How to use progress dialog?

[Phssthpok]

I'm trying to create a UI plugin which processes selected books. All is well, but I end up with a loop of the form:

for book in book_list:
    ... do stuff ...

which does the work successfully enough, but tells me nothing until it finishes.

What I'd like is to have a blocking progress dialog that goes from 0 to len(book_list), updating each time around the loop. The only code sample I can find uses ProgressDialog and seems to involve lots of complication with WorkerThreads and suchlike. Maybe this is the easiest way to do it, maybe not... but can anyone give me some pointers on how to write minimal code to do what I want?

[jackie_w]

I remember going through this exact same learning process. Here's some minimal boiler-plate code for running a modal QProgressDialog with a Cancel button in a calibre User Interface plugin:

Spoiler:

from PyQt5.Qt import (QProgressDialog, QTimer)

class MyProgressDialog(QProgressDialog):

    def __init__(self, gui, book_ids, arg1, arg2, ...):
        self.total_books = len(book_ids)
        QProgressDialog.__init__(self, '', 'Cancel', 0, self.total_books, gui)
        self.gui = gui
        self.book_ids = book_ids
        self.db = self.gui.current_db.new_api
        # ... etc etc ...
        
        self.i = 0
        
        self.setWindowTitle('blah, blah')
        icon = get_icons('images/plugin_icon.png')
        self.setWindowIcon(icon)
        
        QTimer.singleShot(0, self.do_book_action)
        self.exec_()

    def do_book_action(self):
        # Process a single book 
        if self.wasCanceled():
            return self.do_close()
        if self.i >= self.total_books:
            return self.do_close()
        
        # get data for current book, e.g.
        book_id = self.book_ids[self.i]
        title = self.db.field_for('title', book_id)
        pathtoepub = self.db.format(book_id, 'EPUB', as_path=True)
        # ... do stuff ...
        
        self.i += 1
        self.setLabelText('%d of %d' % (self.i, self.total_books))
        self.setValue(self.i)
        QTimer.singleShot(0, self.do_book_action)

    def do_close(self):
        self.hide()
        self.gui = None

Then to run the QProgressDialog from your main process:

dlg = MyProgressDialog(self.gui, self.book_ids, arg1, arg2, ...)
if dlg.wasCanceled():
    # do cancelled stuff
else:
    # do ran-to-completion stuff

[Phssthpok]

Originally Posted by jackie_w

I remember going through this exact same learning process. Here's some minimal boiler-plate code for running a modal QProgressDialog with a Cancel button in a calibre User Interface plugin:

Wow. If that's minimal, I'd hate to see something really complex!

Your help is much appreciated. A bit of expert guidance is much better than burrowing around in the code base looking for relevant snippets. Many thanks.

[davidfor]

An alternative is to grab the common_utils.py from one of kiwidudes plugins, or one of mine. This has a ProgressBar implementation. Here is how it is called:

        pb = ProgressBar(parent=self.gui, window_title=_("Removing annotations"), on_top=True)
        total_books = len(db.data)
        pb.set_maximum(total_books)
        pb.set_value(0)
        pb.set_label('{:^100}'.format(_("Scanning {0} of {1}").format(0, total_books)))
        pb.show()

        for i, record in enumerate(db.data.iterall()):
            pb.set_label('{:^100}'.format(_("Scanning {0} of {1}").format(i, total_books)))
            pb.increment()
            # Do whatever

        # Hide the progress bar
        pb.hide()

This is modal and can't be cancelled. Overall, probably no simpler as it relies on another class, but it feels simpler when actually using it.

[Phssthpok]

Originally Posted by davidfor

An alternative is to grab the common_utils.py from one of kiwidudes plugins, or one of mine. This has a ProgressBar implementation. Here is how it is called:

Many thanks, this looks much simpler! I'll do it next time (if there is one)...

Meanwhile I got my plugin working, but I don't have the time to polish it to make it more professional or error-resistant or to invent an icon for it. I'm attaching it here in case anyone wants to pick it up. What it does is to extract the tables of contents from selected ePub files to generate a CSV file. The idea was to make it easier for me to create a list of the short stories in my collection of anthologies. It incorporates a copy of https://pypi.org/project/Unidecode/ which is used to flatten all strings to ASCII, since Microsoft Excel seems to be allergic to UTF-8. The authors, titles, series and ToC entry are all converted to title case to make it easier to sort the output file. Hope someone will find a use for it besides me.

[Terisa de morgan]

Originally Posted by Phssthpok

Many thanks, this looks much simpler! I'll do it next time (if there is one)...

Meanwhile I got my plugin working, but I don't have the time to polish it to make it more professional or error-resistant or to invent an icon for it. I'm attaching it here in case anyone wants to pick it up. What it does is to extract the tables of contents from selected ePub files to generate a CSV file. The idea was to make it easier for me to create a list of the short stories in my collection of anthologies. It incorporates a copy of https://pypi.org/project/Unidecode/ which is used to flatten all strings to ASCII, since Microsoft Excel seems to be allergic to UTF-8. The authors, titles, series and ToC entry are all converted to title case to make it easier to sort the output file. Hope someone will find a use for it besides me.

Thank you very much, it's useful and comfortable for anthologies. It's in my calibre now If I was able to link it with ePubSplit....

[un_pogaz]

Sorry for the Necro-post, but the solution presented here is not the most optimal.
(Recursive call of a QTimer object in the function)
Too bad, but excepted this, Thanks to this thread, I was able to make my plugin, so I return the elevator.

My optimised version:

class CustomProgressDialog(QProgressDialog):
    
    def __init__(self, gui, book_ids):
        
        # DB API
        self.dbA = gui.current_db;
        # list of books id
        self.book_ids = book_ids;
        # Books count 
        self.book_count = len(self.book_ids);
        # Output book dic 
        self.books_dic = {};
        
        
        QProgressDialog.__init__(self, '', _('Cancel'), 0, self.book_count, gui);
        self.gui = gui;
        
        self.setWindowTitle(_('Progress Bar Name'));
        self.setWindowIcon(get_icon('images/plugin_icon.png'));
        
        self.setValue(0);
        self.setMinimumWidth(500);
        self.setMinimumDuration(100);
        
        self.setAutoClose(True);
        self.setAutoReset(False);
        
        self.hide();
        debug_print('Launch cleaning for {0} book.'.format(self.book_count));
        
        QTimer.singleShot(0, self._do_book_action);
        self.exec_();
        

    def close(self):
        self.dbA = None;
        self.books_dic = None;
        super(CleanerProgressDialog, self).close();

    def _do_book_action(self):
        
        self.setValue(0);
        
        for num, book_id in enumerate(self.book_ids, start=1):
            
            # update ProgressBar
            self.setValue(num);
            self.setLabelText(_('Book {0} of {1}').format(num, self.book_count));
            
            if self.book_count < 100:
                self.hide();
            else:
                self.show();
            
            if self.wasCanceled():
                self.close();
                return;
            
            #
            # Write your code here
            #
            #
            # Example
            
            miA = self.dbA.get_metadata(book_id, index_is_id=True, get_cover=False);
            comment = miA.get('comments');
            
            if comment is not None:
                self.books_dic[book_id] = CleanHTML(comment);
            #
            
        
        
        # end of your code if not canceled
        #
        # update the database library
        debug_print('ProgressDialog - Finish')
        debug_print('Update the database for {0} books...\n'.format(len(self.books_dic)));
        self.setLabelText(_('Update the library for {0} books...').format(len(self.books_dic)));
        
        self.dbA.new_api.set_field('comments', {id:self.books_dic[id] for id in self.books_dic.keys()});
        self.gui.iactions['Edit Metadata'].refresh_gui(self.books_dic.keys(), covers_changed=False);
        
        self.hide();
        return;