Cleanup: Use enum for return values in context callbacks

Define enum `eContextResult` and use its values for returns, instead of
just returning 1, 0, or -1 (and always having some comment that explains
what -1 means).

This also cleans up the mixup between returning `0` and `false`, and `1`
and `true`. An inconsistency was discovered during this cleanup, and
marked with `TODO(sybren)`. It's not fixed here, as it would consititute
a functional change.

The enum isn't used everywhere, as enums in C and C++ can have different
storage sizes. To prevent issues, callback functions are still declared
as returning`int`. To at least make things easier to understand for
humans, I marked those with `int /*eContextResult*/`.

This is a followup of D9090, and is intended to unify how context
callbacks return values. This will make it easier to extend the approach
in D9090 to those functions.

No functional changes.

Differential Revision: https://developer.blender.org/D9095

1 files changed, 140 insertions, 132 deletions

diff --git a/source/blender/editors/screen/screen_context.c b/source/blender/editors/screen/screen_context.c
index e32d374d094..07a571ae464 100644
--- a/source/blender/editors/screen/screen_context.c
+++ b/source/blender/editors/screen/screen_context.c
@@ -114,23 +114,16 @@ const char *screen_context_dir[] = {
 
 /* Each function `screen_ctx_XXX()` will be called when the screen context "XXX" is requested.
  * ensure_ed_screen_context_functions() is responsible for creating the hash map from context
- * member name to function.
- *
- * Each function returns:
- *    1 for "the member name was found and returned data is valid"
- *    0 for "the member name was not found"
- *   -1 for "the member name was found but data is not available"
- *
- * */
+ * member name to function. */
 
-static int screen_ctx_scene(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_scene(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   Scene *scene = WM_window_get_active_scene(win);
   CTX_data_id_pointer_set(result, &scene->id);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_visible_objects(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_visible_objects(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -142,9 +135,9 @@ static int screen_ctx_visible_objects(const bContext *C, bContextDataResult *res
     }
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_selectable_objects(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selectable_objects(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -156,9 +149,9 @@ static int screen_ctx_selectable_objects(const bContext *C, bContextDataResult *
     }
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_selected_objects(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_objects(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -170,9 +163,10 @@ static int screen_ctx_selected_objects(const bContext *C, bContextDataResult *re
     }
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_selected_editable_objects(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_editable_objects(const bContext *C,
+                                                           bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -184,9 +178,9 @@ static int screen_ctx_selected_editable_objects(const bContext *C, bContextDataR
     }
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_editable_objects(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_editable_objects(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -199,9 +193,9 @@ static int screen_ctx_editable_objects(const bContext *C, bContextDataResult *re
     }
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_objects_in_mode(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_objects_in_mode(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -215,9 +209,10 @@ static int screen_ctx_objects_in_mode(const bContext *C, bContextDataResult *res
     FOREACH_OBJECT_IN_MODE_END;
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_objects_in_mode_unique_data(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_objects_in_mode_unique_data(const bContext *C,
+                                                             bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -238,11 +233,11 @@ static int screen_ctx_objects_in_mode_unique_data(const bContext *C, bContextDat
     FOREACH_OBJECT_IN_MODE_END;
   }
   CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_visible_or_editable_bones_(const bContext *C,
-                                                 bContextDataResult *result,
-                                                 const bool editable_bones)
+static eContextResult screen_ctx_visible_or_editable_bones_(const bContext *C,
+                                                            bContextDataResult *result,
+                                                            const bool editable_bones)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -299,21 +294,21 @@ static int screen_ctx_visible_or_editable_bones_(const bContext *C,
     MEM_freeN(objects);
 
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_visible_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_visible_bones(const bContext *C, bContextDataResult *result)
 {
   return screen_ctx_visible_or_editable_bones_(C, result, false);
 }
-static int screen_ctx_editable_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_editable_bones(const bContext *C, bContextDataResult *result)
 {
   return screen_ctx_visible_or_editable_bones_(C, result, true);
 }
-static int screen_ctx_selected_bones_(const bContext *C,
-                                      bContextDataResult *result,
-                                      const bool selected_editable_bones)
+static eContextResult screen_ctx_selected_bones_(const bContext *C,
+                                                 bContextDataResult *result,
+                                                 const bool selected_editable_bones)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -369,19 +364,20 @@ static int screen_ctx_selected_bones_(const bContext *C,
     MEM_freeN(objects);
 
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_bones(const bContext *C, bContextDataResult *result)
 {
   return screen_ctx_selected_bones_(C, result, false);
 }
-static int screen_ctx_selected_editable_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_editable_bones(const bContext *C,
+                                                         bContextDataResult *result)
 {
   return screen_ctx_selected_bones_(C, result, true);
 }
-static int screen_ctx_visible_pose_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_visible_pose_bones(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -405,11 +401,11 @@ static int screen_ctx_visible_pose_bones(const bContext *C, bContextDataResult *
       FOREACH_OBJECT_IN_MODE_END;
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_pose_bones(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_pose_bones(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   View3D *v3d = CTX_wm_view3d(C); /* This may be NULL in a lot of cases. */
@@ -433,12 +429,12 @@ static int screen_ctx_selected_pose_bones(const bContext *C, bContextDataResult
       FOREACH_OBJECT_IN_MODE_END;
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_pose_bones_from_active_object(const bContext *C,
-                                                             bContextDataResult *result)
+static eContextResult screen_ctx_selected_pose_bones_from_active_object(const bContext *C,
+                                                                        bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -458,11 +454,11 @@ static int screen_ctx_selected_pose_bones_from_active_object(const bContext *C,
       FOREACH_PCHAN_SELECTED_IN_OBJECT_END;
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_bone(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_bone(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -472,19 +468,19 @@ static int screen_ctx_active_bone(const bContext *C, bContextDataResult *result)
     if (arm->edbo) {
       if (arm->act_edbone) {
         CTX_data_pointer_set(result, &arm->id, &RNA_EditBone, arm->act_edbone);
-        return 1;
+        return CTX_RESULT_OK;
       }
     }
     else {
       if (arm->act_bone) {
         CTX_data_pointer_set(result, &arm->id, &RNA_Bone, arm->act_bone);
-        return 1;
+        return CTX_RESULT_OK;
       }
     }
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_pose_bone(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_pose_bone(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -495,11 +491,11 @@ static int screen_ctx_active_pose_bone(const bContext *C, bContextDataResult *re
   pchan = BKE_pose_channel_active(obpose);
   if (pchan) {
     CTX_data_pointer_set(result, &obpose->id, &RNA_PoseBone, pchan);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -509,9 +505,9 @@ static int screen_ctx_active_object(const bContext *C, bContextDataResult *resul
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -521,9 +517,9 @@ static int screen_ctx_object(const bContext *C, bContextDataResult *result)
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_edit_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_edit_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -533,9 +529,9 @@ static int screen_ctx_edit_object(const bContext *C, bContextDataResult *result)
     CTX_data_id_pointer_set(result, &obedit->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_sculpt_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_sculpt_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -545,9 +541,9 @@ static int screen_ctx_sculpt_object(const bContext *C, bContextDataResult *resul
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_vertex_paint_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_vertex_paint_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -556,9 +552,9 @@ static int screen_ctx_vertex_paint_object(const bContext *C, bContextDataResult
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_weight_paint_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_weight_paint_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -567,9 +563,9 @@ static int screen_ctx_weight_paint_object(const bContext *C, bContextDataResult
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_image_paint_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_image_paint_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -578,9 +574,10 @@ static int screen_ctx_image_paint_object(const bContext *C, bContextDataResult *
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_particle_edit_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_particle_edit_object(const bContext *C,
+                                                      bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -589,9 +586,9 @@ static int screen_ctx_particle_edit_object(const bContext *C, bContextDataResult
     CTX_data_id_pointer_set(result, &obact->id);
   }
 
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_pose_object(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_pose_object(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ViewLayer *view_layer = WM_window_get_active_view_layer(win);
@@ -600,9 +597,9 @@ static int screen_ctx_pose_object(const bContext *C, bContextDataResult *result)
   if (obpose) {
     CTX_data_id_pointer_set(result, &obpose->id);
   }
-  return 1;
+  return CTX_RESULT_OK;
 }
-static int screen_ctx_sequences(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_sequences(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   Scene *scene = WM_window_get_active_scene(win);
@@ -612,11 +609,11 @@ static int screen_ctx_sequences(const bContext *C, bContextDataResult *result)
       CTX_data_list_add(result, &scene->id, &RNA_Sequence, seq);
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_sequences(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_sequences(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   Scene *scene = WM_window_get_active_scene(win);
@@ -628,11 +625,12 @@ static int screen_ctx_selected_sequences(const bContext *C, bContextDataResult *
       }
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_editable_sequences(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_editable_sequences(const bContext *C,
+                                                             bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   Scene *scene = WM_window_get_active_scene(win);
@@ -644,11 +642,11 @@ static int screen_ctx_selected_editable_sequences(const bContext *C, bContextDat
       }
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_selected_nla_strips(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_nla_strips(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   Scene *scene = WM_window_get_active_scene(win);
@@ -671,11 +669,11 @@ static int screen_ctx_selected_nla_strips(const bContext *C, bContextDataResult
     ANIM_animdata_freelist(&anim_data);
 
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_gpencil_data(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_gpencil_data(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -690,11 +688,11 @@ static int screen_ctx_gpencil_data(const bContext *C, bContextDataResult *result
 
   if (gpd) {
     CTX_data_id_pointer_set(result, &gpd->id);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_gpencil_data_owner(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_gpencil_data_owner(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -710,11 +708,11 @@ static int screen_ctx_gpencil_data_owner(const bContext *C, bContextDataResult *
 
   if (gpd_ptr) {
     CTX_data_pointer_set(result, ptr.owner_id, ptr.type, ptr.data);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_annotation_data(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_annotation_data(const bContext *C, bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   bScreen *screen = CTX_wm_screen(C);
@@ -724,11 +722,12 @@ static int screen_ctx_annotation_data(const bContext *C, bContextDataResult *res
 
   if (gpd) {
     CTX_data_id_pointer_set(result, &gpd->id);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_annotation_data_owner(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_annotation_data_owner(const bContext *C,
+                                                       bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   bScreen *screen = CTX_wm_screen(C);
@@ -743,11 +742,12 @@ static int screen_ctx_annotation_data_owner(const bContext *C, bContextDataResul
 
   if (gpd_ptr) {
     CTX_data_pointer_set(result, ptr.owner_id, ptr.type, ptr.data);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_gpencil_layer(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_gpencil_layer(const bContext *C,
+                                                      bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -760,12 +760,13 @@ static int screen_ctx_active_gpencil_layer(const bContext *C, bContextDataResult
 
     if (gpl) {
       CTX_data_pointer_set(result, &gpd->id, &RNA_GPencilLayer, gpl);
-      return 1;
+      return CTX_RESULT_OK;
     }
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_annotation_layer(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_annotation_layer(const bContext *C,
+                                                         bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   bScreen *screen = CTX_wm_screen(C);
@@ -778,12 +779,13 @@ static int screen_ctx_active_annotation_layer(const bContext *C, bContextDataRes
 
     if (gpl) {
       CTX_data_pointer_set(result, &gpd->id, &RNA_GPencilLayer, gpl);
-      return 1;
+      return CTX_RESULT_OK;
     }
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_gpencil_frame(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_gpencil_frame(const bContext *C,
+                                                      bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -796,12 +798,13 @@ static int screen_ctx_active_gpencil_frame(const bContext *C, bContextDataResult
 
     if (gpl) {
       CTX_data_pointer_set(result, &gpd->id, &RNA_GPencilLayer, gpl->actframe);
-      return 1;
+      return CTX_RESULT_OK;
     }
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_visible_gpencil_layers(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_visible_gpencil_layers(const bContext *C,
+                                                        bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -816,11 +819,12 @@ static int screen_ctx_visible_gpencil_layers(const bContext *C, bContextDataResu
       }
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_editable_gpencil_layers(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_editable_gpencil_layers(const bContext *C,
+                                                         bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -835,11 +839,12 @@ static int screen_ctx_editable_gpencil_layers(const bContext *C, bContextDataRes
       }
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_editable_gpencil_strokes(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_editable_gpencil_strokes(const bContext *C,
+                                                          bContextDataResult *result)
 {
   wmWindow *win = CTX_wm_window(C);
   ScrArea *area = CTX_wm_area(C);
@@ -879,11 +884,11 @@ static int screen_ctx_editable_gpencil_strokes(const bContext *C, bContextDataRe
       }
     }
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_active_operator(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_operator(const bContext *C, bContextDataResult *result)
 {
   wmOperator *op = NULL;
 
@@ -903,13 +908,13 @@ static int screen_ctx_active_operator(const bContext *C, bContextDataResult *res
 
   if (op && op->ptr) {
     CTX_data_pointer_set(result, NULL, &RNA_Operator, op);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_sel_edit_fcurves_(const bContext *C,
-                                        bContextDataResult *result,
-                                        const int extra_filter)
+static eContextResult screen_ctx_sel_edit_fcurves_(const bContext *C,
+                                                   bContextDataResult *result,
+                                                   const int extra_filter)
 {
   bAnimContext ac;
 
@@ -932,27 +937,30 @@ static int screen_ctx_sel_edit_fcurves_(const bContext *C,
     ANIM_animdata_freelist(&anim_data);
 
     CTX_data_type_set(result, CTX_DATA_TYPE_COLLECTION);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
-static int screen_ctx_editable_fcurves(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_editable_fcurves(const bContext *C, bContextDataResult *result)
 {
   return screen_ctx_sel_edit_fcurves_(C, result, ANIMFILTER_FOREDIT);
 }
-static int screen_ctx_visible_fcurves(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_visible_fcurves(const bContext *C, bContextDataResult *result)
 {
   return screen_ctx_sel_edit_fcurves_(C, result, 0);
 }
-static int screen_ctx_selected_editable_fcurves(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_editable_fcurves(const bContext *C,
+                                                           bContextDataResult *result)
 {
   return screen_ctx_sel_edit_fcurves_(C, result, ANIMFILTER_SEL | ANIMFILTER_FOREDIT);
 }
-static int screen_ctx_selected_visible_fcurves(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_selected_visible_fcurves(const bContext *C,
+                                                          bContextDataResult *result)
 {
   return screen_ctx_sel_edit_fcurves_(C, result, ANIMFILTER_SEL);
 }
-static int screen_ctx_active_editable_fcurve(const bContext *C, bContextDataResult *result)
+static eContextResult screen_ctx_active_editable_fcurve(const bContext *C,
+                                                        bContextDataResult *result)
 {
   bAnimContext ac;
 
@@ -972,9 +980,9 @@ static int screen_ctx_active_editable_fcurve(const bContext *C, bContextDataResu
     }
 
     ANIM_animdata_freelist(&anim_data);
-    return 1;
+    return CTX_RESULT_OK;
   }
-  return -1; /* found but not available */
+  return CTX_RESULT_NO_DATA;
 }
 
 /* Registry of context callback functions. */
@@ -1057,13 +1065,13 @@ int ed_screen_context(const bContext *C, const char *member, bContextDataResult
 {
   if (CTX_data_dir(member)) {
     CTX_data_dir_set(result, screen_context_dir);
-    return 1;
+    return CTX_RESULT_OK;
   }
 
   ensure_ed_screen_context_functions();
   context_callback callback = BLI_ghash_lookup(ed_screen_context_functions, member);
   if (callback == NULL) {
-    return 0; /* not found */
+    return CTX_RESULT_MEMBER_NOT_FOUND;
   }
 
   return callback(C, result);