polybar-dwm/include/modules/backlight.hpp
Patrick Ziegler 8e04f15ed6
fix(backlight): %backlight% token appearing on the bar (#3081)
* Fix backlight initial value matching the actual brightness level

The initial value is `0`. If the actual brightness is also `0` you see
`%percentage%` token as text, it’s not being replaced. Since
`m_brightness` is an `int` the initial value could be just `-1` since
the actual brightness is never goes below zero. Thus this bug will never
show up again because actual brightness on first render won’t match
the “old” `m_brightness` value.

See also for more detailed explanation of the bug:
https://github.com/polybar/polybar/discussions/3079#discussioncomment-8169932

* Add docs

---------

Co-authored-by: Viacheslav Lotsmanov <lotsmanov89@gmail.com>
2024-01-20 18:09:12 +01:00

83 lines
2.6 KiB
C++

#pragma once
#include "components/config.hpp"
#include "modules/meta/inotify_module.hpp"
#include "modules/meta/types.hpp"
#include "settings.hpp"
POLYBAR_NS
namespace modules {
/**
* Reads value from `/sys/class/backlight/` to get a brightness value for some device.
*
* There are two file providing brightness values: `brightness` and `actual_brightness`.
* The `actual_brightness` file is usually more reliable, but in some cases does not work (provides completely wrong
* values, doesn't update) depending on kernel version, graphics driver, and/or graphics card.
* Which file is used is controlled by the use-actual-brightness setting.
*
* The general issue with the `brightness` file seems to be that, while it does receive inotify events, the events it
* receives are not for modification of the file and arrive just before the file is updated with a new value. The module
* thus reads and displays an outdated brightness value. To compensate for this, the module periodically (controlled by
* `poll-interval`) forces an update. By default, this is only enabled if the `backlight` file is used.
*/
class backlight_module : public inotify_module<backlight_module> {
public:
struct brightness_handle {
void filepath(const string& path);
float read() const;
private:
string m_path;
};
string get_output();
explicit backlight_module(const bar_settings&, string, const config&);
void idle();
bool on_event(const inotify_event& event);
bool build(builder* builder, const string& tag) const;
static constexpr auto TYPE = BACKLIGHT_TYPE;
static constexpr const char* EVENT_INC = "inc";
static constexpr const char* EVENT_DEC = "dec";
protected:
void action_inc();
void action_dec();
void change_value(int value_mod);
private:
static constexpr auto TAG_LABEL = "<label>";
static constexpr auto TAG_BAR = "<bar>";
static constexpr auto TAG_RAMP = "<ramp>";
ramp_t m_ramp;
label_t m_label;
progressbar_t m_progressbar;
string m_path_backlight;
float m_max_brightness{};
bool m_scroll{false};
int m_scroll_interval{5};
bool m_use_actual_brightness{true};
brightness_handle m_val;
brightness_handle m_max;
/**
* Initial value set to a negative number so that any value read from the backlight file triggers an update during
* the first read.
* Otherwise, tokens may not be replaced
*/
int m_percentage = -1;
chrono::duration<double> m_interval{};
chrono::steady_clock::time_point m_lastpoll;
};
} // namespace modules
POLYBAR_NS_END