Add documentation for Json wrapper

src/libtomahawk/utils/Json.h

@@ -26,10 +26,46 @@
 
 namespace TomahawkUtils
 {
-    /* QJson */
+     /**
+     * Convert a QObject instance to a QVariantMap by adding its properties
+     * as key-value pairs.
+     *
+     * @param object Object that shall be "serialised"
+     * @return All properties of the object stored as QVariantMap
+     */
     DLLEXPORT QVariantMap qobject2qvariant( const QObject* object );
+
+    /**
+     * Write out all key-value pairs into the respective properties of the
+     * given object.
+     *
+     * @param variant The key-value pairs that shall be stored in the object.
+     * @param object The destiation object where we store the key-value pairs of the map as properties.
+     */
     DLLEXPORT void qvariant2qobject( const QVariantMap& variant, QObject* object );
+
+    /**
+     * Parse the JSON string and return the result as a QVariant.
+     *
+     * @param jsonData The string containing the data as JSON.
+     * @param ok Set to true if the conversion was successful, otherwise false.
+     * @return After a successful conversion the parsed data either as QVariantMap or QVariantList.
+     */
     DLLEXPORT QVariant parseJson( const QByteArray& jsonData, bool* ok = 0 );
+
+   /**
+     * Convert a QVariant to a JSON representation.
+     *
+     * This function will accept Strings, Number, QVariantList and QVariantMaps
+     * as input types. Although Qt5's JSON implementation itself does not
+     * support the serialisation of QVariantHash, we will convert a QVariantHash
+     * to a QVariantMap but it is suggest to convert all QVariantHash to
+     * QVariantMap in your code than passing them here.
+     *
+     * @param variant The data to be serialised.
+     * @param ok Set to true if the conversion was successful, otherwise false.
+     * @return After a successful serialisation the data of the QVariant represented as JSON.
+     */
     DLLEXPORT QByteArray toJson( const QVariant &variant, bool* ok = 0 );
 }