feat(backlight): add use-actual-brightness option (#2380)

* add use-actual-brightness option

* added to changelog

* added to changelog 2

* added to changelog 3

CHANGELOG.md

@@ -87,6 +87,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `internal/xworkspaces`: `%nwin%` can be used to display the number of open
   windows per workspace
   ([`#604`](https://github.com/polybar/polybar/issues/604))
+- `internal/backlight`: added `use-actual-brightness` option
 
 ### Changed
 - Slight changes to the value ranges the different ramp levels are responsible
@@ -106,6 +107,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([`#2292`](https://github.com/polybar/polybar/issues/2292))
 - Parser error if click command contained `}`
   ([`#2040`](https://github.com/polybar/polybar/issues/2040))
+- `internal/backlight`: With amdgpu backlights, the brightness indicator was slightly behind.
+  ([`#2367](https://github.com/polybar/polybar/issues/2367))
 
 ## [3.5.4] - 2021-01-07
 ### Fixed

include/modules/backlight.hpp

@@ -48,6 +48,7 @@ namespace modules {
     string m_path_backlight;
     float m_max_brightness;
     bool m_scroll{false};
+    bool m_use_actual_brightness{true};
 
     brightness_handle m_val;
     brightness_handle m_max;

src/modules/backlight.cpp

@@ -54,7 +54,10 @@ namespace modules {
      * The only sensible way is to use the 'brightness' file instead
      * Ref: https://github.com/Alexays/Waybar/issues/335
      */
-    std::string brightness_type = ((card.substr(0, 9) == "amdgpu_bl") ? "brightness" : "actual_brightness");
+    bool card_is_amdgpu = (card.substr(0, 9) == "amdgpu_bl");
+    m_use_actual_brightness = m_conf.get(name(), "use-actual-brightness", !card_is_amdgpu);
+
+    std::string brightness_type = (m_use_actual_brightness ? "actual_brightness" : "brightness");
     auto path_backlight_val = m_path_backlight + "/" + brightness_type;
 
     m_val.filepath(path_backlight_val);