add fallback display for non-printable characters

qbolt/mainwindow.cpp

@@ -91,7 +91,27 @@ void MainWindow::openDatabase(QString file, bool readOnly)
 static const QString getDisplayName(const QByteArray &qba) {
     // FIXME the formatting isn't so great when control characters, etc. are used
     // A C-style escape display, or the unicode-replacement-character would be preferable
-    return QString::fromUtf8(qba);
+    QString ret(QString::fromUtf8(qba));
+
+    bool allPrintable = true;
+    for (auto i = ret.begin(), e = ret.end(); i != e; ++i) {
+        if (! i->isPrint()) {
+            allPrintable = false;
+            break;
+        }
+    }
+
+    if (allPrintable) {
+        return ret; // fine
+    }
+
+    // Some of the characters weren't printable.
+    // Build up a replacement string
+    QString replacement;
+    for (auto i = ret.begin(), e = ret.end(); i != e; ++i) {
+        replacement += i->isPrint() ? *i : QStringLiteral("\\u{%1}").arg(i->unicode());
+    }
+    return replacement;
 }
 
 void MainWindow::refreshBucketTree(QTreeWidgetItem* itm)