chore(core/rust): Simplify LayoutObj

core/embed/rust/src/ui/layout/obj.rs

@@ -43,12 +43,32 @@ where
     }
 }
 
-/// In order to store any type of component in a layout, we need to access it
-/// through an object-safe trait. `Component` itself is not object-safe because
-/// of `Component::Msg` associated type. `ObjComponent` is a simple object-safe
-/// wrapping trait that is implemented for all components where `Component::Msg`
-/// can be converted to `Obj` through the `ComponentMsgObj` trait.
-pub trait ObjComponent {
+#[cfg(feature = "ui_debug")]
+mod maybe_trace {
+    pub trait MaybeTrace: crate::trace::Trace {}
+    impl<T> MaybeTrace for T where T: crate::trace::Trace {}
+}
+
+#[cfg(not(feature = "ui_debug"))]
+mod maybe_trace {
+    pub trait MaybeTrace {}
+    impl<T> MaybeTrace for T {}
+}
+
+/// Stand-in for the optionally-compiled trait `Trace`.
+/// If UI debugging is enabled, `MaybeTrace` implies `Trace` and is implemented
+/// for everything that implements Trace. If disabled, `MaybeTrace` is
+/// implemented for everything.
+use maybe_trace::MaybeTrace;
+
+/// Object-safe interface between trait `Component` and MicroPython world. It
+/// converts the result of `Component::event` into `Obj` via the
+/// `ComponentMsgObj` trait, in order to easily return the value to Python. It
+/// also optionally implies `Trace` for UI debugging.
+/// Note: we need to use an object-safe trait in order to store it in a `Gc<dyn
+/// T>` field. `Component` itself is not object-safe because of `Component::Msg`
+/// associated type.
+pub trait ObjComponent: MaybeTrace {
     fn obj_event(&mut self, ctx: &mut EventCtx, event: Event) -> Result<Obj, Error>;
     fn obj_paint(&mut self);
     fn obj_bounds(&self, sink: &mut dyn FnMut(Rect));
@@ -56,7 +76,7 @@ pub trait ObjComponent {
 
 impl<T> ObjComponent for Child<T>
 where
-    T: ComponentMsgObj,
+    T: ComponentMsgObj + MaybeTrace,
 {
     fn obj_event(&mut self, ctx: &mut EventCtx, event: Event) -> Result<Obj, Error> {
         if let Some(msg) = self.event(ctx, event) {
@@ -75,22 +95,6 @@ where
     }
 }
 
-#[cfg(feature = "ui_debug")]
-mod maybe_trace {
-    pub trait ObjComponentTrace: super::ObjComponent + crate::trace::Trace {}
-    impl<T> ObjComponentTrace for T where T: super::ObjComponent + crate::trace::Trace {}
-}
-
-#[cfg(not(feature = "ui_debug"))]
-mod maybe_trace {
-    pub trait ObjComponentTrace: super::ObjComponent {}
-    impl<T> ObjComponentTrace for T where T: super::ObjComponent {}
-}
-
-/// Trait that combines `ObjComponent` with `Trace` if `ui_debug` is enabled,
-/// and pure `ObjComponent` otherwise.
-use maybe_trace::ObjComponentTrace;
-
 /// `LayoutObj` is a GC-allocated object exported to MicroPython, with type
 /// `LayoutObj::obj_type()`. It wraps a root component through the
 /// `ObjComponent` trait.
@@ -101,17 +105,20 @@ pub struct LayoutObj {
 }
 
 struct LayoutObjInner {
-    root: Gc<dyn ObjComponentTrace>,
+    root: Gc<dyn ObjComponent>,
     event_ctx: EventCtx,
     timer_fn: Obj,
 }
 
 impl LayoutObj {
     /// Create a new `LayoutObj`, wrapping a root component.
-    pub fn new(root: impl ObjComponentTrace + 'static) -> Result<Gc<Self>, Error> {
+    pub fn new(root: impl ComponentMsgObj + MaybeTrace + 'static) -> Result<Gc<Self>, Error> {
+        // Let's wrap the root component into a `Child` to maintain the top-level
+        // invalidation logic.
+        let wrapped_root = Child::new(root);
         // SAFETY: We are coercing GC-allocated sized ptr into an unsized one.
         let root =
-            unsafe { Gc::from_raw(Gc::into_raw(Gc::new(root)?) as *mut dyn ObjComponentTrace) };
+            unsafe { Gc::from_raw(Gc::into_raw(Gc::new(wrapped_root)?) as *mut dyn ObjComponent) };
 
         Gc::new(Self {
             base: Self::obj_type().as_base(),

core/embed/rust/src/ui/model_t1/layout.rs

@@ -3,7 +3,7 @@ use core::convert::TryInto;
 use crate::{
     micropython::{buffer::Buffer, map::Map, obj::Obj, qstr::Qstr},
     ui::{
-        component::{text::paragraphs::Paragraphs, Child, FormattedText},
+        component::{text::paragraphs::Paragraphs, FormattedText},
         display,
         layout::obj::LayoutObj,
     },
@@ -44,7 +44,7 @@ extern "C" fn ui_layout_new_confirm_action(
         let right = verb
             .map(|label| |area, pos| Button::with_text(area, pos, label, theme::button_default()));
 
-        let obj = LayoutObj::new(Child::new(Frame::new(display::screen(), title, |area| {
+        let obj = LayoutObj::new(Frame::new(display::screen(), title, |area| {
             ButtonPage::new(
                 area,
                 |area| {
@@ -54,7 +54,7 @@ extern "C" fn ui_layout_new_confirm_action(
                 },
                 theme::BG,
             )
-        })))?;
+        }))?;
         Ok(obj.into())
     };
     unsafe { util::try_with_args_and_kwargs(n_args, args, kwargs, block) }
@@ -72,7 +72,7 @@ extern "C" fn ui_layout_new_confirm_text(
         let description: Option<Buffer> =
             kwargs.get(Qstr::MP_QSTR_description)?.try_into_option()?;
 
-        let obj = LayoutObj::new(Child::new(Frame::new(display::screen(), title, |area| {
+        let obj = LayoutObj::new(Frame::new(display::screen(), title, |area| {
             ButtonPage::new(
                 area,
                 |area| {
@@ -85,7 +85,7 @@ extern "C" fn ui_layout_new_confirm_text(
                 },
                 theme::BG,
             )
-        })))?;
+        }))?;
         Ok(obj.into())
     };
     unsafe { util::try_with_args_and_kwargs(n_args, args, kwargs, block) }
@@ -125,7 +125,7 @@ mod tests {
 
     #[test]
     fn trace_example_layout() {
-        let layout = Child::new(Dialog::new(
+        let layout = Dialog::new(
             display::screen(),
             |area| {
                 FormattedText::new::<theme::T1DefaultText>(
@@ -136,7 +136,7 @@ mod tests {
             },
             Some(|area, pos| Button::with_text(area, pos, "Left", theme::button_cancel())),
             Some(|area, pos| Button::with_text(area, pos, "Right", theme::button_default())),
-        ));
+        );
         assert_eq!(
             trace(&layout),
             r#"<Dialog content:<Text content:Testing text layout,
@@ -148,7 +148,7 @@ arameters! > left:<Button text:Left > right:<Button text:Right > >"#
 
     #[test]
     fn trace_layout_title() {
-        let layout = Child::new(Frame::new(display::screen(), "Please confirm", |area| {
+        let layout = Frame::new(display::screen(), "Please confirm", |area| {
             Dialog::new(
                 area,
                 |area| {
@@ -161,7 +161,7 @@ arameters! > left:<Button text:Left > right:<Button text:Right > >"#
                 Some(|area, pos| Button::with_text(area, pos, "Left", theme::button_cancel())),
                 Some(|area, pos| Button::with_text(area, pos, "Right", theme::button_default())),
             )
-        }));
+        });
         assert_eq!(
             trace(&layout),
             r#"<Frame title:Please confirm content:<Dialog content:<Text content:Testing text layout,

core/embed/rust/src/ui/model_tt/layout.rs

@@ -52,13 +52,13 @@ where
 #[no_mangle]
 extern "C" fn ui_layout_new_example(_param: Obj) -> Obj {
     let block = move || {
-        let layout = LayoutObj::new(Child::new(HoldToConfirm::new(display::screen(), |area| {
+        let layout = LayoutObj::new(HoldToConfirm::new(display::screen(), |area| {
             FormattedText::new::<theme::TTDefaultText>(
                 area,
                 "Testing text layout, with some text, and some more text. And {param}",
             )
             .with(b"param", b"parameters!")
-        })))?;
+        }))?;
         Ok(layout.into())
     };
     unsafe { util::try_or_raise(block) }