Gizmo: changes to internal drag logic

Minor changes to recent gizmo click/drag logic 08dff7b40bc6a

Changing the gizmos highlighted part in the invoke_prepare
callback is too error prone since it needs to run
before it's known which operator will execute.

Add back 'drag_part', since it simplifies click-drag use.
While this isn't essential with custom keymaps per gizmo
it avoids having to define a keymap in the case a drag
event needs a different action.

4 files changed, 25 insertions, 4 deletions

diff --git a/source/blender/windowmanager/gizmo/WM_gizmo_types.h b/source/blender/windowmanager/gizmo/WM_gizmo_types.h
index 5398c262c72..cd8bcc6696b 100644
--- a/source/blender/windowmanager/gizmo/WM_gizmo_types.h
+++ b/source/blender/windowmanager/gizmo/WM_gizmo_types.h
@@ -199,6 +199,12 @@ struct wmGizmo {
    * -1 when unset, otherwise a valid index. (Used as index to 'op_data'). */
   int highlight_part;
 
+  /**
+   * For gizmos that differentiate between click & drag,
+   * use a different part for any drag events, -1 when unused.
+   */
+  int drag_part;
+
   /** Distance to bias this gizmo above others when picking
    * (in worldspace, scaled by the gizmo scale - when used). */
   float select_bias;
diff --git a/source/blender/windowmanager/gizmo/intern/wm_gizmo.c b/source/blender/windowmanager/gizmo/intern/wm_gizmo.c
index 534112edcc7..b05865aa7bb 100644
--- a/source/blender/windowmanager/gizmo/intern/wm_gizmo.c
+++ b/source/blender/windowmanager/gizmo/intern/wm_gizmo.c
@@ -90,6 +90,8 @@ static wmGizmo *wm_gizmo_create(const wmGizmoType *gzt, PointerRNA *properties)
   unit_m4(gz->matrix_basis);
   unit_m4(gz->matrix_offset);
 
+  gz->drag_part = -1;
+
   return gz;
 }
 
diff --git a/source/blender/windowmanager/gizmo/intern/wm_gizmo_group.c b/source/blender/windowmanager/gizmo/intern/wm_gizmo_group.c
index e0501d9abee..e491b86ea18 100644
--- a/source/blender/windowmanager/gizmo/intern/wm_gizmo_group.c
+++ b/source/blender/windowmanager/gizmo/intern/wm_gizmo_group.c
@@ -360,10 +360,6 @@ static bool gizmo_tweak_start(bContext *C, wmGizmoMap *gzmap, wmGizmo *gz, const
 static bool gizmo_tweak_start_and_finish(
     bContext *C, wmGizmoMap *gzmap, wmGizmo *gz, const wmEvent *event, bool *r_is_modal)
 {
-  if (gz->parent_gzgroup->type->invoke_prepare) {
-    gz->parent_gzgroup->type->invoke_prepare(C, gz->parent_gzgroup, gz, event);
-  }
-
   wmGizmoOpElem *gzop = WM_gizmo_operator_get(gz, gz->highlight_part);
   if (r_is_modal) {
     *r_is_modal = false;
@@ -394,6 +390,9 @@ static bool gizmo_tweak_start_and_finish(
       }
     }
     else {
+      if (gz->parent_gzgroup->type->invoke_prepare) {
+        gz->parent_gzgroup->type->invoke_prepare(C, gz->parent_gzgroup, gz, event);
+      }
       /* Allow for 'button' gizmos, single click to run an action. */
       WM_gizmo_operator_invoke(C, gz, gzop);
     }
@@ -502,12 +501,21 @@ static int gizmo_tweak_invoke(bContext *C, wmOperator *op, const wmEvent *event)
     return (OPERATOR_CANCELLED | OPERATOR_PASS_THROUGH);
   }
 
+  const int highlight_part_init = gz->highlight_part;
+
+  if (gz->drag_part != -1) {
+    if (ISTWEAK(event->type) || (event->val == KM_CLICK_DRAG)) {
+      gz->highlight_part = gz->drag_part;
+    }
+  }
+
   if (gizmo_tweak_start_and_finish(C, gzmap, gz, event, NULL)) {
     return OPERATOR_FINISHED;
   }
 
   if (!gizmo_tweak_start(C, gzmap, gz, event)) {
     /* failed to start */
+    gz->highlight_part = highlight_part_init;
     return OPERATOR_PASS_THROUGH;
   }
 
diff --git a/source/blender/windowmanager/gizmo/intern/wm_gizmo_map.c b/source/blender/windowmanager/gizmo/intern/wm_gizmo_map.c
index 688173f1771..56de2202731 100644
--- a/source/blender/windowmanager/gizmo/intern/wm_gizmo_map.c
+++ b/source/blender/windowmanager/gizmo/intern/wm_gizmo_map.c
@@ -1017,6 +1017,11 @@ void wm_gizmomap_modal_set(
 
     WM_tooltip_clear(C, win);
 
+    /* Use even if we don't have invoke, so we can setup data before an operator runs. */
+    if (gz->parent_gzgroup->type->invoke_prepare) {
+      gz->parent_gzgroup->type->invoke_prepare(C, gz->parent_gzgroup, gz, event);
+    }
+
     if (gz->type->invoke && (gz->type->modal || gz->custom_modal)) {
       const int retval = gz->type->invoke(C, gz, event);
       if ((retval & OPERATOR_RUNNING_MODAL) == 0) {