gui: fix heatmap and render thread issues on database reload

Call destroyMap() in HeatMapDataSource::setChip when the chip changes
to invalidate cached heatmap data. Fix the MapSettingMultiChoice getter
type from const std::string to std::string to avoid std::function
double-wrapping. Stop render threads in saveSettings before serializing
renderer state to prevent races with the render thread on exit.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Eder Monteiro <emrmonteiro@precisioninno.com>

Author: eder-matheus

src/gui/include/gui/heatMap.h

@@ -53,7 +53,7 @@ class HeatMapDataSource
     std::string name;
     std::string label;
     std::function<std::vector<std::string>()> choices;
-    std::function<const std::string()> getter;
+    std::function<std::string()> getter;
     std::function<void(const std::string&)> setter;
   };
 
@@ -92,7 +92,13 @@ class HeatMapDataSource
 
   void registerHeatMap();
 
-  virtual void setChip(odb::dbChip* chip) { chip_ = chip; }
+  virtual void setChip(odb::dbChip* chip)
+  {
+    if (chip_ != chip) {
+      destroyMap();
+    }
+    chip_ = chip;
+  }
   void setUseDBU(bool use_dbu) { use_dbu_ = use_dbu; }
   bool getUseDBU() const { return use_dbu_; }
 

src/gui/src/heatMapCore.cpp

@@ -397,7 +397,6 @@ Renderer::Settings HeatMapDataSource::getSettings() const
       settings[set.name] = set.getter();
     }
   }
-
   return settings;
 }
 

src/gui/src/mainWindow.cpp

@@ -1629,6 +1629,10 @@ void MainWindow::selectHighlightConnectedBufferTrees(bool select_flag,
 
 void MainWindow::saveSettings()
 {
+  // Stop render threads before saving settings to avoid races
+  // between the render thread and the main thread.
+  viewers_->exit();
+
   QSettings settings("OpenRoad Project", "openroad");
   settings.beginGroup("main");
   settings.setValue("geometry", saveGeometry());