From 6232a8429e9ac2764b5a245ed2595ff607d0d7f4 Mon Sep 17 00:00:00 2001
From: William Casarin <jb55@jb55.com>
Date: Sun, 9 Jul 2023 11:11:03 -0700
Subject: [PATCH] timeline: add ui_abbrev_name

This is a simple and fast function for abbreviating usernames in the
timeline. If they are too large they make the timeline too wide. We'll
probably need to make this adjustable based on the timeline width, but
this is ok for now.

Changelog-Added: Abbreviate usernames in timelines
---
 src/abbrev.rs | 20 ++++++++++++++++++++
 src/app.rs    | 13 ++++++++++++-
 src/lib.rs    |  1 +
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 src/abbrev.rs

diff --git a/src/abbrev.rs b/src/abbrev.rs
new file mode 100644
index 00000000..7f5b71f9
--- /dev/null
+++ b/src/abbrev.rs
@@ -0,0 +1,20 @@
+#[inline]
+pub fn floor_char_boundary(s: &str, index: usize) -> usize {
+    if index >= s.len() {
+        s.len()
+    } else {
+        let lower_bound = index.saturating_sub(3);
+        let new_index = s.as_bytes()[lower_bound..=index]
+            .iter()
+            .rposition(|b| is_utf8_char_boundary(*b));
+
+        // SAFETY: we know that the character boundary will be within four bytes
+        unsafe { lower_bound + new_index.unwrap_unchecked() }
+    }
+}
+
+#[inline]
+fn is_utf8_char_boundary(c: u8) -> bool {
+    // This is bit magic equivalent to: b < 128 || b >= 192
+    (c as i8) >= -0x40
+}
diff --git a/src/app.rs b/src/app.rs
index 54960119..ef7ce1bf 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -1,3 +1,4 @@
+use crate::abbrev;
 use crate::contacts::Contacts;
 use crate::fonts::setup_fonts;
 use crate::images::fetch_img;
@@ -321,6 +322,16 @@ fn pfp_image(ui: &mut egui::Ui, img: TextureId, size: f32) -> egui::Response {
     //.with_options()
 }
 
+fn ui_abbreviate_name(ui: &mut egui::Ui, name: &str, len: usize) {
+    if name.len() > len {
+        let closest = abbrev::floor_char_boundary(name, len);
+        ui.strong(&name[..closest]);
+        ui.strong("...");
+    } else {
+        ui.strong(name);
+    }
+}
+
 fn render_username(ui: &mut egui::Ui, contacts: &Contacts, pk: &Pubkey) {
     #[cfg(feature = "profiling")]
     puffin::profile_function!();
@@ -329,7 +340,7 @@ fn render_username(ui: &mut egui::Ui, contacts: &Contacts, pk: &Pubkey) {
         //ui.spacing_mut().item_spacing.x = 0.0;
         if let Some(prof) = contacts.profiles.get(pk) {
             if let Some(display_name) = prof.display_name() {
-                ui.strong(display_name);
+                ui_abbreviate_name(ui, &display_name, 20);
             }
         } else {
             ui.strong("nostrich");
diff --git a/src/lib.rs b/src/lib.rs
index 74e9d5a8..787fe425 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@ mod contacts;
 mod error;
 //mod note;
 //mod block;
+mod abbrev;
 mod fonts;
 mod images;
 mod result;