Qt: Set the LabelStack CSS only when it changes.

We call fillLabel repeatedly while loading a capture. Try to avoid
applying a style sheet when we do since it can affect performance.

Change-Id: I9ee188cb79f7cad340ba35b12011b82004ed8262
Reviewed-on: https://code.wireshark.org/review/16571
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Gerald Combs <gerald@wireshark.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/ui/qt/label_stack.cpp b/ui/qt/label_stack.cpp
index 1f0507f396..731a6f2ff5 100644
--- a/ui/qt/label_stack.cpp
+++ b/ui/qt/label_stack.cpp
@@ -77,7 +77,10 @@ void LabelStack::fillLabel() {
     }
 
     style_sheet += "}";
-    setStyleSheet(style_sheet);
+    if (styleSheet().size() != style_sheet.size()) {
+        // Can be computationally expensive.
+        setStyleSheet(style_sheet);
+    }
     setText(si.text);
 }