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, 33 insertions, 39 deletions

diff --git a/source/blender/editors/space_action/space_action.c b/source/blender/editors/space_action/space_action.c
index ff0201f9702..9cb7ec69df1 100644
--- a/source/blender/editors/space_action/space_action.c
+++ b/source/blender/editors/space_action/space_action.c
@@ -305,12 +305,11 @@ static void action_header_region_draw(const bContext *C, ARegion *region)
   ED_region_header(C, region);
 }
 
-static void action_channel_region_listener(wmWindow *UNUSED(win),
-                                           ScrArea *UNUSED(area),
-                                           ARegion *region,
-                                           wmNotifier *wmn,
-                                           const Scene *UNUSED(scene))
+static void action_channel_region_listener(wmRegionListenerParams *params)
 {
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
+
   /* context changes */
   switch (wmn->category) {
     case NC_ANIMATION:
@@ -356,14 +355,13 @@ static void action_channel_region_listener(wmWindow *UNUSED(win),
   }
 }
 
-static void saction_channel_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 saction_channel_region_message_subscribe(wmRegionMessageSubscribeParams *params)
 {
+  struct wmMsgBus *mbus = params->message_bus;
+  bScreen *screen = params->screen;
+  ScrArea *area = params->area;
+  ARegion *region = params->region;
+
   PointerRNA ptr;
   RNA_pointer_create(&screen->id, &RNA_SpaceDopeSheetEditor, area->spacedata.first, &ptr);
 
@@ -401,12 +399,11 @@ static void saction_channel_region_message_subscribe(const struct bContext *UNUS
   }
 }
 
-static void action_main_region_listener(wmWindow *UNUSED(win),
-                                        ScrArea *UNUSED(area),
-                                        ARegion *region,
-                                        wmNotifier *wmn,
-                                        const Scene *UNUSED(scene))
+static void action_main_region_listener(wmRegionListenerParams *params)
 {
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
+
   /* context changes */
   switch (wmn->category) {
     case NC_ANIMATION:
@@ -460,14 +457,14 @@ static void action_main_region_listener(wmWindow *UNUSED(win),
   }
 }
 
-static void saction_main_region_message_subscribe(const struct bContext *C,
-                                                  struct WorkSpace *workspace,
-                                                  struct Scene *scene,
-                                                  struct bScreen *screen,
-                                                  struct ScrArea *area,
-                                                  struct ARegion *region,
-                                                  struct wmMsgBus *mbus)
+static void saction_main_region_message_subscribe(wmRegionMessageSubscribeParams *params)
 {
+  struct wmMsgBus *mbus = params->message_bus;
+  Scene *scene = params->scene;
+  bScreen *screen = params->screen;
+  ScrArea *area = params->area;
+  ARegion *region = params->region;
+
   PointerRNA ptr;
   RNA_pointer_create(&screen->id, &RNA_SpaceDopeSheetEditor, area->spacedata.first, &ptr);
 
@@ -502,15 +499,14 @@ static void saction_main_region_message_subscribe(const struct bContext *C,
   }
 
   /* Now run the general "channels region" one - since channels and main should be in sync */
-  saction_channel_region_message_subscribe(C, workspace, scene, screen, area, region, mbus);
+  saction_channel_region_message_subscribe(params);
 }
 
 /* editor level listener */
-static void action_listener(wmWindow *UNUSED(win),
-                            ScrArea *area,
-                            wmNotifier *wmn,
-                            Scene *UNUSED(scene))
+static void action_listener(wmSpaceTypeListenerParams *params)
 {
+  ScrArea *area = params->area;
+  wmNotifier *wmn = params->notifier;
   SpaceAction *saction = (SpaceAction *)area->spacedata.first;
 
   /* context changes */
@@ -660,12 +656,11 @@ static void action_listener(wmWindow *UNUSED(win),
   }
 }
 
-static void action_header_region_listener(wmWindow *UNUSED(win),
-                                          ScrArea *area,
-                                          ARegion *region,
-                                          wmNotifier *wmn,
-                                          const Scene *UNUSED(scene))
+static void action_header_region_listener(wmRegionListenerParams *params)
 {
+  ScrArea *area = params->area;
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
   SpaceAction *saction = (SpaceAction *)area->spacedata.first;
 
   /* context changes */
@@ -737,12 +732,11 @@ static void action_buttons_area_draw(const bContext *C, ARegion *region)
   ED_region_panels(C, region);
 }
 
-static void action_region_listener(wmWindow *UNUSED(win),
-                                   ScrArea *UNUSED(area),
-                                   ARegion *region,
-                                   wmNotifier *wmn,
-                                   const Scene *UNUSED(scene))
+static void action_region_listener(wmRegionListenerParams *params)
 {
+  ARegion *region = params->region;
+  wmNotifier *wmn = params->notifier;
+
   /* context changes */
   switch (wmn->category) {
     case NC_ANIMATION: