feat(core/mercury): introduce binary_selection

This commit adds a Component which prompts a user with a pair of two
buttons - left and right. The Component is parametrized by the buttons
contents and styles.

[no changelog]

core/embed/rust/src/ui/model_mercury/component/binary_selection.rs

@@ -0,0 +1,90 @@
+use crate::ui::{
+    component::{Component, Event, EventCtx},
+    geometry::{Alignment2D, Offset, Rect},
+    shape::Renderer,
+};
+
+use super::{super::cshape, theme, Button, ButtonContent, ButtonMsg, ButtonStyleSheet};
+
+pub enum BinarySelectionMsg {
+    Left,
+    Right,
+}
+
+/// Component presenting a binary choice represented as two buttons, left and
+/// right. Both buttons are parameterized with content and style.
+#[derive(Clone)]
+pub struct BinarySelection {
+    buttons_area: Rect,
+    button_left: Button,
+    button_right: Button,
+}
+
+impl BinarySelection {
+    pub fn new(
+        left_content: ButtonContent,
+        right_content: ButtonContent,
+        left_style: ButtonStyleSheet,
+        right_style: ButtonStyleSheet,
+    ) -> Self {
+        Self {
+            buttons_area: Rect::zero(),
+            button_left: Button::new(left_content).styled(left_style),
+            button_right: Button::new(right_content).styled(right_style),
+        }
+    }
+}
+
+impl Component for BinarySelection {
+    type Msg = BinarySelectionMsg;
+
+    fn place(&mut self, bounds: Rect) -> Rect {
+        // Ensure reasonable space. Other than that, this component fits itself into any
+        // bounds.
+        let bounds_width = bounds.width();
+        let bounds_height = bounds.height();
+        assert!(bounds_width > 62);
+        assert!(bounds_height > 30);
+
+        let buttons_area = Rect::snap(
+            bounds.center(),
+            Offset::new(bounds_width, theme::BUTTON_HEIGHT.min(bounds_height)),
+            Alignment2D::CENTER,
+        );
+        let (left_area, _, right_area) = buttons_area.split_center(theme::SPACING);
+        self.button_left.place(left_area);
+        self.button_right.place(right_area);
+
+        self.buttons_area = buttons_area;
+        bounds
+    }
+
+    fn event(&mut self, ctx: &mut EventCtx, event: Event) -> Option<Self::Msg> {
+        if let Some(ButtonMsg::Clicked) = self.button_left.event(ctx, event) {
+            return Some(BinarySelectionMsg::Left);
+        }
+        if let Some(ButtonMsg::Clicked) = self.button_right.event(ctx, event) {
+            return Some(BinarySelectionMsg::Right);
+        }
+        None
+    }
+
+    fn paint(&mut self) {
+        unimplemented!()
+    }
+
+    fn render<'s>(&'s self, target: &mut impl Renderer<'s>) {
+        self.button_left.render(target);
+        self.button_right.render(target);
+        cshape::KeyboardOverlay::new(self.buttons_area).render(target);
+    }
+}
+
+#[cfg(feature = "ui_debug")]
+impl crate::trace::Trace for BinarySelection {
+    fn trace(&self, t: &mut dyn crate::trace::Tracer) {
+        t.component("BinarySelection");
+        t.child("button_left", &self.button_left);
+        t.child("button_right", &self.button_right);
+    }
+}

core/embed/rust/src/ui/model_mercury/component/mod.rs

@@ -1,5 +1,7 @@
 #[cfg(feature = "translations")]
 mod address_details;
+#[cfg(feature = "ui_overlay")]
+mod binary_selection;
 pub mod bl_confirm;
 mod button;
 #[cfg(feature = "translations")]
@@ -41,6 +43,8 @@ mod welcome_screen;
 
 #[cfg(feature = "translations")]
 pub use address_details::AddressDetails;
+#[cfg(feature = "ui_overlay")]
+pub use binary_selection::{BinarySelection, BinarySelectionMsg};
 pub use button::{
     Button, ButtonContent, ButtonMsg, ButtonStyle, ButtonStyleSheet, CancelConfirmMsg,
     CancelInfoConfirmMsg, IconText,