[libhandy] shadow-helper: Support hidpi

[Adrien Plazas <aplazas src gnome org>]

commit 7538617d6053a1a3762d9e2aec7752091dc866ac
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Wed Nov 11 18:19:44 2020 +0500

    shadow-helper: Support hidpi

 src/hdy-shadow-helper.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
---
diff --git a/src/hdy-shadow-helper.c b/src/hdy-shadow-helper.c
index 929f04a3..14712ecc 100644
--- a/src/hdy-shadow-helper.c
+++ b/src/hdy-shadow-helper.c
@@ -115,13 +115,16 @@ get_element_size (GtkStyleContext *context,
 static cairo_pattern_t *
 create_element_pattern (GtkStyleContext *context,
                         gint             width,
-                        gint             height)
+                        gint             height,
+                        gint             scale)
 {
   g_autoptr (cairo_surface_t) surface =
-    cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
+    cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width * scale, height * scale);
   g_autoptr (cairo_t) cr = cairo_create (surface);
   cairo_pattern_t *pattern;
 
+  cairo_surface_set_device_scale (surface, scale, scale);
+
   gtk_render_background (context, cr, 0, 0, width, height);
   gtk_render_frame (context, cr, 0, 0, width, height);
 
@@ -162,15 +165,15 @@ cache_shadow (HdyShadowHelper *self,
   border_size = get_element_size (border_context, direction);
   outline_size = get_element_size (outline_context, direction);
 
-  self->dimming_pattern = create_element_pattern (dim_context, width, height);
+  self->dimming_pattern = create_element_pattern (dim_context, width, height, scale);
   if (direction == GTK_PAN_DIRECTION_LEFT || direction == GTK_PAN_DIRECTION_RIGHT) {
-    self->shadow_pattern = create_element_pattern (shadow_context, shadow_size, height);
-    self->border_pattern = create_element_pattern (border_context, border_size, height);
-    self->outline_pattern = create_element_pattern (outline_context, outline_size, height);
+    self->shadow_pattern = create_element_pattern (shadow_context, shadow_size, height, scale);
+    self->border_pattern = create_element_pattern (border_context, border_size, height, scale);
+    self->outline_pattern = create_element_pattern (outline_context, outline_size, height, scale);
   } else {
-    self->shadow_pattern = create_element_pattern (shadow_context, width, shadow_size);
-    self->border_pattern = create_element_pattern (border_context, width, border_size);
-    self->outline_pattern = create_element_pattern (outline_context, width, outline_size);
+    self->shadow_pattern = create_element_pattern (shadow_context, width, shadow_size, scale);
+    self->border_pattern = create_element_pattern (border_context, width, border_size, scale);
+    self->outline_pattern = create_element_pattern (outline_context, width, outline_size, scale);
   }
 
   self->border_size = border_size;