From: Simon Tatham <anakin@pobox.com>
Date: Sun, 31 Dec 2023 15:11:07 +0000 (+0000)
Subject: Fix panic when going to Read Mentions.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=38f3474b4d2884fde08b9e3dd6d271569462b308;p=mastodonochrome.git

Fix panic when going to Read Mentions.

My rewrite of the ensure_enough_rendered loop introduced a further bug
in which we counted the number of visible lines of the bottom item
_plus_ its full height. Should have been _instead of_ its full height.
So we didn't get right to the top of the screen.
---

diff --git a/src/file.rs b/src/file.rs
index 8727c55..28409e8 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -187,9 +187,22 @@ impl<Type: FeedType> FeedFile<Type> {
         let (item, line) = self.refine_pos(w);
 
         let mut item = item;
-        let mut lines_rendered = line;
+        let mut lines_rendered = 0;
+        // We count most items we render for their full height, but
+        // not the one we can only see the top segment of
+        let mut line_count_override = Some(line);
+
         loop {
-            lines_rendered += self.ensure_item_rendered(item, w).len();
+            let item_height = self.ensure_item_rendered(item, w).len();
+
+            let item_height = if let Some(over) = line_count_override {
+                min(item_height, over)
+            } else {
+                item_height
+            };
+            line_count_override = None;
+            lines_rendered += item_height;
+
             if lines_rendered >= h {
                 break;
             }