Animation: Blend To Default Implementation

Add a new operator to the Graph Editor that blends selected keyframes
to their default value.
The operator can be accessed from
Key>Slider Operators>Blend To Default Value

Reviewed by: Sybren A. Stüvel
Differential Revision: https://developer.blender.org/D9376
Ref: D9367

3 files changed, 130 insertions, 0 deletions

diff --git a/source/blender/editors/space_graph/graph_intern.h b/source/blender/editors/space_graph/graph_intern.h
index fe8005892cf..2eb64e5b115 100644
--- a/source/blender/editors/space_graph/graph_intern.h
+++ b/source/blender/editors/space_graph/graph_intern.h
@@ -113,6 +113,7 @@ void GRAPH_OT_clean(struct wmOperatorType *ot);
 void GRAPH_OT_blend_to_neighbor(struct wmOperatorType *ot);
 void GRAPH_OT_breakdown(struct wmOperatorType *ot);
 void GRAPH_OT_decimate(struct wmOperatorType *ot);
+void GRAPH_OT_blend_to_default(struct wmOperatorType *ot);
 void GRAPH_OT_sample(struct wmOperatorType *ot);
 void GRAPH_OT_bake(struct wmOperatorType *ot);
 void GRAPH_OT_unbake(struct wmOperatorType *ot);
diff --git a/source/blender/editors/space_graph/graph_ops.c b/source/blender/editors/space_graph/graph_ops.c
index b00e069470d..128925d4591 100644
--- a/source/blender/editors/space_graph/graph_ops.c
+++ b/source/blender/editors/space_graph/graph_ops.c
@@ -457,6 +457,7 @@ void graphedit_operatortypes(void)
   WM_operatortype_append(GRAPH_OT_decimate);
   WM_operatortype_append(GRAPH_OT_blend_to_neighbor);
   WM_operatortype_append(GRAPH_OT_breakdown);
+  WM_operatortype_append(GRAPH_OT_blend_to_default);
   WM_operatortype_append(GRAPH_OT_euler_filter);
   WM_operatortype_append(GRAPH_OT_delete);
   WM_operatortype_append(GRAPH_OT_duplicate);
diff --git a/source/blender/editors/space_graph/graph_slider_ops.c b/source/blender/editors/space_graph/graph_slider_ops.c
index 1a3355b0139..6166ad128de 100644
--- a/source/blender/editors/space_graph/graph_slider_ops.c
+++ b/source/blender/editors/space_graph/graph_slider_ops.c
@@ -802,3 +802,131 @@ void GRAPH_OT_breakdown(wmOperatorType *ot)
 }
 
 /** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Blend To Default Value Operator
+ * \{ */
+
+static void blend_to_default_graph_keys(bAnimContext *ac, const float factor)
+{
+  ListBase anim_data = {NULL, NULL};
+  ANIM_animdata_filter(ac, &anim_data, OPERATOR_DATA_FILTER, ac->data, ac->datatype);
+
+  LISTBASE_FOREACH (bAnimListElem *, ale, &anim_data) {
+    FCurve *fcu = (FCurve *)ale->key_data;
+
+    /* Check if the curves actually have any points. */
+    if (fcu == NULL || fcu->bezt == NULL || fcu->totvert == 0) {
+      continue;
+    }
+
+    PointerRNA id_ptr;
+    RNA_id_pointer_create(ale->id, &id_ptr);
+
+    blend_to_default_fcurve(&id_ptr, fcu, factor);
+    ale->update |= ANIM_UPDATE_DEFAULT;
+  }
+
+  ANIM_animdata_update(ac, &anim_data);
+  ANIM_animdata_freelist(&anim_data);
+}
+
+static void blend_to_default_draw_status_header(bContext *C, tGraphSliderOp *gso)
+{
+  char status_str[UI_MAX_DRAW_STR];
+  char mode_str[32];
+  char slider_string[UI_MAX_DRAW_STR];
+
+  ED_slider_status_string_get(gso->slider, slider_string, UI_MAX_DRAW_STR);
+
+  strcpy(mode_str, TIP_("Blend To Default Value"));
+
+  if (hasNumInput(&gso->num)) {
+    char str_ofs[NUM_STR_REP_LEN];
+
+    outputNumInput(&gso->num, str_ofs, &gso->scene->unit);
+
+    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, str_ofs);
+  }
+  else {
+    BLI_snprintf(status_str, sizeof(status_str), "%s: %s", mode_str, slider_string);
+  }
+
+  ED_workspace_status_text(C, status_str);
+}
+
+static void blend_to_default_modal_update(bContext *C, wmOperator *op)
+{
+  tGraphSliderOp *gso = op->customdata;
+
+  blend_to_default_draw_status_header(C, gso);
+
+  /* Set notifier that keyframes have changed. */
+  reset_bezts(gso);
+  const float factor = ED_slider_factor_get(gso->slider);
+  RNA_property_float_set(op->ptr, gso->factor_prop, factor);
+  blend_to_default_graph_keys(&gso->ac, factor);
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+}
+
+static int blend_to_default_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+  const int invoke_result = graph_slider_invoke(C, op, event);
+
+  if (invoke_result == OPERATOR_CANCELLED) {
+    return invoke_result;
+  }
+
+  tGraphSliderOp *gso = op->customdata;
+  gso->modal_update = blend_to_default_modal_update;
+  gso->factor_prop = RNA_struct_find_property(op->ptr, "factor");
+  blend_to_default_draw_status_header(C, gso);
+
+  return invoke_result;
+}
+
+static int blend_to_default_exec(bContext *C, wmOperator *op)
+{
+  bAnimContext ac;
+
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  const float factor = RNA_float_get(op->ptr, "factor");
+
+  blend_to_default_graph_keys(&ac, factor);
+
+  /* Set notifier that keyframes have changed. */
+  WM_event_add_notifier(C, NC_ANIMATION | ND_KEYFRAME | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GRAPH_OT_blend_to_default(wmOperatorType *ot)
+{
+  /* Identifiers. */
+  ot->name = "Blend To Default Value";
+  ot->idname = "GRAPH_OT_blend_to_default";
+  ot->description = "Blend selected keys to their default value from their current position";
+
+  /* API callbacks. */
+  ot->invoke = blend_to_default_invoke;
+  ot->modal = graph_slider_modal;
+  ot->exec = blend_to_default_exec;
+  ot->poll = graphop_editable_keyframes_poll;
+
+  /* Flags. */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  RNA_def_float_factor(ot->srna,
+                       "factor",
+                       1.0f / 3.0f,
+                       -FLT_MAX,
+                       FLT_MAX,
+                       "Factor",
+                       "How much to blend to the default value",
+                       0.0f,
+                       1.0f);
+}
+/** \} */