完善下载页面按钮的功能

inc/spkdownload.h

@@ -27,6 +27,7 @@ class SpkDownloadMgr : public QObject
       FailCannotCreateFile, ///< Failed because destination file cannot be created
       FailNoVaibleServer, ///< Failed because no server provides file size or download stalled on
                           ///< all of them
+      FailCancel, ///< User has cancelled the task
       Fail
     };
 
@@ -67,6 +68,8 @@ class SpkDownloadMgr : public QObject
      */
     static RemoteFileInfo GetRemoteFileInfo(QUrl url);
 
+    QString GetDestFilePath(QString downloadPath);
+
   private:
     QList<QString> mServers; ///< Multithreaded download