Maybe fixing icon issue on MacOS

Author: Matthias Koefferlein

src/layui/layui/layWidgets.cc

@@ -707,6 +707,12 @@ LayerSelectionComboBox::do_update_layer_list ()
       int icon_width = iconSize ().width ();
       int icon_height = iconSize ().height ();
 
+#if QT_VERSION >= 0x050000
+      double dpr = devicePixelRatio ();
+#else
+      double dpr = 1.0;
+#endif
+
       LPIPairCompareOp cmp_op;
       std::map<std::pair<db::LayerProperties, int>, std::string, LPIPairCompareOp> name_for_layer (cmp_op);
       std::map<std::pair<db::LayerProperties, int>, QIcon, LPIPairCompareOp> icon_for_layer;
@@ -715,7 +721,7 @@ LayerSelectionComboBox::do_update_layer_list ()
         if (lp->cellview_index () == mp_private->cv_index && ! lp->has_children () && (mp_private->all_layers || lp->layer_index () >= 0) && lp->source (true).layer_props () != db::LayerProperties ()) {
           std::pair <db::LayerProperties, int> k (lp->source (true).layer_props (), lp->layer_index ());
           name_for_layer.insert (std::make_pair (k, lp->display_string (mp_private->view, true, true /*always show source*/)));
-          QIcon icon = QIcon (QPixmap::fromImage (mp_private->view->icon_for_layer (lp, icon_width, icon_height).to_image ()));
+          QIcon icon = QIcon (QPixmap::fromImage (mp_private->view->icon_for_layer (lp, icon_width, icon_height, dpr, 0, true).to_image ()));
           icon_for_layer.insert (std::make_pair (k, icon));
           mp_private->layers.push_back (k);
         }