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>

2 files changed, 15 insertions, 3 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();
diff --git a/ui/qt/wlan_statistics_dialog.cpp b/ui/qt/wlan_statistics_dialog.cpp
index 4a3f18ccc9..b577a64f1f 100644
--- a/ui/qt/wlan_statistics_dialog.cpp
+++ b/ui/qt/wlan_statistics_dialog.cpp
@@ -127,10 +127,13 @@ public:
         }
         if (wlan_hdr->type != MGT_BEACON) packets_++;
     }
-    void draw(address *bssid, int num_packets _U_) {
-        if(packets_){
+    void draw(address *bssid, int num_packets) {
+        if(packets_ && num_packets > 0) {
             setData(col_pct_packets_, Qt::UserRole, QVariant::fromValue<double>(packets_ * 100.0 / num_packets));
             setData(col_pct_retry_, Qt::UserRole, QVariant::fromValue<double>(retry_ * 100.0 / packets_));
+        } else {
+            setData(col_pct_packets_, Qt::UserRole, QVariant::fromValue<double>(0));
+            setData(col_pct_retry_, Qt::UserRole, QVariant::fromValue<double>(0));
         }
         setText(col_beacons_, QString::number(sent_));
         setText(col_data_packets_, QString::number(received_));