feat(app): add context view method for creating About views

examples/about/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "about"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+tracing = "0.1.37"
+tracing-subscriber = "0.3.17"
+tracing-log = "0.2.0"
+
+[dependencies.libcosmic]
+path = "../../"
+default-features = false
+features = [
+    "debug",
+    "winit",
+    "tokio",
+    "xdg-portal",
+    "dbus-config",
+    "desktop",
+    "a11y",
+    "wayland",
+    "wgpu",
+    "single-instance",
+    "multi-window",
+]

examples/about/src/main.rs

@@ -0,0 +1,165 @@
+// Copyright 2023 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+//! Application API example
+
+use cosmic::app::{about::About, Core, Settings, Task};
+use cosmic::iced::widget::column;
+use cosmic::iced_core::Size;
+use cosmic::widget::{self, nav_bar};
+use cosmic::{executor, iced, ApplicationExt, Element};
+
+/// Runs application with these settings
+#[rustfmt::skip]
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    tracing_subscriber::fmt::init();
+    let _ = tracing_log::LogTracer::init();
+
+    let settings = Settings::default()
+        .size(Size::new(1024., 768.));
+
+    cosmic::app::run::<App>(settings, ())?;
+
+    Ok(())
+}
+
+/// Messages that are used specifically by our [`App`].
+#[derive(Clone, Debug)]
+pub enum Message {
+    ToggleAbout,
+    Cosmic(cosmic::app::cosmic::Message),
+}
+
+/// The [`App`] stores application-specific state.
+pub struct App {
+    core: Core,
+    nav_model: nav_bar::Model,
+    about: About,
+}
+
+/// 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 = ();
+
+    /// Message type specific to our [`App`].
+    type Message = Message;
+
+    /// The unique application ID to supply to the window manager.
+    const APP_ID: &'static str = "org.cosmic.AboutDemo";
+
+    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, _flags: Self::Flags) -> (Self, Task<Self::Message>) {
+        let nav_model = nav_bar::Model::default();
+
+        let about = About::default()
+            .set_application_name("About Demo")
+            .set_application_icon(Self::APP_ID)
+            .set_developer_name("System 76")
+            .set_license_type("GPL-3.0")
+            .set_website("https://system76.com/cosmic")
+            .set_repository_url("https://github.com/pop-os/libcosmic")
+            .set_support_url("https://github.com/pop-os/libcosmic/issues")
+            .set_developers([("Michael Murphy".into(), "mmstick@system76.com".into())]);
+
+        let mut app = App {
+            core,
+            nav_model,
+            about,
+        };
+
+        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) -> Task<Self::Message> {
+        self.nav_model.activate(id);
+        self.update_title()
+    }
+
+    fn context_drawer(&self) -> Option<Element<Self::Message>> {
+        if !self.core.window.show_context {
+            return None;
+        }
+
+        if let Some(abuot_view) = self.about_view() {
+            Some(abuot_view.map(Message::Cosmic))
+        } else {
+            None
+        }
+    }
+
+    /// Handle application events here.
+    fn update(&mut self, message: Self::Message) -> Task<Self::Message> {
+        match message {
+            Message::ToggleAbout => {
+                self.core.window.show_context = !self.core.window.show_context;
+                self.core.set_show_context(self.core.window.show_context)
+            }
+            Message::Cosmic(message) => {
+                return cosmic::command::message(cosmic::app::Message::Cosmic(message))
+            }
+        }
+        Task::none()
+    }
+
+    fn about(&self) -> Option<&About> {
+        Some(&self.about)
+    }
+
+    /// Creates a view after each update.
+    fn view(&self) -> Element<Self::Message> {
+        let centered = cosmic::widget::container(
+            column![widget::button::text("Show about").on_press(Message::ToggleAbout)]
+                .width(iced::Length::Fill)
+                .height(iced::Length::Shrink)
+                .align_x(iced::alignment::Horizontal::Center),
+        )
+        .width(iced::Length::Fill)
+        .height(iced::Length::Shrink)
+        .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) -> Task<Message> {
+        let header_title = self.active_page_title().to_owned();
+        let window_title = format!("{header_title} — COSMIC AppDemo");
+        self.set_header_title(header_title);
+        if let Some(id) = self.core.main_window_id() {
+            self.set_window_title(window_title, id)
+        } else {
+            Task::none()
+        }
+    }
+}