[gtk] gl renderer: Reset offset when rendering offscreen

[Timm Bäder <baedert src gnome org>]

commit 574ebafa46b9a6755907c2b20d176d15a49a240a
Author: Timm Bäder <mail baedert org>
Date:   Sun Dec 2 08:12:44 2018 +0100

    gl renderer: Reset offset when rendering offscreen
    
    We want to apply the offset to the rendered texture, not to the
    offscreen-rendered content.

 gsk/gl/gskglrenderer.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index 89be24fadc..0629bcd0e1 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -2324,6 +2324,8 @@ add_offscreen_ops (GskGLRenderer   *self,
   const float scale = ops_get_scale (builder);
   const float width = (max_x - min_x) * scale;
   const float height = (max_y - min_y) * scale;
+  const float dx = builder->dx;
+  const float dy = builder->dy;
   int render_target;
   int prev_render_target;
   RenderOp op;
@@ -2391,9 +2393,14 @@ add_offscreen_ops (GskGLRenderer   *self,
                               &GSK_ROUNDED_RECT_INIT (min_x * scale,
                                                       min_y * scale,
                                                       width, height));
+  builder->dx = 0;
+  builder->dy = 0;
 
   gsk_gl_renderer_add_render_ops (self, child_node, builder);
 
+  builder->dx = dx;
+  builder->dy = dy;
+
   if (reset_clip)
     ops_set_clip (builder, &prev_clip);