Require a StrokeKind when painting rectangles with strokes (#5648)

This is a breaking change, requiring users to think about wether the
stroke is inside/centered/outside the rect.

When in doubt, add `egui::StrokeKind::Inside` to the function call.

crates/epaint/src/shapes/rect_shape.rs

@@ -16,10 +16,8 @@ pub struct RectShape {
 
     /// The thickness and color of the outline.
     ///
-    /// The stroke extends _outside_ the edge of [`Self::rect`],
-    /// i.e. using [`crate::StrokeKind::Outside`].
-    ///
-    /// This means the [`Self::visual_bounding_rect`] is `rect.size() + 2.0 * stroke.width`.
+    /// Whether or not the stroke is inside or outside the edge of [`Self::rect`],
+    /// is controlled by [`Self::stroke_kind`].
     pub stroke: Stroke,
 
     /// Is the stroke on the inside, outside, or centered on the rectangle?
@@ -62,20 +60,21 @@ fn rect_shape_size() {
 }
 
 impl RectShape {
-    /// The stroke extends _outside_ the [`Rect`].
+    /// See also [`Self::filled`] and [`Self::stroke`].
     #[inline]
     pub fn new(
         rect: Rect,
         rounding: impl Into<Rounding>,
         fill_color: impl Into<Color32>,
         stroke: impl Into<Stroke>,
+        stroke_kind: StrokeKind,
     ) -> Self {
         Self {
             rect,
             rounding: rounding.into(),
             fill: fill_color.into(),
             stroke: stroke.into(),
-            stroke_kind: StrokeKind::Outside,
+            stroke_kind,
             round_to_pixels: None,
             blur_width: 0.0,
             brush: Default::default(),
@@ -88,14 +87,24 @@ impl RectShape {
         rounding: impl Into<Rounding>,
         fill_color: impl Into<Color32>,
     ) -> Self {
-        Self::new(rect, rounding, fill_color, Stroke::NONE)
+        Self::new(
+            rect,
+            rounding,
+            fill_color,
+            Stroke::NONE,
+            StrokeKind::Outside, // doesn't matter
+        )
     }
 
-    /// The stroke extends _outside_ the [`Rect`].
     #[inline]
-    pub fn stroke(rect: Rect, rounding: impl Into<Rounding>, stroke: impl Into<Stroke>) -> Self {
+    pub fn stroke(
+        rect: Rect,
+        rounding: impl Into<Rounding>,
+        stroke: impl Into<Stroke>,
+        stroke_kind: StrokeKind,
+    ) -> Self {
         let fill = Color32::TRANSPARENT;
-        Self::new(rect, rounding, fill, stroke)
+        Self::new(rect, rounding, fill, stroke, stroke_kind)
     }
 
     /// Set if the stroke is on the inside, outside, or centered on the rectangle.
@@ -146,8 +155,12 @@ impl RectShape {
         if self.fill == Color32::TRANSPARENT && self.stroke.is_empty() {
             Rect::NOTHING
         } else {
-            let Stroke { width, .. } = self.stroke; // Make sure we remember to update this if we change `stroke` to `PathStroke`
-            self.rect.expand(width + self.blur_width / 2.0)
+            let expand = match self.stroke_kind {
+                StrokeKind::Inside => 0.0,
+                StrokeKind::Middle => self.stroke.width / 2.0,
+                StrokeKind::Outside => self.stroke.width,
+            };
+            self.rect.expand(expand + self.blur_width / 2.0)
         }
     }
 

crates/epaint/src/shapes/shape.rs

@@ -7,7 +7,7 @@ use emath::{pos2, Align2, Pos2, Rangef, Rect, TSTransform, Vec2};
 use crate::{
     stroke::PathStroke,
     text::{FontId, Fonts, Galley},
-    Color32, Mesh, Rounding, Stroke, TextureId,
+    Color32, Mesh, Rounding, Stroke, StrokeKind, TextureId,
 };
 
 use super::{
@@ -275,6 +275,7 @@ impl Shape {
         Self::Ellipse(EllipseShape::stroke(center, radius, stroke))
     }
 
+    /// See also [`Self::rect_stroke`].
     #[inline]
     pub fn rect_filled(
         rect: Rect,
@@ -284,14 +285,15 @@ impl Shape {
         Self::Rect(RectShape::filled(rect, rounding, fill_color))
     }
 
-    /// The stroke extends _outside_ the [`Rect`].
+    /// See also [`Self::rect_filled`].
     #[inline]
     pub fn rect_stroke(
         rect: Rect,
         rounding: impl Into<Rounding>,
         stroke: impl Into<Stroke>,
+        stroke_kind: StrokeKind,
     ) -> Self {
-        Self::Rect(RectShape::stroke(rect, rounding, stroke))
+        Self::Rect(RectShape::stroke(rect, rounding, stroke, stroke_kind))
     }
 
     #[allow(clippy::needless_pass_by_value)]

crates/epaint/src/tessellator.rs

@@ -1400,7 +1400,7 @@ impl Tessellator {
                 if self.options.debug_paint_text_rects {
                     let rect = text_shape.galley.rect.translate(text_shape.pos.to_vec2());
                     self.tessellate_rect(
-                        &RectShape::stroke(rect.expand(0.5), 2.0, (0.5, Color32::GREEN)),
+                        &RectShape::stroke(rect, 2.0, (0.5, Color32::GREEN), StrokeKind::Outside),
                         out,
                     );
                 }
@@ -2189,7 +2189,12 @@ impl Tessellator {
             .flat_map(|clipped_primitive| {
                 let mut clip_rect_mesh = Mesh::default();
                 self.tessellate_shape(
-                    Shape::rect_stroke(clipped_primitive.clip_rect, 0.0, stroke),
+                    Shape::rect_stroke(
+                        clipped_primitive.clip_rect,
+                        0.0,
+                        stroke,
+                        StrokeKind::Outside,
+                    ),
                     &mut clip_rect_mesh,
                 );