Image previews

Additionally to enable the preview feature, one must add it to
config.json:
```json
    "image_preview": {}
```
See documentation for additional settings - they shouldn't be necessary
in most cases.

Windows is basically unsupported, but it is possible to force the
feature, if the `protocol` option is set with `type` and `font_size`.

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.ratatui-image]
+version = "0.3.2"
+features = ["serde"]
+
+[target.'cfg(not(target_os = "windows"))'.dependencies.ratatui-image]
+version = "0.3.2"
+features = ["serde", "sixel", "rustix"]
+
 [dev-dependencies]
 lazy_static = "1.4.0"
 pretty_assertions = "1.4.0"
 
 [profile.release]
 lto = true
 incremental = false
+

README.md

@@ -104,6 +104,7 @@ two other TUI clients and Element Web:
 | Room upgrades                           | ❌ ([#41])  | ✔️        | ❌               | ✔️                   |
 | Localisations                           | ❌          | 1        | ❌               | 44                  |
 | SSO Support                             | ❌          | ✔️        | ✔️                | ✔️                   |
+| Image preview                           | ✔️           | ❌       | ❌               | ✔️                   |
                                                                                        
 ## License
 

docs/example_config.json

@@ -23,7 +23,16 @@
 				"color": "magenta"
 			}
 		},
-		"default_room": "#iamb-users:0x.badd.cafe"
+		"default_room": "#iamb-users:0x.badd.cafe",
+ 		"image_preview": {
+      "protocol": {
+        "type": "sixel"
+      },
+      "size": {
+        "width": 66,
+        "height": 10
+      }
+    }
 	},
 	"dirs": {
 		"cache":     "/home/user/.cache/iamb/",

docs/iamb.5.md

@@ -82,6 +82,18 @@ overridden as described in *PROFILES*.
 **default_room** (type: string)
 > The room to show by default instead of a welcome-screen.
 
+**image_preview** (type: image_preview object)
+> Enable image previews and configure it. An empty object will enable the
+> feature with default settings, omitting it will disable the feature.
+> *size* is an optional object with *width* and *height* numbers, which are
+> used te set the preview size in characters. Defaults to 66 and 10.
+> *protocol* is an optional object to override settings that should normally
+> be guessed automatically.
+> *protocol.type* is an optional string with one of the protocol types:
+> _sixel_, _kitty_, _halfblocks_.
+> *protocol.font_size* is an optional list of two numbers representing font
+> width and height in pixels.
+
 ## USER OVERRIDES
 
 Overrides are mapped onto matrix User IDs such as _@user:matrix.org_ and are
@@ -127,6 +139,9 @@ Specifies the directories to save data in. Configured as a map under the key
 **downloads** (type: string)
 > Specifies where to store downloaded files.
 
+**image_previews** (type: string)
+> Specifies where to store automatically downloaded image previews.
+
 # SEE ALSO
 
 *iamb(1)*

flake.nix

@@ -22,18 +22,24 @@
           pname = "iamb";
           version = "0.0.7";
           src = ./.;
-          cargoLock.lockFile = ./Cargo.lock;
+          cargoLock = {
+            lockFile = ./Cargo.lock;
+            outputHashes = {
+              "modalkit-0.0.16" = "sha256-mjAD1v0r2+SzPdoB2wZ/5iJ1NZK+3OSvCYcUZ5Ef38Y=";
+            };
+          };
           nativeBuildInputs = [ pkgs.pkgconfig ];
           buildInputs = [ pkgs.openssl ] ++ pkgs.lib.optionals pkgs.stdenv.isDarwin
             (with pkgs.darwin.apple_sdk.frameworks; [ AppKit Security ]);
         };
         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

@@ -11,6 +11,7 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use emojis::Emoji;
+use ratatui_image::picker::Picker;
 use serde::{
     de::Error as SerdeError,
     de::Visitor,
@@ -81,6 +82,8 @@ use modalkit::{
     },
 };
 
+use crate::message::ImageBackend;
+use crate::preview::{source_from_event, spawn_insert_preview};
 use crate::{
     message::{Message, MessageEvent, MessageKey, MessageTimeStamp, Messages},
     worker::Requester,
@@ -487,6 +490,12 @@ pub enum IambError {
     /// A failure to access the system's clipboard.
     #[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> {
@@ -607,6 +616,10 @@ 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()?)
+    }
+
     /// Insert a reaction to a message.
     pub fn insert_reaction(&mut self, react: ReactionEvent) {
         match react {
@@ -697,6 +710,35 @@ impl RoomInfo {
         }
     }
 
+    pub fn insert_with_preview(
+        &mut self,
+        room_id: OwnedRoomId,
+        store: AsyncProgramStore,
+        picker: Option<Picker>,
+        ev: matrix_sdk::ruma::events::MessageLikeEvent<RoomMessageEventContent>,
+        settings: &mut ApplicationSettings,
+        media: matrix_sdk::Media,
+    ) {
+        let source = picker.and_then(|_| source_from_event(&ev));
+        self.insert(ev);
+
+        if let Some((event_id, source)) = source {
+            if let (Some(msg), Some(image_preview)) =
+                (self.get_event_mut(&event_id), &settings.tunables.image_preview)
+            {
+                msg.image_backend = ImageBackend::Downloading(image_preview.size.clone());
+                spawn_insert_preview(
+                    store,
+                    room_id,
+                    event_id,
+                    source,
+                    media,
+                    settings.dirs.image_previews.clone(),
+                )
+            }
+        }
+    }
+
     /// Indicates whether we've recently fetched scrollback for this room.
     pub fn recently_fetched(&self) -> bool {
         self.fetch_last.map_or(false, |i| i.elapsed() < ROOM_FETCH_DEBOUNCE)
@@ -850,6 +892,7 @@ pub struct ChatStore {
 
     /// Information gathered by the background thread.
     pub sync_info: SyncInfo,
+    pub picker: Option<Picker>,
 }
 
 impl ChatStore {
@@ -858,7 +901,7 @@ impl ChatStore {
         ChatStore {
             worker,
             settings,
-
+            picker: None,
             cmds: crate::commands::setup_commands(),
             emojis: emoji_map(),
 

src/config.rs

@@ -11,6 +11,7 @@ use std::process;
 
 use clap::Parser;
 use matrix_sdk::ruma::{OwnedRoomAliasId, OwnedRoomId, OwnedUserId, UserId};
+use ratatui_image::picker::ProtocolType;
 use serde::{de::Error as SerdeError, de::Visitor, Deserialize, Deserializer};
 use tracing::Level;
 use url::Url;
@@ -246,6 +247,31 @@ pub enum UserDisplayStyle {
     DisplayName,
 }
 
+#[derive(Clone, Deserialize)]
+pub struct ImagePreviewValues {
+    pub size: ImagePreviewSize,
+    pub protocol: Option<ImagePreviewProtocolValues>,
+}
+#[derive(Clone, Deserialize)]
+pub struct ImagePreviewProtocolValues {
+    pub r#type: Option<ProtocolType>,
+    pub font_size: Option<(u16, u16)>,
+}
+impl Default for ImagePreviewValues {
+    fn default() -> Self {
+        ImagePreviewValues {
+            size: ImagePreviewSize { width: 66, height: 10 },
+            protocol: None,
+        }
+    }
+}
+
+#[derive(Clone, Deserialize)]
+pub struct ImagePreviewSize {
+    pub width: usize,
+    pub height: usize,
+}
+
 #[derive(Clone)]
 pub struct TunableValues {
     pub log_level: Level,
@@ -260,6 +286,7 @@ pub struct TunableValues {
     pub username_display: UserDisplayStyle,
     pub default_room: Option<String>,
     pub open_command: Option<Vec<String>>,
+    pub image_preview: Option<ImagePreviewValues>,
 }
 
 #[derive(Clone, Default, Deserialize)]
@@ -276,6 +303,7 @@ pub struct Tunables {
     pub username_display: Option<UserDisplayStyle>,
     pub default_room: Option<String>,
     pub open_command: Option<Vec<String>>,
+    pub image_preview: Option<ImagePreviewValues>,
 }
 
 impl Tunables {
@@ -295,6 +323,7 @@ impl Tunables {
             username_display: self.username_display.or(other.username_display),
             default_room: self.default_room.or(other.default_room),
             open_command: self.open_command.or(other.open_command),
+            image_preview: self.image_preview.or(other.image_preview),
         }
     }
 
@@ -312,6 +341,7 @@ impl Tunables {
             username_display: self.username_display.unwrap_or_default(),
             default_room: self.default_room,
             open_command: self.open_command,
+            image_preview: self.image_preview,
         }
     }
 }
@@ -321,13 +351,15 @@ pub struct DirectoryValues {
     pub cache: PathBuf,
     pub logs: PathBuf,
     pub downloads: Option<PathBuf>,
+    pub image_previews: PathBuf,
 }
 
 #[derive(Clone, Default, Deserialize)]
 pub struct Directories {
     pub cache: Option<PathBuf>,
     pub logs: Option<PathBuf>,
     pub downloads: Option<PathBuf>,
+    pub image_previews: Option<PathBuf>,
 }
 
 impl Directories {
@@ -336,6 +368,7 @@ impl Directories {
             cache: self.cache.or(other.cache),
             logs: self.logs.or(other.logs),
             downloads: self.downloads.or(other.downloads),
+            image_previews: self.image_previews.or(other.image_previews),
         }
     }
 
@@ -357,7 +390,13 @@ impl Directories {
 
         let downloads = self.downloads.or_else(dirs::download_dir);
 
-        DirectoryValues { cache, logs, downloads }
+        let image_previews = self.image_previews.unwrap_or_else(|| {
+            let mut dir = cache.clone();
+            dir.push("image_preview_downloads");
+            dir
+        });
+
+        DirectoryValues { cache, logs, downloads, image_previews }
     }
 }