Fix T80424: Image not scaled when rendering

This is was caused by incorrectly set `preview_render_size` in VSE
rendering context. Value was set to `SEQ_PROXY_RENDER_SIZE_FULL`, but
it should be `SEQ_PROXY_RENDER_SIZE_SCENE` as scene render size is
being used.

Alternatively we can check for `context->for_render` in
`input_preprocess()`, but I think fix above is more correct.

Reviewed By: sergey, brecht

Maniphest Tasks: T80424

Differential Revision: https://developer.blender.org/D8838

source/blender/render/intern/source/pipeline.c

@@ -36,6 +36,7 @@
 #include "DNA_particle_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_sequence_types.h"
+#include "DNA_space_types.h"
 #include "DNA_userdef_types.h"
 
 #include "MEM_guardedalloc.h"
@@ -1502,8 +1503,14 @@ static void do_render_seq(Render *re)
   tot_views = BKE_scene_multiview_num_views_get(&re->r);
   ibuf_arr = MEM_mallocN(sizeof(ImBuf *) * tot_views, "Sequencer Views ImBufs");
 
-  BKE_sequencer_new_render_data(
-      re->main, re->pipeline_depsgraph, re->scene, re_x, re_y, 100, true, &context);
+  BKE_sequencer_new_render_data(re->main,
+                                re->pipeline_depsgraph,
+                                re->scene,
+                                re_x,
+                                re_y,
+                                SEQ_PROXY_RENDER_SIZE_SCENE,
+                                true,
+                                &context);
 
   /* the renderresult gets destroyed during the rendering, so we first collect all ibufs
    * and then we populate the final renderesult */