refactor: overhaul .desktop and image resolver systems

Rewrites the desktop file parser code and image resolver code to introduce caching system and make fully async. They should be much faster now.

BREAKING CHANGE: The `icon_theme` setting has been moved from per-bar to top-level

src/main.rs

@@ -29,6 +29,7 @@ use crate::channels::SyncSenderExt;
 use crate::clients::Clients;
 use crate::clients::wayland::OutputEventType;
 use crate::config::{Config, MonitorConfig};
+use crate::desktop_file::DesktopFiles;
 use crate::error::ExitCode;
 #[cfg(feature = "ipc")]
 use crate::ironvar::{VariableManager, WritableNamespace};
@@ -106,7 +107,7 @@ fn run_with_args() {
                         error!("{err:#}");
                         exit(ExitCode::IpcResponseError as i32)
                     }
-                };
+                }
             });
         }
         None => start_ironbar(),
@@ -119,17 +120,26 @@ pub struct Ironbar {
     clients: Rc<RefCell<Clients>>,
     config: Rc<RefCell<Config>>,
     config_dir: PathBuf,
+
+    desktop_files: DesktopFiles,
+    image_provider: image::Provider,
 }
 
 impl Ironbar {
     fn new() -> Self {
-        let (config, config_dir) = load_config();
+        let (mut config, config_dir) = load_config();
+
+        let desktop_files = DesktopFiles::new();
+        let image_provider =
+            image::Provider::new(desktop_files.clone(), &mut config.icon_overrides);
 
         Self {
             bars: Rc::new(RefCell::new(vec![])),
             clients: Rc::new(RefCell::new(Clients::new())),
             config: Rc::new(RefCell::new(config)),
             config_dir,
+            desktop_files,
+            image_provider,
         }
     }
 
@@ -215,6 +225,10 @@ impl Ironbar {
                 let _hold = activate_rx.recv().expect("to receive activation signal");
                 debug!("Received activation signal, initialising bars");
 
+                instance
+                    .image_provider
+                    .set_icon_theme(instance.config.borrow().icon_theme.as_deref());
+
                 while let Ok(event) = rx_outputs.recv().await {
                     match event.event_type {
                         OutputEventType::New => {
@@ -270,6 +284,16 @@ impl Ironbar {
             .clone()
     }
 
+    #[must_use]
+    pub fn desktop_files(&self) -> DesktopFiles {
+        self.desktop_files.clone()
+    }
+
+    #[must_use]
+    pub fn image_provider(&self) -> image::Provider {
+        self.image_provider.clone()
+    }
+
     /// Gets clones of bars by their name.
     ///
     /// Since the bars contain mostly GTK objects,