add scrollarea

crates/theme/src/lib.rs

@@ -51,6 +51,8 @@ pub struct Theme {
     pub elevations: Elevations,
     /// Overlay transition timing; gpui's animation primitives do the rest.
     pub motion: Motion,
+    /// Overlay scrollbar geometry.
+    pub scrollbar: Scrollbar,
     /// The platform's native root font size; rem-based sizing scales with it.
     pub root_font_size: Pixels,
     pub sizes: SizeTable,
@@ -82,8 +84,8 @@ impl Default for Radius {
     }
 }
 
-/// One drop shadow of a floating layer, transcribed from the platform's
-/// native overlay shadows.
+/// One drop shadow of a floating layer,
+/// transcribed from the platform's native overlay shadows.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Elevation {
     pub offset_y: Pixels,
@@ -149,6 +151,27 @@ impl Default for Motion {
     }
 }
 
+/// Overlay scrollbar geometry, transcribed from the platform's overlay crollbars.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Scrollbar {
+    /// The painted thumb's thickness.
+    pub width: Pixels,
+    /// Edge padding between the thumb and the viewport it floats over.
+    pub inset: Pixels,
+    /// The thumb never shrinks below this length, so it stays grabbable.
+    pub min_thumb: Pixels,
+}
+
+impl Default for Scrollbar {
+    fn default() -> Self {
+        Self {
+            width: px(8.),
+            inset: px(2.),
+            min_thumb: px(24.),
+        }
+    }
+}
+
 /// A named control size class.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub enum Size {
@@ -176,8 +199,7 @@ pub struct ControlMetrics {
     pub avatar_size: Pixels,
 }
 
-/// The control metrics for every size class, derived from the theme's root
-/// font size so controls scale with the platform's native type.
+/// The control metrics for every size class.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct SizeTable {
     pub small: ControlMetrics,
@@ -246,6 +268,7 @@ impl Theme {
             radius: resolved.radius,
             elevations: resolved.elevations,
             motion: resolved.motion,
+            scrollbar: resolved.scrollbar,
             root_font_size: resolved.root_font_size,
             sizes: resolved.sizes,
             accessibility: resolved.accessibility,