implement phase 4; add flags

src/app.rs

@@ -3,8 +3,11 @@ use std::time::Duration;
 
 use eframe::egui;
 
+use std::collections::HashMap;
+
 use crate::config::Config;
 use crate::countries::{get_countries, Country};
+use crate::flags;
 use crate::nordvpn::{self, CmdResult, Poller};
 use crate::ui::country_selector::CountrySelector;
 
@@ -14,24 +17,34 @@ pub struct App {
     poller: Poller,
     cmd_tx: Sender<CmdResult>,
     cmd_rx: mpsc::Receiver<CmdResult>,
+    /// Receives rasterized flag images from the background loader thread.
+    flag_rx: mpsc::Receiver<(String, egui::ColorImage)>,
+    /// Fully loaded flag textures, keyed by nordvpn_key.
+    flag_textures: HashMap<String, egui::TextureHandle>,
     selector: CountrySelector,
     /// Last connect/disconnect result shown inline below the status bar.
     notification: Option<String>,
 }
 
 impl App {
-    pub fn new(_cc: &eframe::CreationContext<'_>) -> Self {
+    pub fn new(cc: &eframe::CreationContext<'_>) -> Self {
         let config = Config::load();
         let countries = get_countries(&config.external_app);
         let poller = Poller::new(config.external_app.clone(), config.refresh_rate);
         let (cmd_tx, cmd_rx) = mpsc::channel();
 
+        // Kick off background flag rasterization.
+        let (flag_tx, flag_rx) = mpsc::channel();
+        flags::spawn_loader(flags::flag_paths(&countries), flag_tx);
+
         Self {
             config,
             countries,
             poller,
             cmd_tx,
             cmd_rx,
+            flag_rx,
+            flag_textures: HashMap::new(),
             selector: CountrySelector::default(),
             notification: None,
         }
@@ -57,6 +70,12 @@ impl App {
 
 impl eframe::App for App {
     fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        // Upload any newly rasterized flag textures.
+        while let Ok((key, image)) = self.flag_rx.try_recv() {
+            let handle = ctx.load_texture(&key, image, egui::TextureOptions::LINEAR);
+            self.flag_textures.insert(key, handle);
+        }
+
         // Drain completed command results.
         while let Ok(result) = self.cmd_rx.try_recv() {
             self.notification = Some(match result {
@@ -129,6 +148,7 @@ impl eframe::App for App {
                         &self.countries,
                         &self.config.favorites,
                         status.country.as_deref(),
+                        &self.flag_textures,
                     )
                 })
                 .inner;