Render image previews lazily

docs/iamb.5

@@ -138,6 +138,13 @@ Enable image previews and configure it.
 An empty object will enable the feature with default settings, omitting it will disable the feature.
 The available fields in this object are:
 .Bl -tag -width Ds
+.It Sy lazy_load
+If
+.Sy true
+(the default), download and render image previews when viewing a message with an image.
+If
+.Sy false ,
+load previews as soon as a message with an image is received.
 .It Sy size
 An optional object with
 .Sy width
@@ -538,8 +545,6 @@ Configured as an object under the key
 .It Sy cache
 Specifies where to store assets and temporary data in.
 (For example,
-.Sy image_preview
-and
 .Sy logs
 will also go in here by default.)
 Defaults to
@@ -555,11 +560,6 @@ Specifies where to store downloaded files.
 Defaults to
 .Ev $XDG_DOWNLOAD_DIR .
 
-.It Sy image_previews
-Specifies where to store automatically downloaded image previews.
-Defaults to
-.Ev ${cache}/image_preview_downloads .
-
 .It Sy logs
 Specifies where to store log files.
 Defaults to

src/base.rs

@@ -91,9 +91,8 @@ use modalkit::{
 };
 
 use crate::config::ImagePreviewProtocolValues;
-use crate::message::ImageStatus;
 use crate::notifications::NotificationHandle;
-use crate::preview::{source_from_event, spawn_insert_preview};
+use crate::preview::{source_from_event, PreviewManager};
 use crate::{
     message::{Message, MessageEvent, MessageKey, MessageTimeStamp, Messages},
     worker::Requester,
@@ -1233,33 +1232,23 @@ impl RoomInfo {
         }
     }
 
-    /// Insert a new message event, and spawn a task for image-preview if it has an image
-    /// attachment.
+    /// Insert a new message event, and prepare for image-preview if it has an image attachment.
     pub fn insert_with_preview(
         &mut self,
-        room_id: OwnedRoomId,
-        store: AsyncProgramStore,
-        picker: Option<Picker>,
         ev: RoomMessageEvent,
-        settings: &mut ApplicationSettings,
-        media: matrix_sdk::Media,
+        settings: &ApplicationSettings,
+        previews: &mut PreviewManager,
+        worker: &Requester,
     ) {
-        let source = picker.and_then(|_| source_from_event(&ev));
+        let source = 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_preview = ImageStatus::Downloading(image_preview.size.clone());
-                spawn_insert_preview(
-                    store,
-                    room_id,
-                    event_id,
-                    source,
-                    media,
-                    settings.dirs.image_previews.clone(),
-                )
+                msg.image_preview = Some(source.clone());
+                previews.register_preview(settings, source, image_preview.size, worker)
             }
         }
     }
@@ -1601,8 +1590,8 @@ pub struct ChatStore {
     /// Information gathered by the background thread.
     pub sync_info: SyncInfo,
 
-    /// Image preview "protocol" picker.
-    pub picker: Option<Picker>,
+    /// Rendered image previews.
+    pub previews: PreviewManager,
 
     /// Last draw time, used to match with RoomInfo's draw_last.
     pub draw_curr: Option<Instant>,
@@ -1628,7 +1617,7 @@ impl ChatStore {
         ChatStore {
             worker,
             settings,
-            picker,
+            previews: PreviewManager::new(picker),
             cmds: crate::commands::setup_commands(),
             emojis: emoji_map(),
 

src/config.rs

@@ -489,26 +489,29 @@ pub struct Notifications {
 
 #[derive(Clone)]
 pub struct ImagePreviewValues {
+    pub lazy_load: bool,
     pub size: ImagePreviewSize,
     pub protocol: Option<ImagePreviewProtocolValues>,
 }
 
 #[derive(Clone, Default, Deserialize)]
 pub struct ImagePreview {
+    pub lazy_load: Option<bool>,
     pub size: Option<ImagePreviewSize>,
     pub protocol: Option<ImagePreviewProtocolValues>,
 }
 
 impl ImagePreview {
     fn values(self) -> ImagePreviewValues {
         ImagePreviewValues {
+            lazy_load: self.lazy_load.unwrap_or(true),
             size: self.size.unwrap_or_default(),
             protocol: self.protocol,
         }
     }
 }
 
-#[derive(Clone, Deserialize)]
+#[derive(Clone, Copy, Deserialize, Debug)]
 pub struct ImagePreviewSize {
     pub width: usize,
     pub height: usize,
@@ -683,19 +686,17 @@ pub struct DirectoryValues {
     pub data: PathBuf,
     pub logs: PathBuf,
     pub downloads: Option<PathBuf>,
-    pub image_previews: PathBuf,
 }
 
 impl DirectoryValues {
     fn create_dir_all(&self) -> std::io::Result<()> {
         use std::fs::create_dir_all;
 
-        let Self { cache, data, logs, downloads, image_previews } = self;
+        let Self { cache, data, logs, downloads } = self;
 
         create_dir_all(cache)?;
         create_dir_all(data)?;
         create_dir_all(logs)?;
-        create_dir_all(image_previews)?;
 
         if let Some(downloads) = downloads {
             create_dir_all(downloads)?;
@@ -711,7 +712,6 @@ pub struct Directories {
     pub data: Option<String>,
     pub logs: Option<String>,
     pub downloads: Option<String>,
-    pub image_previews: Option<String>,
 }
 
 impl Directories {
@@ -721,7 +721,6 @@ impl Directories {
             data: self.data.or(other.data),
             logs: self.logs.or(other.logs),
             downloads: self.downloads.or(other.downloads),
-            image_previews: self.image_previews.or(other.image_previews),
         }
     }
 
@@ -776,20 +775,7 @@ impl Directories {
             })
             .or_else(dirs::download_dir);
 
-        let image_previews = self
-            .image_previews
-            .map(|dir| {
-                let dir = shellexpand::full(&dir)
-                    .expect("unable to expand shell variables in dirs.cache");
-                Path::new(dir.as_ref()).to_owned()
-            })
-            .unwrap_or_else(|| {
-                let mut dir = cache.clone();
-                dir.push("image_preview_downloads");
-                dir
-            });
-
-        DirectoryValues { cache, data, logs, downloads, image_previews }
+        DirectoryValues { cache, data, logs, downloads }
     }
 }
 

src/message/mod.rs

@@ -11,6 +11,7 @@ use std::ops::{Deref, DerefMut};
 use chrono::{DateTime, Local as LocalTz};
 use humansize::{format_size, DECIMAL};
 use matrix_sdk::ruma::events::receipt::ReceiptThread;
+use matrix_sdk::ruma::events::room::MediaSource;
 use matrix_sdk::ruma::room_version_rules::RedactionRules;
 use serde_json::json;
 use unicode_width::UnicodeWidthStr;
@@ -58,6 +59,7 @@ use modalkit::prelude::*;
 use ratatui_image::protocol::Protocol;
 
 use crate::config::ImagePreviewSize;
+use crate::preview::{ImageStatus, PreviewManager};
 use crate::{
     base::RoomInfo,
     config::ApplicationSettings,
@@ -731,6 +733,7 @@ impl<'a> MessageFormatter<'a> {
         text: &mut Text<'a>,
         info: &'a RoomInfo,
         settings: &'a ApplicationSettings,
+        previews: &'a PreviewManager,
     ) -> Option<ProtocolPreview<'a>> {
         let reply_style = if settings.tunables.message_user_color {
             style.patch(settings.get_user_color(&msg.sender))
@@ -740,7 +743,7 @@ impl<'a> MessageFormatter<'a> {
 
         let width = self.width();
         let w = width.saturating_sub(2);
-        let (mut replied, proto) = msg.show_msg(w, reply_style, true, settings);
+        let (mut replied, proto) = msg.show_msg(w, reply_style, true, settings, previews);
         let mut sender = msg.sender_span(info, self.settings);
         let sender_width = UnicodeWidthStr::width(sender.content.as_ref());
         let trailing = w.saturating_sub(sender_width + 1);
@@ -841,20 +844,13 @@ impl<'a> MessageFormatter<'a> {
     }
 }
 
-pub enum ImageStatus {
-    None,
-    Downloading(ImagePreviewSize),
-    Loaded(Protocol),
-    Error(String),
-}
-
 pub struct Message {
     pub event: MessageEvent,
     pub sender: OwnedUserId,
     pub timestamp: MessageTimeStamp,
     pub downloaded: bool,
     pub html: Option<StyleTree>,
-    pub image_preview: ImageStatus,
+    pub image_preview: Option<MediaSource>,
 }
 
 impl Message {
@@ -868,7 +864,7 @@ impl Message {
             timestamp,
             downloaded,
             html,
-            image_preview: ImageStatus::None,
+            image_preview: None,
         }
     }
 
@@ -893,7 +889,7 @@ impl Message {
         }
     }
 
-    fn thread_root(&self) -> Option<OwnedEventId> {
+    pub fn thread_root(&self) -> Option<OwnedEventId> {
         let content = match &self.event {
             MessageEvent::EncryptedOriginal(_) => return None,
             MessageEvent::EncryptedRedacted(_) => return None,
@@ -1000,6 +996,7 @@ impl Message {
         vwctx: &ViewportContext<MessageCursor>,
         info: &'a RoomInfo,
         settings: &'a ApplicationSettings,
+        previews: &'a PreviewManager,
     ) -> (Text<'a>, [Option<ProtocolPreview<'a>>; 2]) {
         let width = vwctx.get_width();
 
@@ -1015,11 +1012,11 @@ impl Message {
             .and_then(|e| info.get_event(&e));
         let proto_reply = reply.as_ref().and_then(|r| {
             // Format the reply header, push it into the `Text` buffer, and get any image.
-            fmt.push_in_reply(r, style, &mut text, info, settings)
+            fmt.push_in_reply(r, style, &mut text, info, settings, previews)
         });
 
         // Now show the message contents, and the inlined reply if we couldn't find it above.
-        let (msg, proto) = self.show_msg(width, style, reply.is_some(), settings);
+        let (msg, proto) = self.show_msg(width, style, reply.is_some(), settings, previews);
 
         // Given our text so far, determine the image offset.
         let proto_main = proto.map(|p| {
@@ -1057,8 +1054,9 @@ impl Message {
         vwctx: &ViewportContext<MessageCursor>,
         info: &'a RoomInfo,
         settings: &'a ApplicationSettings,
+        previews: &'a PreviewManager,
     ) -> Text<'a> {
-        self.show_with_preview(prev, selected, vwctx, info, settings).0
+        self.show_with_preview(prev, selected, vwctx, info, settings, previews).0
     }
 
     fn show_msg<'a>(
@@ -1067,6 +1065,7 @@ impl Message {
         style: Style,
         hide_reply: bool,
         settings: &'a ApplicationSettings,
+        previews: &'a PreviewManager,
     ) -> (Text<'a>, Option<&'a Protocol>) {
         if let Some(html) = &self.html {
             (html.to_text(width, style, hide_reply, settings), None)
@@ -1081,17 +1080,21 @@ impl Message {
             }
 
             let mut proto = None;
-            let placeholder = match &self.image_preview {
-                ImageStatus::None => None,
-                ImageStatus::Downloading(image_preview_size) => {
-                    placeholder_frame(Some("Downloading..."), width, image_preview_size)
-                },
-                ImageStatus::Loaded(backend) => {
-                    proto = Some(backend);
-                    placeholder_frame(Some("No Space..."), width, &backend.area().into())
-                },
-                ImageStatus::Error(err) => Some(format!("[Image error: {err}]\n")),
-            };
+            let placeholder =
+                match self.image_preview.as_ref().and_then(|source| previews.get(source)) {
+                    None => None,
+                    Some(ImageStatus::Queued(image_preview_size)) => {
+                        placeholder_frame(Some("Queued..."), width, image_preview_size)
+                    },
+                    Some(ImageStatus::Downloading(image_preview_size)) => {
+                        placeholder_frame(Some("Downloading..."), width, image_preview_size)
+                    },
+                    Some(ImageStatus::Loaded(backend)) => {
+                        proto = Some(backend);
+                        placeholder_frame(Some("No Space..."), width, &backend.area().into())
+                    },
+                    Some(ImageStatus::Error(err)) => Some(format!("[Image error: {err}]\n")),
+                };
 
             if let Some(placeholder) = placeholder {
                 msg.to_mut().insert_str(0, &placeholder);
@@ -1143,7 +1146,7 @@ impl Message {
         self.event.redact(redaction, rules);
         self.html = None;
         self.downloaded = false;
-        self.image_preview = ImageStatus::None;
+        self.image_preview = None;
     }
 }