From 849e6493f81a2961a4ed5588d1ce94f3d7760418 Mon Sep 17 00:00:00 2001
From: harrierpigeon <college.joseph.robertson@gmail.com>
Date: Thu, 6 Aug 2026 03:54:19 -0500
Subject: [PATCH] Belt brim: offer "Leading edge only" only on belt printers

"Leading edge only" describes where a part meets a moving belt, so it has no
meaning on a fixed bed and should not clutter the Brim type dropdown there.

Filtered the same way support_style and wipe_tower_wall_type already are a few
lines above in TabPrint::toggle_options(): the field holds its own copy of the
option definition, and Choice maps the combobox selection straight onto that
copy's enum_values, so rewriting the values, the labels and the combobox items
together keeps the mapping correct.

The entry is kept when it is the current value, so opening a project that uses
it on a non-belt printer cannot leave the control displaying an option it does
not offer - which would silently rewrite the setting on the next edit.
Print::validate() already warns that it prints as an ordinary outer brim there.

Matches the scope of the existing precedents: the per-object override panel is
not filtered.
---
 src/slic3r/GUI/Tab.cpp | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 7a4cefe4fa..5508b6e099 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -3227,6 +3227,41 @@ void TabPrint::toggle_options()
         cb->SetValue(n);
     }
 
+    // "Leading edge only" describes where a part meets a moving belt, so it is offered only
+    // on belt printers.  Same pattern as support_style above: the field owns a copy of the
+    // option definition, and Choice maps the combobox selection straight onto that copy's
+    // enum_values, so rewriting both together keeps the mapping correct.
+    field = m_active_page->get_field("brim_type");
+    if (auto choice = dynamic_cast<Choice *>(field)) {
+        bool is_belt_printer = false;
+        if (m_preset_bundle) {
+            const auto *belt_opt = m_preset_bundle->printers.get_edited_preset().config.option<ConfigOptionBool>("belt_printer");
+            if (belt_opt)
+                is_belt_printer = belt_opt->value;
+        }
+        auto        def = print_config_def.get("brim_type");
+        const auto  current = m_config->opt_enum<BrimType>("brim_type");
+        auto       &opt = const_cast<ConfigOptionDef &>(field->m_opt);
+        auto        cb  = dynamic_cast<ComboBox *>(choice->window);
+        if (cb != nullptr) {
+            auto n = cb->GetValue();
+            opt.enum_values.clear();
+            opt.enum_labels.clear();
+            cb->Clear();
+            for (size_t i = 0; i < def->enum_values.size(); ++ i) {
+                // Keep the entry if it is already selected, so switching to a non-belt
+                // printer cannot leave the control showing a value it does not offer.
+                if (def->enum_values[i] == "leading_edge_only" && ! is_belt_printer
+                    && current != btLeadingEdgeOnly)
+                    continue;
+                opt.enum_values.push_back(def->enum_values[i]);
+                opt.enum_labels.push_back(def->enum_labels[i]);
+                cb->Append(_(def->enum_labels[i]));
+            }
+            cb->SetValue(n);
+        }
+    }
+
     // BBL printers do not support cone wipe tower
     field = m_active_page->get_field("wipe_tower_wall_type");
     if (auto choice = dynamic_cast<Choice*>(field)) {