[nautilus/2161-laggy-scrolling-with-adwaita-theme: 103/103] canvas-item: Use 0px border-radius for thumbnails

[António Fernandes <antoniof src gnome org>]

commit b4d356f0ec15f4c3cf38af005a113c8f2a2aa6eb
Author: António Fernandes <antoniof gnome org>
Date:   Mon Feb 28 14:39:29 2022 +0000

    canvas-item: Use 0px border-radius for thumbnails
    
    The border-radius intended for drawing the selection rectangle around
    labels is also causing black artifacts in the corners of thumbnails.
    
    This was not noticeable before because thumbnails had a rounded frame.
    
    So, set the radius to 0 when drawing the thumbnails, but restore the
    radius for the labels.

 src/nautilus-canvas-item.c    | 5 +++++
 src/resources/css/Adwaita.css | 1 +
 2 files changed, 6 insertions(+)
---
diff --git a/src/nautilus-canvas-item.c b/src/nautilus-canvas-item.c
index f51967d23..26253c484 100644
--- a/src/nautilus-canvas-item.c
+++ b/src/nautilus-canvas-item.c
@@ -1364,6 +1364,7 @@ nautilus_canvas_item_draw (EelCanvasItem  *item,
     gtk_style_context_add_class (context, "nautilus-canvas-item");
     if (details->is_thumbnail)
     {
+        gtk_style_context_save (context);
         gtk_style_context_add_class (context, "thumbnail");
     }
 
@@ -1374,6 +1375,10 @@ nautilus_canvas_item_draw (EelCanvasItem  *item,
                              temp_surface,
                              icon_rect.x0, icon_rect.y0);
     cairo_surface_destroy (temp_surface);
+    if (details->is_thumbnail)
+    {
+        gtk_style_context_restore (context);
+    }
 
     /* Draw the label text. */
     draw_label_text (canvas_item, cr, icon_rect);
diff --git a/src/resources/css/Adwaita.css b/src/resources/css/Adwaita.css
index 1135871be..100a1c02c 100644
--- a/src/resources/css/Adwaita.css
+++ b/src/resources/css/Adwaita.css
@@ -13,6 +13,7 @@
 }
 
 .nautilus-canvas-item.thumbnail {
+  border-radius: 0px;
   -gtk-icon-shadow:  0px -1px  alpha(@borders, 0.2),
                      2px  0px  alpha(@borders, 0.2),
                     -2px  0px  alpha(@borders, 0.2),