Unknown Unknowns

Yesterday I checked off pagedata as coded and tested. That's the last remaining support or background module needed to allow the editor to run. So the next thing to tackle is editview.py, the visual face of the editable document. I imagine this as a widget containing, principally, the QPlainTextEdit, and below it a bar with five items:

• A QLabel containing the filename of the document. This will change its font style with the document's modified status, becoming perhaps bold and magenta when a save is needed (for the document or for metadata).
• A QLabel with the current folio number—a label because it isn't changeable by the user; folios are changed by modifying the folio rules in the Pages panel.
• A numeric text entry field with room for four digits, displaying the scan image number corresponding to the cursor position. Editable; you can type a new number to effect a jump.
• A numeric text entry field with room for 6 digits, displaying the current text block (line) number, updating as the cursor moves. Again, type a new number to jump in the document.
• A QLabel with the current "column" number in the current line. Not editable. (Use an arrow key or just click.)

The latter four items of course update dynamically as the cursor moves, on receipt of the cursor movement signal from the editor.

So, if I understand all this (not difficult given it's almost the same as the status bar area of the PPQT main window), where are the Unknown Unknowns of the title? Hah. Well, they are actually known, at least by category, but just the same I feel anxious about launching into this phase. They are:

1. Using Designer

The Qt Designer is a graphic tool for designing a layout. I played with it a bit a couple of years ago when starting PPQT but ended up doing all my widget layouts "by hand" with explicit code like this (one of the simplest ones)

        vbox = QVBoxLayout()
        # the image gets a high stretch and default alignment, the text
        # label hugs the bottom and doesn't stretch at all.
        vbox.addWidget(self.txLabel,0,Qt.AlignBottom)
        vbox.addWidget(self.scarea,10)
        vbox.addLayout(zhbox,0)
        self.setLayout(vbox)

It makes the __init__() rawther lengthy. With Qt Designer you supposedly separate your UI design from the code. Designer saves a file of UI info; you apply a PyQt utility to convert this into something Python can execute; you import it and execute it. Covered in Summerfield's book and in the Qt docs. But I have lots of questions, like: how are signals connected between elements; how are elements connected to the methods that update them; how do label texts set in Designer get tr() translated; just generally a fog of unknowns. But I'd like to give it a try and the editview widget should be a good test case.

I18N

Does anybody use that term any more? "I18N" was a thing back in the 80s, late 70s even at IBM. (It means "Internationalization", duh.) Anyway, I've committed to PGDP Canada that PPQT2 will be translatable. Meaning every damn user-visible text string has to be wrapped in a tr() call. And editview is the first module that has user-visible strings (log messages don't count). The tr() call is all I know about. I am anxious about the whole rest of Qt's I18N system. How do the tr'd strings get collected; how does a translator create an alternate translation; will I have to start using Qt Make; what the heck is Locale and how do I control it for testing purposes... gaaahhh. Much reading to do.

GUI Unit Tests

With this first UI module I enter the world of automated UI testing and I haven't a clue. Well, one clue: QTest. There's a multi-chapter writeup on QTest and simulation of GUI events. I presume I'll use that. There are third-party packages like FrogLogic's "Squish" but they are very expensive, at least that on is. There are open-source packages for test automation but the ones I've seen are single-platform. So I suppose I'll be rolling my own using QTest. But I really have no idea.

So: the known Unknowns are just packed with unknown unknowns. I will be learning as I go, and I will be posting what I learn to this blog. Because that's one way I have of consolidating what I've learned. You're welcome.