[gtk/gtk-3-24: 1/2] cssshadowvalue: Apply device scale to the offset when blurring text

[Matthias Clasen <matthiasc src gnome org>]

commit 86da4e0c97ec037cd80edc783c7804268a0d2fc8
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Wed Mar 24 18:28:25 2021 +0800

    cssshadowvalue: Apply device scale to the offset when blurring text
    
    Although the surface already has the device scale set, that doesn't
    apply to the offset which is in raw device units. So we need to scale
    the device offset explicitly.
    
    Fixes: https://gitlab.com/rastersoft/desktop-icons-ng/-/issues/119

 gtk/gtkcssshadowvalue.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkcssshadowvalue.c b/gtk/gtkcssshadowvalue.c
index 864bdef4b4..3c0d977566 100644
--- a/gtk/gtkcssshadowvalue.c
+++ b/gtk/gtkcssshadowvalue.c
@@ -485,7 +485,9 @@ make_blurred_pango_surface (cairo_t           *existing_cr,
                                                 x_scale * (ink_rect.width + 2 * clip_radius),
                                                 y_scale * (ink_rect.height + 2 * clip_radius));
   cairo_surface_set_device_scale (surface, x_scale, y_scale);
-  cairo_surface_set_device_offset (surface, -ink_rect.x + clip_radius, -ink_rect.y + clip_radius);
+  cairo_surface_set_device_offset (surface,
+                                   x_scale * (-ink_rect.x + clip_radius),
+                                   y_scale * (-ink_rect.y + clip_radius));
   cr = cairo_create (surface);
   cairo_move_to (cr, 0, 0);
   _gtk_pango_fill_layout (cr, layout);