Settings: Add a very simple Settings application

This is really just a launcher app that gathers all the installed apps
in the "Settings" category and presents them in a single window.

Userland/Applications/CMakeLists.txt

@@ -23,6 +23,7 @@ add_subdirectory(PDFViewer)
 add_subdirectory(Piano)
 add_subdirectory(PixelPaint)
 add_subdirectory(Run)
+add_subdirectory(Settings)
 add_subdirectory(SoundPlayer)
 add_subdirectory(SpaceAnalyzer)
 add_subdirectory(Spreadsheet)

Userland/Applications/Settings/CMakeLists.txt

@@ -0,0 +1,12 @@
+serenity_component(
+    Settings
+    REQUIRED
+    TARGETS Settings
+)
+
+set(SOURCES
+    main.cpp
+)
+
+serenity_app(Settings ICON app-settings)
+target_link_libraries(Settings LibGUI LibDesktop)

Userland/Applications/Settings/main.cpp

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibDesktop/AppFile.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/BoxLayout.h>
+#include <LibGUI/Icon.h>
+#include <LibGUI/IconView.h>
+#include <LibGUI/Menu.h>
+#include <LibGUI/Model.h>
+#include <LibGUI/Statusbar.h>
+#include <LibGUI/Window.h>
+#include <serenity.h>
+#include <spawn.h>
+#include <stdio.h>
+#include <unistd.h>
+
+class SettingsAppsModel final : public GUI::Model {
+public:
+    SettingsAppsModel()
+    {
+        Desktop::AppFile::for_each([&](Desktop::AppFile& app_file) {
+            if (app_file.category() != "Settings")
+                return;
+            m_apps.append(app_file);
+        });
+    }
+    virtual int row_count(GUI::ModelIndex const&) const override { return m_apps.size(); }
+    virtual int column_count(GUI::ModelIndex const&) const override { return 1; }
+
+    virtual GUI::ModelIndex index(int row, int column, GUI::ModelIndex const&) const override
+    {
+        if (row < 0 || row >= (int)m_apps.size())
+            return {};
+        return create_index(row, column, &m_apps[row]);
+    }
+
+    virtual GUI::Variant data(GUI::ModelIndex const& index, GUI::ModelRole role) const override
+    {
+        auto& app = m_apps[index.row()];
+        if (role == GUI::ModelRole::Icon) {
+            return app.icon();
+        }
+        if (role == GUI::ModelRole::Display) {
+            String name;
+            if (app.name().ends_with(" Settings"sv)) {
+                name = app.name().substring(0, app.name().length() - " Settings"sv.length());
+            } else {
+                name = app.name();
+            }
+            return name;
+        }
+        if (role == GUI::ModelRole::Custom) {
+            return app.executable();
+        }
+        return {};
+    }
+
+    virtual void update() override { }
+
+private:
+    NonnullRefPtrVector<Desktop::AppFile> m_apps;
+};
+
+int main(int argc, char** argv)
+{
+    if (pledge("stdio thread recvfd sendfd rpath cpath wpath unix proc exec", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    auto app = GUI::Application::construct(argc, argv);
+
+    if (pledge("stdio thread recvfd sendfd rpath cpath wpath proc exec", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    auto app_icon = GUI::Icon::default_icon("app-settings");
+
+    auto window = GUI::Window::construct();
+    window->set_title("Settings");
+    window->resize(400, 300);
+
+    auto& file_menu = window->add_menu("&File");
+    file_menu.add_action(GUI::CommonActions::make_quit_action([&](auto&) {
+        app->quit();
+    }));
+
+    auto& help_menu = window->add_menu("&Help");
+    help_menu.add_action(GUI::CommonActions::make_about_action("Settings", app_icon, window));
+
+    auto& main_widget = window->set_main_widget<GUI::Widget>();
+    main_widget.set_fill_with_background_color(true);
+    main_widget.set_layout<GUI::VerticalBoxLayout>();
+
+    auto& icon_view = main_widget.add<GUI::IconView>();
+    icon_view.set_should_hide_unnecessary_scrollbars(true);
+    auto model = adopt_ref(*new SettingsAppsModel);
+    icon_view.set_model(*model);
+
+    icon_view.on_activation = [&](GUI::ModelIndex const& index) {
+        auto& app = *(Desktop::AppFile*)index.internal_data();
+        auto executable = app.executable();
+
+        auto launch_origin_rect = icon_view.to_widget_rect(icon_view.content_rect(index)).translated(icon_view.screen_relative_rect().location());
+        setenv("__libgui_launch_origin_rect", String::formatted("{},{},{},{}", launch_origin_rect.x(), launch_origin_rect.y(), launch_origin_rect.width(), launch_origin_rect.height()).characters(), 1);
+
+        pid_t child_pid;
+        const char* argv[] = { executable.characters(), nullptr };
+
+        if ((errno = posix_spawn(&child_pid, executable.characters(), nullptr, nullptr, const_cast<char**>(argv), environ))) {
+            perror("posix_spawn");
+            return;
+        }
+
+        if (disown(child_pid) < 0)
+            perror("disown");
+    };
+
+    auto& statusbar = main_widget.add<GUI::Statusbar>();
+
+    icon_view.on_selection_change = [&] {
+        auto index = icon_view.selection().first();
+        if (!index.is_valid()) {
+            statusbar.set_text({});
+            return;
+        }
+
+        auto& app = *(Desktop::AppFile*)index.internal_data();
+        statusbar.set_text(app.description());
+    };
+
+    window->set_icon(app_icon.bitmap_for_size(16));
+
+    window->show();
+    return app->exec();
+}