From 75574d285fb49ccb252cc0a44106061e4bd40244 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9ana=20=E6=B1=9F?= <leana.jiang+git@icloud.com>
Date: Fri, 19 Sep 2025 20:40:35 +0800
Subject: [PATCH] vanadium/autorandr: set contrast for external display

---
 nix/configurations/vanadium/nixos/display.nix | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/nix/configurations/vanadium/nixos/display.nix b/nix/configurations/vanadium/nixos/display.nix
index 9ac80233..d8cabb5d 100644
--- a/nix/configurations/vanadium/nixos/display.nix
+++ b/nix/configurations/vanadium/nixos/display.nix
@@ -75,7 +75,15 @@
           brightness, # [0..1]
         }:
           singleton "10_ddc_brightness" ''
-            ddcutil --model ${modelName} setvcp 10 ${toString (brightness * 100)}
+            ddcutil --model ${modelName} setvcp 10 ${toString (builtins.floor (brightness * 100))}
+          '';
+
+        setDDCContrast = {
+          modelName, # obtain with `ddcutil detect`
+          contrast, # [0..1]
+        }:
+          singleton "10_ddc_contrast" ''
+            ddcutil --model ${modelName} setvcp 12 ${toString (builtins.floor (contrast * 100))}
           '';
       };
 
@@ -115,13 +123,17 @@
         config = configs.allOff // configs.enableDevice name;
         hooks.postswitch =
           switches.setDPI {dpi = 110;}
+          // switches.setSoftwareBrightness {
+            device = name;
+            brightness = 1;
+          }
           // switches.setDDCBrightness {
             modelName = "VG27AQL3A";
             brightness = 0;
           }
-          // switches.setSoftwareBrightness {
-            device = name;
-            brightness = 1;
+          // switches.setDDCContrast {
+            modelName = "VG27AQL3A";
+            contrast = 0.5;
           };
       };
     in