Demos: Add Starfield screensaver demo

Author: https://github.com/danielledeleo
Commit: https://github.com/SerenityOS/serenity/commit/cec8488d9d9
Pull-request: https://github.com/SerenityOS/serenity/pull/6655

Base/res/apps/Starfield.af

@@ -0,0 +1,4 @@
+[App]
+Name=Starfield
+Executable=/bin/Starfield
+Category=Demos

Userland/Demos/CMakeLists.txt

@@ -6,4 +6,5 @@ add_subdirectory(LibGfxDemo)
 add_subdirectory(LibGfxScaleDemo)
 add_subdirectory(Mouse)
 add_subdirectory(Screensaver)
+add_subdirectory(Starfield)
 add_subdirectory(WidgetGallery)

Userland/Demos/Starfield/CMakeLists.txt

@@ -0,0 +1,6 @@
+set(SOURCES
+    Starfield.cpp
+)
+
+serenity_app(Starfield ICON app-screensaver)
+target_link_libraries(Starfield LibGUI LibCore LibGfx)

Userland/Demos/Starfield/Starfield.cpp

@@ -0,0 +1,181 @@
+/*
+ * Copyright (c) 2021, Jagger De Leo <jcdl@fastmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Vector.h>
+#include <LibCore/ArgsParser.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/Event.h>
+#include <LibGUI/Icon.h>
+#include <LibGUI/Painter.h>
+#include <LibGUI/Widget.h>
+#include <LibGUI/Window.h>
+#include <LibGfx/Bitmap.h>
+#include <WindowServer/Screen.h>
+#include <stdio.h>
+#include <time.h>
+#include <unistd.h>
+
+struct Coordinate {
+    int x;
+    int y;
+    int z;
+
+    operator Gfx::IntPoint() const
+    {
+        return { x, y };
+    }
+};
+
+class Starfield final : public GUI::Widget {
+    C_OBJECT(Starfield)
+public:
+    virtual ~Starfield() override;
+    void create_stars(int, int, int);
+
+private:
+    Starfield(int);
+    RefPtr<Gfx::Bitmap> m_bitmap;
+
+    void draw();
+    virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void timer_event(Core::TimerEvent&) override;
+    virtual void keydown_event(GUI::KeyEvent&) override;
+    virtual void mousedown_event(GUI::MouseEvent& event) override;
+    virtual void mousemove_event(GUI::MouseEvent& event) override;
+
+    Vector<Coordinate> m_stars;
+    int m_sweep_plane = 2000;
+};
+
+Starfield::Starfield(int interval)
+{
+    srand(time(nullptr));
+    stop_timer();
+    start_timer(interval);
+}
+
+void Starfield::create_stars(int width, int height, int stars)
+{
+    m_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRx8888, { width, height });
+
+    m_stars.grow_capacity(stars);
+    for (int i = 0; i < stars; i++) {
+        m_stars.append({ rand() % width - width / 2,
+            rand() % height - height / 2,
+            rand() % 1999 + 1 });
+    }
+    draw();
+}
+
+Starfield::~Starfield()
+{
+}
+
+void Starfield::mousemove_event(GUI::MouseEvent&)
+{
+}
+
+void Starfield::mousedown_event(GUI::MouseEvent&)
+{
+    ::exit(0);
+}
+
+void Starfield::keydown_event(GUI::KeyEvent&)
+{
+    ::exit(0);
+}
+
+void Starfield::paint_event(GUI::PaintEvent& event)
+{
+
+    GUI::Painter painter(*this);
+    painter.add_clip_rect(event.rect());
+
+    painter.draw_scaled_bitmap(event.rect(), *m_bitmap, m_bitmap->rect());
+}
+
+void Starfield::timer_event(Core::TimerEvent&)
+{
+    m_bitmap->fill(Color::Black);
+
+    auto computed_point = Gfx::IntPoint();
+    auto half_x = width() / 2;
+    auto half_y = height() / 2;
+
+    for (auto star : m_stars) {
+        auto z = ((star.z + m_sweep_plane) % 2000) * 0.0005;
+        computed_point.set_x(half_x + star.x / z);
+        computed_point.set_y(half_y + star.y / z);
+
+        if (computed_point.x() < 0 || computed_point.x() >= width() || computed_point.y() < 0 || computed_point.y() >= height())
+            continue;
+
+        u8 falloff = (1 - z * z) * 255;
+        m_bitmap->set_pixel(computed_point, Color(falloff, falloff, falloff));
+    }
+    m_sweep_plane -= 1;
+    if (m_sweep_plane < 0)
+        m_sweep_plane = 2000;
+    update();
+}
+
+void Starfield::draw()
+{
+    GUI::Painter painter(*m_bitmap);
+    painter.fill_rect(m_bitmap->rect(), Color::Black);
+}
+
+int main(int argc, char** argv)
+{
+
+    if (pledge("stdio recvfd sendfd rpath wpath cpath accept unix fattr", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    int star_count = 0;
+    int refresh_rate = 0;
+
+    Core::ArgsParser args_parser;
+    args_parser.set_general_help("The classic starfield screensaver.");
+    args_parser.add_option(star_count, "Number of stars to draw (default = 1000)", "stars", 'c', "number");
+    args_parser.add_option(refresh_rate, "Refresh rate (default = 16)", "rate", 'r', "milliseconds");
+    args_parser.parse(argc, argv);
+
+    if (star_count == 0)
+        star_count = 1000;
+
+    if (refresh_rate == 0)
+        refresh_rate = 16;
+
+    auto app = GUI::Application::construct(argc, argv);
+
+    auto app_icon = GUI::Icon::default_icon("app-screensaver");
+    auto window = GUI::Window::construct();
+
+    window->set_double_buffering_enabled(true);
+    window->set_title("Starfield");
+    window->set_resizable(false);
+    window->set_frameless(true);
+    window->set_fullscreen(true);
+    window->set_minimizable(false);
+    window->set_icon(app_icon.bitmap_for_size(16));
+
+    auto& starfield_window = window->set_main_widget<Starfield>(refresh_rate);
+    starfield_window.set_fill_with_background_color(false);
+    starfield_window.set_override_cursor(Gfx::StandardCursor::Hidden);
+    starfield_window.update();
+    window->show();
+
+    starfield_window.create_stars(window->width(), window->height(), star_count);
+    starfield_window.update();
+
+    window->move_to_front();
+    window->set_cursor(Gfx::StandardCursor::Hidden);
+    window->update();
+
+    return app->exec();
+}