UI: Drag and Drop Modifiers, Layout Updates

This patch implements the list panel system D7490 for modifiers.
It also moves modifier drawing to a callback in ModifierTypeInfo
in line with the extensible architecture refactoring goal T75724.

This adds a PanelRegister callback and utilities for registering
panels and subpanels. It also adds the callbacks for expansion saving
and drag and drop reordering described in D7490.

These utilities, callbacks, and other common UI elements shared
between modifiers live in MOD_ui_common.c.

Because modifier buttons are now in panels, we can make use of
subpanels for organization. The UI layouts also use the single
column layout style consistently used elsewhere in Blender.
Additionally, the mode-setting buttons are aligned and ordered
consistently with the outliner.

However, the large number of UI changes in this patch may mean
that additional polishing is required in master.

Thanks to William Reynish (@billreynish) who did a fair amount of the
layout work and to Julian Eisel (@Severin) for consistent help.

Differential Revision: https://developer.blender.org/D7498

1 files changed, 426 insertions, 0 deletions

diff --git a/source/blender/modifiers/intern/MOD_ui_common.c b/source/blender/modifiers/intern/MOD_ui_common.c
new file mode 100644
index 00000000000..973afe5fef6
--- /dev/null
+++ b/source/blender/modifiers/intern/MOD_ui_common.c
@@ -0,0 +1,426 @@
+/* This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software  Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup modifiers
+ */
+
+#include <string.h>
+
+#include "BLI_listbase.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "BKE_context.h"
+#include "BKE_modifier.h"
+#include "BKE_object.h"
+#include "BKE_screen.h"
+
+#include "DNA_object_force_types.h"
+#include "DNA_object_types.h"
+#include "DNA_particle_types.h"
+#include "DNA_scene_types.h"
+#include "DNA_screen_types.h"
+#include "DNA_space_types.h"
+
+#include "ED_object.h"
+
+#include "BLT_translation.h"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "RNA_access.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "MOD_modifiertypes.h"
+#include "MOD_ui_common.h" /* Self include */
+
+static Object *get_modifier_object(const bContext *C)
+{
+  SpaceProperties *sbuts = CTX_wm_space_properties(C);
+  if (sbuts != NULL && (sbuts->pinid != NULL) && GS(sbuts->pinid->name) == ID_OB) {
+    return (Object *)sbuts->pinid;
+  }
+  else {
+    return CTX_data_active_object(C);
+  }
+}
+
+/**
+ * Poll function so these modifier panels don't show for other object types with modifiers (only
+ * grease pencil currently).
+ */
+static bool modifier_ui_poll(const bContext *C, PanelType *UNUSED(pt))
+{
+  Object *ob = get_modifier_object(C);
+
+  return (ob != NULL) && (ob->type != OB_GPENCIL);
+}
+
+/* -------------------------------------------------------------------- */
+/** \name Panel Drag and Drop, Expansion Saving
+ * \{ */
+
+/**
+ * Move a modifier to the index it's moved to after a drag and drop.
+ */
+static void modifier_reorder(bContext *C, Panel *panel, int new_index)
+{
+  Object *ob = get_modifier_object(C);
+
+  ModifierData *md = BLI_findlink(&ob->modifiers, panel->runtime.list_index);
+  PointerRNA props_ptr;
+  wmOperatorType *ot = WM_operatortype_find("OBJECT_OT_modifier_move_to_index", false);
+  WM_operator_properties_create_ptr(&props_ptr, ot);
+  RNA_string_set(&props_ptr, "modifier", md->name);
+  RNA_int_set(&props_ptr, "index", new_index);
+  WM_operator_name_call_ptr(C, ot, WM_OP_INVOKE_DEFAULT, &props_ptr);
+  WM_operator_properties_free(&props_ptr);
+}
+
+static short get_modifier_expand_flag(const bContext *C, Panel *panel)
+{
+  Object *ob = get_modifier_object(C);
+  ModifierData *md = BLI_findlink(&ob->modifiers, panel->runtime.list_index);
+  return md->ui_expand_flag;
+}
+
+static void set_modifier_expand_flag(const bContext *C, Panel *panel, short expand_flag)
+{
+  Object *ob = get_modifier_object(C);
+  ModifierData *md = BLI_findlink(&ob->modifiers, panel->runtime.list_index);
+  md->ui_expand_flag = expand_flag;
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Modifier Panel Layouts
+ * \{ */
+
+/**
+ * Draw modifier error message.
+ */
+void modifier_panel_end(uiLayout *layout, PointerRNA *ptr)
+{
+  ModifierData *md = ptr->data;
+  if (md->error) {
+    uiLayout *row = uiLayoutRow(layout, false);
+    uiItemL(row, IFACE_(md->error), ICON_ERROR);
+  }
+}
+
+/**
+ * Gets RNA pointers for the active object and the panel's modifier data. Also locks
+ * the layout if the modifer is from a linked object, and sets the context pointer.
+ */
+#define ERROR_LIBDATA_MESSAGE TIP_("External library data")
+void modifier_panel_get_property_pointers(const bContext *C,
+                                          Panel *panel,
+                                          PointerRNA *r_ob_ptr,
+                                          PointerRNA *r_md_ptr)
+{
+  Object *ob = get_modifier_object(C);
+
+  ModifierData *md = BLI_findlink(&ob->modifiers, panel->runtime.list_index);
+
+  RNA_pointer_create(&ob->id, &RNA_Modifier, md, r_md_ptr);
+
+  if (r_ob_ptr != NULL) {
+    RNA_pointer_create(&ob->id, &RNA_Object, ob, r_ob_ptr);
+  }
+
+  uiBlock *block = uiLayoutGetBlock(panel->layout);
+  UI_block_lock_set(
+      block, BKE_object_obdata_is_libdata(ob) || ID_IS_LINKED(ob), ERROR_LIBDATA_MESSAGE);
+
+  uiLayoutSetContextPointer(panel->layout, "modifier", r_md_ptr);
+}
+
+/**
+ * Helper function for modifier layouts to draw vertex group settings.
+ */
+void modifier_vgroup_ui(uiLayout *layout,
+                        PointerRNA *ptr,
+                        PointerRNA *ob_ptr,
+                        const char *vgroup_prop,
+                        const char *invert_vgroup_prop,
+                        const char *text)
+{
+  bool has_vertex_group = RNA_string_length(ptr, vgroup_prop) != 0;
+
+  uiLayout *row = uiLayoutRow(layout, true);
+  uiItemPointerR(row, ptr, vgroup_prop, ob_ptr, "vertex_groups", text, ICON_NONE);
+  if (invert_vgroup_prop != NULL) {
+    uiLayout *sub = uiLayoutRow(row, true);
+    uiLayoutSetActive(sub, has_vertex_group);
+    uiLayoutSetPropDecorate(sub, false);
+    uiItemR(sub, ptr, invert_vgroup_prop, 0, "", ICON_ARROW_LEFTRIGHT);
+  }
+  if (uiLayoutGetPropDecorate(layout)) {
+    uiItemL(row, "", ICON_BLANK1);
+  }
+}
+
+/**
+ * Check whether Modifier is a simulation or not. Used for switching to the
+ * physics/particles context tab.
+ */
+static int modifier_is_simulation(ModifierData *md)
+{
+  /* Physic Tab */
+  if (ELEM(md->type,
+           eModifierType_Cloth,
+           eModifierType_Collision,
+           eModifierType_Fluidsim,
+           eModifierType_Fluid,
+           eModifierType_Softbody,
+           eModifierType_Surface,
+           eModifierType_DynamicPaint)) {
+    return 1;
+  }
+  /* Particle Tab */
+  else if (md->type == eModifierType_ParticleSystem) {
+    return 2;
+  }
+  else {
+    return 0;
+  }
+}
+
+static bool modifier_can_delete(ModifierData *md)
+{
+  /* fluid particle modifier can't be deleted here */
+  if (md->type == eModifierType_ParticleSystem) {
+    short particle_type = ((ParticleSystemModifierData *)md)->psys->part->type;
+    if (ELEM(particle_type,
+             PART_FLUID,
+             PART_FLUID_FLIP,
+             PART_FLUID_FOAM,
+             PART_FLUID_SPRAY,
+             PART_FLUID_BUBBLE,
+             PART_FLUID_TRACER,
+             PART_FLUID_SPRAYFOAM,
+             PART_FLUID_SPRAYBUBBLE,
+             PART_FLUID_FOAMBUBBLE,
+             PART_FLUID_SPRAYFOAMBUBBLE)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+static void modifier_ops_extra_draw(bContext *UNUSED(C), uiLayout *layout, void *md_v)
+{
+  ModifierData *md = (ModifierData *)md_v;
+
+  uiLayoutSetOperatorContext(layout, WM_OP_INVOKE_DEFAULT);
+
+  uiItemEnumO(layout,
+              "OBJECT_OT_modifier_apply",
+              CTX_IFACE_(BLT_I18NCONTEXT_OPERATOR_DEFAULT, "Apply"),
+              0,
+              "apply_as",
+              MODIFIER_APPLY_DATA);
+
+  if (BKE_modifier_is_same_topology(md) && !BKE_modifier_is_non_geometrical(md)) {
+    uiItemEnumO(layout,
+                "OBJECT_OT_modifier_apply",
+                CTX_IFACE_(BLT_I18NCONTEXT_OPERATOR_DEFAULT, "Apply As Shapekey"),
+                ICON_SHAPEKEY_DATA,
+                "apply_as",
+                MODIFIER_APPLY_SHAPE);
+  }
+
+  if (!ELEM(md->type,
+            eModifierType_Fluidsim,
+            eModifierType_Softbody,
+            eModifierType_ParticleSystem,
+            eModifierType_Cloth,
+            eModifierType_Fluid)) {
+    uiItemO(layout,
+            CTX_IFACE_(BLT_I18NCONTEXT_OPERATOR_DEFAULT, "Duplicate"),
+            ICON_DUPLICATE,
+            "OBJECT_OT_modifier_copy");
+  }
+
+  if (modifier_can_delete(md) && !modifier_is_simulation(md)) {
+    uiItemO(layout,
+            CTX_IFACE_(BLT_I18NCONTEXT_OPERATOR_DEFAULT, "Delete"),
+            ICON_X,
+            "OBJECT_OT_modifier_remove");
+  }
+}
+
+static void modifier_panel_header(const bContext *C, Panel *panel)
+{
+  uiLayout *row, *sub;
+  uiLayout *layout = panel->layout;
+
+  PointerRNA ptr;
+  Object *ob = get_modifier_object(C);
+
+  /* Don't use #modifier_panel_get_property_pointers, we don't want to lock the header. */
+  ModifierData *md = BLI_findlink(&ob->modifiers, panel->runtime.list_index);
+  RNA_pointer_create(&ob->id, &RNA_Modifier, md, &ptr);
+  uiLayoutSetContextPointer(panel->layout, "modifier", &ptr);
+
+  const ModifierTypeInfo *mti = BKE_modifier_get_info(md->type);
+  Scene *scene = CTX_data_scene(C);
+  int index = panel->runtime.list_index;
+  bool narrow_panel = (panel->sizex < UI_UNIT_X * 8 && panel->sizex != 0);
+
+  /* Modifier Icon. */
+  row = uiLayoutRow(layout, false);
+  if (mti->isDisabled && mti->isDisabled(scene, md, 0)) {
+    uiLayoutSetRedAlert(row, true);
+  }
+  uiItemL(row, "", RNA_struct_ui_icon(ptr.type));
+
+  /* Modifier Name. */
+  if (!narrow_panel) {
+    uiItemR(layout, &ptr, "name", 0, "", ICON_NONE);
+  }
+
+  /* Switch context buttons. */
+  if (modifier_is_simulation(md) == 1) {
+    uiItemStringO(
+        layout, "", ICON_PROPERTIES, "WM_OT_properties_context_change", "context", "PHYSICS");
+  }
+  else if (modifier_is_simulation(md) == 2) {
+    uiItemStringO(
+        layout, "", ICON_PROPERTIES, "WM_OT_properties_context_change", "context", "PARTICLES");
+  }
+
+  /* Mode switching buttons. */
+  row = uiLayoutRow(layout, true);
+  if (ob->type == OB_MESH) {
+    int last_cage_index;
+    int cage_index = BKE_modifiers_get_cage_index(scene, ob, &last_cage_index, 0);
+    if (BKE_modifier_supports_cage(scene, md) && (index <= last_cage_index)) {
+      sub = uiLayoutRow(row, true);
+      if (index < cage_index || !BKE_modifier_couldbe_cage(scene, md)) {
+        uiLayoutSetActive(sub, false);
+      }
+      uiItemR(sub, &ptr, "show_on_cage", 0, "", ICON_NONE);
+    }
+  } /* Tessellation point for curve-typed objects. */
+  else if (ELEM(ob->type, OB_CURVE, OB_SURF, OB_FONT)) {
+    if (mti->type != eModifierTypeType_Constructive) {
+      /* Constructive modifiers tessellates curve before applying. */
+      uiItemR(layout, &ptr, "use_apply_on_spline", 0, "", ICON_NONE);
+    }
+  }
+  /* Collision and Surface are always enabled, hide buttons. */
+  if (((md->type != eModifierType_Collision) || !(ob->pd && ob->pd->deflect)) &&
+      (md->type != eModifierType_Surface)) {
+    if (mti->flags & eModifierTypeFlag_SupportsEditmode) {
+      sub = uiLayoutRow(row, true);
+      uiLayoutSetActive(sub, (md->mode & eModifierMode_Realtime));
+      uiItemR(sub, &ptr, "show_in_editmode", 0, "", ICON_NONE);
+    }
+    uiItemR(row, &ptr, "show_viewport", 0, "", ICON_NONE);
+    uiItemR(row, &ptr, "show_render", 0, "", ICON_NONE);
+  }
+
+  row = uiLayoutRow(layout, false);
+  uiItemMenuF(row, "", ICON_DOWNARROW_HLT, modifier_ops_extra_draw, md);
+
+  /* Some padding at the end, so the buttons aren't too close to the drag button. */
+  uiItemS(layout);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Modifier Registration Helpers
+ * \{ */
+
+/**
+ * Create a panel in the context's region
+ */
+PanelType *modifier_panel_register(ARegionType *region_type, ModifierType type, PanelDrawFn draw)
+{
+  /* Get the name for the modifier's panel. */
+  char panel_idname[BKE_ST_MAXNAME];
+  BKE_modifier_type_panel_id(type, panel_idname);
+
+  PanelType *panel_type = MEM_callocN(sizeof(PanelType), panel_idname);
+
+  strcpy(panel_type->idname, panel_idname);
+  strcpy(panel_type->label, "");
+  strcpy(panel_type->context, "modifier");
+  strcpy(panel_type->translation_context, BLT_I18NCONTEXT_DEFAULT_BPYRNA);
+
+  panel_type->draw_header = modifier_panel_header;
+  panel_type->draw = draw;
+  panel_type->poll = modifier_ui_poll;
+
+  /* Give the panel the special flag that says it was built here and corresponds to a
+   * modifer rather than a PanelType. */
+  panel_type->flag = PNL_LAYOUT_HEADER_EXPAND | PNL_DRAW_BOX | PNL_INSTANCED;
+  panel_type->reorder = modifier_reorder;
+  panel_type->get_list_data_expand_flag = get_modifier_expand_flag;
+  panel_type->set_list_data_expand_flag = set_modifier_expand_flag;
+
+  BLI_addtail(&region_type->paneltypes, panel_type);
+
+  return panel_type;
+}
+
+/**
+ * Add a shild panel to the parent.
+ *
+ * \note To create the panel type's idname, it appends the \a name argument to the \a parent's
+ * idname.
+ */
+PanelType *modifier_subpanel_register(ARegionType *region_type,
+                                      const char *name,
+                                      const char *label,
+                                      PanelDrawFn draw_header,
+                                      PanelDrawFn draw,
+                                      PanelType *parent)
+{
+  /* Create the subpanel's ID name. */
+  char panel_idname[BKE_ST_MAXNAME];
+  strcpy(panel_idname, parent->idname);
+  strcat(panel_idname, "_");
+  strcat(panel_idname, name);
+
+  PanelType *panel_type = MEM_callocN(sizeof(PanelType), panel_idname);
+
+  strcpy(panel_type->idname, panel_idname);
+  strcpy(panel_type->label, label);
+  strcpy(panel_type->context, "modifier");
+  strcpy(panel_type->translation_context, BLT_I18NCONTEXT_DEFAULT_BPYRNA);
+
+  panel_type->draw_header = draw_header;
+  panel_type->draw = draw;
+  panel_type->poll = modifier_ui_poll;
+  panel_type->flag = (PNL_DEFAULT_CLOSED | PNL_DRAW_BOX);
+
+  BLI_assert(parent != NULL);
+  strcpy(panel_type->parent_id, parent->idname);
+  panel_type->parent = parent;
+  BLI_addtail(&parent->children, BLI_genericNodeN(panel_type));
+  BLI_addtail(&region_type->paneltypes, panel_type);
+
+  return panel_type;
+}
+
+/** \} */