Fix wrong usages of region align enumerations

`ARegion.alignment` unfortunately is a mixture of value and bitflag
enumerations. When checking for left/right/top/bottom region alignment,
the flags have to be masked out usually.
Most of the fixed cases here probably didn't cause issues in practice,
but could in fact break at any point when surrounding logic changes.

In fact the assert in #region_visible_rect_calc() failed in an older
file from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=949035. This
fixes it.

12 files changed, 56 insertions, 40 deletions

diff --git a/source/blender/editors/interface/interface_align.c b/source/blender/editors/interface/interface_align.c
index cc68e303e4a..c058fefb4fa 100644
--- a/source/blender/editors/interface/interface_align.c
+++ b/source/blender/editors/interface/interface_align.c
@@ -124,7 +124,7 @@ bool ui_but_can_align(const uiBut *but)
 
 int ui_but_align_opposite_to_area_align_get(const ARegion *ar)
 {
-  switch (ar->alignment) {
+  switch (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment)) {
     case RGN_ALIGN_TOP:
       return UI_BUT_ALIGN_DOWN;
     case RGN_ALIGN_BOTTOM:
diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 05d5f03a363..16996681695 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -1886,11 +1886,13 @@ static bool ui_but_drag_init(bContext *C,
                RGN_TYPE_HEADER,
                RGN_TYPE_TOOL_HEADER,
                RGN_TYPE_FOOTER)) {
+        const int ar_alignment = RGN_ALIGN_ENUM_FROM_MASK(data->region->alignment);
         int lock_axis = -1;
-        if (ELEM(data->region->alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
+
+        if (ELEM(ar_alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
           lock_axis = 0;
         }
-        else if (ELEM(data->region->alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
+        else if (ELEM(ar_alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
           lock_axis = 1;
         }
         if (lock_axis != -1) {
diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index 68cd450a451..179fe84264f 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -1241,17 +1241,19 @@ static void ui_item_menu_hold(struct bContext *C, ARegion *butregion, uiBut *but
 
   char direction = UI_DIR_DOWN;
   if (!but->drawstr[0]) {
-    if (butregion->alignment == RGN_ALIGN_LEFT) {
-      direction = UI_DIR_RIGHT;
-    }
-    else if (butregion->alignment == RGN_ALIGN_RIGHT) {
-      direction = UI_DIR_LEFT;
-    }
-    else if (butregion->alignment == RGN_ALIGN_BOTTOM) {
-      direction = UI_DIR_UP;
-    }
-    else {
-      direction = UI_DIR_DOWN;
+    switch (RGN_ALIGN_ENUM_FROM_MASK(butregion->alignment)) {
+      case RGN_ALIGN_LEFT:
+        direction = UI_DIR_RIGHT;
+        break;
+      case RGN_ALIGN_RIGHT:
+        direction = UI_DIR_LEFT;
+        break;
+      case RGN_ALIGN_BOTTOM:
+        direction = UI_DIR_UP;
+        break;
+      default:
+        direction = UI_DIR_DOWN;
+        break;
     }
   }
   UI_block_direction_set(block, direction);
diff --git a/source/blender/editors/interface/interface_panel.c b/source/blender/editors/interface/interface_panel.c
index 8adb82a22c8..3b21b689ba0 100644
--- a/source/blender/editors/interface/interface_panel.c
+++ b/source/blender/editors/interface/interface_panel.c
@@ -1065,7 +1065,7 @@ static bool uiAlignPanelStep(ScrArea *sa, ARegion *ar, const float fac, const bo
   ps->pa->ofsy = -get_panel_size_y(ps->pa);
 
   if (has_category_tabs) {
-    if (align == BUT_VERTICAL && (ar->alignment != RGN_ALIGN_RIGHT)) {
+    if (align == BUT_VERTICAL && (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) != RGN_ALIGN_RIGHT)) {
       ps->pa->ofsx += UI_PANEL_CATEGORY_MARGIN_WIDTH;
     }
   }
@@ -1913,7 +1913,7 @@ void UI_panel_category_draw_all(ARegion *ar, const char *category_id_active)
 {
   /* no tab outlines for */
   // #define USE_FLAT_INACTIVE
-  const bool is_left = (ar->alignment != RGN_ALIGN_RIGHT);
+  const bool is_left = RGN_ALIGN_ENUM_FROM_MASK(ar->alignment != RGN_ALIGN_RIGHT);
   View2D *v2d = &ar->v2d;
   uiStyle *style = UI_style_get();
   const uiFontStyle *fstyle = &style->widget;
@@ -2201,7 +2201,7 @@ static int ui_handle_panel_category_cycling(const wmEvent *event,
 {
   const bool is_mousewheel = ELEM(event->type, WHEELUPMOUSE, WHEELDOWNMOUSE);
   const bool inside_tabregion =
-      ((ar->alignment != RGN_ALIGN_RIGHT) ?
+      ((RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) != RGN_ALIGN_RIGHT) ?
            (event->mval[0] < ((PanelCategoryDyn *)ar->panels_category.first)->rect.xmax) :
            (event->mval[0] > ((PanelCategoryDyn *)ar->panels_category.first)->rect.xmin));
 
diff --git a/source/blender/editors/interface/interface_region_menu_popup.c b/source/blender/editors/interface/interface_region_menu_popup.c
index fed3c0b3d11..560c6146afe 100644
--- a/source/blender/editors/interface/interface_region_menu_popup.c
+++ b/source/blender/editors/interface/interface_region_menu_popup.c
@@ -280,13 +280,13 @@ static uiBlock *ui_block_func_POPUP(bContext *C, uiPopupBlockHandle *handle, voi
       ARegion *ar = CTX_wm_region(C);
       if (sa && ar) {
         if (ELEM(ar->regiontype, RGN_TYPE_HEADER, RGN_TYPE_TOOL_HEADER)) {
-          if (ED_area_header_alignment(sa) == RGN_ALIGN_BOTTOM) {
+          if (RGN_ALIGN_ENUM_FROM_MASK(ED_area_header_alignment(sa)) == RGN_ALIGN_BOTTOM) {
             UI_block_direction_set(block, UI_DIR_UP);
             UI_block_order_flip(block);
           }
         }
         if (ar->regiontype == RGN_TYPE_FOOTER) {
-          if (ED_area_footer_alignment(sa) == RGN_ALIGN_BOTTOM) {
+          if (RGN_ALIGN_ENUM_FROM_MASK(ED_area_footer_alignment(sa)) == RGN_ALIGN_BOTTOM) {
             UI_block_direction_set(block, UI_DIR_UP);
             UI_block_order_flip(block);
           }
diff --git a/source/blender/editors/interface/interface_region_popover.c b/source/blender/editors/interface/interface_region_popover.c
index cd0421dde09..2042c15ed96 100644
--- a/source/blender/editors/interface/interface_region_popover.c
+++ b/source/blender/editors/interface/interface_region_popover.c
@@ -189,12 +189,12 @@ static uiBlock *ui_block_func_POPOVER(bContext *C, uiPopupBlockHandle *handle, v
       /* Prefer popover from header to be positioned into the editor. */
       else if (sa && ar) {
         if (ELEM(ar->regiontype, RGN_TYPE_HEADER, RGN_TYPE_TOOL_HEADER)) {
-          if (ED_area_header_alignment(sa) == RGN_ALIGN_BOTTOM) {
+          if (RGN_ALIGN_ENUM_FROM_MASK(ED_area_header_alignment(sa)) == RGN_ALIGN_BOTTOM) {
             UI_block_direction_set(block, UI_DIR_UP | UI_DIR_CENTER_X);
           }
         }
         if (ar->regiontype == RGN_TYPE_FOOTER) {
-          if (ED_area_footer_alignment(sa) == RGN_ALIGN_BOTTOM) {
+          if (RGN_ALIGN_ENUM_FROM_MASK(ED_area_footer_alignment(sa)) == RGN_ALIGN_BOTTOM) {
             UI_block_direction_set(block, UI_DIR_UP | UI_DIR_CENTER_X);
           }
         }
diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index f4d9c353102..39b2c060ba4 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -1141,6 +1141,9 @@ static void region_overlap_fix(ScrArea *sa, ARegion *ar)
     }
   }
 
+  /* Guard against flags slipping through that would have to be masked out in usages below. */
+  BLI_assert(align1 == RGN_ALIGN_ENUM_FROM_MASK(align1));
+
   /* translate or close */
   if (ar1) {
     if (align1 == RGN_ALIGN_LEFT) {
@@ -2585,7 +2588,7 @@ void ED_region_panels_draw(const bContext *C, ARegion *ar)
   /* scrollers */
   const rcti *mask = NULL;
   rcti mask_buf;
-  if (ar->runtime.category && (ar->alignment == RGN_ALIGN_RIGHT)) {
+  if (ar->runtime.category && (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_RIGHT)) {
     UI_view2d_mask_from_win(v2d, &mask_buf);
     mask_buf.xmax -= UI_PANEL_CATEGORY_MARGIN_WIDTH;
     mask = &mask_buf;
@@ -3347,7 +3350,9 @@ static void region_visible_rect_calc(ARegion *ar, rcti *rect)
   for (; arn; arn = arn->next) {
     if (ar != arn && arn->overlap) {
       if (BLI_rcti_isect(rect, &arn->winrct, NULL)) {
-        if (ELEM(arn->alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
+        int alignment = RGN_ALIGN_ENUM_FROM_MASK(arn->alignment);
+
+        if (ELEM(alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
           /* Overlap left, also check 1 pixel offset (2 regions on one side). */
           if (ABS(rect->xmin - arn->winrct.xmin) < 2) {
             rect->xmin = arn->winrct.xmax;
@@ -3358,7 +3363,7 @@ static void region_visible_rect_calc(ARegion *ar, rcti *rect)
             rect->xmax = arn->winrct.xmin;
           }
         }
-        else if (ELEM(arn->alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
+        else if (ELEM(alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
           /* Same logic as above for vertical regions. */
           if (ABS(rect->ymin - arn->winrct.ymin) < 2) {
             rect->ymin = arn->winrct.ymax;
@@ -3367,7 +3372,7 @@ static void region_visible_rect_calc(ARegion *ar, rcti *rect)
             rect->ymax = arn->winrct.ymin;
           }
         }
-        else if (arn->alignment == RGN_ALIGN_FLOAT) {
+        else if (alignment == RGN_ALIGN_FLOAT) {
           /* Skip floating. */
         }
         else {
diff --git a/source/blender/editors/screen/area_query.c b/source/blender/editors/screen/area_query.c
index 46559efc614..942050aaffd 100644
--- a/source/blender/editors/screen/area_query.c
+++ b/source/blender/editors/screen/area_query.c
@@ -67,10 +67,12 @@ bool ED_region_panel_category_gutter_calc_rect(const ARegion *ar, rcti *r_ar_gut
   if (UI_panel_category_is_visible(ar)) {
     const int category_tabs_width = round_fl_to_int(UI_view2d_scale_get_x(&ar->v2d) *
                                                     UI_PANEL_CATEGORY_MARGIN_WIDTH);
-    if (ar->alignment == RGN_ALIGN_LEFT) {
+    const int alignment = RGN_ALIGN_ENUM_FROM_MASK(ar->alignment);
+
+    if (alignment == RGN_ALIGN_LEFT) {
       r_ar_gutter->xmax = r_ar_gutter->xmin + category_tabs_width;
     }
-    else if (ar->alignment == RGN_ALIGN_RIGHT) {
+    else if (alignment == RGN_ALIGN_RIGHT) {
       r_ar_gutter->xmin = r_ar_gutter->xmax - category_tabs_width;
     }
     else {
@@ -141,14 +143,16 @@ bool ED_region_contains_xy(const ARegion *ar, const int event_xy[2])
       else {
         /* Side-bar & any other kind of overlapping region. */
 
+        const int alignment = RGN_ALIGN_ENUM_FROM_MASK(ar->alignment);
+
         /* Check alignment to avoid region tabs being clipped out
          * by only clipping a single axis for aligned regions. */
-        if (ELEM(ar->alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
+        if (ELEM(alignment, RGN_ALIGN_TOP, RGN_ALIGN_BOTTOM)) {
           if (!ED_region_overlap_isect_x_with_margin(ar, event_xy[0], overlap_margin)) {
             return false;
           }
         }
-        else if (ELEM(ar->alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
+        else if (ELEM(alignment, RGN_ALIGN_LEFT, RGN_ALIGN_RIGHT)) {
           if (ED_region_panel_category_gutter_isect_xy(ar, event_xy)) {
             /* pass */
           }
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index dd09def2df6..9ea8c8293d4 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -4114,8 +4114,9 @@ void ED_screens_header_tools_menu_create(bContext *C, uiLayout *layout, void *UN
 {
   ScrArea *sa = CTX_wm_area(C);
   ARegion *ar = CTX_wm_region(C);
-  const char *but_flip_str = (ar->alignment == RGN_ALIGN_TOP) ? IFACE_("Flip to Bottom") :
-                                                                IFACE_("Flip to Top");
+  const char *but_flip_str = (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_TOP) ?
+                                 IFACE_("Flip to Bottom") :
+                                 IFACE_("Flip to Top");
   {
     PointerRNA ptr;
     RNA_pointer_create((ID *)CTX_wm_screen(C), &RNA_Space, sa->spacedata.first, &ptr);
@@ -4160,8 +4161,9 @@ void ED_screens_footer_tools_menu_create(bContext *C, uiLayout *layout, void *UN
 {
   ScrArea *sa = CTX_wm_area(C);
   ARegion *ar = CTX_wm_region(C);
-  const char *but_flip_str = (ar->alignment == RGN_ALIGN_TOP) ? IFACE_("Flip to Bottom") :
-                                                                IFACE_("Flip to Top");
+  const char *but_flip_str = (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_TOP) ?
+                                 IFACE_("Flip to Bottom") :
+                                 IFACE_("Flip to Top");
   {
     PointerRNA ptr;
     RNA_pointer_create((ID *)CTX_wm_screen(C), &RNA_Space, sa->spacedata.first, &ptr);
@@ -4186,8 +4188,9 @@ void ED_screens_footer_tools_menu_create(bContext *C, uiLayout *layout, void *UN
 void ED_screens_navigation_bar_tools_menu_create(bContext *C, uiLayout *layout, void *UNUSED(arg))
 {
   const ARegion *ar = CTX_wm_region(C);
-  const char *but_flip_str = (ar->alignment == RGN_ALIGN_LEFT) ? IFACE_("Flip to Right") :
-                                                                 IFACE_("Flip to Left");
+  const char *but_flip_str = (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_LEFT) ?
+                                 IFACE_("Flip to Right") :
+                                 IFACE_("Flip to Left");
 
   /* default is WM_OP_INVOKE_REGION_WIN, which we don't want here. */
   uiLayoutSetOperatorContext(layout, WM_OP_INVOKE_DEFAULT);
diff --git a/source/blender/editors/space_statusbar/space_statusbar.c b/source/blender/editors/space_statusbar/space_statusbar.c
index 63f27b4d74a..69060daa171 100644
--- a/source/blender/editors/space_statusbar/space_statusbar.c
+++ b/source/blender/editors/space_statusbar/space_statusbar.c
@@ -81,7 +81,7 @@ static SpaceLink *statusbar_duplicate(SpaceLink *sl)
 /* add handlers, stuff you only do once or on area/region changes */
 static void statusbar_header_region_init(wmWindowManager *UNUSED(wm), ARegion *region)
 {
-  if (ELEM(region->alignment, RGN_ALIGN_RIGHT)) {
+  if (ELEM(RGN_ALIGN_ENUM_FROM_MASK(region->alignment), RGN_ALIGN_RIGHT)) {
     region->flag |= RGN_FLAG_DYNAMIC_SIZE;
   }
   ED_region_header_init(region);
diff --git a/source/blender/editors/space_topbar/space_topbar.c b/source/blender/editors/space_topbar/space_topbar.c
index 725a49e417e..d62fcf45d68 100644
--- a/source/blender/editors/space_topbar/space_topbar.c
+++ b/source/blender/editors/space_topbar/space_topbar.c
@@ -103,7 +103,7 @@ static void topbar_main_region_init(wmWindowManager *wm, ARegion *region)
   wmKeyMap *keymap;
 
   /* force delayed UI_view2d_region_reinit call */
-  if (ELEM(region->alignment, RGN_ALIGN_RIGHT)) {
+  if (ELEM(RGN_ALIGN_ENUM_FROM_MASK(region->alignment), RGN_ALIGN_RIGHT)) {
     region->flag |= RGN_FLAG_DYNAMIC_SIZE;
   }
   UI_view2d_region_reinit(&region->v2d, V2D_COMMONVIEW_HEADER, region->winx, region->winy);
@@ -123,7 +123,7 @@ static void topbar_keymap(struct wmKeyConfig *UNUSED(keyconf))
 /* add handlers, stuff you only do once or on area/region changes */
 static void topbar_header_region_init(wmWindowManager *UNUSED(wm), ARegion *ar)
 {
-  if ((ar->alignment & ~RGN_SPLIT_PREV) == RGN_ALIGN_RIGHT) {
+  if (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_RIGHT) {
     ar->flag |= RGN_FLAG_DYNAMIC_SIZE;
   }
   ED_region_header_init(ar);
diff --git a/source/blender/windowmanager/intern/wm_draw.c b/source/blender/windowmanager/intern/wm_draw.c
index 14d4e05b77a..a26a728461d 100644
--- a/source/blender/windowmanager/intern/wm_draw.c
+++ b/source/blender/windowmanager/intern/wm_draw.c
@@ -514,12 +514,12 @@ void wm_draw_region_blend(ARegion *ar, int view, bool blend)
 
   /* Slide vertical panels */
   float ofs_x = BLI_rcti_size_x(&ar->winrct) * (1.0f - alpha_easing);
-  if (ar->alignment == RGN_ALIGN_RIGHT) {
+  if (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_RIGHT) {
     rect_geo.xmin += ofs_x;
     rect_tex.xmax *= alpha_easing;
     alpha = 1.0f;
   }
-  else if (ar->alignment == RGN_ALIGN_LEFT) {
+  else if (RGN_ALIGN_ENUM_FROM_MASK(ar->alignment) == RGN_ALIGN_LEFT) {
     rect_geo.xmax -= ofs_x;
     rect_tex.xmin += 1.0f - alpha_easing;
     alpha = 1.0f;