Cleanup: Remove scene frame macros (`CFRA` et al.)

Removes the following macros for scene/render frame values:
- `CFRA`
- `SUBFRA`
- `SFRA`
- `EFRA`

These macros don't add much, other than saving a few characters when typing.
It's not immediately clear what they refer to, they just hide what they
actually access. Just be explicit and clear about that.
Plus these macros gave read and write access to the variables, so eyesores like
this would be done (eyesore because it looks like assigning to a constant):
```
CFRA = some_frame_nbr;
```

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D15311

3 files changed, 7 insertions, 6 deletions

diff --git a/source/blender/editors/space_image/image_buttons.c b/source/blender/editors/space_image/image_buttons.c
index d0c21f85472..0a774ee679c 100644
--- a/source/blender/editors/space_image/image_buttons.c
+++ b/source/blender/editors/space_image/image_buttons.c
@@ -1218,7 +1218,7 @@ void uiTemplateImageInfo(uiLayout *layout, bContext *C, Image *ima, ImageUser *i
   if (ELEM(ima->source, IMA_SRC_SEQUENCE, IMA_SRC_MOVIE)) {
     /* don't use iuser->framenr directly because it may not be updated if auto-refresh is off */
     Scene *scene = CTX_data_scene(C);
-    const int framenr = BKE_image_user_frame_get(iuser, CFRA, NULL);
+    const int framenr = BKE_image_user_frame_get(iuser, scene->r.cfra, NULL);
     char str[MAX_IMAGE_INFO_LEN];
     int duration = 0;
 
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 048c7345b97..f6f9428213f 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -515,7 +515,8 @@ void draw_image_cache(const bContext *C, ARegion *region)
   SpaceImage *sima = CTX_wm_space_image(C);
   Scene *scene = CTX_data_scene(C);
   Image *image = ED_space_image(sima);
-  float x, cfra = CFRA, sfra = SFRA, efra = EFRA, framelen = region->winx / (efra - sfra + 1);
+  float x, cfra = scene->r.cfra, sfra = scene->r.sfra, efra = scene->r.efra,
+           framelen = region->winx / (efra - sfra + 1);
   Mask *mask = NULL;
 
   if (!ED_space_image_show_cache(sima)) {
diff --git a/source/blender/editors/space_image/image_ops.c b/source/blender/editors/space_image/image_ops.c
index 537132ac428..b77bdc11ca5 100644
--- a/source/blender/editors/space_image/image_ops.c
+++ b/source/blender/editors/space_image/image_ops.c
@@ -3580,9 +3580,9 @@ static void change_frame_apply(bContext *C, wmOperator *op)
   Scene *scene = CTX_data_scene(C);
 
   /* set the new frame number */
-  CFRA = RNA_int_get(op->ptr, "frame");
-  FRAMENUMBER_MIN_CLAMP(CFRA);
-  SUBFRA = 0.0f;
+  scene->r.cfra = RNA_int_get(op->ptr, "frame");
+  FRAMENUMBER_MIN_CLAMP(scene->r.cfra);
+  scene->r.subframe = 0.0f;
 
   /* do updates */
   DEG_id_tag_update(&scene->id, ID_RECALC_FRAME_CHANGE);
@@ -3603,7 +3603,7 @@ static int frame_from_event(bContext *C, const wmEvent *event)
   int framenr = 0;
 
   if (region->regiontype == RGN_TYPE_WINDOW) {
-    float sfra = SFRA, efra = EFRA, framelen = region->winx / (efra - sfra + 1);
+    float sfra = scene->r.sfra, efra = scene->r.efra, framelen = region->winx / (efra - sfra + 1);
 
     framenr = sfra + event->mval[0] / framelen;
   }