[gnome-shell] st/private: Multiply position in fb coordinates with resource scale

[Florian Müllner <fmuellner src gnome org>]

commit 18155fc6ea9cbc7e414314c82940459f4a157b25
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Sun Jul 26 13:26:20 2020 +0200

    st/private: Multiply position in fb coordinates with resource scale
    
    The framebuffer we use for rendering shadows is scaled by the resource
    scale, that means we also need to offset coordinates when translating
    them to the framebuffers coordinate system.
    
    So far we forgot to do that when translating the framebuffer using the
    position of the actor, which lead to small rendering bugs of
    text-shadows for actors allocated at non-zero origins. To fix that,
    simply multiply those positions with the actors resource scale.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1390

 src/st/st-private.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/st/st-private.c b/src/st/st-private.c
index a491c19535..129c87f51e 100644
--- a/src/st/st-private.c
+++ b/src/st/st-private.c
@@ -508,6 +508,8 @@ _st_create_shadow_pipeline_from_actor (StShadow     *shadow_spec,
 
       cogl_color_init_from_4ub (&clear_color, 0, 0, 0, 0);
       clutter_actor_get_position (actor, &x, &y);
+      x *= resource_scale;
+      y *= resource_scale;
 
       cogl_framebuffer_clear (fb, COGL_BUFFER_BIT_COLOR, &clear_color);
       cogl_framebuffer_translate (fb, -x, -y, 0);