[KPhotoAlbum] Improvements to delete

[Robert L Krawitz]

   From: "Jesper K. Pedersen" <blackie at blackie.dk>
   Date: Sat, 11 Feb 2006 12:25:02 -0500

   Thanks for the analysis. For your pleasure and information, I chose
   a sligtly different approach to solve the problem than you.

   The real problem lay in the fact that we do lookup for all the
   images in a list, which gives us complexity O(n^2). I exchanged the
   list with a set (see set.h), and that gives us complexity O(n).

As long as the set operations are fast, that's a sensible approach.

   On Thursday 09 February 2006 22:16, Robert L Krawitz wrote:
   | This speeds up delete dramatically (particularly if you cancel out of
   | the delete!)
   |
   | --- mainview.cpp~       2006-01-28 23:38:52.000000000 -0500
   | +++ mainview.cpp        2006-02-09 22:08:10.000000000 -0500
   | @@ -369,19 +369,21 @@
   |
   |  void MainView::slotDeleteSelected()
   |  {
   | +    QStringList selectedList = selected();
   |      if ( ! _deleteDialog )
   |          _deleteDialog = new DeleteDialog( this );
   | -    if ( _deleteDialog->exec( selected() ) == QDialog::Accepted )
   | +    if ( _deleteDialog->exec( selected() ) == QDialog::Accepted &&
   | +        selectedList.count() > 0) {
   |          setDirty( true );
   |
   | -    QStringList images = _thumbnailView->imageList();
   | -    QStringList allImages = ImageDB::instance()->images();
   | -    QStringList newSet;
   | -    for( QStringList::Iterator it = images.begin(); it != images.end();
   | ++it ) { -        if ( allImages.contains( *it ) )
   | -            newSet.append(*it);
   | +       QStringList images = _thumbnailView->imageList();
   | +       QStringList newSet;
   | +       for( QStringList::Iterator it = images.begin(); it != images.end();
   | ++it ) { +           if ( ! selectedList.contains( *it ) )
   | +                newSet.append(*it);
   | +       }
   | +       showThumbNails( newSet );
   |      }
   | -    showThumbNails( newSet );
   |  }
   |
   |
   | This gets rid of the silly warning if you try to delete a file that
   | doesn't exist (there's no good reason for warning in that case -- if
   | the file does already exist and the delete fails, the user certainly
   | should be warned!)
   |
   | --- deletedialog.cpp~   2006-01-28 23:38:52.000000000 -0500
   | +++ deletedialog.cpp    2006-02-09 22:12:44.000000000 -0500
   | @@ -65,7 +65,7 @@
   |          for( QStringList::ConstIterator it = _list.begin(); it !=
   | _list.end(); ++it ) { Util::removeThumbNail( *it );
   |              if ( ImageDB::instance()->info(*it)->imageOnDisk() ) { //
   | PENDING(blackie) we don't need imageinfo for this -                bool ok
   | = QFile( *it ).remove();
   | +                bool ok = !(QFile( *it ).exists()) ||  QFile( *it
   | ).remove(); if ( !ok ) {
   |                      KMessageBox::error( this, i18n("Unable to delete file
   | '%1'.").arg(*it), i18n("Error Deleting Files") );
   |
   | _______________________________________________
   | KPhotoAlbum mailing list
   | KPhotoAlbum at mail.kdab.net
   | http://mail.kdab.net/mailman/listinfo/kphotoalbum

   -- 
   Jesper K. Pedersen          |  Klarälvdalens Datakonsult
   Senior Software Engineer    |  www.klaralvdalens-datakonsult.se
   Prinsensgade 4a st.         |
   9800 Hjørring               |  Platform-independent
   Denmark                     |  software solutions