Qt+extcap: Add editable extcap selectors.

Add an "editselector" argument type, which lets the user override a
predefined selection list with a custom value.

doc/extcap.adoc

@@ -71,6 +71,7 @@ Argument type for UI filtering for raw, or UI type for selector:
     long (may include scientific / special notation)
     float
     selector (display selector table, all values as strings)
+    editselector (selector table which can be overridden, all values as strings)
     boolean (display checkbox)
     radio (display group of radio buttons with provided values, all values as strings)
     fileselect (display a dialog to select a file from the filesystem, value as string)

docbook/wsdg_src/WSDG_chapter_capture.adoc

@@ -285,10 +285,11 @@ When _mustexist=false_ is used, the GUI shows the user a file dialog for saving
 arg {number=3}{call=--logfile}{display=Logfile}{tooltip=A file for log messages}{type=fileselect}{mustexist=false}
 ----
 
-_selector_, _radio_, _multicheck_::
+_selector_, __editselector__, _radio_, _multicheck_::
 Option fields where the user may choose from one or more options.
 If _parent_ is provided for the value items, the option fields for _multicheck_ and _selector_ are presented in a tree-like structure.
-_selector_ and _radio_ values must present a default value, which will be the value provided to the extcap binary for this argument
+_selector_ and _radio_ values must present a default value, which will be the value provided to the extcap binary for this argument.
+_editselector_ option fields let the user select from a list of items or enter a custom value.
 +
 [source,python]
 ----

extcap_parser.c

@@ -519,6 +519,8 @@ static extcap_arg *extcap_parse_arg_sentence(GList *args, extcap_token_sentence
             target_arg->arg_type = EXTCAP_ARG_BOOLFLAG;
         } else if (g_ascii_strcasecmp(param_value, "selector") == 0) {
             target_arg->arg_type = EXTCAP_ARG_SELECTOR;
+        } else if (g_ascii_strcasecmp(param_value, "editselector") == 0) {
+            target_arg->arg_type = EXTCAP_ARG_EDIT_SELECTOR;
         } else if (g_ascii_strcasecmp(param_value, "radio") == 0) {
             target_arg->arg_type = EXTCAP_ARG_RADIO;
         } else if (g_ascii_strcasecmp(param_value, "string") == 0) {

extcap_parser.h

@@ -39,6 +39,7 @@ typedef enum {
     EXTCAP_ARG_PASSWORD,
     /* Complex GUI types which are populated with value sentences */
     EXTCAP_ARG_SELECTOR,
+    EXTCAP_ARG_EDIT_SELECTOR,
     EXTCAP_ARG_RADIO,
     EXTCAP_ARG_MULTICHECK,
     EXTCAP_ARG_FILESELECT,

ui/qt/extcap_argument.cpp

@@ -263,6 +263,49 @@ void ExtArgSelector::setDefaultValue()
 }
 
 
+ExtArgEditSelector::ExtArgEditSelector(extcap_arg * argument, QObject * parent) :
+        ExtArgSelector(argument, parent) {}
+
+QWidget * ExtArgEditSelector::createEditor(QWidget * parent)
+{
+    QWidget *editor = ExtArgSelector::createEditor(parent);
+
+    boxSelection->setEditable(true);
+    boxSelection->setInsertPolicy(QComboBox::NoInsert);
+
+    return editor;
+}
+
+QString ExtArgEditSelector::value()
+{
+    if (boxSelection == nullptr) {
+        return QString();
+    }
+
+    return boxSelection->currentText();
+}
+
+void ExtArgEditSelector::setDefaultValue()
+{
+    ExtArgSelector::setDefaultValue();
+
+    if (boxSelection == nullptr) {
+        return;
+    }
+
+    const char *prefval = (_argument->pref_valptr && strlen(*_argument->pref_valptr)) ? *_argument->pref_valptr : NULL;
+    QString stored(prefval ? prefval : "");
+    QVariant data = boxSelection->currentData();
+
+    if (data.toString() != stored) {
+        // Apparently createEditor hasn't been called at this point.
+        boxSelection->setEditable(true);
+        boxSelection->setInsertPolicy(QComboBox::NoInsert);
+        boxSelection->setEditText(stored);
+    }
+
+}
+
 
 ExtArgRadio::ExtArgRadio(extcap_arg * argument, QObject * parent) :
         ExtcapArgument(argument, parent), selectorGroup(0), callStrings(0) {}
@@ -943,6 +986,8 @@ ExtcapArgument * ExtcapArgument::create(extcap_arg * argument, QObject *parent)
         result = new ExtArgBool(argument, parent);
     else if (argument->arg_type == EXTCAP_ARG_SELECTOR)
         result = new ExtArgSelector(argument, parent);
+    else if (argument->arg_type == EXTCAP_ARG_EDIT_SELECTOR)
+        result = new ExtArgEditSelector(argument, parent);
     else if (argument->arg_type == EXTCAP_ARG_RADIO)
         result = new ExtArgRadio(argument, parent);
     else if (argument->arg_type == EXTCAP_ARG_FILESELECT)

ui/qt/extcap_argument.h

@@ -182,8 +182,7 @@ public:
 public Q_SLOTS:
     virtual void setDefaultValue();
 
-private:
-
+protected:
     QComboBox * boxSelection;
 
 private Q_SLOTS:
@@ -192,6 +191,19 @@ private Q_SLOTS:
 };
 
 
+class ExtArgEditSelector : public ExtArgSelector
+{
+    Q_OBJECT
+
+public:
+    ExtArgEditSelector(extcap_arg * argument, QObject *parent = Q_NULLPTR);
+    virtual QWidget * createEditor(QWidget * parent);
+    virtual QString value();
+
+public Q_SLOTS:
+    virtual void setDefaultValue();
+};
+
 
 class ExtArgRadio : public ExtcapArgument
 {