How can I make a progress bar for Inkscape extension?

Question

My Inkscape extension written in Python does some extensive work that takes rather long time. How can I add a progress bar to show a current percent of processed data and "Cancel" button?

Answer 1

Create a call back function that is called after every operation.

Consider the following scenario. Imagine do_work is the method that is worker function. Create a function fallback that will be called after every operation for which you need a status update.

def do_work(*args, **kwargs, fallback=None):

    while processing_some_condition:

        # You will need to find a way to get your total data value
        total_data = total_value

        """
            Do your processing call with *args & **kwargs
            ....
            ....
            ....
            ....
        """

        elapsed_data = some_value  # Get the remaining amount of data

        if elapsed_data == total_data:
            break

        if fallback:
            fallback(elapsed, total)

    return your_result

Now, comes the question of how would you implement the fallback to show a progress bar. Here is a gist that explains that https://gist.github.com/ab9-er/843d1af20049e72e2016

Another simple fallback could be something as simple as this

def fallback(elapsed, total):
    tx_pc = lambda chunk, full: chunk * 100 / full
    print str(tx_pc(elapsed, total)) + "% operation completed"

    if tx_pc(elapsed, total) == 100:
        print "Operation complete: 100%"

Hope this helps. Let me know if it doesn't.