screensaver/modules/Huey/Huey.cpp

#include "Huey.hpp"
#include <libscscreensaver.hpp>
#include <string>
#include <sstream>
#include <iomanip>

class Huey : public ScreensaverPlugin {
    public:
        Huey() = default;
        ~Huey() = default;

        int fps() const override;
        void update() override;
        void render() override;

    private:
        double _hue {0};
};

ScreensaverPlugin* create_instance() {
    return new Huey;
}

int Huey::fps() const {
    return 50;
}

void Huey::update() {

}

void Huey::render() {
    // next color
    HSB hsb;
    hsb.h = _hue;
    hsb.s = 1.0;
    hsb.b = 0.4;

    // convert to rgb
    Color color {hsb};
    RGB rgb {RGB(color)};

    // setup color, fill whole window
    cairo_set_source_rgb(_c, rgb.r, rgb.g, rgb.b);
    cairo_rectangle(_c, _r.x, _r.y, _r.width, _r.height);
    cairo_fill(_c);

    // build hue text
    std::ostringstream hue_oss;
    hue_oss << "hue: " << std::setw(3) << static_cast<int>(_hue);

    // build rgb text
    std::ostringstream rgb_oss;
    rgb_oss << "red: " << std::setw(3) << static_cast<int>(255 * rgb.r);
    rgb_oss << ", green: " << std::setw(3) << static_cast<int>(255 * rgb.g);
    rgb_oss << ", blue: " << std::setw(3) << static_cast<int>(255 * rgb.b);

    // font setup
    cairo_select_font_face(_c, "Hack", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
    cairo_set_font_size(_c, 24);

    // render hue and rgb texts in black (shadow)
    cairo_set_source_rgb(_c, 0, 0, 0);
    cairo_move_to(_c, 31, 51);
    cairo_show_text(_c, hue_oss.str().c_str());
    cairo_move_to(_c, 31, 87);
    cairo_show_text(_c, rgb_oss.str().c_str());

    // render hue and rgb texts in white, sligtly offset
    cairo_set_source_rgb(_c, 1, 1, 1);
    cairo_move_to(_c, 29, 49);
    cairo_show_text(_c, hue_oss.str().c_str());
    cairo_move_to(_c, 29, 85);
    cairo_show_text(_c, rgb_oss.str().c_str());

    // update for next frame
    _hue += 0.5;
    if (_hue >= 360.0) {
        _hue -= 360.0;
    }
}