added text edit history / undo (ctrl-z)

src/core/text/edit.rs

@@ -11,6 +11,7 @@ use winit::{
 pub struct TextEdit {
     pub(super) view: TextView,
     pub(super) selection: TextSelection,
+    pub(super) history: Vec<(String, TextSelection)>,
 }
 
 impl TextEdit {
@@ -180,6 +181,13 @@ impl<'a> TextEditCtx<'a> {
         text
     }
 
+    pub fn set(&mut self, text: &str) {
+        self.text
+            .buf
+            .set_text(self.font_system, text, &Attrs::new(), SHAPING, None);
+        self.text.selection.clear();
+    }
+
     pub fn motion(&mut self, motion: Motion) {
         if let TextSelection::Pos(cursor) = self.text.selection
             && let Some(cursor) = self.buf_motion(cursor, motion)
@@ -372,6 +380,24 @@ impl<'a> TextEditCtx<'a> {
     }
 
     pub fn apply_event(&mut self, event: &KeyEvent, modifiers: &Modifiers) -> TextInputResult {
+        let old = (self.text.content(), self.text.selection);
+        let mut undo = false;
+        let res = self.apply_event_inner(event, modifiers, &mut undo);
+        if undo && let Some((old, selection)) = self.text.history.pop() {
+            self.set(&old);
+            self.text.selection = selection;
+        } else if self.text.content() != old.0 {
+            self.text.history.push(old);
+        }
+        res
+    }
+
+    fn apply_event_inner(
+        &mut self,
+        event: &KeyEvent,
+        modifiers: &Modifiers,
+        undo: &mut bool,
+    ) -> TextInputResult {
         match &event.logical_key {
             Key::Named(named) => match named {
                 NamedKey::Backspace => self.backspace(modifiers.control),
@@ -429,6 +455,9 @@ impl<'a> TextEditCtx<'a> {
                                 };
                             }
                         }
+                        "z" => {
+                            *undo = true;
+                        }
                         _ => self.insert(text),
                     }
                 } else {
@@ -463,7 +492,7 @@ pub enum TextInputResult {
     Paste,
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Clone, Copy)]
 pub enum TextSelection {
     #[default]
     None,