Cleanup: use enum types for screen direction variables

The term direction was used in 3 different ways in screen editing code,
making it hard to follow:

- 0-3 for as magic numbers mapped to [west,north,east,south].
- `h`, `v` characters for [horizontal,vertical] axes.
- Cycle direction SPACE_CONTEXT_CYCLE_PREV, SPACE_CONTEXT_CYCLE_NEXT

The following changes have been made:

- Add `eScreenDir` for [west,north,east,south], use variable name `dir`.
- Add `eScreenAxis` for [horizontal,vertical] values, use variable name
  `dir_axis`.
- Add `eScreenCycle` for existing enum `SPACE_CONTEXT_CYCLE_{PREV/NEXT}`.
- Add macros `SCREEN_DIR_IS_VERTICAL(dir)`,
  `SCREEN_DIR_IS_HORIZONTAL(dir)`.
  Replacing `ELEM(dir, 1, 3)`, `ELEM(dir, 0, 2)`.
- Move `ED_screen_draw_join_highlight`, `ED_screen_draw_split_preview`
  to `screen_intern.h`.

Reviewed By: Severin

Ref D11245

1 files changed, 32 insertions, 4 deletions

diff --git a/source/blender/editors/screen/screen_intern.h b/source/blender/editors/screen/screen_intern.h
index 9fc8913f583..683f2844371 100644
--- a/source/blender/editors/screen/screen_intern.h
+++ b/source/blender/editors/screen/screen_intern.h
@@ -29,6 +29,29 @@ struct bContextDataResult;
 
 /* internal exports only */
 
+typedef enum eScreenDir {
+  /** This can mean unset, unknown or invalid. */
+  SCREEN_DIR_NONE = -1,
+  /** West/Left. */
+  SCREEN_DIR_W = 0,
+  /** North/Up. */
+  SCREEN_DIR_N = 1,
+  /** East/Right. */
+  SCREEN_DIR_E = 2,
+  /** South/Down. */
+  SCREEN_DIR_S = 3,
+} eScreenDir;
+
+#define SCREEN_DIR_IS_VERTICAL(dir) (ELEM(dir, SCREEN_DIR_N, SCREEN_DIR_S))
+#define SCREEN_DIR_IS_HORIZONTAL(dir) (ELEM(dir, SCREEN_DIR_W, SCREEN_DIR_E))
+
+typedef enum eScreenAxis {
+  /** Horizontal. */
+  SCREEN_AXIS_H = 'h',
+  /** Vertical. */
+  SCREEN_AXIS_V = 'v',
+} eScreenAxis;
+
 #define AZONESPOTW UI_HEADER_OFFSET         /* width of corner #AZone - max */
 #define AZONESPOTH (0.6f * U.widget_unit)   /* height of corner #AZone */
 #define AZONEFADEIN (5.0f * U.widget_unit)  /* when #AZone is totally visible */
@@ -46,6 +69,10 @@ void ED_area_data_copy(ScrArea *area_dst, ScrArea *area_src, const bool do_free)
 void ED_area_data_swap(ScrArea *area_dst, ScrArea *area_src);
 void region_toggle_hidden(struct bContext *C, ARegion *region, const bool do_fade);
 
+/* screen_draw.c */
+void screen_draw_join_highlight(struct ScrArea *sa1, struct ScrArea *sa2);
+void screen_draw_split_preview(struct ScrArea *area, const eScreenAxis dir_axis, const float fac);
+
 /* screen_edit.c */
 bScreen *screen_add(struct Main *bmain, const char *name, const rcti *rect);
 void screen_data_copy(bScreen *to, bScreen *from);
@@ -59,12 +86,13 @@ void screen_change_prepare(bScreen *screen_old,
 ScrArea *area_split(const wmWindow *win,
                     bScreen *screen,
                     ScrArea *area,
-                    char dir,
+                    const eScreenAxis dir_axis,
                     const float fac,
                     const bool merge);
 int screen_area_join(struct bContext *C, bScreen *screen, ScrArea *sa1, ScrArea *sa2);
-int area_getorientation(ScrArea *sa_a, ScrArea *sa_b);
-void area_getoffsets(ScrArea *sa_a, ScrArea *sa_b, const int dir, int *r_offset1, int *r_offset2);
+eScreenDir area_getorientation(ScrArea *sa_a, ScrArea *sa_b);
+void area_getoffsets(
+    ScrArea *sa_a, ScrArea *sa_b, const eScreenDir dir, int *r_offset1, int *r_offset2);
 bool screen_area_close(struct bContext *C, bScreen *screen, ScrArea *area);
 struct AZone *ED_area_actionzone_find_xy(ScrArea *area, const int xy[2]);
 
@@ -87,7 +115,7 @@ ScrEdge *screen_geom_find_active_scredge(const wmWindow *win,
 void screen_geom_vertices_scale(const wmWindow *win, bScreen *screen);
 short screen_geom_find_area_split_point(const ScrArea *area,
                                         const rcti *window_rect,
-                                        char dir,
+                                        const eScreenAxis dir_axis,
                                         float fac);
 void screen_geom_select_connected_edge(const wmWindow *win, ScrEdge *edge);