render markdown message in community

crates/community_ui/src/lib.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{BTreeMap, HashMap};
 use std::fmt;
 
 use anyhow::Result;
@@ -19,6 +19,7 @@ use ui::avatar::Avatar;
 use ui::button::{Button, ButtonVariants};
 use ui::dock::{Panel, PanelEvent};
 use ui::input::{InputEvent, Textarea, TextareaState};
+use ui::markdown::RenderedText;
 use ui::message::WelcomeMessage;
 use ui::notification::Notification;
 use ui::scroll::Scrollbar;
@@ -98,6 +99,8 @@ pub struct CommunityPanel {
     channel: Option<ChannelId>,
     /// The selected channel's timeline (oldest first)
     rows: Vec<ChatMessage>,
+    /// Rendered markdown content, keyed by message id and dropped when a row changes
+    rendered_texts_by_id: BTreeMap<EventId, RenderedText>,
     /// Whether the store holds rows older than `rows`
     has_more: bool,
     /// A round or a page read is in flight
@@ -163,34 +166,32 @@ impl CommunityPanel {
             },
         ));
 
-        let panel = Self {
+        cx.defer_in(window, |this, window, cx| {
+            this.list_state.set_follow_mode(FollowMode::Tail);
+            this.list_state.set_scroll_handler(cx.listener(
+                |this, event: &ListScrollEvent, window, cx| {
+                    if event.visible_range.start <= LOAD_OLDER_THRESHOLD {
+                        this.load_older(window, cx);
+                    }
+                },
+            ));
+            this.load(window, cx);
+        });
+
+        Self {
             id,
             focus_handle: cx.focus_handle(),
             community: community.downgrade(),
             channel,
             rows: Vec::new(),
+            rendered_texts_by_id: BTreeMap::new(),
             has_more: false,
             loading: false,
             list_state: ListState::new(0, ListAlignment::Bottom, px(1024.)),
             input,
             tasks: smallvec![],
             _subscriptions: subscriptions,
-        };
-
-        panel.list_state.set_follow_mode(FollowMode::Tail);
-        panel.list_state.set_scroll_handler(cx.listener(
-            |this, event: &ListScrollEvent, window, cx| {
-                if event.visible_range.start <= LOAD_OLDER_THRESHOLD {
-                    this.load_older(window, cx);
-                }
-            },
-        ));
-
-        cx.defer_in(window, |this, window, cx| {
-            this.load(window, cx);
-        });
-
-        panel
+        }
     }
 
     /// The channel to show, following the community's selection.
@@ -204,6 +205,7 @@ impl CommunityPanel {
         if channel != self.channel {
             self.channel = channel;
             self.rows.clear();
+            self.rendered_texts_by_id.clear();
             self.has_more = false;
             self.loading = false;
             self.list_state.reset(2);
@@ -493,6 +495,7 @@ impl CommunityPanel {
 
         if !connected {
             self.rows = messages;
+            self.rendered_texts_by_id.clear();
             self.has_more = has_more;
             self.list_state.reset(self.item_count());
             cx.notify();
@@ -527,7 +530,13 @@ impl CommunityPanel {
 
         for message in messages {
             match shown.get(&message.id).copied() {
-                Some(ix) => self.rows[ix] = message,
+                Some(ix) => {
+                    // Drop the cached render when the text changes, so edits re-parse.
+                    if self.rows[ix].content != message.content {
+                        self.rendered_texts_by_id.remove(&message.id);
+                    }
+                    self.rows[ix] = message;
+                }
                 None => fresh.push(message),
             }
         }
@@ -690,7 +699,7 @@ impl CommunityPanel {
     fn render_message(
         &mut self,
         ix: usize,
-        _window: &mut Window,
+        window: &mut Window,
         cx: &mut Context<Self>,
     ) -> AnyElement {
         if ix == 0 {
@@ -708,7 +717,16 @@ impl CommunityPanel {
 
         let show_author = self.opens_run(ix - 2);
 
-        message::render(ix, message, show_author, cx)
+        let content = if message.deleted {
+            message::deleted(cx)
+        } else {
+            self.rendered_texts_by_id
+                .entry(message.id)
+                .or_insert_with(|| RenderedText::new(&message.content, &[], true))
+                .element(ix.into(), window, cx)
+        };
+
+        message::render(ix, message, content, show_author, cx)
     }
 
     fn render_composer(&self, cx: &mut Context<Self>) -> impl IntoElement {

crates/community_ui/src/message.rs

@@ -12,7 +12,13 @@ use ui::avatar::Avatar;
 use ui::h_flex;
 use ui::message::MessageRow;
 
-pub(crate) fn render(ix: usize, message: &ChatMessage, show_author: bool, cx: &App) -> AnyElement {
+pub(crate) fn render(
+    ix: usize,
+    message: &ChatMessage,
+    content: AnyElement,
+    show_author: bool,
+    cx: &App,
+) -> AnyElement {
     let persons = PersonRegistry::global(cx);
     let author = persons.read(cx).get(&message.author, cx);
     let hide_avatar = AppSettings::get_hide_avatar(cx);
@@ -30,23 +36,18 @@ pub(crate) fn render(ix: usize, message: &ChatMessage, show_author: bool, cx: &A
         .when(message.edited_at.is_some(), |this| {
             this.header_extra(div().child("(edited)"))
         })
-        .child(content(message, cx))
+        .child(content)
         .when(!message.reactions.is_empty(), |this| {
             this.child(reactions(message, cx))
         })
         .into_any_element()
 }
 
-fn content(message: &ChatMessage, cx: &App) -> AnyElement {
-    if message.deleted {
-        return div()
-            .text_color(cx.theme().text_danger)
-            .child("Message deleted")
-            .into_any_element();
-    }
-
+/// The placeholder shown in place of the body of a deleted message.
+pub(crate) fn deleted(cx: &App) -> AnyElement {
     div()
-        .child(SharedString::from(&message.content))
+        .text_color(cx.theme().text_danger)
+        .child("Message deleted")
         .into_any_element()
 }