sort of fix text editing (better but still bad)

src/core/text.rs

@@ -63,18 +63,23 @@ impl Text {
 
         match &mut self.cursor {
             Cursor::None => (),
-            Cursor::Select { line, col } => {
+            Cursor::Select { col, .. } => {
                 *col += 1;
             }
         }
+        self.update_cursor();
     }
 
     pub fn backspace(&mut self) {
-        if let Some(i) = self.update_cursor().checked_sub(1) {
+        if let Some(i) = self
+            .update_cursor()
+            .checked_sub(1)
+            .map(|i| self.content.floor_char_boundary(i))
+        {
             self.content.remove(i);
             match &mut self.cursor {
                 Cursor::None => (),
-                Cursor::Select { line, col } => {
+                Cursor::Select { col, .. } => {
                     *col -= 1;
                 }
             }
@@ -89,6 +94,7 @@ impl Text {
     }
 
     pub fn move_cursor(&mut self, dir: Dir) {
+        self.update_cursor();
         if let Cursor::Select { line, col } = &mut self.cursor {
             match dir {
                 Dir::LEFT => *col -= 1,
@@ -114,13 +120,13 @@ impl Text {
                 let mut l = 0;
                 let mut c = 0;
                 let mut cur_len = 0;
-                for (i, ch) in self.content.chars().enumerate() {
+                for (i, ch) in self.content.char_indices() {
                     if ch == '\n' {
                         l += 1;
                         c = 0;
                     } else {
                         if l == *line {
-                            cur_len = i as isize + 1;
+                            cur_len = c + 1;
                             if c == *col {
                                 idx = i;
                             }

src/layout/text.rs

@@ -28,7 +28,7 @@ pub struct TextAttrs {
     pub family: Family<'static>,
 }
 
-#[derive(Default)]
+#[derive(Default, Debug, Copy, Clone)]
 pub enum Cursor {
     #[default]
     None,

src/lib.rs

@@ -4,6 +4,7 @@
 #![feature(const_from)]
 #![feature(map_try_insert)]
 #![feature(trait_alias)]
+#![feature(round_char_boundary)]
 
 pub mod core;
 pub mod layout;