wlan_statistics_dialog (Qt): Fix display when there is no packets_

Make sure we don't pass an invalid value to PercentBarDelegate. Make
sure PercentBarDelegate handles invalid values more gracefully.

Change-Id: I18f07542be3432d0fcf5dff479eef2ea4d5e7931
Reviewed-on: https://code.wireshark.org/review/18276
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Roland Knall <rknall@gmail.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/ui/qt/percent_bar_delegate.cpp b/ui/qt/percent_bar_delegate.cpp
index 31555aec38..2a8ea0b2f2 100644
--- a/ui/qt/percent_bar_delegate.cpp
+++ b/ui/qt/percent_bar_delegate.cpp
@@ -47,6 +47,16 @@ void PercentBarDelegate::paint(QPainter *painter, const QStyleOptionViewItem &op
         return;
     }
 
+    // If our value is out range our caller has a bug. Clamp the graph and
+    // Print the numeric value so that the bug is obvious.
+    QString pct_str = QString::number(value, 'f', 1);
+    if (value < 0) {
+        value = 0;
+    }
+    if (value > 100.0) {
+        value = 100.0;
+    }
+
     if (QApplication::style()->objectName().contains("vista")) {
         // QWindowsVistaStyle::drawControl does this internally. Unfortunately there
         // doesn't appear to be a more general way to do this.
@@ -80,7 +90,6 @@ void PercentBarDelegate::paint(QPainter *painter, const QStyleOptionViewItem &op
     painter->restore();
 
     painter->save();
-    QString pct_str = QString::number(value, 'f', 1);
     painter->setPen(text_color);
     painter->drawText(option.rect, Qt::AlignCenter, pct_str);
     painter->restore();