Bring in mime icon implementation from cosmic-edit

src/mime_icon.rs

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+use cosmic::widget::icon;
+use std::{collections::HashMap, path::Path, sync::Mutex};
+
+pub const FALLBACK_MIME_ICON: &str = "text-x-generic";
+
+#[derive(Debug, Eq, Hash, PartialEq)]
+struct MimeIconKey {
+    path: String,
+    size: u16,
+}
+
+struct MimeIconCache {
+    cache: HashMap<MimeIconKey, Option<icon::Handle>>,
+}
+
+impl MimeIconCache {
+    pub fn new() -> Self {
+        Self {
+            cache: HashMap::new(),
+        }
+    }
+
+    pub fn get(&mut self, key: MimeIconKey) -> Option<icon::Handle> {
+        self.cache
+            .entry(key)
+            .or_insert_with_key(|key| match systemicons::get_icon(&key.path, key.size) {
+                Ok(icon_kind) => match icon_kind {
+                    systemicons::Icon::Png(bytes) => Some(icon::from_raster_bytes(bytes)),
+                    systemicons::Icon::Svg(bytes) => Some(icon::from_svg_bytes(bytes)),
+                },
+                Err(err) => {
+                    log::warn!("failed to get icon for {:?}: {:?}", key, err);
+                    None
+                }
+            })
+            .clone()
+    }
+}
+
+lazy_static::lazy_static! {
+    static ref MIME_ICON_CACHE: Mutex<MimeIconCache> = Mutex::new(MimeIconCache::new());
+}
+
+pub fn mime_icon<P: AsRef<Path>>(path: P, size: u16) -> icon::Icon {
+    //TODO: smarter path handling
+    let path = path
+        .as_ref()
+        .to_str()
+        .expect("failed to convert path to UTF-8")
+        .to_owned();
+    let mut mime_icon_cache = MIME_ICON_CACHE.lock().unwrap();
+    match mime_icon_cache.get(MimeIconKey { path, size }) {
+        Some(handle) => icon::icon(handle).size(size),
+        None => icon::from_name(FALLBACK_MIME_ICON).size(size).icon(),
+    }
+}