Image previews

The `sixel` flag enables sixel support in `ratatu-image`, which then
needs libsixel to build.

Additionally to enable the preview feature, one must add it to
config.json:
```json
    "image_preview": {
      "size": {
        "width": 60,
        "height": 10,
      }
    }
```

There is a `backend: "halfblocks"` option in `image_preview` to force a
specific backend rather than guessing it, which might not be 100%
reliable in all terminals.

Cargo.toml

@@ -67,10 +67,19 @@ features = ["e2e-encryption", "sled", "rustls-tls"]
 version = "1.24.1"
 features = ["macros", "net", "rt-multi-thread", "sync", "time"]
 
+[dependencies.ratatu-image]
+version = "0.1.1"
+optional = true
+features = ["serde", "rustix"]
+
 [dev-dependencies]
 lazy_static = "1.4.0"
 pretty_assertions = "1.4.0"
 
 [profile.release]
 lto = true
 incremental = false
+
+[features]
+default = ["sixel"]
+sixel = ["ratatu-image/sixel"]

flake.nix

@@ -29,11 +29,12 @@
         };
         devShell = mkShell {
           buildInputs = [
-            (rustNightly.override { extensions = [ "rust-src" ]; })
+            (rustNightly.override {
+              extensions = [ "rust-src" "rust-analyzer-preview" "rustfmt" "clippy" ]; 
+            })
             pkg-config
             cargo-tarpaulin
-            rust-analyzer
-            rustfmt
+            cargo-watch
           ];
         };
       });

src/base.rs

@@ -8,6 +8,7 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use emojis::Emoji;
+use ratatu_image::picker::Picker;
 use serde::{
     de::Error as SerdeError,
     de::Visitor,
@@ -383,6 +384,12 @@ pub enum IambError {
 
     #[error("Could not use system clipboard data")]
     Clipboard,
+
+    #[error("IO error: {0}")]
+    IOError(#[from] std::io::Error),
+
+    #[error("Preview error: {0}")]
+    Preview(String),
 }
 
 impl From<IambError> for UIError<IambInfo> {
@@ -482,6 +489,10 @@ impl RoomInfo {
         self.messages.get(self.get_message_key(event_id)?)
     }
 
+    pub fn get_event_mut(&mut self, event_id: &EventId) -> Option<&mut Message> {
+        self.messages.get_mut(self.keys.get(event_id)?.to_message_key()?)
+    }
+
     pub fn insert_reaction(&mut self, react: ReactionEvent) {
         match react {
             MessageLikeEvent::Original(react) => {
@@ -670,14 +681,15 @@ pub struct ChatStore {
     pub need_load: HashSet<OwnedRoomId>,
     pub emojis: CompletionMap<String, &'static Emoji>,
     pub sync_info: SyncInfo,
+    pub picker: Option<Picker>,
 }
 
 impl ChatStore {
     pub fn new(worker: Requester, settings: ApplicationSettings) -> Self {
         ChatStore {
             worker,
             settings,
-
+            picker: None,
             cmds: crate::commands::setup_commands(),
             emojis: emoji_map(),