UI: ShaderFx Drag and Drop, Layout Updates

This patch implements the list panel system D7490 for grease pencil
shader effects. It also moves their drawing to a callback in
ShaderFxTypeInfo in line with the extensible architecture refactoring
goal T75724.

The implementation is basically exactly the same as for the modifier
patch (9b099c86123fc82).

Thanks to Matias Mendiola (@mendio) for helping to develop the layout
changes.

Differential Revision: https://developer.blender.org/D7985

3 files changed, 88 insertions, 0 deletions

diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index 8feeb3b6067..3dbd1de123d 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -199,6 +199,7 @@ void OBJECT_OT_shaderfx_add(struct wmOperatorType *ot);
 void OBJECT_OT_shaderfx_remove(struct wmOperatorType *ot);
 void OBJECT_OT_shaderfx_move_up(struct wmOperatorType *ot);
 void OBJECT_OT_shaderfx_move_down(struct wmOperatorType *ot);
+void OBJECT_OT_shaderfx_move_to_index(struct wmOperatorType *ot);
 
 /* object_constraint.c */
 void OBJECT_OT_constraint_add(struct wmOperatorType *ot);
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index 1060a808cfe..29058175e25 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -161,6 +161,7 @@ void ED_operatortypes_object(void)
   WM_operatortype_append(OBJECT_OT_shaderfx_remove);
   WM_operatortype_append(OBJECT_OT_shaderfx_move_up);
   WM_operatortype_append(OBJECT_OT_shaderfx_move_down);
+  WM_operatortype_append(OBJECT_OT_shaderfx_move_to_index);
 
   WM_operatortype_append(OBJECT_OT_correctivesmooth_bind);
   WM_operatortype_append(OBJECT_OT_meshdeform_bind);
diff --git a/source/blender/editors/object/object_shader_fx.c b/source/blender/editors/object/object_shader_fx.c
index 5db4a5a4f57..5abba70e008 100644
--- a/source/blender/editors/object/object_shader_fx.c
+++ b/source/blender/editors/object/object_shader_fx.c
@@ -200,6 +200,40 @@ int ED_object_shaderfx_move_down(ReportList *UNUSED(reports), Object *ob, Shader
   return 1;
 }
 
+bool ED_object_shaderfx_move_to_index(ReportList *reports,
+                                      Object *ob,
+                                      ShaderFxData *fx,
+                                      const int index)
+{
+  BLI_assert(fx != NULL);
+  BLI_assert(index >= 0);
+  if (index >= BLI_listbase_count(&ob->shader_fx)) {
+    BKE_report(reports, RPT_WARNING, "Cannot move effect beyond the end of the stack");
+    return false;
+  }
+
+  int fx_index = BLI_findindex(&ob->shader_fx, fx);
+  BLI_assert(fx_index != -1);
+  if (fx_index < index) {
+    /* Move shaderfx down in list. */
+    for (; fx_index < index; fx_index++) {
+      if (!ED_object_shaderfx_move_down(reports, ob, fx)) {
+        break;
+      }
+    }
+  }
+  else {
+    /* Move shaderfx up in list. */
+    for (; fx_index > index; fx_index--) {
+      if (!ED_object_shaderfx_move_up(reports, ob, fx)) {
+        break;
+      }
+    }
+  }
+
+  return true;
+}
+
 /************************ add effect operator *********************/
 
 static int shaderfx_add_exec(bContext *C, wmOperator *op)
@@ -487,3 +521,55 @@ void OBJECT_OT_shaderfx_move_down(wmOperatorType *ot)
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
   edit_shaderfx_properties(ot);
 }
+
+/************************ move shaderfx to index operator *********************/
+
+static bool shaderfx_move_to_index_poll(bContext *C)
+{
+  return edit_shaderfx_poll_generic(C, &RNA_ShaderFx, 0);
+}
+
+static int shaderfx_move_to_index_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = ED_object_active_context(C);
+  ShaderFxData *fx = edit_shaderfx_property_get(op, ob, 0);
+  int index = RNA_int_get(op->ptr, "index");
+
+  if (!fx || !ED_object_shaderfx_move_to_index(op->reports, ob, fx, index)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_OBJECT | ND_MODIFIER, ob);
+
+  return OPERATOR_FINISHED;
+}
+
+static int shaderfx_move_to_index_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(event))
+{
+  if (edit_shaderfx_invoke_properties(C, op)) {
+    return shaderfx_move_to_index_exec(C, op);
+  }
+  else {
+    return OPERATOR_CANCELLED;
+  }
+}
+
+void OBJECT_OT_shaderfx_move_to_index(wmOperatorType *ot)
+{
+  ot->name = "Move Effect to Index";
+  ot->idname = "OBJECT_OT_shaderfx_move_to_index";
+  ot->description =
+      "Change the effect's position in the list so it evaluates after the set number of "
+      "others";
+
+  ot->invoke = shaderfx_move_to_index_invoke;
+  ot->exec = shaderfx_move_to_index_exec;
+  ot->poll = shaderfx_move_to_index_poll;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_INTERNAL;
+  edit_shaderfx_properties(ot);
+  RNA_def_int(
+      ot->srna, "index", 0, 0, INT_MAX, "Index", "The index to move the effect to", 0, INT_MAX);
+}