.encode64(bytes.pack('C*'))}</data>
  <key>DisplayVendorID</key>
  <integer>#{vendorid}</integer>
  <key>DisplayProductID</key>
  <integer>#{productid}</integer>
</dict>  
</plist>"  
f.close  

生成

  1. 盖上MacBook屏幕,仅输出外置屏幕
  2. 打开终端并执行刚刚保存的.rb文件, 如:ruby patch-edid.rb
  3. 将生成的文件夹拖动到目录/System/Library/Displays/Overrides
  4. 重启系统

配置

配合SwitchResXRetina DisplayMenu即可开启HIDPI