[gtk/wip/baedert/outline-radius] css boxes: Compute inline box from border box

[Timm Bäder <baedert src gnome org>]

commit 8561860aa12c1d223f058075b9a46ef9692e81d4
Author: Timm Bäder <mail baedert org>
Date:   Tue Feb 11 08:29:11 2020 +0100

    css boxes: Compute inline box from border box
    
    We can't just use the outline rect and apply the border radius because
    the outline box is the border box grown by the outline offset, which
    will also grow the resulting border radius.
    
    Fixes #2425

 gtk/gtkcssboxesimplprivate.h | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)
---
diff --git a/gtk/gtkcssboxesimplprivate.h b/gtk/gtkcssboxesimplprivate.h
index 242ff5880c..a250de6212 100644
--- a/gtk/gtkcssboxesimplprivate.h
+++ b/gtk/gtkcssboxesimplprivate.h
@@ -471,16 +471,45 @@ gtk_css_boxes_compute_content_box (GtkCssBoxes *boxes)
 static inline void
 gtk_css_boxes_compute_outline_box (GtkCssBoxes *boxes)
 {
+  const GskRoundedRect *src;
+  GskRoundedRect *dest;
+  double d;
+  int i;
+
   if (boxes->has_box[GTK_CSS_AREA_OUTLINE_BOX])
     return;
 
-  gtk_css_boxes_compute_outline_rect (boxes);
+  gtk_css_boxes_compute_border_box (boxes);
 
-  gtk_css_boxes_apply_border_radius (&boxes->box[GTK_CSS_AREA_OUTLINE_BOX],
-                                     boxes->style->border->border_top_left_radius,
-                                     boxes->style->border->border_top_right_radius,
-                                     boxes->style->border->border_bottom_right_radius,
-                                     boxes->style->border->border_bottom_left_radius);
+  src = &boxes->box[GTK_CSS_AREA_BORDER_BOX];
+  dest = &boxes->box[GTK_CSS_AREA_OUTLINE_BOX];
+
+  d = _gtk_css_number_value_get (boxes->style->outline->outline_offset, 100) +
+      _gtk_css_number_value_get (boxes->style->outline->outline_width, 100);
+
+  /* Grow border rect into outline rect */
+  dest->bounds.origin.x = src->bounds.origin.x - d;
+  dest->bounds.origin.y = src->bounds.origin.y - d;
+  dest->bounds.size.width = src->bounds.size.width + d + d;
+  dest->bounds.size.height = src->bounds.size.height + d + d;
+
+  /* Grow corner radii of border rect */
+  for (i = 0; i < 4; i ++)
+    {
+      if (src->corner[i].width > 0) dest->corner[i].width = src->corner[i].width + d;
+      if (src->corner[i].height > 0) dest->corner[i].height = src->corner[i].height + d;
+
+      if (dest->corner[i].width <= 0 || dest->corner[i].height <= 0)
+        {
+          dest->corner[i].width = 0;
+          dest->corner[i].height = 0;
+        }
+      else
+        {
+          dest->corner[i].width = MIN (dest->corner[i].width, dest->bounds.size.width);
+          dest->corner[i].height = MIN (dest->corner[i].height, dest->bounds.size.height);
+        }
+    }
 
   boxes->has_box[GTK_CSS_AREA_OUTLINE_BOX] = TRUE;
 }