Tool System: experimental fallback tool support

Implement T66304 as an experimental option,
available under the preferences "Experimental" section.

- When enabled most tools in the 3D view have a gizmo.
- Dragging outside the gizmo uses the 'fallback' tool.
- The fallback tool can be changed or disabled in the tool options
  or from a pie menu (Alt-W).

3 files changed, 60 insertions, 1 deletions

diff --git a/source/blender/windowmanager/gizmo/WM_gizmo_types.h b/source/blender/windowmanager/gizmo/WM_gizmo_types.h
index 7bb77375934..d3aa333daea 100644
--- a/source/blender/windowmanager/gizmo/WM_gizmo_types.h
+++ b/source/blender/windowmanager/gizmo/WM_gizmo_types.h
@@ -120,6 +120,12 @@ typedef enum eWM_GizmoFlagGroupTypeFlag {
    * We could even move the options into the key-map item.
    * ~ campbell. */
   WM_GIZMOGROUPTYPE_TOOL_INIT = (1 << 6),
+
+  /**
+   * This gizmo type supports using the fallback tools keymap.
+   * #wmGizmoGroup.use_tool_fallback will need to be set too.
+   */
+  WM_GIZMOGROUPTYPE_TOOL_FALLBACK_KEYMAP = (1 << 7),
 } eWM_GizmoFlagGroupTypeFlag;
 
 /**
@@ -443,6 +449,8 @@ typedef struct wmGizmoGroup {
 
   bool tag_remove;
 
+  bool use_fallback_keymap;
+
   void *customdata;
   /** For freeing customdata from above. */
   void (*customdata_free)(void *);
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 180a518de2b..d65cf2324a9 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -3728,8 +3728,40 @@ wmKeyMap *WM_event_get_keymap_from_toolsystem(wmWindowManager *wm, wmEventHandle
   handler->keymap_tool = NULL;
   bToolRef_Runtime *tref_rt = sa->runtime.tool ? sa->runtime.tool->runtime : NULL;
   if (tref_rt && tref_rt->keymap[0]) {
+    const char *keymap_id = tref_rt->keymap;
+
+    /* Support for the gizmo owning the tool keymap. */
+    if (U.experimental.use_tool_fallback) {
+      if (tref_rt->gizmo_group[0] != '\0') {
+        wmGizmoMap *gzmap = NULL;
+        wmGizmoGroup *gzgroup = NULL;
+        for (ARegion *ar = sa->regionbase.first; ar; ar = ar->next) {
+          if (ar->gizmo_map != NULL) {
+            gzmap = ar->gizmo_map;
+            gzgroup = WM_gizmomap_group_find(gzmap, tref_rt->gizmo_group);
+            if (gzgroup != NULL) {
+              break;
+            }
+          }
+        }
+        if (gzgroup != NULL) {
+          if (gzgroup->type->flag & WM_GIZMOGROUPTYPE_TOOL_FALLBACK_KEYMAP) {
+            /* If all are hidden, don't override. */
+            if (gzgroup->use_fallback_keymap) {
+              wmGizmo *highlight = wm_gizmomap_highlight_get(gzmap);
+              if (highlight == NULL) {
+                if (tref_rt->keymap_fallback[0]) {
+                  keymap_id = tref_rt->keymap_fallback;
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+
     wmKeyMap *km = WM_keymap_list_find_spaceid_or_empty(
-        &wm->userconf->keymaps, tref_rt->keymap, sa->spacetype, RGN_TYPE_WINDOW);
+        &wm->userconf->keymaps, keymap_id, sa->spacetype, RGN_TYPE_WINDOW);
     /* We shouldn't use keymaps from unrelated spaces. */
     if (km != NULL) {
       handler->keymap_tool = sa->runtime.tool;
diff --git a/source/blender/windowmanager/intern/wm_toolsystem.c b/source/blender/windowmanager/intern/wm_toolsystem.c
index f64acf20581..d714fdaa19e 100644
--- a/source/blender/windowmanager/intern/wm_toolsystem.c
+++ b/source/blender/windowmanager/intern/wm_toolsystem.c
@@ -351,6 +351,25 @@ void WM_toolsystem_ref_set_from_runtime(struct bContext *C,
     *tref->runtime = *tref_rt;
   }
 
+  /* FIXME: ideally Python could check this gizmo group flag and not
+   * pass in the argument to begin with. */
+  bool use_fallback_keymap = false;
+
+  if (U.experimental.use_tool_fallback) {
+    if (tref_rt->gizmo_group[0]) {
+      wmGizmoGroupType *gzgt = WM_gizmogrouptype_find(tref_rt->gizmo_group, false);
+      if (gzgt) {
+        if (gzgt->flag & WM_GIZMOGROUPTYPE_TOOL_FALLBACK_KEYMAP) {
+          use_fallback_keymap = true;
+        }
+      }
+    }
+  }
+  if (use_fallback_keymap == false) {
+    tref->runtime->idname_fallback[0] = '\0';
+    tref->runtime->keymap_fallback[0] = '\0';
+  }
+
   toolsystem_ref_link(C, workspace, tref);
 
   toolsystem_refresh_screen_from_active_tool(bmain, workspace, tref);