UI: Improve node editor breadcrumbs display

This patch upgrades node editor breadcrumbs to have slightly more
visual weight, to including the base path of object/modifier/world,
etc, have more visually pleasing spacing, and contain icons.

In the code, a generic "context path" is added to interface code.
The idea is that this could be used to draw other breadcrumbs in areas
like the property editor or the spreadsheet, and features could be added
to all of those areas at the same time.

Ideally we would be able to control the color of the breadcrumbs with a
specific theme color, but since they are drawn with the regular layout
system, that is not easily possible.

Thanks to @fabian_schempp for the original patch.

Differential Revision: https://developer.blender.org/D10413

5 files changed, 224 insertions, 29 deletions

diff --git a/source/blender/editors/space_node/CMakeLists.txt b/source/blender/editors/space_node/CMakeLists.txt
index 80d3b43bf6b..600309c2c86 100644
--- a/source/blender/editors/space_node/CMakeLists.txt
+++ b/source/blender/editors/space_node/CMakeLists.txt
@@ -40,6 +40,7 @@ set(INC
 set(SRC
   drawnode.cc
   node_add.cc
+  node_context_path.cc
   node_draw.cc
   node_edit.cc
   node_geometry_attribute_search.cc
diff --git a/source/blender/editors/space_node/node_context_path.cc b/source/blender/editors/space_node/node_context_path.cc
new file mode 100644
index 00000000000..a0ff7f3ce25
--- /dev/null
+++ b/source/blender/editors/space_node/node_context_path.cc
@@ -0,0 +1,184 @@
+/*
+ * 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.
+ *
+ * The Original Code is Copyright (C) 2008 Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup spnode
+ * \brief Node breadcrumbs drawing
+ */
+
+#include "BLI_vector.hh"
+
+#include "DNA_node_types.h"
+
+#include "BKE_context.h"
+#include "BKE_material.h"
+#include "BKE_modifier.h"
+#include "BKE_object.h"
+
+#include "BKE_screen.h"
+
+#include "RNA_access.h"
+
+#include "ED_screen.h"
+
+#include "UI_interface.h"
+#include "UI_interface.hh"
+#include "UI_resources.h"
+
+#include "UI_interface.hh"
+
+#include "node_intern.h"
+
+struct Mesh;
+struct Curve;
+struct Light;
+struct World;
+struct Material;
+
+namespace blender::ed::space_node {
+
+static void context_path_add_object_data(Vector<ui::ContextPathItem> &path, Object &object)
+{
+  if (object.type == OB_MESH && object.data) {
+    Mesh *mesh = (Mesh *)object.data;
+    ui::context_path_add_generic(path, RNA_Mesh, mesh);
+  }
+  if (object.type == OB_LAMP && object.data) {
+    Light *light = (Light *)object.data;
+    ui::context_path_add_generic(path, RNA_Light, light);
+  }
+  if (ELEM(object.type, OB_CURVE, OB_FONT, OB_SURF) && object.data) {
+    Curve *curve = (Curve *)object.data;
+    ui::context_path_add_generic(path, RNA_Curve, curve);
+  }
+}
+
+static void context_path_add_node_tree_and_node_groups(const SpaceNode &snode,
+                                                       Vector<ui::ContextPathItem> &path,
+                                                       const bool skip_base = false)
+{
+  Vector<const bNodeTreePath *> tree_path = snode.treepath;
+  for (const bNodeTreePath *path_item : tree_path.as_span().drop_front(int(skip_base))) {
+    ui::context_path_add_generic(path, RNA_NodeTree, path_item->nodetree, ICON_NODETREE);
+  }
+}
+
+static void get_context_path_node_shader(const bContext &C,
+                                         SpaceNode &snode,
+                                         Vector<ui::ContextPathItem> &path)
+{
+  if (snode.flag & SNODE_PIN) {
+    if (snode.shaderfrom == SNODE_SHADER_WORLD) {
+      Scene *scene = CTX_data_scene(&C);
+      ui::context_path_add_generic(path, RNA_Scene, scene);
+      if (scene != nullptr) {
+        World *world = scene->world;
+        ui::context_path_add_generic(path, RNA_World, world);
+      }
+      /* Skip the base node tree here, because the world contains a node tree already. */
+      context_path_add_node_tree_and_node_groups(snode, path, true);
+    }
+    else {
+      context_path_add_node_tree_and_node_groups(snode, path);
+    }
+  }
+  else {
+    Object *object = CTX_data_active_object(&C);
+    if (snode.shaderfrom == SNODE_SHADER_OBJECT && object != nullptr) {
+      ui::context_path_add_generic(path, RNA_Object, object);
+      if (!(object->matbits && object->matbits[object->actcol - 1])) {
+        context_path_add_object_data(path, *object);
+      }
+      Material *material = BKE_object_material_get(object, object->actcol);
+      ui::context_path_add_generic(path, RNA_Material, material);
+    }
+    else if (snode.shaderfrom == SNODE_SHADER_WORLD) {
+      Scene *scene = CTX_data_scene(&C);
+      ui::context_path_add_generic(path, RNA_Scene, scene);
+      if (scene != nullptr) {
+        World *world = scene->world;
+        ui::context_path_add_generic(path, RNA_World, world);
+      }
+    }
+#ifdef WITH_FREESTYLE
+    else if (snode.shaderfrom == SNODE_SHADER_LINESTYLE) {
+      ViewLayer *viewlayer = CTX_data_view_layer(&C);
+      FreestyleLineStyle *linestyle = BKE_linestyle_active_from_view_layer(viewlayer);
+      ui::context_path_add_generic(path, RNA_ViewLayer, viewlayer);
+      Material *mat = BKE_object_material_get(object, object->actcol);
+      ui::context_path_add_generic(path, RNA_Material, mat);
+    }
+#endif
+    context_path_add_node_tree_and_node_groups(snode, path, true);
+  }
+}
+
+static void get_context_path_node_compositor(const bContext &C,
+                                             SpaceNode &snode,
+                                             Vector<ui::ContextPathItem> &path)
+{
+  if (snode.flag & SNODE_PIN) {
+    context_path_add_node_tree_and_node_groups(snode, path);
+  }
+  else {
+    Scene *scene = CTX_data_scene(&C);
+    ui::context_path_add_generic(path, RNA_Scene, scene);
+    context_path_add_node_tree_and_node_groups(snode, path);
+  }
+}
+
+static void get_context_path_node_geometry(const bContext &C,
+                                           SpaceNode &snode,
+                                           Vector<ui::ContextPathItem> &path)
+{
+  if (snode.flag & SNODE_PIN) {
+    context_path_add_node_tree_and_node_groups(snode, path);
+  }
+  else {
+    Object *object = CTX_data_active_object(&C);
+    ui::context_path_add_generic(path, RNA_Object, object);
+    ModifierData *modifier = BKE_object_active_modifier(object);
+    ui::context_path_add_generic(path, RNA_Modifier, modifier, ICON_MODIFIER);
+    context_path_add_node_tree_and_node_groups(snode, path);
+  }
+}
+
+Vector<ui::ContextPathItem> context_path_for_space_node(const bContext &C)
+{
+  SpaceNode *snode = CTX_wm_space_node(&C);
+  if (snode == nullptr) {
+    return {};
+  }
+
+  Vector<ui::ContextPathItem> context_path;
+
+  if (snode->edittree->type == NTREE_GEOMETRY) {
+    get_context_path_node_geometry(C, *snode, context_path);
+  }
+  else if (snode->edittree->type == NTREE_SHADER) {
+    get_context_path_node_shader(C, *snode, context_path);
+  }
+  else if (snode->edittree->type == NTREE_COMPOSIT) {
+    get_context_path_node_compositor(C, *snode, context_path);
+  }
+
+  return context_path;
+}
+
+}  // namespace blender::ed::space_node
diff --git a/source/blender/editors/space_node/node_draw.cc b/source/blender/editors/space_node/node_draw.cc
index 9e91d394fef..ea65eaa0a14 100644
--- a/source/blender/editors/space_node/node_draw.cc
+++ b/source/blender/editors/space_node/node_draw.cc
@@ -71,8 +71,10 @@
 
 #include "ED_gpencil.h"
 #include "ED_node.h"
+#include "ED_screen.h"
 #include "ED_space_api.h"
 
+#include "UI_interface.hh"
 #include "UI_resources.h"
 #include "UI_view2d.h"
 
@@ -2158,15 +2160,34 @@ void node_draw_nodetree(const bContext *C,
   }
 }
 
-/* Draw tree path info in lower left corner. */
-static void draw_tree_path(SpaceNode *snode)
+/* Draw the breadcrumb on the bottom of the editor. */
+static void draw_tree_path(const bContext &C, ARegion &region)
 {
-  char info[256];
+  using namespace blender;
 
-  ED_node_tree_path_get_fixedbuf(snode, info, sizeof(info));
+  GPU_matrix_push_projection();
+  wmOrtho2_region_pixelspace(&region);
 
-  UI_FontThemeColor(BLF_default(), TH_TEXT_HI);
-  BLF_draw_default(1.5f * UI_UNIT_X, 1.5f * UI_UNIT_Y, 0.0f, info, sizeof(info));
+  const rcti *rect = ED_region_visible_rect(&region);
+
+  const uiStyle *style = UI_style_get_dpi();
+  const float padding_x = 16 * UI_DPI_FAC;
+  const int x = rect->xmin + padding_x;
+  const int y = region.winy - UI_UNIT_Y * 0.6f;
+  const int width = BLI_rcti_size_x(rect) - 2 * padding_x;
+
+  uiBlock *block = UI_block_begin(&C, &region, __func__, UI_EMBOSS_NONE);
+  uiLayout *layout = UI_block_layout(
+      block, UI_LAYOUT_VERTICAL, UI_LAYOUT_PANEL, x, y, width, 1, 0, style);
+
+  Vector<ui::ContextPathItem> context_path = ed::space_node::context_path_for_space_node(C);
+  ui::template_breadcrumbs(*layout, context_path);
+
+  UI_block_layout_resolve(block, nullptr, nullptr);
+  UI_block_end(&C, block);
+  UI_block_draw(&C, block);
+
+  GPU_matrix_pop_projection();
 }
 
 static void snode_setup_v2d(SpaceNode *snode, ARegion *region, const float center[2])
@@ -2336,8 +2357,10 @@ void node_draw_space(const bContext *C, ARegion *region)
     }
   }
 
-  /* Tree path info. */
-  draw_tree_path(snode);
+  /* Draw context path. */
+  if (snode->edittree) {
+    draw_tree_path(*C, *region);
+  }
 
   /* Scrollers. */
   UI_view2d_scrollers_draw(v2d, nullptr);
diff --git a/source/blender/editors/space_node/node_intern.h b/source/blender/editors/space_node/node_intern.h
index f069038cc09..e7d9a12a52c 100644
--- a/source/blender/editors/space_node/node_intern.h
+++ b/source/blender/editors/space_node/node_intern.h
@@ -341,3 +341,11 @@ extern const char *node_context_dir[];
 #ifdef __cplusplus
 }
 #endif
+
+#ifdef __cplusplus
+#  include "BLI_vector.hh"
+#  include "UI_interface.hh"
+namespace blender::ed::space_node {
+Vector<ui::ContextPathItem> context_path_for_space_node(const bContext &C);
+}
+#endif
\ No newline at end of file
diff --git a/source/blender/editors/space_node/space_node.c b/source/blender/editors/space_node/space_node.c
index 8c015a56fa1..0b5d7cdda82 100644
--- a/source/blender/editors/space_node/space_node.c
+++ b/source/blender/editors/space_node/space_node.c
@@ -201,27 +201,6 @@ void ED_node_tree_path_get(SpaceNode *snode, char *value)
   }
 }
 
-void ED_node_tree_path_get_fixedbuf(SpaceNode *snode, char *value, int max_length)
-{
-  int size;
-
-  value[0] = '\0';
-  int i = 0;
-  LISTBASE_FOREACH_INDEX (bNodeTreePath *, path, &snode->treepath, i) {
-    if (i == 0) {
-      size = BLI_strncpy_rlen(value, path->display_name, max_length);
-    }
-    else {
-      size = BLI_snprintf_rlen(value, max_length, "/%s", path->display_name);
-    }
-    max_length -= size;
-    if (max_length <= 0) {
-      break;
-    }
-    value += size;
-  }
-}
-
 void ED_node_set_active_viewer_key(SpaceNode *snode)
 {
   bNodeTreePath *path = snode->treepath.last;