Current Line Revisited

A few days ago I described my progress on editview, but just today I stumbled on a big improvement. Here's how it looks now.

If you click through you find that's a quite large image. The reason is, it's from a retina macbook so what looks like quite a modest window, when captured, comes out 1500px wide. Here are the improvements from the prior version.

• The current-line highlight now extends the full width of the window. Before it was only as long as the text on that line.
• Scanno highlighting (the lilac highlights) is implemented. You can load a file of common OCR errors and they are marked wherever they appear.
• Spellcheck highlighting (wiggly magenta underlines) is implemented, including alternate dictionaries. Note the line with <span lang='fr_FR'>; those words get checked against the french dictionary instead of the default one.

Pretty much all that remains is to finish an automated unit test of these features. I have one simple unit test driver now that uses QTest to automate a number of keystrokes, but I need to also automate exercising a pop-up context menu. That'll be an adventure I'm sure.

In the previous post I kvetched about how, although a QTextBlock has a format (QTextBlockFormat), you could only interrogate it, and modifying it didn't change the format. As a result, what I expected would be a simple way to set a current-line highlight, by setting the background brush of the current text block, didn't work.

Then today, browsing around the QTextCursor documentation, what should my eye fall upon but a setBlockFormat method! You can ask a QTextBlock for its format, but in order to set it, you have to aim a QTextCursor at that block, and then tell the cursor to set the block's format.

Bizarre.

Well, at any rate, not how I'd have designed it. But I didn't, so...

So I realized that my previous method of highlighting the current line using the extraSelections mechanism was over-complicated. I changed the logic to set a background brush on the current block. The cursor-moved logic now reads as follows:

Note: The following is still not the correct way to set a current-line highlight. Do not emulate this code. See this post for the problem with it and a later post for the correct approach.

    def _cursor_moved(self):
        tc = QTextCursor(self.Editor.textCursor())
        self.ColNumber.setText(str(tc.positionInBlock()))
        tb = tc.block()
        if tb == self.last_text_block:
            return # still on same line, nothing more to do
        # Fill in line-number widget, line #s are origin-1
        self.LineNumber.setText(str(tb.blockNumber()+1))
        # Fill in the image name and folio widgets
        pn = self.page_model.page_index(tc.position())
        if pn is not None : # the page model has info on this position
            self.ImageFilename.setText(self.page_model.filename(pn))
            self.Folio.setText(self.page_model.folio_string(pn))
        else: # no image data, or cursor is above page 1
            self.ImageFilename.setText('')
            self.Folio.setText('')
        # clear any highlight on the previous current line
        self.last_cursor.setBlockFormat(self.normal_line_fmt)
        # remember this new current line
        self.last_cursor = tc
        self.last_text_block = tb
        # and set its highlight
        tc.setBlockFormat(self.current_line_fmt)