input: Refactor InputEvent::Change to not include the text. (#1246)

Change this to avoid Rope `to_string` performance cost. Ref #1220 

The listeners of `InputEvent::Change` may not be going to use entire of
text.

## Break Change

- The `InputEvent::Change(SharedString)` removed value.

```diff
- pub enum InputEvent {
-    Change(SharedString),
+ pub enum InputEvent {
+    Change,
```

crates/story/src/input_story.rs

@@ -134,13 +134,16 @@ impl InputStory {
 
     fn on_input_event(
         &mut self,
-        _: &Entity<InputState>,
+        state: &Entity<InputState>,
         event: &InputEvent,
         _window: &mut Window,
         _cx: &mut Context<Self>,
     ) {
         match event {
-            InputEvent::Change(text) => println!("Change: {}", text),
+            InputEvent::Change => {
+                let text = state.read(_cx).value();
+                println!("Change: {}", text)
+            }
             InputEvent::PressEnter { secondary } => println!("PressEnter secondary: {}", secondary),
             InputEvent::Focus => println!("Focus"),
             InputEvent::Blur => println!("Blur"),

crates/story/src/label_story.rs

@@ -47,9 +47,9 @@ impl LabelStory {
 
         let _subscriptions =
             vec![
-                cx.subscribe(&highlights_input, |this, _, e: &InputEvent, cx| {
-                    if let InputEvent::Change(v) = e {
-                        this.highlights_text = v.clone();
+                cx.subscribe(&highlights_input, |this, state, e: &InputEvent, cx| {
+                    if let InputEvent::Change = e {
+                        this.highlights_text = state.read(cx).value();
                         cx.notify();
                     }
                 }),

crates/story/src/main.rs

@@ -22,7 +22,7 @@ impl Gallery {
     pub fn new(init_story: Option<&str>, window: &mut Window, cx: &mut Context<Self>) -> Self {
         let search_input = cx.new(|cx| InputState::new(window, cx).placeholder("Search..."));
         let _subscriptions = vec![cx.subscribe(&search_input, |this, _, e, cx| match e {
-            InputEvent::Change(_) => {
+            InputEvent::Change => {
                 this.active_group_index = Some(0);
                 this.active_index = Some(0);
                 cx.notify()

crates/story/src/number_input_story.rs

@@ -132,22 +132,23 @@ impl NumberInputStory {
 
     fn on_input_event(
         &mut self,
-        this: &Entity<InputState>,
+        state: &Entity<InputState>,
         event: &InputEvent,
         _: &mut Window,
-        _: &mut Context<Self>,
+        cx: &mut Context<Self>,
     ) {
         match event {
-            InputEvent::Change(text) => {
-                if this == &self.number_input1 {
+            InputEvent::Change => {
+                let text = state.read(cx).value();
+                if state == &self.number_input1 {
                     if let Ok(value) = text.parse::<i64>() {
                         self.number_input1_value = value;
                     }
-                } else if this == &self.number_input2 {
+                } else if state == &self.number_input2 {
                     if let Ok(value) = text.parse::<u64>() {
                         self.number_input2_value = value;
                     }
-                } else if this == &self.number_input3 {
+                } else if state == &self.number_input3 {
                     if let Ok(value) = text.parse::<f64>() {
                         self.number_input3_value = value;
                     }

crates/story/src/otp_input_story.rs

@@ -59,16 +59,16 @@ impl OtpInputStory {
     fn new(window: &mut Window, cx: &mut Context<Self>) -> Self {
         let otp_state = cx.new(|cx| OtpState::new(6, window, cx).masked(true));
 
-        let _subscriptions =
-            vec![
-                cx.subscribe(&otp_state, |this, _, ev: &InputEvent, cx| match ev {
-                    InputEvent::Change(text) => {
-                        this.otp_value = Some(text.clone());
-                        cx.notify();
-                    }
-                    _ => {}
-                }),
-            ];
+        let _subscriptions = vec![
+            cx.subscribe(&otp_state, |this, state, ev: &InputEvent, cx| match ev {
+                InputEvent::Change => {
+                    let text = state.read(cx).value();
+                    this.otp_value = Some(text.clone());
+                    cx.notify();
+                }
+                _ => {}
+            }),
+        ];
 
         Self {
             otp_masked: true,

crates/ui/src/color_picker.rs

@@ -74,9 +74,10 @@ impl ColorPickerState {
         let _subscriptions = vec![cx.subscribe_in(
             &state,
             window,
-            |this, _, ev: &InputEvent, window, cx| match ev {
-                InputEvent::Change(value) => {
-                    if let Ok(color) = Hsla::parse_hex(value) {
+            |this, state, ev: &InputEvent, window, cx| match ev {
+                InputEvent::Change => {
+                    let value = state.read(cx).value();
+                    if let Ok(color) = Hsla::parse_hex(value.as_str()) {
                         this.value = Some(color);
                         this.hovered_color = Some(color);
                     }

crates/ui/src/input/otp_input.rs

@@ -133,7 +133,7 @@ impl OtpState {
         self.value = SharedString::from(chars.iter().collect::<String>());
 
         if self.value.chars().count() == self.length {
-            cx.emit(InputEvent::Change(self.value.clone()));
+            cx.emit(InputEvent::Change);
         }
         cx.notify()
     }

crates/ui/src/input/state.rs

@@ -95,7 +95,7 @@ actions!(
 
 #[derive(Clone)]
 pub enum InputEvent {
-    Change(SharedString),
+    Change,
     PressEnter { secondary: bool },
     Focus,
     Blur,
@@ -2236,7 +2236,7 @@ impl EntityInputHandler for InputState {
         self.update_scroll_offset(None, cx);
         self.mode.update_auto_grow(&self.text_wrapper);
         self.handle_completion_trigger(&range, &new_text, window, cx);
-        cx.emit(InputEvent::Change(self.unmask_value()));
+        cx.emit(InputEvent::Change);
         cx.notify();
     }
 
@@ -2289,7 +2289,7 @@ impl EntityInputHandler for InputState {
                 .into();
         }
         self.mode.update_auto_grow(&self.text_wrapper);
-        cx.emit(InputEvent::Change(self.unmask_value()));
+        cx.emit(InputEvent::Change);
         cx.notify();
     }
 

crates/ui/src/inspector.rs

@@ -115,9 +115,10 @@ impl DivInspector {
             cx.subscribe_in(
                 &json_input_state,
                 window,
-                |this: &mut DivInspector, _, event: &InputEvent, window, cx| match event {
-                    InputEvent::Change(new_style) => {
-                        this.edit_json(new_style, window, cx);
+                |this: &mut DivInspector, state, event: &InputEvent, window, cx| match event {
+                    InputEvent::Change => {
+                        let new_style = state.read(cx).value();
+                        this.edit_json(new_style.as_str(), window, cx);
                     }
                     _ => {}
                 },
@@ -125,9 +126,10 @@ impl DivInspector {
             cx.subscribe_in(
                 &rust_input_state,
                 window,
-                |this: &mut DivInspector, _, event: &InputEvent, window, cx| match event {
-                    InputEvent::Change(new_style) => {
-                        this.edit_rust(new_style, window, cx);
+                |this: &mut DivInspector, state, event: &InputEvent, window, cx| match event {
+                    InputEvent::Change => {
+                        let new_style = state.read(cx).value();
+                        this.edit_rust(new_style.as_str(), window, cx);
                     }
                     _ => {}
                 },

crates/ui/src/list/list.rs

@@ -238,13 +238,14 @@ where
 
     fn on_query_input_event(
         &mut self,
-        _: &Entity<InputState>,
+        state: &Entity<InputState>,
         event: &InputEvent,
         window: &mut Window,
         cx: &mut Context<Self>,
     ) {
         match event {
-            InputEvent::Change(text) => {
+            InputEvent::Change => {
+                let text = state.read(cx).value();
                 let text = text.trim().to_string();
                 if Some(&text) == self.last_query.as_ref() {
                     return;