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

7 files changed, 139 insertions, 107 deletions

diff --git a/source/blender/editors/include/ED_object.h b/source/blender/editors/include/ED_object.h
index 0cc926987b2..73c58753531 100644
--- a/source/blender/editors/include/ED_object.h
+++ b/source/blender/editors/include/ED_object.h
@@ -453,6 +453,10 @@ int ED_object_shaderfx_move_down(struct ReportList *reports,
 int ED_object_shaderfx_move_up(struct ReportList *reports,
                                struct Object *ob,
                                struct ShaderFxData *fx);
+bool ED_object_shaderfx_move_to_index(struct ReportList *reports,
+                                      struct Object *ob,
+                                      struct ShaderFxData *fx,
+                                      const int index);
 
 /* object_select.c */
 void ED_object_select_linked_by_id(struct bContext *C, struct ID *id);
diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index 8e9591c1963..bcbee51246e 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -2005,6 +2005,7 @@ void uiTemplatePathBuilder(uiLayout *layout,
                            const char *text);
 void uiTemplateModifiers(uiLayout *layout, struct bContext *C);
 void uiTemplateGpencilModifiers(uiLayout *layout, struct bContext *C);
+void uiTemplateShaderFx(uiLayout *layout, struct bContext *C);
 void uiTemplateConstraints(uiLayout *layout, struct bContext *C, bool use_bone_constraints);
 
 uiLayout *uiTemplateGpencilModifier(uiLayout *layout, struct bContext *C, struct PointerRNA *ptr);
@@ -2017,8 +2018,6 @@ void uiTemplateGpencilColorPreview(uiLayout *layout,
                                    float scale,
                                    int filter);
 
-uiLayout *uiTemplateShaderFx(uiLayout *layout, struct bContext *C, struct PointerRNA *ptr);
-
 void uiTemplateOperatorRedoProperties(uiLayout *layout, const struct bContext *C);
 
 void uiTemplateConstraintHeader(uiLayout *layout, struct PointerRNA *ptr);
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index 56a71970f90..c3a432d6bcc 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -2090,123 +2090,52 @@ void uiTemplateGpencilModifiers(uiLayout *UNUSED(layout), bContext *C)
 #define ERROR_LIBDATA_MESSAGE TIP_("Can't edit external library data")
 
 /* -------------------------------------------------------------------- */
-/** \name Grease Pencil Shader FX Template
+/** \name ShaderFx Template
+ *
+ *  Template for building the panel layout for the active object's grease pencil shader effects.
  * \{ */
 
-static uiLayout *gpencil_draw_shaderfx(uiLayout *layout, Object *ob, ShaderFxData *md)
+/**
+ * Function with void * argument for #uiListPanelIDFromDataFunc.
+ */
+static void shaderfx_panel_id(void *fx_v, char *r_idname)
 {
-  const ShaderFxTypeInfo *mti = BKE_shaderfx_get_info(md->type);
-  PointerRNA ptr;
-  uiBlock *block;
-  uiLayout *box, *column, *row, *sub;
-  uiLayout *result = NULL;
-
-  /* create RNA pointer */
-  RNA_pointer_create(&ob->id, &RNA_ShaderFx, md, &ptr);
-
-  column = uiLayoutColumn(layout, true);
-  uiLayoutSetContextPointer(column, "shaderfx", &ptr);
-
-  /* rounded header ------------------------------------------------------------------- */
-  box = uiLayoutBox(column);
-
-  row = uiLayoutRow(box, false);
-  block = uiLayoutGetBlock(row);
-
-  UI_block_emboss_set(block, UI_EMBOSS_NONE);
-  /* Open/Close .................................  */
-  uiItemR(row, &ptr, "show_expanded", 0, "", ICON_NONE);
-
-  /* shader-type icon */
-  uiItemL(row, "", RNA_struct_ui_icon(ptr.type));
-  UI_block_emboss_set(block, UI_EMBOSS);
-
-  /* effect name */
-  if (mti->isDisabled && mti->isDisabled(md, 0)) {
-    uiLayoutSetRedAlert(row, true);
-  }
-  uiItemR(row, &ptr, "name", 0, "", ICON_NONE);
-  uiLayoutSetRedAlert(row, false);
-
-  /* mode enabling buttons */
-  UI_block_align_begin(block);
-  uiItemR(row, &ptr, "show_render", 0, "", ICON_NONE);
-  uiItemR(row, &ptr, "show_viewport", 0, "", ICON_NONE);
-
-  if (mti->flags & eShaderFxTypeFlag_SupportsEditmode) {
-    sub = uiLayoutRow(row, true);
-    uiLayoutSetActive(sub, false);
-    uiItemR(sub, &ptr, "show_in_editmode", 0, "", ICON_NONE);
-  }
-
-  UI_block_align_end(block);
-
-  /* Up/Down + Delete ........................... */
-  UI_block_align_begin(block);
-  uiItemO(row, "", ICON_TRIA_UP, "OBJECT_OT_shaderfx_move_up");
-  uiItemO(row, "", ICON_TRIA_DOWN, "OBJECT_OT_shaderfx_move_down");
-  UI_block_align_end(block);
-
-  UI_block_emboss_set(block, UI_EMBOSS_NONE);
-  uiItemO(row, "", ICON_X, "OBJECT_OT_shaderfx_remove");
-  UI_block_emboss_set(block, UI_EMBOSS);
-
-  /* effect settings (under the header) --------------------------------------------------- */
-  if (md->mode & eShaderFxMode_Expanded) {
-    /* apply/convert/copy */
-    box = uiLayoutBox(column);
-    row = uiLayoutRow(box, false);
-
-    /* only here obdata, the rest of effect is ob level */
-    UI_block_lock_set(block, BKE_object_obdata_is_libdata(ob), ERROR_LIBDATA_MESSAGE);
-
-    /* result is the layout block inside the box,
-     * that we return so that effect settings can be drawn */
-    result = uiLayoutColumn(box, false);
-    block = uiLayoutAbsoluteBlock(box);
-  }
-
-  /* error messages */
-  if (md->error) {
-    box = uiLayoutBox(column);
-    row = uiLayoutRow(box, false);
-    uiItemL(row, md->error, ICON_ERROR);
-  }
-
-  return result;
+  ShaderFxData *fx = (ShaderFxData *)fx_v;
+  BKE_shaderfxType_panel_id(fx->type, r_idname);
 }
 
-uiLayout *uiTemplateShaderFx(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
+/**
+ * Check if the shader effect panels don't match the data and rebuild the panels if so.
+ */
+void uiTemplateShaderFx(uiLayout *UNUSED(layout), bContext *C)
 {
-  Object *ob;
-  ShaderFxData *fx, *vfx;
-  int i;
+  ScrArea *sa = CTX_wm_area(C);
+  ARegion *region = CTX_wm_region(C);
+  Object *ob = get_context_object(C);
+  ListBase *shaderfx = &ob->shader_fx;
 
-  /* verify we have valid data */
-  if (!RNA_struct_is_a(ptr->type, &RNA_ShaderFx)) {
-    RNA_warning("Expected shader fx on object");
-    return NULL;
-  }
+  bool panels_match = UI_panel_list_matches_data(region, shaderfx, shaderfx_panel_id);
 
-  ob = (Object *)ptr->owner_id;
-  fx = ptr->data;
+  if (!panels_match) {
+    UI_panels_free_instanced(C, region);
+    ShaderFxData *fx = shaderfx->first;
+    for (int i = 0; fx; i++, fx = fx->next) {
+      char panel_idname[MAX_NAME];
+      shaderfx_panel_id(fx, panel_idname);
 
-  if (!ob || !(GS(ob->id.name) == ID_OB)) {
-    RNA_warning("Expected shader fx on object");
-    return NULL;
+      Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
+      if (new_panel != NULL) {
+        UI_panel_set_expand_from_list_data(C, new_panel);
+      }
+    }
   }
-
-  UI_block_lock_set(uiLayoutGetBlock(layout), (ob && ID_IS_LINKED(ob)), ERROR_LIBDATA_MESSAGE);
-
-  /* find modifier and draw it */
-  vfx = ob->shader_fx.first;
-  for (i = 0; vfx; i++, vfx = vfx->next) {
-    if (fx == vfx) {
-      return gpencil_draw_shaderfx(layout, ob, fx);
+  else {
+    /* The expansion might have been changed elsewhere, so we still need to set it. */
+    LISTBASE_FOREACH (Panel *, panel, &region->panels) {
+      if ((panel->type != NULL) && (panel->type->flag & PNL_INSTANCED))
+        UI_panel_set_expand_from_list_data(C, panel);
     }
   }
-
-  return NULL;
 }
 
 /** \} */
@@ -2515,6 +2444,8 @@ void uiTemplateOperatorRedoProperties(uiLayout *layout, const bContext *C)
 /** \name Constraint Header Template
  * \{ */
 
+#define ERROR_LIBDATA_MESSAGE TIP_("Can't edit external library data")
+
 static void constraint_active_func(bContext *UNUSED(C), void *ob_v, void *con_v)
 {
   ED_object_constraint_active_set(ob_v, con_v);
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);
+}
diff --git a/source/blender/editors/space_buttons/space_buttons.c b/source/blender/editors/space_buttons/space_buttons.c
index 2cc9679dd3f..71b86996989 100644
--- a/source/blender/editors/space_buttons/space_buttons.c
+++ b/source/blender/editors/space_buttons/space_buttons.c
@@ -33,6 +33,7 @@
 #include "BKE_gpencil_modifier.h" /* Types for registering panels. */
 #include "BKE_modifier.h"
 #include "BKE_screen.h"
+#include "BKE_shader_fx.h"
 
 #include "ED_screen.h"
 #include "ED_space_api.h"
@@ -648,6 +649,15 @@ void ED_spacetype_buttons(void)
       mti->panelRegister(art);
     }
   }
+  for (int i = 0; i < NUM_SHADER_FX_TYPES; i++) {
+    if (i == eShaderFxType_Light_deprecated) {
+      continue;
+    }
+    const ShaderFxTypeInfo *fxti = BKE_shaderfx_get_info(i);
+    if (fxti != NULL && fxti->panelRegister != NULL) {
+      fxti->panelRegister(art);
+    }
+  }
 
   /* regions: header */
   art = MEM_callocN(sizeof(ARegionType), "spacetype buttons region");