Add comments and handle paint_insets with the bounding_rect

masonry/src/contexts.rs

@@ -658,7 +658,7 @@ impl ComposeCtx<'_> {
         self.widget_state.needs_compose
     }
 
-    /// Set a translation for the child widget.
+    /// Set the scroll translation for the child widget.
     ///
     /// The translation is applied on top of the position from [`LayoutCtx::place_child`].
     pub fn set_child_scroll_translation<W: Widget>(
@@ -949,6 +949,7 @@ impl_context_method!(MutateCtx<'_>, EventCtx<'_>, UpdateCtx<'_>, {
         self.request_layout();
     }
 
+    /// Indicate that the transform of this widget has changed.
     pub fn transform_changed(&mut self) {
         trace!("transform_changed");
         self.widget_state.transform_changed = true;
@@ -986,6 +987,9 @@ impl_context_method!(MutateCtx<'_>, EventCtx<'_>, UpdateCtx<'_>, {
         self.widget_state.is_explicitly_disabled = disabled;
     }
 
+    /// Set the transform for this widget.
+    ///
+    /// It behaves similarly as CSS transforms
     pub fn set_transform(&mut self, transform: Affine) {
         self.widget_state.transform = transform;
         self.transform_changed();

masonry/src/passes/compose.rs

@@ -36,7 +36,7 @@ fn compose_widget(
     state.item.window_transform =
         parent_window_transform * state.item.transform.then_translate(local_translation);
 
-    let local_rect = state.item.size.to_rect();
+    let local_rect = state.item.size.to_rect() + state.item.paint_insets;
     state.item.bounding_rect = state.item.window_transform.transform_rect_bbox(local_rect);
 
     let mut ctx = ComposeCtx {

masonry/src/passes/paint.rs

@@ -92,6 +92,7 @@ fn paint_widget(
         },
     );
 
+    // draw the global axis aligned bounding rect of the widget
     if debug_paint {
         const BORDER_WIDTH: f64 = 1.0;
         let color = get_debug_color(id.to_raw());

masonry/src/widget/widget_mut.rs

@@ -48,6 +48,9 @@ impl<W: Widget> WidgetMut<'_, W> {
         }
     }
 
+    /// Set the local transform of this widget.
+    ///
+    /// It behaves similarly as CSS transforms.
     pub fn set_transform(&mut self, transform: Affine) {
         self.ctx.set_transform(transform);
     }

masonry/src/widget/widget_state.rs

@@ -58,7 +58,7 @@ pub(crate) struct WidgetState {
     /// The size of the widget; this is the value returned by the widget's layout
     /// method.
     pub(crate) size: Size,
-    /// The origin of the widget in the parent's coordinate space; together with
+    /// The origin of the widget in the `window_transform` coordinate space; together with
     /// `size` these constitute the widget's layout rect.
     pub(crate) origin: Point,
     /// The insets applied to the layout rect to generate the paint rect.
@@ -68,7 +68,7 @@ pub(crate) struct WidgetState {
     // TODO - Document
     // The computed paint rect, in local coordinates.
     pub(crate) local_paint_rect: Rect,
-    /// An axis aligned bounding rect (AABB in 2D), containing itself and all its descendents in window coordinates.
+    /// An axis aligned bounding rect (AABB in 2D), containing itself and all its descendents in window coordinates. Includes `paint_insets`.
     pub(crate) bounding_rect: Rect,
     /// The offset of the baseline relative to the bottom of the widget.
     ///
@@ -98,8 +98,11 @@ pub(crate) struct WidgetState {
 
     /// This is being computed out of all ancestor transforms and `translation`
     pub(crate) window_transform: Affine,
+    /// Local transform of this widget in the parent coordinate space.
     pub(crate) transform: Affine,
+    /// translation applied by scrolling, this is applied after applying `transform` to this widget.
     pub(crate) scroll_translation: Vec2,
+    /// The `transform` or `scroll_translation` has changed.
     pub(crate) transform_changed: bool,
 
     // --- PASSES ---
@@ -274,7 +277,7 @@ impl WidgetState {
         Rect::from_origin_size(self.origin, self.size)
     }
 
-    /// The axis aligned bounding rect of this widget in window coordinates.
+    /// The axis aligned bounding rect of this widget in window coordinates. Includes `paint_insets`.
     pub fn bounding_rect(&self) -> Rect {
         self.bounding_rect
     }