UI Code Quality: Use "params" struct for area and region callbacks

These functions with many arguments can be unwieldy. Aside from the obvious issues
with rewriting the list of arguments and the opportunities for error and frustration
that presents, the long list of arguments make these systems hard to change. So when
an argument should be added, someone might skip that and add some hack instead.

So, as proposed in T73586#1037210, this patch instead uses a "params" struct for
each of these callbacks.

- Use param argument for `ARegionType.listener`
    - Remove unused window field in region listener
- Use param argument for `SpaceType.listener`
- Use params struct for `ARegionType.message_subscribe`

Differential Revision: https://developer.blender.org/D9750

1 files changed, 20 insertions, 34 deletions

diff --git a/source/blender/editors/space_file/space_file.c b/source/blender/editors/space_file/space_file.c
index 9fb69c7301a..273532c6b84 100644
--- a/source/blender/editors/space_file/space_file.c
+++ b/source/blender/editors/space_file/space_file.c
@@ -392,11 +392,10 @@ static void file_refresh(const bContext *C, ScrArea *area)
   ED_area_tag_redraw(area);
 }
 
-static void file_listener(wmWindow *UNUSED(win),
-                          ScrArea *area,
-                          wmNotifier *wmn,
-                          Scene *UNUSED(scene))
+static void file_listener(wmSpaceTypeListenerParams *params)
 {
+  ScrArea *area = params->area;
+  wmNotifier *wmn = params->notifier;
   SpaceFile *sfile = (SpaceFile *)area->spacedata.first;
 
   /* context changes */
@@ -447,12 +446,11 @@ static void file_main_region_init(wmWindowManager *wm, ARegion *region)
   WM_event_add_keymap_handler_v2d_mask(&region->handlers, keymap);
 }
 
-static void file_main_region_listener(wmWindow *UNUSED(win),
-                                      ScrArea *UNUSED(area),
-                                      ARegion *region,
-                                      wmNotifier *wmn,
-                                      const Scene *UNUSED(scene))
+static void file_main_region_listener(wmRegionListenerParams *params)
 {
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
+
   /* context changes */
   switch (wmn->category) {
     case NC_SPACE:
@@ -468,16 +466,15 @@ static void file_main_region_listener(wmWindow *UNUSED(win),
   }
 }
 
-static void file_main_region_message_subscribe(const struct bContext *UNUSED(C),
-                                               struct WorkSpace *UNUSED(workspace),
-                                               struct Scene *UNUSED(scene),
-                                               struct bScreen *screen,
-                                               struct ScrArea *area,
-                                               struct ARegion *region,
-                                               struct wmMsgBus *mbus)
+static void file_main_region_message_subscribe(wmRegionMessageSubscribeParams *params)
 {
+  struct wmMsgBus *mbus = params->message_bus;
+  bScreen *screen = params->screen;
+  ScrArea *area = params->area;
+  ARegion *region = params->region;
   SpaceFile *sfile = area->spacedata.first;
-  FileSelectParams *params = ED_fileselect_ensure_active_params(sfile);
+
+  FileSelectParams *file_params = ED_fileselect_ensure_active_params(sfile);
   /* This is a bit odd that a region owns the subscriber for an area,
    * keep for now since all subscribers for WM are regions.
    * May be worth re-visiting later. */
@@ -499,7 +496,7 @@ static void file_main_region_message_subscribe(const struct bContext *UNUSED(C),
   /* FileSelectParams */
   {
     PointerRNA ptr;
-    RNA_pointer_create(&screen->id, &RNA_FileSelectParams, params, &ptr);
+    RNA_pointer_create(&screen->id, &RNA_FileSelectParams, file_params, &ptr);
 
     /* All properties for this space type. */
     WM_msg_subscribe_rna(mbus, &ptr, NULL, &msg_sub_value_area_tag_refresh, __func__);
@@ -649,18 +646,8 @@ static void file_tools_region_draw(const bContext *C, ARegion *region)
   ED_region_panels(C, region);
 }
 
-static void file_tools_region_listener(wmWindow *UNUSED(win),
-                                       ScrArea *UNUSED(area),
-                                       ARegion *UNUSED(region),
-                                       wmNotifier *UNUSED(wmn),
-                                       const Scene *UNUSED(scene))
+static void file_tools_region_listener(wmRegionListenerParams *UNUSED(params))
 {
-#if 0
-  /* context changes */
-  switch (wmn->category) {
-    /* pass */
-  }
-#endif
 }
 
 /* add handlers, stuff you only do once or on area/region changes */
@@ -717,12 +704,11 @@ static void file_execution_region_draw(const bContext *C, ARegion *region)
   ED_region_panels(C, region);
 }
 
-static void file_ui_region_listener(wmWindow *UNUSED(win),
-                                    ScrArea *UNUSED(area),
-                                    ARegion *region,
-                                    wmNotifier *wmn,
-                                    const Scene *UNUSED(scene))
+static void file_ui_region_listener(wmRegionListenerParams *params)
 {
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
+
   /* context changes */
   switch (wmn->category) {
     case NC_SPACE: