UI: Drag and Drop Constraints, Layout Updates

This patch implements the list panel system D7490 for constraints.
In this case the panels are still defined in Python.

The layouts are also updated to use subpanels and the a more organized
single column layout. There may be more tweaks necessary for the
layouts.

Reviewed By: Severin, billreynish, Mets

Differential Revision: https://developer.blender.org/D7499

2 files changed, 205 insertions, 106 deletions

diff --git a/source/blender/editors/interface/interface_panel.c b/source/blender/editors/interface/interface_panel.c
index 4fff80d5def..924b886f167 100644
--- a/source/blender/editors/interface/interface_panel.c
+++ b/source/blender/editors/interface/interface_panel.c
@@ -387,9 +387,19 @@ bool UI_panel_list_matches_data(ARegion *region,
                                 ListBase *data,
                                 uiListPanelIDFromDataFunc panel_idname_func)
 {
-  int data_len = BLI_listbase_count(data);
+  /* Check for NULL data. */
+  int data_len = 0;
+  Link *data_link = NULL;
+  if (data == NULL) {
+    data_len = 0;
+    data_link = NULL;
+  }
+  else {
+    data_len = BLI_listbase_count(data);
+    data_link = data->first;
+  }
+
   int i = 0;
-  Link *data_link = data->first;
   LISTBASE_FOREACH (Panel *, panel, &region->panels) {
     if (panel->type != NULL && panel->type->flag & PNL_INSTANCED) {
       /* The panels were reordered by drag and drop. */
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index 1ce1e2950d5..189441a1f10 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -1823,6 +1823,20 @@ void uiTemplatePathBuilder(uiLayout *layout,
  *  Template for building the panel layout for the active object's modifiers.
  * \{ */
 
+/**
+ * Get the active object or the property region's pinned object.
+ */
+static Object *get_context_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);
+  }
+}
+
 static void modifier_panel_id(void *md_link, char *r_name)
 {
   ModifierData *md = (ModifierData *)md_link;
@@ -1834,14 +1848,7 @@ void uiTemplateModifiers(uiLayout *UNUSED(layout), bContext *C)
   ScrArea *sa = CTX_wm_area(C);
   ARegion *region = CTX_wm_region(C);
 
-  Object *ob;
-  SpaceProperties *sbuts = CTX_wm_space_properties(C);
-  if (sbuts != NULL && (sbuts->pinid != NULL) && GS(sbuts->pinid->name) == ID_OB) {
-    ob = (Object *)sbuts->pinid;
-  }
-  else {
-    ob = CTX_data_active_object(C);
-  }
+  Object *ob = get_context_object(C);
   ListBase *modifiers = &ob->modifiers;
 
   bool panels_match = UI_panel_list_matches_data(region, modifiers, modifier_panel_id);
@@ -1874,6 +1881,162 @@ void uiTemplateModifiers(uiLayout *UNUSED(layout), bContext *C)
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name Constraints Template
+ *
+ *  Template for building the panel layout for the active object or bone's constraints.
+ * \{ */
+
+/** For building the panel UI for constraints. */
+#define CONSTRAINT_TYPE_PANEL_PREFIX "OBJECT_PT_"
+#define CONSTRAINT_BONE_TYPE_PANEL_PREFIX "BONE_PT_"
+
+/**
+ * Check if the panel's ID starts with 'BONE', meaning it is a bone constraint.
+ */
+static bool constraint_panel_is_bone(Panel *panel)
+{
+  return (panel->panelname[0] == 'B') && (panel->panelname[1] == 'O') &&
+         (panel->panelname[2] == 'N') && (panel->panelname[3] == 'E');
+}
+
+/**
+ * Get the constraints for the active pose bone or the active / pinned object.
+ */
+static ListBase *get_constraints(const bContext *C, bool use_bone_constraints)
+{
+  ListBase *constraints = {NULL};
+  if (use_bone_constraints) {
+    bPoseChannel *pose_bone = CTX_data_pointer_get(C, "pose_bone").data;
+    if (pose_bone != NULL) {
+      constraints = &pose_bone->constraints;
+    }
+  }
+  else {
+    Object *ob = get_context_object(C);
+    if (ob != NULL) {
+      constraints = &ob->constraints;
+    }
+  }
+  return constraints;
+}
+
+/**
+ * Move a constraint to the index it's moved to after a drag and drop.
+ */
+static void constraint_reorder(bContext *C, Panel *panel, int new_index)
+{
+  bool constraint_from_bone = constraint_panel_is_bone(panel);
+  ListBase *lb = get_constraints(C, constraint_from_bone);
+
+  bConstraint *con = BLI_findlink(lb, panel->runtime.list_index);
+  PointerRNA props_ptr;
+  wmOperatorType *ot = WM_operatortype_find("CONSTRAINT_OT_move_to_index", false);
+  WM_operator_properties_create_ptr(&props_ptr, ot);
+  RNA_string_set(&props_ptr, "constraint", con->name);
+  RNA_int_set(&props_ptr, "index", new_index);
+  /* Set owner to #EDIT_CONSTRAINT_OWNER_OBJECT or #EDIT_CONSTRAINT_OWNER_BONE. */
+  RNA_enum_set(&props_ptr, "owner", constraint_from_bone ? 1 : 0);
+  WM_operator_name_call_ptr(C, ot, WM_OP_INVOKE_DEFAULT, &props_ptr);
+  WM_operator_properties_free(&props_ptr);
+}
+
+/**
+ * Get the expand flag from the active constraint to use for the panel.
+ */
+static short get_constraint_expand_flag(const bContext *C, Panel *panel)
+{
+  bool constraint_from_bone = constraint_panel_is_bone(panel);
+  ListBase *lb = get_constraints(C, constraint_from_bone);
+
+  bConstraint *con = BLI_findlink(lb, panel->runtime.list_index);
+  return con->ui_expand_flag;
+}
+
+/**
+ * Save the expand flag for the panel and subpanels to the constraint.
+ */
+static void set_constraint_expand_flag(const bContext *C, Panel *panel, short expand_flag)
+{
+  bool constraint_from_bone = constraint_panel_is_bone(panel);
+  ListBase *lb = get_constraints(C, constraint_from_bone);
+
+  bConstraint *con = BLI_findlink(lb, panel->runtime.list_index);
+  con->ui_expand_flag = expand_flag;
+}
+
+/**
+ * Function with void * argument for #uiListPanelIDFromDataFunc.
+ *
+ * \note: Constraint panel types are assumed to be named with the struct name field
+ * concatenated to the defined prefix.
+ */
+static void object_constraint_panel_id(void *md_link, char *r_name)
+{
+  bConstraint *con = (bConstraint *)md_link;
+  const bConstraintTypeInfo *cti = BKE_constraint_typeinfo_from_type(con->type);
+
+  strcpy(r_name, CONSTRAINT_TYPE_PANEL_PREFIX);
+  strcat(r_name, cti->structName);
+}
+
+static void bone_constraint_panel_id(void *md_link, char *r_name)
+{
+  bConstraint *con = (bConstraint *)md_link;
+  const bConstraintTypeInfo *cti = BKE_constraint_typeinfo_from_type(con->type);
+
+  strcpy(r_name, CONSTRAINT_BONE_TYPE_PANEL_PREFIX);
+  strcat(r_name, cti->structName);
+}
+
+/**
+ * Check if the constraint panels don't match the data and rebuild the panels if so.
+ */
+void uiTemplateConstraints(uiLayout *UNUSED(layout), bContext *C, bool use_bone_constraints)
+{
+  ScrArea *sa = CTX_wm_area(C);
+  ARegion *region = CTX_wm_region(C);
+
+  ListBase *constraints = get_constraints(C, use_bone_constraints);
+
+  /* Switch between the bone panel ID function and the object panel ID function. */
+  uiListPanelIDFromDataFunc panel_id_func = use_bone_constraints ? bone_constraint_panel_id :
+                                                                   object_constraint_panel_id;
+
+  bool panels_match = UI_panel_list_matches_data(region, constraints, panel_id_func);
+
+  if (!panels_match) {
+    UI_panels_free_instanced(C, region);
+    bConstraint *con = (constraints == NULL) ? NULL : constraints->first;
+    for (int i = 0; con; i++, con = con->next) {
+      char panel_idname[MAX_NAME];
+      panel_id_func(con, panel_idname);
+
+      Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
+      if (new_panel) {
+        /* Set the list panel functionality function pointers since we don't do it with python. */
+        new_panel->type->set_list_data_expand_flag = set_constraint_expand_flag;
+        new_panel->type->get_list_data_expand_flag = get_constraint_expand_flag;
+        new_panel->type->reorder = constraint_reorder;
+
+        UI_panel_set_expand_from_list_data(C, new_panel);
+      }
+    }
+  }
+  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);
+    }
+  }
+}
+
+#undef CONSTRAINT_TYPE_PANEL_PREFIX
+#undef CONSTRAINT_BONE_TYPE_PANEL_PREFIX
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name Grease Pencil Modifier Template
  * \{ */
 
@@ -2441,7 +2604,7 @@ void uiTemplateOperatorRedoProperties(uiLayout *layout, const bContext *C)
 /** \} */
 
 /* -------------------------------------------------------------------- */
-/** \name Constraint Template
+/** \name Constraint Header Template
  * \{ */
 
 static void constraint_active_func(bContext *UNUSED(C), void *ob_v, void *con_v)
@@ -2449,30 +2612,15 @@ static void constraint_active_func(bContext *UNUSED(C), void *ob_v, void *con_v)
   ED_object_constraint_active_set(ob_v, con_v);
 }
 
-/* draw panel showing settings for a constraint */
-static uiLayout *draw_constraint(uiLayout *layout, Object *ob, bConstraint *con)
+static void draw_constraint_header(uiLayout *layout, Object *ob, bConstraint *con)
 {
   bPoseChannel *pchan = BKE_pose_channel_active(ob);
-  const bConstraintTypeInfo *cti;
   uiBlock *block;
-  uiLayout *result = NULL, *col, *box, *row;
+  uiLayout *sub;
   PointerRNA ptr;
-  char typestr[32];
   short proxy_protected, xco = 0, yco = 0;
   // int rb_col; // UNUSED
 
-  /* get constraint typeinfo */
-  cti = BKE_constraint_typeinfo_get(con);
-  if (cti == NULL) {
-    /* exception for 'Null' constraint - it doesn't have constraint typeinfo! */
-    BLI_strncpy(typestr,
-                (con->type == CONSTRAINT_TYPE_NULL) ? IFACE_("Null") : IFACE_("Unknown"),
-                sizeof(typestr));
-  }
-  else {
-    BLI_strncpy(typestr, IFACE_(cti->name), sizeof(typestr));
-  }
-
   /* determine whether constraint is proxy protected or not */
   if (BKE_constraints_proxylocked_owner(ob, pchan)) {
     proxy_protected = (con->flag & CONSTRAINT_PROXY_LOCAL) == 0;
@@ -2487,36 +2635,23 @@ static uiLayout *draw_constraint(uiLayout *layout, Object *ob, bConstraint *con)
 
   RNA_pointer_create(&ob->id, &RNA_Constraint, con, &ptr);
 
-  col = uiLayoutColumn(layout, true);
-  uiLayoutSetContextPointer(col, "constraint", &ptr);
-
-  box = uiLayoutBox(col);
-  row = uiLayoutRow(box, false);
-  block = uiLayoutGetBlock(box);
-
-  /* Draw constraint header */
+  uiLayoutSetContextPointer(layout, "constraint", &ptr);
 
-  /* open/close */
-  UI_block_emboss_set(block, UI_EMBOSS_NONE);
-  uiItemR(row, &ptr, "show_expanded", 0, "", ICON_NONE);
+  /* Constraint type icon. */
+  sub = uiLayoutRow(layout, false);
+  uiLayoutSetEmboss(sub, false);
+  uiLayoutSetRedAlert(sub, (con->flag & CONSTRAINT_DISABLE));
+  uiItemL(sub, "", RNA_struct_ui_icon(ptr.type));
 
-  /* constraint-type icon */
-  uiItemL(row, "", RNA_struct_ui_icon(ptr.type));
   UI_block_emboss_set(block, UI_EMBOSS);
 
-  if (con->flag & CONSTRAINT_DISABLE) {
-    uiLayoutSetRedAlert(row, true);
-  }
-
   if (proxy_protected == 0) {
-    uiItemR(row, &ptr, "name", 0, "", ICON_NONE);
+    uiItemR(layout, &ptr, "name", 0, "", ICON_NONE);
   }
   else {
-    uiItemL(row, con->name, ICON_NONE);
+    uiItemL(layout, con->name, ICON_NONE);
   }
 
-  uiLayoutSetRedAlert(row, false);
-
   /* proxy-protected constraints cannot be edited, so hide up/down + close buttons */
   if (proxy_protected) {
     UI_block_emboss_set(block, UI_EMBOSS_NONE);
@@ -2555,54 +2690,20 @@ static uiLayout *draw_constraint(uiLayout *layout, Object *ob, bConstraint *con)
     UI_block_emboss_set(block, UI_EMBOSS);
   }
   else {
-    short prev_proxylock, show_upbut, show_downbut;
-
-    /* Up/Down buttons:
-     * Proxy-constraints are not allowed to occur after local (non-proxy) constraints
-     * as that poses problems when restoring them, so disable the "up" button where
-     * it may cause this situation.
-     *
-     * Up/Down buttons should only be shown (or not grayed - todo) if they serve some purpose.
-     */
-    if (BKE_constraints_proxylocked_owner(ob, pchan)) {
-      if (con->prev) {
-        prev_proxylock = (con->prev->flag & CONSTRAINT_PROXY_LOCAL) ? 0 : 1;
-      }
-      else {
-        prev_proxylock = 0;
-      }
-    }
-    else {
-      prev_proxylock = 0;
-    }
-
-    show_upbut = ((prev_proxylock == 0) && (con->prev));
-    show_downbut = (con->next) ? 1 : 0;
-
     /* enabled */
     UI_block_emboss_set(block, UI_EMBOSS_NONE);
-    uiItemR(row, &ptr, "mute", 0, "", 0);
+    uiItemR(layout, &ptr, "mute", 0, "", 0);
     UI_block_emboss_set(block, UI_EMBOSS);
 
-    uiLayoutSetOperatorContext(row, WM_OP_INVOKE_DEFAULT);
-
-    /* up/down */
-    if (show_upbut || show_downbut) {
-      UI_block_align_begin(block);
-      if (show_upbut) {
-        uiItemO(row, "", ICON_TRIA_UP, "CONSTRAINT_OT_move_up");
-      }
-
-      if (show_downbut) {
-        uiItemO(row, "", ICON_TRIA_DOWN, "CONSTRAINT_OT_move_down");
-      }
-      UI_block_align_end(block);
-    }
+    uiLayoutSetOperatorContext(layout, WM_OP_INVOKE_DEFAULT);
 
     /* Close 'button' - emboss calls here disable drawing of 'button' behind X */
     UI_block_emboss_set(block, UI_EMBOSS_NONE);
-    uiItemO(row, "", ICON_X, "CONSTRAINT_OT_delete");
+    uiItemO(layout, "", ICON_X, "CONSTRAINT_OT_delete");
     UI_block_emboss_set(block, UI_EMBOSS);
+
+    /* Some extra padding at the end, so the 'x' icon isn't too close to drag button. */
+    uiItemS(layout);
   }
 
   /* Set but-locks for protected settings (magic numbers are used here!) */
@@ -2610,23 +2711,11 @@ static uiLayout *draw_constraint(uiLayout *layout, Object *ob, bConstraint *con)
     UI_block_lock_set(block, true, TIP_("Cannot edit Proxy-Protected Constraint"));
   }
 
-  /* Draw constraint data */
-  if ((con->flag & CONSTRAINT_EXPAND) == 0) {
-    (yco) -= 10.5f * UI_UNIT_Y;
-  }
-  else {
-    box = uiLayoutBox(col);
-    block = uiLayoutAbsoluteBlock(box);
-    result = box;
-  }
-
   /* clear any locks set up for proxies/lib-linking */
   UI_block_lock_clear(block);
-
-  return result;
 }
 
-uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
+void uiTemplateConstraintHeader(uiLayout *layout, PointerRNA *ptr)
 {
   Object *ob;
   bConstraint *con;
@@ -2634,7 +2723,7 @@ uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
   /* verify we have valid data */
   if (!RNA_struct_is_a(ptr->type, &RNA_Constraint)) {
     RNA_warning("Expected constraint on object");
-    return NULL;
+    return;
   }
 
   ob = (Object *)ptr->owner_id;
@@ -2642,7 +2731,7 @@ uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
 
   if (!ob || !(GS(ob->id.name) == ID_OB)) {
     RNA_warning("Expected constraint on object");
-    return NULL;
+    return;
   }
 
   UI_block_lock_set(uiLayoutGetBlock(layout), (ob && ID_IS_LINKED(ob)), ERROR_LIBDATA_MESSAGE);
@@ -2651,11 +2740,11 @@ uiLayout *uiTemplateConstraint(uiLayout *layout, PointerRNA *ptr)
   if (con->type == CONSTRAINT_TYPE_KINEMATIC) {
     bKinematicConstraint *data = con->data;
     if (data->flag & CONSTRAINT_IK_TEMP) {
-      return NULL;
+      return;
     }
   }
 
-  return draw_constraint(layout, ob, con);
+  draw_constraint_header(layout, ob, con);
 }
 
 /** \} */