kstars/kstars/filesource.h

   1 /***************************************************************************
   2                           filesource.h  -  description
   3                              -------------------
   4     begin                : Son Feb 10 2002
   5     copyright            : (C) 2002 by Thomas Kabelmann
   6     email                : tk78@gmx.de
   7  ***************************************************************************/
   8
   9 /***************************************************************************
  10  *                                                                         *
  11  *   This program is free software; you can redistribute it and/or modify  *
  12  *   it under the terms of the GNU General Public License as published by  *
  13  *   the Free Software Foundation; either version 2 of the License, or     *
  14  *   (at your option) any later version.                                   *
  15  *                                                                         *
  16  ***************************************************************************/
  17
  18 #ifndef FILESOURCE_H
  19 #define FILESOURCE_H
  20
  21 /**@class FileSource
  22         *FileSource is an asynchronous class for reloading star data while running
  23         *the program. It's basing on QDataSource class and implements the function
  24         *for reading a file step by step and send these data to an QDataSink object.
  25         *KStarsData uses this class for asynchronous io.
  26         *@author Thomas Kabelmann
  27         *@version 1.0
  28         */
  29
  30 #include <qasyncio.h>
  31 #include <qstring.h>
  32
  33 class KStarsData;
  34 class KSFileReader;
  35
  36 class FileSource : public QDataSource  {
  37
  38         public:
  39         /**constructor needs an KStarsData object, a file name and the new magnitude
  40                 */
  41                 FileSource( KStarsData *ksdata, float magnitude );
  42
  43         /** destructor */
  44                 ~FileSource();
  45
  46         /**send a value indicating whether the object is ready to send data.
  47                 *@return 1 if data is ready to send; return -1 if the stream is finished.
  48                 */
  49                 int readyToSend();
  50
  51         /**Is this object rewindable?
  52                 *@return false, because it's not needed to rewind.
  53                 */
  54                 bool rewindable() { return false; }
  55
  56         /**The function for sending data to an QDataSink object. Here will all data
  57                 *operations defined. Because this function is virtual, we need a second int
  58                 *parameter, but we don't use it, so it's unnamed.
  59                 *@p sink pointer to the QDataSink object which will receive the data stream
  60                 */
  61                 void sendTo( QDataSink *sink, int );
  62
  63         /**@return current magnitude to load (always returns maxMagnitude)
  64                 */
  65                 float magnitude() { return maxMagnitude; }
  66
  67         private:
  68
  69                 bool readingData;
  70
  71                 KSFileReader *fileReader;
  72
  73                 // which sao file should be opened and which line
  74                 int fileNumber, lineNumber;
  75
  76                 // counts blocksize
  77                 int counter;
  78
  79                 // new magnitude to load
  80                 float maxMagnitude;
  81
  82                 KStarsData *data;
  83
  84         /**maxLines defines how many lines in data file should be read and
  85                 *send to QDataSink. This is only needed if a data block is longer
  86                 *than the max defined lines. I figured out this value of 500
  87                 *on a fast system, so if it is to high the value might be decreased.
  88                 *A high value means faster reloading but perhaps on slow systems this
  89                 *might interrupt the main event loop.
  90                 *A low value needs longer to reload data, but it doesn't interrupt the
  91                 *main event loop (it's smoother).
  92                 *But it's important to know that 500 lines to read is very fast, but
  93                 *appending to QList in StarDataSink will take the most time and this
  94                 *will also defined with this value.
  95                 */
  96                 #define maxLines 500
  97
  98         /**The loaded data will stored in a string array and a pointer to first
  99                 *object in array will send to StarDataSink.
 100                 */
 101                 QString stringArray[ maxLines ];
 102
 103 };
 104
 105 #endif