From e62633f7e857f88dcc869b826b9b4c31f34659dd Mon Sep 17 00:00:00 2001
From: Mike Dilger <mike@ezicheq.com>
Date: Fri, 17 Feb 2023 12:28:01 +1300
Subject: [PATCH] Remember heights of rendered posts, use for more accurate
 scrolling

---
 src/ui/feed/mod.rs | 15 ++++++++++++---
 src/ui/mod.rs      |  2 ++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/ui/feed/mod.rs b/src/ui/feed/mod.rs
index 437dd2d8..1a100212 100644
--- a/src/ui/feed/mod.rs
+++ b/src/ui/feed/mod.rs
@@ -172,13 +172,16 @@ fn render_post_maybe_fake(
 
     // If too far off of the screen, don't actually render the post, just make some space
     // so the scrollbar isn't messed up
-    let estimated_height = estimate_height(&event, maybe_person);
+    let height = match app.height.get(&id) {
+        Some(h) => *h,
+        None => estimate_height(&event, maybe_person),
+    };
     let after_the_bottom = pos2.y > screen_rect.max.y;
-    let before_the_top = pos2.y + estimated_height < 0.0;
+    let before_the_top = pos2.y + height < 0.0;
 
     if after_the_bottom || before_the_top {
         // Don't actually render, just make space for scrolling purposes
-        ui.add_space(estimated_height);
+        ui.add_space(height);
 
         // Yes, and we need to fake render threads to get their approx height too.
         if threaded && !as_reply_to {
@@ -234,6 +237,8 @@ fn render_post_actual(
     }
     let event = maybe_event.unwrap();
 
+    let top = ui.next_widget_position();
+
     // Only render TextNote events
     let enable_reposts = GLOBALS.settings.blocking_read().reposts;
     if event.kind != EventKind::TextNote && !(enable_reposts && (event.kind == EventKind::Repost)) {
@@ -301,6 +306,10 @@ fn render_post_actual(
         app.viewed.insert(id);
     }
 
+    // Store actual rendered height for future reference
+    let bottom = ui.next_widget_position();
+    app.height.insert(id, bottom.y - top.y);
+
     ui.separator();
 
     if threaded && !as_reply_to {
diff --git a/src/ui/mod.rs b/src/ui/mod.rs
index a3b10763..8f837c52 100644
--- a/src/ui/mod.rs
+++ b/src/ui/mod.rs
@@ -89,6 +89,7 @@ struct GossipUi {
     render_raw: Option<Id>,
     render_qr: Option<Id>,
     viewed: HashSet<Id>,
+    height: HashMap<Id, f32>,
 
     // Person page rendering ('npub', 'nprofile', or 'lud06')
     person_qr: Option<&'static str>,
@@ -231,6 +232,7 @@ impl GossipUi {
             render_raw: None,
             render_qr: None,
             viewed: HashSet::new(),
+            height: HashMap::new(),
             person_qr: None,
             setting_active_person: false,
             page: start_page,