Graph editor viewer UI token support (AcademySoftwareFoundation#2605)

This PR adds fallback token resolution logic to the Graph Editor and Viewer to display available tokens and their source in the UI.

For the Graph Editor, if the current element has no tokens, it will check the nodegraph, then the nodedef. For the Viewer, if a material has no tokens, it traverses upstream nodes and their definitions to collect tokens from nodedefs and nodegraphs.

This handles the cases outlined within the [token_graph.mtlx](https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/resources/Materials/TestSuite/stdlib/texture/token_graph.mtlx) and the [token_graph_material.mtlx](https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/resources/Materials/TestSuite/stdlib/texture/token_graph_material.mtlx) test cases.

Fixes #[AcademySoftwareFoundation#2611](AcademySoftwareFoundation#2611)

Author: xipaja

resources/Materials/TestSuite/stdlib/texture/token_graph.mtlx

@@ -21,7 +21,7 @@
     <output name="out" type="color3" nodename="tiledimage" />
   </nodegraph>
 
-  <!-- top level tokens are not support. bmp will be the found token -->
+  <!-- top level tokens are not support. png will be the found token -->
   <token name="Image_Extension" type="string" value="jpg" uiname="Image Extension" />
   <nodegraph name="Tokenized_Image_top_level">
     <tiledimage name="tiledimage" type="color3" nodedef="ND_tiledimage_color3">

source/MaterialXGraphEditor/Graph.cpp

@@ -3705,6 +3705,44 @@ void Graph::propertyEditor()
             }
             ImGui::Checkbox("Show all inputs", &_currUiNode->_showAllInputs);
         }
+      
+        // Find tokens within currUiNode
+        mx::ConstNodePtr node = _currUiNode->getNode();
+        if (node != nullptr)
+        {
+            mx::StringResolverPtr resolver = node->createStringResolver();
+            const mx::StringMap& tokens = resolver->getFilenameSubstitutions();
+
+            if (!tokens.empty())
+            {
+                ImGui::Text("Tokens");
+             
+                ImVec2 tableSize(0.0f, TEXT_BASE_HEIGHT * std::min(SCROLL_LINE_COUNT, static_cast<int>(tokens.size())));
+                bool haveTable = ImGui::BeginTable("tokens_node_table", 2, tableFlags, tableSize);
+                if (haveTable)
+                {
+                    ImGui::SetWindowFontScale(_fontScale);
+
+                    for (const auto& [token, value] : tokens)
+                    {
+                               
+                        ImGui::TableNextRow();
+                        ImGui::TableNextColumn();
+                        ImGui::PushID(&token);
+
+                        ImGui::Text("%s", token.c_str());
+                        ImGui::TableNextColumn();
+                        ImGui::Text("%s", value.c_str());
+
+                        ImGui::PopID();
+                    }
+                        
+                    ImGui::EndTable();
+                    ImGui::SetWindowFontScale(1.0f);
+                }
+            }
+        }
+
         ImGui::PopStyleColor();
         ImGui::PopStyleColor();
 

source/MaterialXView/Editor.cpp

@@ -711,6 +711,36 @@ void PropertyEditor::updateContents(Viewer* viewer)
             }
         }
     }
+
+    mx::StringResolverPtr resolver = elem->createStringResolver();
+    if (node != nullptr)
+    {
+        // Find tokens upstream of Material
+        for (mx::Edge edge : node->traverseGraph())
+        {
+            if (edge.getUpstreamElement())
+            {
+                resolver->addTokenSubstitutions(edge.getUpstreamElement()->asA<mx::Element>());
+            }
+        }   
+    }
+
+    const mx::StringMap& tokensMap = resolver->getFilenameSubstitutions();
+    if (!tokensMap.empty())
+    {
+        ng::ref<ng::Label> tokenLabel = new ng::Label(_container, "Tokens");
+        tokenLabel->set_font_size(20);
+        tokenLabel->set_font("sans-bold");
+
+        ng::ref<ng::Widget> tokensGroup = new ng::Widget(_container);
+        tokensGroup->set_layout(new ng::GroupLayout(5, 0, 0, 20));
+
+        for (const auto& [token, value] : tokensMap)
+        {
+            new ng::Label(tokensGroup, token + ": " + value);
+        }
+    }
+
     if (!addedItems)
     {
         new ng::Label(_container, "No Shader Inputs");