screensaver/main.cpp

//
// main.cpp
// screensaver
//
// Created by Bob Polis at 2020-10-23
// Copyright (c) 2020 SwiftCoder. All rights reserved.
//

#include <iostream>
#include <cstdlib>
#include <string>
#include <stdexcept>
#include <getopt.h>
#include <libscgui.hpp>
#include <unistd.h>
#include <cairo/cairo.h>
#include <signal.h>
#include <time.h>
#include <libscerror.hpp>

const int WIDTH {700};
const int HEIGHT {700};

sc::gui::Window* main_window {nullptr};
sc::gui::Image* main_image {nullptr};
cairo_t* cr {nullptr};
bool timer_expired {true};

void print_help() {
    std::cout << "usage: screensaver [-h|--version]\n";
    std::cout << "  -h, --help    show this help text and exit\n";
    std::cout << "  --version     show version number and exit\n";
}

void print_version() {
    std::cout << "screensaver version 1.0\n";
}

void timer_signal_handler(int /*sig*/, siginfo_t* /*si*/, void* /*uc*/) {
    // timer_t* tmr {si->si_value.sival_ptr};
    timer_expired = true;
}

void draw() {
    static int x = 300;
    static int y = 300;
    static int dx = 1;
    static int dy = 1;
    static double r = 0;
    static double dr = 0.01;

    if (timer_expired) {
        timer_expired = false;
        sc::gui::ImageLock lock {*main_image};

        // white background
        cairo_set_source_rgb(cr, 1, 1, 1);
        cairo_rectangle(cr, 0, 0, WIDTH, HEIGHT);
        cairo_fill(cr);

        // orange rectangle
        cairo_rectangle(cr, x, y, 100, 100);
        cairo_set_source_rgb(cr, 1, 0.5, 0);
        cairo_fill(cr);

        // black rectangle
        cairo_rectangle(cr, 200, 200, 100, 100);
        cairo_set_source_rgb(cr, r, 0, 0);
        cairo_fill(cr);

        // dark green text
        cairo_set_source_rgb(cr, 0.2, 0.5, 0);
        cairo_select_font_face(cr, "Helvetica", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
        cairo_set_font_size(cr, 42);
        cairo_move_to(cr, 50, 100);
        cairo_show_text(cr, "abcdefghijklmnopqrstuvwxyz");

        // show
        main_window->show_image(*main_image);

        // update
        x += dx;
        y += dy;
        if (x > 400) dx = -1;
        if (y > 400) dy = -1;
        if (x < 300) dx = 1;
        if (y < 300) dy = 1;
        r += dr;
        if (r > 1) r = 0;
    }
}

int main(int argc, const char * argv[]) {
    try {
        int opt_char, opt_val;
        struct option long_options[] = {
            {"help", no_argument, nullptr, 'h'},
            {"version", no_argument, &opt_val, 1},
            {nullptr, 0, nullptr, 0}
        };
        while ((opt_char = getopt_long(argc, const_cast<char* const *>(argv), "h", long_options, nullptr)) != -1) {
            std::string arg {optarg ? optarg : ""};
            switch (opt_char) {
                case 0: {
                    // handle long-only options here
                    switch (opt_val) {
                        case 1:
                            print_version();
                            return EXIT_SUCCESS;
                    }
                    break;
                }
                case 'h':
                    print_help();
                    return EXIT_SUCCESS;
                case '?':
                    throw std::runtime_error("unrecognized option");
            }
        }
        // if (optind == argc) {
        //     // here when no file args
        // }
        // for (int i = optind; i < argc; ++i) {
        //     try {
        //         // process file argv[i]
        //     } catch (const std::runtime_error& ex) {
        //         std::cerr << "screensaver: " << ex.what() << '\n';
        //     }
        // }

        // install timer signal handler
        struct sigaction sa;
        sa.sa_flags = SA_SIGINFO;
        sa.sa_sigaction = timer_signal_handler;
        sigemptyset(&sa.sa_mask);
        throw_if_min1(sigaction(SIGRTMAX, &sa, nullptr));

        // setup repeating timer with 100 ms interval
        timer_t timer;
        struct sigevent sev;
        sev.sigev_notify = SIGEV_SIGNAL;
        sev.sigev_signo = SIGRTMAX;
        sev.sigev_value.sival_ptr = &timer;
        struct itimerspec ts;
        ts.it_interval.tv_sec = 0;
        ts.it_interval.tv_nsec = 25000000;
        ts.it_value.tv_sec = 0;
        ts.it_value.tv_nsec = 1;
        throw_if_min1(timer_create(CLOCK_REALTIME, &sev, &timer));
        throw_if_min1(timer_settime(timer, 0, &ts, nullptr));

        // RAII instances
        sc::gui::SDLWrapper sdl2;
        sc::gui::SDLImageWrapper sdl_image;

        // main window
        sc::gui::Window& window {sc::gui::Window::new_window("living art")};
        main_window = &window;
        window.add_event_handler([](const SDL_Event& event, bool quit) -> bool {
            std::cerr << "closing window " << event.window.windowID << '\n';
            return quit;
        }, SDL_WINDOWEVENT_CLOSE);

        SDL_Surface* s {SDL_CreateRGBSurface(0, WIDTH, HEIGHT, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0)};
        sc::gui::Image image {s};
        main_image = &image;
        cairo_surface_t* cs {cairo_image_surface_create_for_data(static_cast<unsigned char*>(s->pixels),
                                                                 CAIRO_FORMAT_RGB24, s->w, s->h, s->pitch)};
        cr = cairo_create(cs);

        sc::gui::app().add_run_loop_action(draw);
        sc::gui::app().run();

        cairo_surface_destroy(cs);
        cairo_destroy(cr);

    } catch (const std::exception& ex) {
        std::cerr << "screensaver: " << ex.what() << '\n';
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}