From 79a09ee6140f04126417ee7a198b228ccd8be9c9 Mon Sep 17 00:00:00 2001
From: Jonathan Johnson <jon@khonsulabs.com>
Date: Tue, 12 Dec 2023 19:27:41 -0800
Subject: [PATCH] Shadow blur now can cause expansion

Rather than clip or cause shadows to be weirdly shaped, the shape is
adjusted if the blur radius is too large for the given geometry. This
ensures the shadows always draw correctly, but it also forces shadows to
render their full blur + spread gradients.
---
 examples/container-shadow.rs |   4 +-
 src/widgets/container.rs     | 102 ++++++++++++++++++++---------------
 2 files changed, 63 insertions(+), 43 deletions(-)

diff --git a/examples/container-shadow.rs b/examples/container-shadow.rs
index 81a6685..76b2b6a 100644
--- a/examples/container-shadow.rs
+++ b/examples/container-shadow.rs
@@ -63,6 +63,7 @@ fn main() -> gooey::Result {
         .and(
             "Preview"
                 .h3()
+                .align_left()
                 .and(
                     Space::clear()
                         .size(Size::squared(Lp::inches(2)))
@@ -73,7 +74,8 @@ fn main() -> gooey::Result {
                 .into_rows(),
         )
         .into_columns()
+        .expand()
         .contain()
-        .centered()
+        .pad()
         .run()
 }
diff --git a/src/widgets/container.rs b/src/widgets/container.rs
index 07d8f38..61cd624 100644
--- a/src/widgets/container.rs
+++ b/src/widgets/container.rs
@@ -266,7 +266,21 @@ impl Widget for Container {
             .into_signed(),
         );
 
-        child_size + padding_amount + child_shadow_offset_amount + shadow_spread * 2
+        let corner_radii = context.get(&CornerRadius).into_upx(context.gfx.scale());
+        let max_corner = corner_radii
+            .top_left
+            .max(corner_radii.top_right)
+            .max(corner_radii.bottom_left)
+            .max(corner_radii.bottom_right);
+        let max_blur = (child_size
+            .width
+            .min(child_size.height)
+            .saturating_sub(shadow.spread.into_unsigned())
+            / 2)
+        .saturating_sub(max_corner);
+        let blur_overage = shadow.blur_radius.into_unsigned().saturating_sub(max_blur);
+
+        child_size + padding_amount + child_shadow_offset_amount + shadow_spread * 2 + blur_overage
     }
 
     fn root_behavior(
@@ -315,14 +329,19 @@ fn render_shadow(
     let shadow_color =
         shadow_color.with_alpha_f32(shadow_color.alpha_f32() * background.alpha_f32());
 
-    let gradient_size = (shadow.spread + shadow.blur_radius)
-        .min(child_area.size.width)
-        .min(child_area.size.height);
+    let max_corner = corner_radii
+        .top_left
+        .max(corner_radii.top_right)
+        .max(corner_radii.bottom_left)
+        .max(corner_radii.bottom_right);
+
+    let max_blur =
+        (child_area.size.width.min(child_area.size.height) - shadow.spread) / 2 - max_corner;
+    let blur = shadow.blur_radius.min(max_blur);
+    let gradient_size = shadow.spread + blur;
+
     if gradient_size > 0 {
-        let mut solid_area = Rect::new(
-            Point::squared(gradient_size),
-            child_area.size - shadow.blur_radius * 2,
-        );
+        let mut solid_area = Rect::new(Point::squared(gradient_size), child_area.size - blur * 2);
         solid_area.origin += shadow.offset.max(Point::ZERO);
 
         let transparent = shadow_color.with_alpha(0);
@@ -370,18 +389,6 @@ fn render_shadow(
                 .filled(),
             );
         }
-
-        // Top Right
-        shadow_arc(
-            Point::new(solid_right_at_top, solid_top_at_right),
-            corner_radii.top_right,
-            gradient_size,
-            shadow_color,
-            transparent,
-            Angle::degrees(270),
-            context,
-        );
-
         // Right
         context.gfx.draw_shape(
             &PathBuilder::new((Point::new(solid_right, solid_top_at_right), shadow_color))
@@ -412,17 +419,6 @@ fn render_shadow(
             .filled(),
         );
 
-        // Bottom Right
-        shadow_arc(
-            Point::new(solid_right_at_bottom, solid_bottom_at_right),
-            corner_radii.bottom_right,
-            gradient_size,
-            shadow_color,
-            transparent,
-            Angle::degrees(0),
-            context,
-        );
-
         // Bottom
         context.gfx.draw_shape(
             &PathBuilder::new((
@@ -450,17 +446,6 @@ fn render_shadow(
             .filled(),
         );
 
-        // Bottom Left
-        shadow_arc(
-            Point::new(solid_left_at_bottom, solid_bottom_at_left),
-            corner_radii.bottom_left,
-            gradient_size,
-            shadow_color,
-            transparent,
-            Angle::degrees(90),
-            context,
-        );
-
         // Left
         context.gfx.draw_shape(
             &PathBuilder::new((
@@ -491,6 +476,39 @@ fn render_shadow(
                 .filled(),
         );
 
+        // Top Right
+        shadow_arc(
+            Point::new(solid_right_at_top, solid_top_at_right),
+            corner_radii.top_right,
+            gradient_size,
+            shadow_color,
+            transparent,
+            Angle::degrees(270),
+            context,
+        );
+
+        // Bottom Right
+        shadow_arc(
+            Point::new(solid_right_at_bottom, solid_bottom_at_right),
+            corner_radii.bottom_right,
+            gradient_size,
+            shadow_color,
+            transparent,
+            Angle::degrees(0),
+            context,
+        );
+
+        // Bottom Left
+        shadow_arc(
+            Point::new(solid_left_at_bottom, solid_bottom_at_left),
+            corner_radii.bottom_left,
+            gradient_size,
+            shadow_color,
+            transparent,
+            Angle::degrees(90),
+            context,
+        );
+
         // Top Left
         shadow_arc(
             Point::new(solid_left_at_top, solid_top_at_left),