Several months ago, I wrote a stock quote lens using Michael Hall‘s Singlet. After installing Quantal in September, I started playing with the preview feature in lenses and I really liked it, so I got motivated to add it to my lens. Turns out, it’s super easy. During the process, I also added real charts for the preview icons and fixed a bug when displaying news stories (they were missing the publication date).
First a quick look at the new graphs and previews, then I’ll go over the code.
The preview mode offers two buttons for stock quotes, the first one “More Info” takes you to the standard stock quote page. The second one, Interactive Chart, takes you to a large interactive stock chart, both at Yahoo Finance.
If you want to install the new version with quotes, you need version 0.6 or later. You can get them from the Scopes Packagers PPA, I’ve uploaded versions for Precise, Quantal, and Raring.
Now, let’s look at the code, you can find it here, or just branch it with: bzr branch lp:~mfisch/onehundredscopes/unity-stock-ticker-lens. The relevant changes are in revision 11, look at the preview function in the scope code (yahoostock-scope). I’ve simplified what’s in my code some to make it easier to follow:
def preview(self, result_item, result_model): preview = Unity.GenericPreview.new(result_item['title'], result_item['description'], None) preview.props.image_source_uri = 'http://chart.finance.yahoo.com/t?s=%s&lang=en-US®ion=US&width=380&height=380' % result_item['title'] open_chart = Unity.PreviewAction.new("open_chart", "Interactive Chart", None) open_chart.connect('activated', self.open_chart) preview.add_action(open_chart) return preview
The first two lines setup the preview, the first one sets the large font title and the smaller font text. The second line sets the large preview image. The open_chart lines define an action, which becomes a button in the UI. The button text is “Interactive Chart” and the button action is a function called open_chart. The open_chart function (not listed, but available in the bzr branch munges the inbound URL some and then opens a webbrowser to the Yahoo interactive chart page.
And that’s it! Very simple! I had this up and running in about 30 minutes, while watching The Pacific on TV,
You can read more about previews in Singlet 0.3 in Michael Hall’s blog post about it. Special thanks to Chris Wayne for his git hub lens which was inspiration for these changes. You can look at Chris’s code for some other examples, his may be easier to follow than mine.