Make TextBox generic over its data

This data must be TextStorage + EditableText, which means
that *currently* it is only String, but just imagine
what the future might hold?

Discussion: there's still something funny going on with
the TextStorage trait; this stuff as written isn't
suitable for use with xi_rope, which was sort of the
whole point.

docs/book_examples/src/custom_widgets_md.rs

@@ -49,10 +49,10 @@ impl TextBoxActionController {
     }
 }
 
-impl Controller<String, TextBox> for TextBoxActionController {
+impl Controller<String, TextBox<String>> for TextBoxActionController {
     fn event(
         &mut self,
-        child: &mut TextBox,
+        child: &mut TextBox<String>,
         ctx: &mut EventCtx,
         event: &Event,
         data: &mut String,

druid/src/widget/textbox.rs

@@ -17,7 +17,9 @@
 use std::time::Duration;
 
 use crate::kurbo::{Affine, Insets, Point, Size, Vec2};
-use crate::text::{BasicTextInput, EditAction, Editor, TextInput, TextLayout};
+use crate::text::{
+    BasicTextInput, EditAction, EditableText, Editor, TextInput, TextLayout, TextStorage,
+};
 use crate::theme;
 use crate::widget::prelude::*;
 use crate::{
@@ -32,9 +34,9 @@ const CURSOR_BLINK_DURATION: Duration = Duration::from_millis(500);
 
 /// A widget that allows user text input.
 #[derive(Debug, Clone)]
-pub struct TextBox {
+pub struct TextBox<T> {
     placeholder: TextLayout<String>,
-    editor: Editor<String>,
+    editor: Editor<T>,
     // this can be Box<dyn TextInput> in the future
     input_handler: BasicTextInput,
     hscroll_offset: f64,
@@ -45,13 +47,15 @@ pub struct TextBox {
     multiline: bool,
 }
 
-impl TextBox {
+impl TextBox<()> {
     /// Perform an `EditAction`. The payload *must* be an `EditAction`.
     pub const PERFORM_EDIT: Selector<EditAction> =
         Selector::new("druid-builtin.textbox.perform-edit");
+}
 
+impl<T> TextBox<T> {
     /// Create a new TextBox widget
-    pub fn new() -> TextBox {
+    pub fn new() -> Self {
         let mut placeholder = TextLayout::from_text("");
         placeholder.set_text_color(theme::PLACEHOLDER_COLOR);
         Self {
@@ -67,7 +71,7 @@ impl TextBox {
     }
 
     /// Create a new multi-line `TextBox`.
-    pub fn multiline() -> TextBox {
+    pub fn multiline() -> Self {
         let mut this = TextBox::new();
         this.editor.set_multiline(true);
         this.multiline = true;
@@ -127,7 +131,9 @@ impl TextBox {
         self.editor.layout().set_font(font.clone());
         self.placeholder.set_font(font);
     }
+}
 
+impl<T: TextStorage + EditableText> TextBox<T> {
     /// Calculate a stateful scroll offset
     fn update_hscroll(&mut self, self_width: f64) {
         let cursor_x = self.editor.cursor_line().p0.x;
@@ -162,8 +168,8 @@ impl TextBox {
     }
 }
 
-impl Widget<String> for TextBox {
-    fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut String, _env: &Env) {
+impl<T: TextStorage + EditableText> Widget<T> for TextBox<T> {
+    fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut T, _env: &Env) {
         self.suppress_adjust_hscroll = false;
         match event {
             Event::MouseDown(mouse) => {
@@ -237,7 +243,7 @@ impl Widget<String> for TextBox {
         }
     }
 
-    fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &String, env: &Env) {
+    fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &T, env: &Env) {
         match event {
             LifeCycle::WidgetAdded => {
                 ctx.register_for_focus();
@@ -252,7 +258,7 @@ impl Widget<String> for TextBox {
         }
     }
 
-    fn update(&mut self, ctx: &mut UpdateCtx, _: &String, data: &String, env: &Env) {
+    fn update(&mut self, ctx: &mut UpdateCtx, _: &T, data: &T, env: &Env) {
         self.editor.update(ctx, data, env);
         if !self.suppress_adjust_hscroll && !self.multiline {
             self.update_hscroll(ctx.size().width);
@@ -262,13 +268,7 @@ impl Widget<String> for TextBox {
         }
     }
 
-    fn layout(
-        &mut self,
-        ctx: &mut LayoutCtx,
-        bc: &BoxConstraints,
-        _data: &String,
-        env: &Env,
-    ) -> Size {
+    fn layout(&mut self, ctx: &mut LayoutCtx, bc: &BoxConstraints, _data: &T, env: &Env) -> Size {
         self.placeholder.rebuild_if_needed(ctx.text(), env);
         if self.multiline {
             self.editor
@@ -286,7 +286,7 @@ impl Widget<String> for TextBox {
         bc.constrain((width, height))
     }
 
-    fn paint(&mut self, ctx: &mut PaintCtx, data: &String, env: &Env) {
+    fn paint(&mut self, ctx: &mut PaintCtx, data: &T, env: &Env) {
         let size = ctx.size();
         let text_size = self.editor.layout().size();
         let background_color = env.get(theme::BACKGROUND_LIGHT);
@@ -357,7 +357,7 @@ impl Widget<String> for TextBox {
     }
 }
 
-impl Default for TextBox {
+impl<T> Default for TextBox<T> {
     fn default() -> Self {
         TextBox::new()
     }

druid/src/widget/widget_ext.rs

@@ -286,21 +286,21 @@ impl<T: Data, W> EnvScope<T, W> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::widget::TextBox;
+    use crate::widget::Slider;
     use crate::Color;
 
     #[test]
     fn container_reuse() {
-        // this should be Container<Align<Container<TextBox>>>
-        let widget = TextBox::new()
+        // this should be Container<Align<Container<Slider>>>
+        let widget = Slider::new()
             .background(Color::BLACK)
             .align_left()
             .border(Color::BLACK, 1.0);
         assert!(widget.border_is_some());
         assert!(!widget.background_is_some());
 
-        // this should be Container<TextBox>
-        let widget = TextBox::new()
+        // this should be Container<Slider>
+        let widget = Slider::new()
             .background(Color::BLACK)
             .border(Color::BLACK, 1.0);
         assert!(widget.background_is_some());
@@ -309,12 +309,12 @@ mod tests {
 
     #[test]
     fn sized_box_reuse() {
-        // this should be SizedBox<Align<SizedBox<TextBox>>>
-        let widget = TextBox::new().fix_height(10.0).align_left().fix_width(1.0);
+        // this should be SizedBox<Align<SizedBox<Slider>>>
+        let widget = Slider::new().fix_height(10.0).align_left().fix_width(1.0);
         assert_eq!(widget.width_and_height(), (Some(1.0), None));
 
-        // this should be SizedBox<TextBox>
-        let widget = TextBox::new().fix_height(10.0).fix_width(1.0);
+        // this should be SizedBox<Slider>
+        let widget = Slider::new().fix_height(10.0).fix_width(1.0);
         assert_eq!(widget.width_and_height(), (Some(1.0), Some(10.0)));
     }
 }