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polybar/include/modules/backlight.hpp
patrick96 aebdb5328a fix(backlight): Poll if necessary
The `backlight` file seems to not receive modification events for
inotify (it does receive other events though).
These other events still trigger an update, but the value read is still
the old value because the events arrive just slightly before the file is
updated.

The new `poll-interval` setting will inject an event every X seconds to
force an update.
If the actual_brightness file is used, the interval is set to 0 and thus
turned off.

This does not add any more wakeups to the module, the inotify modules
wake up every second anyway and during that time, the interval is
checked.

Fixes #2835
2023-10-21 20:32:11 +02:00

77 lines
2.4 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* thus reads and displays an outdated brightness value.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;
int m_percentage = 0;
chrono::duration<double> m_interval{};
chrono::steady_clock::time_point m_lastpoll;
};
} // namespace modules
POLYBAR_NS_END