feat!: implement Application API

examples/application/src/main.rs

@@ -0,0 +1,131 @@
+// Copyright 2023 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+//! Testing ground for improving COSMIC application API ergonomics.
+
+use cosmic::app::{Command, Core, Settings};
+use cosmic::widget::nav_bar;
+use cosmic::{executor, iced, ApplicationExt, Element};
+
+/// Runs application with these settings
+#[rustfmt::skip]
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let input = vec![
+        ("Page 1".into(), "🖖 Hello from libcosmic.".into()),
+        ("Page 2".into(), "🌟 This is an example application.".into()),
+        ("Page 3".into(), "🚧 The libcosmic API is not stable yet.".into()),
+        ("Page 4".into(), "🚀 Copy the source code and experiment today!".into()),
+    ];
+
+    let settings = Settings::default()
+        .antialiasing(true)
+        .client_decorations(true)
+        .debug(false)
+        .default_icon_theme("Pop")
+        .default_text_size(16.0)
+        .scale_factor(1.0)
+        .size((1024, 768))
+        .theme(cosmic::Theme::dark());
+
+    cosmic::app::run::<App>(settings, input)?;
+
+    Ok(())
+}
+
+/// Messages that are used specifically by our [`App`].
+#[derive(Clone, Debug)]
+pub enum Message {}
+
+/// The [`App`] stores application-specific state.
+pub struct App {
+    core: Core,
+    nav_model: nav_bar::Model,
+}
+
+/// Implement [`cosmic::Application`] to integrate with COSMIC.
+impl cosmic::Application for App {
+    /// Default async executor to use with the app.
+    type Executor = executor::Default;
+
+    /// Argument received [`cosmic::Application::new`].
+    type Flags = Vec<(String, String)>;
+
+    /// Message type specific to our [`App`].
+    type Message = Message;
+
+    const APP_ID: &'static str = "org.cosmic.AppDemo";
+
+    fn core(&self) -> &Core {
+        &self.core
+    }
+
+    fn core_mut(&mut self) -> &mut Core {
+        &mut self.core
+    }
+
+    /// Creates the application, and optionally emits command on initialize.
+    fn init(core: Core, input: Self::Flags) -> (Self, Command<Self::Message>) {
+        let mut nav_model = nav_bar::Model::default();
+
+        for (title, content) in input {
+            nav_model.insert().text(title).data(content);
+        }
+
+        nav_model.activate_position(0);
+
+        let mut app = App { core, nav_model };
+
+        let command = app.update_title();
+
+        (app, command)
+    }
+
+    /// Allows COSMIC to integrate with your application's [`nav_bar::Model`].
+    fn nav_model(&self) -> Option<&nav_bar::Model> {
+        Some(&self.nav_model)
+    }
+
+    /// Called when a navigation item is selected.
+    fn on_nav_select(&mut self, id: nav_bar::Id) -> Command<Self::Message> {
+        self.nav_model.activate(id);
+        self.update_title()
+    }
+
+    fn update(&mut self, _message: Self::Message) -> Command<Self::Message> {
+        Command::none()
+    }
+
+    fn view(&self) -> Element<Self::Message> {
+        let page_content = self
+            .nav_model
+            .active_data::<String>()
+            .map(String::as_str)
+            .unwrap_or("No page selected");
+
+        let text = cosmic::widget::text(page_content);
+
+        let centered = iced::widget::container(text)
+            .width(iced::Length::Fill)
+            .height(iced::Length::Fill)
+            .align_x(iced::alignment::Horizontal::Center)
+            .align_y(iced::alignment::Vertical::Center);
+
+        Element::from(centered)
+    }
+}
+
+impl App
+where
+    Self: cosmic::Application,
+{
+    fn active_page_title(&mut self) -> &str {
+        self.nav_model
+            .text(self.nav_model.active())
+            .unwrap_or("Unknown Page")
+    }
+
+    fn update_title(&mut self) -> Command<Message> {
+        let title = self.active_page_title().to_owned();
+        self.set_title(title)
+    }
+}