Add box_shadow spread, h_offset, and v_offset

src/style.rs

@@ -76,6 +76,21 @@
 pub struct BoxShadow {
     pub blur_radius: f64,
     pub color: Color,
+    pub spread: f64,
+    pub h_offset: f64,
+    pub v_offset: f64,
+}
+
+impl Default for BoxShadow {
+    fn default() -> Self {
+        Self {
+            blur_radius: 0.0,
+            color: Color::BLACK,
+            spread: 0.0,
+            h_offset: 0.0,
+            v_offset: 0.0,
+        }
+    }
 }
 
 /// The value for a [`Style`] property
@@ -615,7 +630,7 @@
 
         self.box_shadow = Some(BoxShadow {
             blur_radius,
-            color: Color::BLACK,
+            ..Default::default()
         })
         .into();
         self
@@ -630,8 +645,56 @@
         }
 
         self.box_shadow = Some(BoxShadow {
-            blur_radius: 0.0,
             color,
+            ..Default::default()
+        })
+        .into();
+        self
+    }
+
+    pub fn box_shadow_spread(mut self, spread: f64) -> Self {
+        if let Some(box_shadow) = self.box_shadow.as_mut() {
+            if let Some(box_shadow) = box_shadow.as_mut() {
+                box_shadow.spread = spread;
+                return self;
+            }
+        }
+
+        self.box_shadow = Some(BoxShadow {
+            spread,
+            ..Default::default()
+        })
+        .into();
+        self
+    }
+
+    pub fn box_shadow_h_offset(mut self, h_offset: f64) -> Self {
+        if let Some(box_shadow) = self.box_shadow.as_mut() {
+            if let Some(box_shadow) = box_shadow.as_mut() {
+                box_shadow.h_offset = h_offset;
+                return self;
+            }
+        }
+
+        self.box_shadow = Some(BoxShadow {
+            h_offset,
+            ..Default::default()
+        })
+        .into();
+        self
+    }
+
+    pub fn box_shadow_v_offset(mut self, v_offset: f64) -> Self {
+        if let Some(box_shadow) = self.box_shadow.as_mut() {
+            if let Some(box_shadow) = box_shadow.as_mut() {
+                box_shadow.v_offset = v_offset;
+                return self;
+            }
+        }
+
+        self.box_shadow = Some(BoxShadow {
+            v_offset,
+            ..Default::default()
         })
         .into();
         self

src/view.rs

@@ -87,7 +87,7 @@
 
 use bitflags::bitflags;
 use floem_renderer::Renderer;
-use kurbo::{Affine, Circle, Line, Point, Rect, Size};
+use kurbo::{Affine, Circle, Insets, Line, Point, Rect, RoundedRect, Size};
 use taffy::prelude::Node;
 
 use crate::{
@@ -795,24 +795,16 @@
             };
             cx.fill(&circle, bg, 0.0);
         } else {
-            let rect = rect.to_rounded_rect(radius as f64);
-            if let Some(shadow) = style.box_shadow.as_ref() {
-                if shadow.blur_radius > 0.0 {
-                    cx.fill(&rect, shadow.color, shadow.blur_radius);
-                }
-            }
+            paint_box_shadow(cx, style, rect, Some(radius as f64));
             let bg = match style.background {
                 Some(color) => color,
                 None => return,
             };
-            cx.fill(&rect, bg, 0.0);
+            let rounded_rect = rect.to_rounded_rect(radius as f64);
+            cx.fill(&rounded_rect, bg, 0.0);
         }
     } else {
-        if let Some(shadow) = style.box_shadow.as_ref() {
-            if shadow.blur_radius > 0.0 {
-                cx.fill(&size.to_rect(), shadow.color, shadow.blur_radius);
-            }
-        }
+        paint_box_shadow(cx, style, size.to_rect(), None);
         let bg = match style.background {
             Some(color) => color,
             None => return,
@@ -821,6 +813,24 @@
     }
 }
 
+fn paint_box_shadow(cx: &mut PaintCx, style: &ComputedStyle, rect: Rect, rect_radius: Option<f64>) {
+    if let Some(shadow) = style.box_shadow.as_ref() {
+        let inset = Insets::new(
+            -shadow.h_offset / 2.0,
+            -shadow.v_offset / 2.0,
+            shadow.h_offset / 2.0,
+            shadow.v_offset / 2.0,
+        );
+        let rect = rect.inflate(shadow.spread, shadow.spread).inset(inset);
+        if let Some(radii) = rect_radius {
+            let rounded_rect = RoundedRect::from_rect(rect, radii + shadow.spread);
+            cx.fill(&rounded_rect, shadow.color, shadow.blur_radius);
+        } else {
+            cx.fill(&rect, shadow.color, shadow.blur_radius);
+        }
+    }
+}
+
 fn paint_outline(cx: &mut PaintCx, style: &ComputedStyle, size: Size) {
     if style.outline == 0. {
         // TODO: we should warn! when outline is < 0