use egui_virtual_list for rendering

absolutely insane performance increase

Fixes: https://github.com/damus-io/notedeck/issues/32
Suggested-by: @lucasmerlin
Signed-off-by: William Casarin <jb55@jb55.com>

src/timeline.rs

@@ -1,3 +1,110 @@
+use crate::{ui, Damus};
+use egui::containers::scroll_area::ScrollBarVisibility;
+use egui_virtual_list::VirtualList;
+use enostr::Filter;
+use nostrdb::{NoteKey, Subscription, Transaction};
+use std::cmp::Ordering;
+use std::sync::{Arc, Mutex};
+
+use log::warn;
+
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+pub struct NoteRef {
+    pub key: NoteKey,
+    pub created_at: u64,
+}
+
+impl Ord for NoteRef {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match self.created_at.cmp(&other.created_at) {
+            Ordering::Equal => self.key.cmp(&other.key),
+            Ordering::Less => Ordering::Greater,
+            Ordering::Greater => Ordering::Less,
+        }
+    }
+}
+
+impl PartialOrd for NoteRef {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+pub struct Timeline {
+    pub filter: Vec<Filter>,
+    pub notes: Vec<NoteRef>,
+
+    /// Our nostrdb subscription
+    pub subscription: Option<Subscription>,
+
+    /// State for our virtual list egui widget
+    pub list: Arc<Mutex<VirtualList>>,
+}
+
+impl Timeline {
+    pub fn new(filter: Vec<Filter>) -> Self {
+        let notes: Vec<NoteRef> = Vec::with_capacity(1000);
+        let subscription: Option<Subscription> = None;
+        let list = Arc::new(Mutex::new(VirtualList::new()));
+
+        Timeline {
+            filter,
+            notes,
+            subscription,
+            list,
+        }
+    }
+}
+
+pub fn timeline_view(ui: &mut egui::Ui, app: &mut Damus, timeline: usize) {
+    //padding(4.0, ui, |ui| ui.heading("Notifications"));
+    /*
+    let font_id = egui::TextStyle::Body.resolve(ui.style());
+    let row_height = ui.fonts(|f| f.row_height(&font_id)) + ui.spacing().item_spacing.y;
+    */
+
+    egui::ScrollArea::vertical()
+        .scroll_bar_visibility(ScrollBarVisibility::AlwaysVisible)
+        //.auto_shrink([false; 2])
+        /*
+        .show_viewport(ui, |ui, viewport| {
+            render_notes_in_viewport(ui, app, viewport, row_height, font_id);
+        });
+        */
+        .show(ui, |ui| {
+            let len = app.timelines[timeline].notes.len();
+            let list = app.timelines[timeline].list.clone();
+            list.lock()
+                .unwrap()
+                .ui_custom_layout(ui, len, |ui, start_index| {
+                    ui.spacing_mut().item_spacing.y = 0.0;
+                    ui.spacing_mut().item_spacing.x = 4.0;
+
+                    let note_key = app.timelines[timeline].notes[start_index].key;
+
+                    let txn = if let Ok(txn) = Transaction::new(&app.ndb) {
+                        txn
+                    } else {
+                        warn!("failed to create transaction for {:?}", note_key);
+                        return 0;
+                    };
+
+                    let note = if let Ok(note) = app.ndb.get_note_by_key(&txn, note_key) {
+                        note
+                    } else {
+                        warn!("failed to query note {:?}", note_key);
+                        return 0;
+                    };
+
+                    let note_ui = ui::Note::new(app, &note);
+                    ui.add(note_ui);
+                    ui.add(egui::Separator::default().spacing(0.0));
+
+                    1
+                });
+        });
+}
+
 pub fn merge_sorted_vecs<T: Ord + Copy>(vec1: &[T], vec2: &[T]) -> Vec<T> {
     let mut merged = Vec::with_capacity(vec1.len() + vec2.len());
     let mut i = 0;