Show "No Available Printers" Instead of an Empty Printer Dropdown

A ComboBox with no items opened a one-row-high popup that DropDown never
paints, leaving a blank strip with stale pixels under the box. Don't open
the list when it is empty, and label the printer box in the print and
send-to-printer dialogs when no printer is available.

docs/HLSD/filament_id.md

@@ -350,11 +350,8 @@ identity default and translates nothing. `NetworkAgent` forwards both to the liv
 comparison sites below reach them through `wxGetApp().getAgent()` and leave an id untranslated
 while no agent is live. Whole documents are Bambu's business alone:
 `BBLPrinterAgent::to_orca_payload` and `from_orca_payload` rewrite every string under
-`tray_info_idx`, `filament_id`, `filamentId`, `cate` or `fila_id` at any depth; text that does not
-parse, or carries none of those keys, comes back unchanged. The last two are the H2C nozzle rack's:
-`cate` in the auto nozzle mapping request, `fila_id` in the rack status. A new Bambu message that
-carries a filament id under another key needs that key added to `filament_id_keys`, or the id
-crosses the boundary untranslated. The map is loaded once, lazily; a missing or malformed
+`tray_info_idx`, `filament_id` or `filamentId` at any depth; text that does not parse, or carries
+none of those keys, comes back unchanged. The map is loaded once, lazily; a missing or malformed
 file degrades to identity with a log line rather than failing.
 
 | Boundary | Where it translates |

src/slic3r/GUI/SelectMachine.cpp

@@ -4087,7 +4087,7 @@ void SelectMachineDialog::update_user_printer()
     {
         m_printer_last_select = "";
         update_select_layout(nullptr);
-        m_printer_box->GetPrinterComboBox()->SetTextLabel("");
+        m_printer_box->GetPrinterComboBox()->SetValue(_L("No available printers"));
     }
 
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << "for send task, current printer id =  " << m_printer_last_select << std::endl;

src/slic3r/GUI/SendToPrinter.cpp

@@ -1229,7 +1229,7 @@ void SendToPrinterDialog::update_user_printer()
     }
     else {
         m_printer_last_select = "";
-        m_comboBox_printer->SetTextLabel("");
+        m_comboBox_printer->SetValue(_L("No available printers"));
     }
 
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << "for send task, current printer id =  " << m_printer_last_select << std::endl;

src/slic3r/GUI/Widgets/ComboBox.cpp

@@ -287,7 +287,7 @@ void ComboBox::DoDeleteOneItem(unsigned int pos)
 
 void ComboBox::ForceDropdownOpen()
 {
-    if (!IsEnabled())
+    if (!IsEnabled() || items.empty())
         return;
 
     if (!drop_down) {
@@ -398,7 +398,7 @@ void ComboBox::mouseDown(wxMouseEvent &event)
     SetFocus();
     if (drop_down) {
         drop.Hide();
-    } else if (drop.HasDismissLongTime()) {
+    } else if (!items.empty() && drop.HasDismissLongTime()) { // DropDown paints nothing for an empty list
         drop.autoPosition();
         drop_down = true;
         drop.Popup(&drop);
@@ -426,7 +426,7 @@ void ComboBox::keyDown(wxKeyEvent& event)
         case WXK_SPACE:
             if (drop_down) {
                 drop.DismissAndNotify();
-            } else if (drop.HasDismissLongTime()) {
+            } else if (!items.empty() && drop.HasDismissLongTime()) {
                 drop.autoPosition();
                 drop_down = true;
                 drop.Popup();

src/slic3r/Utils/BBLPrinterAgent.cpp

@@ -7,8 +7,6 @@
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/DeviceCore/DevManager.h"
 
-#include <algorithm>
-#include <array>
 #include <boost/format.hpp>
 #include <boost/log/trivial.hpp>
 #include <boost/nowide/fstream.hpp>
@@ -18,7 +16,6 @@
 #include <cmath>
 #include <slic3r/GUI/DeviceManager.hpp>
 #include <string>
-#include <string_view>
 #include <utility>
 #include <vector>
 using json = nlohmann::json;
@@ -67,16 +64,12 @@ const BambuFilamentIdMap& bambu_filament_id_map()
     return map;
 }
 
-// Keys whose string value is a filament id. "cate" and "fila_id" are the H2C nozzle rack's: the
-// auto nozzle mapping request and the rack status in the push message.
-constexpr std::array<std::string_view, 5> filament_id_keys{"tray_info_idx", "filament_id", "filamentId", "cate", "fila_id"};
-
-// Rewrites every string under a filament id key, at any depth, in place.
+// Rewrites every string under "tray_info_idx", "filament_id" or "filamentId", at any depth, in place.
 void rewrite_filament_ids(json& j, const std::unordered_map<std::string, std::string>& map)
 {
     if (j.is_object()) {
         for (auto& [key, value] : j.items()) {
-            if (value.is_string() && std::find(filament_id_keys.begin(), filament_id_keys.end(), key) != filament_id_keys.end()) {
+            if (value.is_string() && (key == "tray_info_idx" || key == "filament_id" || key == "filamentId")) {
                 auto it = map.find(value.get_ref<const std::string&>());
                 if (it != map.end())
                     value = it->second;
@@ -91,8 +84,8 @@ void rewrite_filament_ids(json& j, const std::unordered_map<std::string, std::st
 // Text that does not parse as JSON, or that mentions none of the id keys, comes back byte-identical.
 std::string rewrite_filament_ids(std::string text, const std::unordered_map<std::string, std::string>& map)
 {
-    if (map.empty() || std::none_of(filament_id_keys.begin(), filament_id_keys.end(),
-                                    [&text](std::string_view key) { return text.find(key) != std::string::npos; }))
+    if (map.empty() || (text.find("tray_info_idx") == std::string::npos && text.find("filament_id") == std::string::npos &&
+                        text.find("filamentId") == std::string::npos))
         return text;                                        // nothing to map, skip the parse (moved, not copied)
     try {
         json j = json::parse(text);

tests/slic3rutils/test_bambu_filament_ids.cpp

@@ -81,24 +81,3 @@ TEST_CASE("Payload rewrite covers nested trays, calibration lists and mapping in
     CHECK(BBLPrinterAgent::from_orca_payload("not json") == "not json");
     CHECK(BBLPrinterAgent::from_orca_payload(R"({"print":{"command":"pushall"}})") == R"({"print":{"command":"pushall"}})");
 }
-
-TEST_CASE("Payload rewrite covers the nozzle rack status and the auto nozzle mapping request", "[BambuFilamentIds]")
-{
-    const ScopedRepoResourcesDir repo_resources;
-    const std::string petg_hf = orca_id_of("GFG96");
-
-    const std::string rack_status =
-        R"({"print":{"device":{"nozzle":{"info":[{"id":16,"fila_id":"GFG96","color_m":"FFFFFFFF"},{"id":17,"fila_id":"P22f54c9"}]}}}})";
-    json inbound = json::parse(BBLPrinterAgent::to_orca_payload(rack_status));
-    CHECK(inbound["print"]["device"]["nozzle"]["info"][0]["fila_id"] == petg_hf);
-    CHECK(inbound["print"]["device"]["nozzle"]["info"][1]["fila_id"] == "P22f54c9");    // user id: untouched
-
-    const std::string request = R"({"print":{"command":"get_auto_nozzle_mapping","ams_mapping":[65535,65024],)"
-                                R"("fila_info":[{"id":2,"cate":")" + petg_hf + R"(","color":"FFFFFFFF"}],)"
-                                R"("nozzle_info":[{"pos":16,"cate":")" + petg_hf + R"(","color":"FFFFFFFF"},{"pos":1,"cate":""}]}})";
-    json outbound = json::parse(BBLPrinterAgent::from_orca_payload(request));
-    CHECK(outbound["print"]["fila_info"][0]["cate"] == "GFG96");
-    CHECK(outbound["print"]["nozzle_info"][0]["cate"] == "GFG96");
-    CHECK(outbound["print"]["nozzle_info"][1]["cate"] == "");                         // empty nozzle
-    CHECK(outbound["print"]["ams_mapping"] == json::parse("[65535,65024]"));
-}