cache LayoutJob

Signed-off-by: kernelkind <kernelkind@gmail.com>

crates/notedeck_columns/src/draft.rs

@@ -1,3 +1,4 @@
+use egui::text::LayoutJob;
 use poll_promise::Promise;
 
 use crate::{media_upload::Nip94Event, post::PostBuffer, ui::note::PostType, Error};
@@ -6,6 +7,7 @@ use std::collections::HashMap;
 #[derive(Default)]
 pub struct Draft {
     pub buffer: PostBuffer,
+    pub cur_layout: Option<(String, LayoutJob)>, // `PostBuffer::text_buffer` to current `LayoutJob`
     pub cur_mention_hint: Option<MentionHint>,
     pub uploaded_media: Vec<Nip94Event>, // media uploads to include
     pub uploading_media: Vec<Promise<Result<Nip94Event, Error>>>, // promises that aren't ready yet

crates/notedeck_columns/src/post.rs

@@ -247,6 +247,7 @@ pub struct PostBuffer {
     pub mention_indicator: char,
     pub mentions: HashMap<MentionKey, MentionInfo>,
     mentions_key: MentionKey,
+    pub selected_mention: bool,
 
     // the start index of a mention is inclusive
     pub mention_starts: BTreeMap<usize, MentionKey>, // maps the mention start index with the correct `MentionKey`
@@ -260,6 +261,7 @@ impl Default for PostBuffer {
         Self {
             mention_indicator: '@',
             mentions_key: 0,
+            selected_mention: false,
             text_buffer: Default::default(),
             mentions: Default::default(),
             mention_starts: Default::default(),
@@ -306,6 +308,7 @@ impl PostBuffer {
     pub fn select_full_mention(&mut self, mention_key: usize, pk: Pubkey) {
         if let Some(info) = self.mentions.get_mut(&mention_key) {
             info.mention_type = MentionType::Finalized(pk);
+            self.selected_mention = true;
         } else {
             error!("Error selecting mention for index: {mention_key}. Have the following mentions: {:?}", self.mentions);
         }
@@ -402,6 +405,18 @@ impl PostBuffer {
 
         job
     }
+
+    pub fn need_new_layout(&self, cache: Option<&(String, LayoutJob)>) -> bool {
+        if let Some((text, _)) = cache {
+            if self.selected_mention {
+                return true;
+            }
+
+            self.text_buffer != *text
+        } else {
+            true
+        }
+    }
 }
 
 fn char_indices_to_byte(text: &str, char_range: Range<usize>) -> Option<Range<usize>> {

crates/notedeck_columns/src/ui/note/post.rs

@@ -130,13 +130,28 @@ impl<'a> PostView<'a> {
             );
         }
 
+        let mut updated_layout = false;
         let mut layouter = |ui: &egui::Ui, buf: &dyn TextBuffer, wrap_width: f32| {
-            let mut layout_job = if let Some(post_buffer) = downcast_post_buffer(buf) {
-                post_buffer.to_layout_job(ui)
+            if let Some(post_buffer) = downcast_post_buffer(buf) {
+                let maybe_job = if post_buffer.need_new_layout(self.draft.cur_layout.as_ref()) {
+                    Some(post_buffer.to_layout_job(ui))
+                } else {
+                    None
+                };
+
+                if let Some(job) = maybe_job {
+                    self.draft.cur_layout = Some((post_buffer.text_buffer.clone(), job));
+                    updated_layout = true;
+                }
+            };
+
+            let mut layout_job = if let Some((_, job)) = &self.draft.cur_layout {
+                job.clone()
             } else {
                 error!("Failed to get custom mentions layouter");
                 text_edit_default_layout(ui, buf.as_str().to_owned(), wrap_width)
             };
+
             layout_job.wrap.max_width = wrap_width;
             ui.fonts(|f| f.layout_job(layout_job))
         };
@@ -149,6 +164,10 @@ impl<'a> PostView<'a> {
 
         let out = textedit.show(ui);
 
+        if updated_layout {
+            self.draft.buffer.selected_mention = false;
+        }
+
         if let Some(cursor_index) = get_cursor_index(&out.state.cursor.char_range()) {
             self.show_mention_hints(txn, ui, cursor_index, &out);
         }