polybar/src/modules/xbacklight.cpp

#include "modules/xbacklight.hpp"
#include "utils/math.hpp"

LEMONBUDDY_NS

namespace modules {
  /**
   * Bootstrap the module by grabbing all required components
   */
  void xbacklight_module::setup() {
    auto output = m_conf.get<string>(name(), "output", m_bar.monitor->name);

    // Grab a list of all outputs and try to find the one defined in the config
    for (auto&& mon : randr_util::get_monitors(m_connection, m_connection.root())) {
      if (mon->name == output) {
        m_output.swap(mon);
        break;
      }
    }

    // If we didn't get a match we stop the module
    if (!m_output) {
      throw module_error("No matching output found for \"" + output + "\", stopping module...");
    }

    // Query randr for the backlight max and min value
    try {
      auto& backlight = m_output->backlight;
      randr_util::get_backlight_range(m_connection, m_output, backlight);
      randr_util::get_backlight_value(m_connection, m_output, backlight);
    } catch (const std::exception& err) {
      throw module_error("No backlight data found for \"" + output + "\", stopping module...");
    }

    // Connect with the event registry and tell randr that we
    // want to get notified when an output property gets modified
    m_connection.attach_sink(this, 1);
    m_connection.select_input_checked(
        m_connection.screen()->root, XCB_RANDR_NOTIFY_MASK_OUTPUT_PROPERTY);

    // Create a throttle so that we limit the amount of events
    // to handle since randr can burst out quite a few
    // We will allow 1 event per 60 ms. The updates still look smooth
    // using this setting which is important.
    m_throttler = throttle_util::make_throttler(1, 60ms);

    // Add formats and elements
    m_formatter->add(DEFAULT_FORMAT, TAG_LABEL, {TAG_LABEL, TAG_BAR, TAG_RAMP});

    if (m_formatter->has(TAG_LABEL))
      m_label = load_optional_label(m_conf, name(), TAG_LABEL, "%percentage%");
    if (m_formatter->has(TAG_BAR))
      m_progressbar = load_progressbar(m_bar, m_conf, name(), TAG_BAR);
    if (m_formatter->has(TAG_RAMP))
      m_ramp = load_ramp(m_conf, name(), TAG_RAMP);

    // Trigger the initial draw event
    update();
  }

  /**
   * Handler for XCB_RANDR_NOTIFY events
   */
  void xbacklight_module::handle(const evt::randr_notify& evt) {
    if (evt->subCode != XCB_RANDR_NOTIFY_OUTPUT_PROPERTY)
      return;
    else if (evt->u.op.output != m_output->randr_output)
      return;
    else if (evt->u.op.atom == Backlight)
      update();
    else if (evt->u.op.atom == BACKLIGHT)
      update();
  }

  /**
   * Query the RandR extension for the new values
   */
  void xbacklight_module::update() {
    // Test if we are allowed to handle the event
    if (!m_throttler->passthrough(throttle_util::strategy::try_once_or_leave_yolo{}))
      return;

    // Query for the new backlight value
    auto& bl = m_output->backlight;
    randr_util::get_backlight_value(m_connection, m_output, bl);
    m_percentage = math_util::percentage(bl.val, bl.min, bl.max);

    // Update label tokens
    if (m_label) {
      m_label->reset_tokens();
      m_label->replace_token("%percentage%", to_string(m_percentage) + "%");
    }

    // Emit a broadcast notification so that
    // the new data will be drawn to the bar
    broadcast();
  }

  /**
   * Output content as defined in the config
   */
  bool xbacklight_module::build(builder* builder, string tag) const {
    if (tag == TAG_BAR)
      builder->node(m_progressbar->output(m_percentage));
    else if (tag == TAG_RAMP)
      builder->node(m_ramp->get_by_percentage(m_percentage));
    else if (tag == TAG_LABEL)
      builder->node(m_label);
    else
      return false;
    return true;
  }
}

LEMONBUDDY_NS_END