A couple of years ago, I developed growing-degree-day graphs to display codling moth development using *weeWX*.
o http://lacusveris.com/cydia/index.shtml I've been lurking on the weewx-user@googlegroups.com mailing list since then. Now, I'm finally ready to upgrade to *weeWX 4*, but I have some embroidery on the *python 2* code that I need to migrate to *python 3*. The magnitude of this task causes me to rethink my two-year-old approach. I cloned weeWX's *ImageGenerator* to access its own database, do its own growing-degree-day calculations, and generate its own Python Imaging Lib (PIL) images. This was not easy, but it was good enough ... then. Today, I'm bedeviled by notions that perhaps a more general approach would be nearly as easy (or hard) to achieve and might find utility for other *weeWX* applications. I guess you'd say I've fallen in love with *cheetah* and have taken to looking at all problems as templating applications. (Full disclosure: I seem to recall that, in a previous life, I was a SPERRY (Univac/UNiSYS) *SKEL* programmer.) ... so I ask this somewhat rhetorical question: Has there been any discussion about templating image generation through *cheetah*? I don't recall seeing any such discussion although I've seen some talk about others' frustrations with the limitations of *ImageGenerator* that mirror my own. Apparently the limitation of not being able to draw y-axis horizons has been lifted in *weeWX 4*, but limitations such as not being able to apply a second y-axis have not. To be sure, these limitations do not wreck the whole notion of *weeWX* or prevent users' workarounds like mine. On the other hand, they are examples only and surely don't exhaust the kinds of drawings that *ImageGenerator* in particular and PIL in general are NOT suited to. In my mind templating is for text only, so I'm mystified by what I'm asking. I can't feature what an imaging template would look like. On the other hand, I'm attracted to the notion of providing the growing-degree-day calculations through *get_extension_list* for use by *cheetah* in templates for ... generating images. o Perhaps images could be conjured in real-time using something like Google Chart's Visualization JavaScript APIs. Embedding the JavaScript (and data) in *cheetah* templates should be straightforward. This relies on (an indeterminate amount of) client horsepower being available to conjure the images. Also, the host site will wish to serve the (huge burden of) JavaScript on every access to avoid the appearance of cross-site scripting if possible. And it makes any such application dependent on a big, fickle outside software-development organization, which will be forever totally oblivious of the needs of the *weeWX* community among others. o Perhaps images could be conjured ahead of time as they are now using a *python* script, but the script itself would be a *cheetah* template. This would allow specially calculated data to be embedded. Images could then be uploaded and served to all comers without further modification until the next generation cycle with great savings of client-side and server-side resources. I'm not talking here about a generalized image-scripting language, but a *python* module that imports some handy special-purpose classes to make *weeWX* image generation fairly terse. Of course, images are deceptively simple things that hide excruciatingly detailed specs. Templating images will not be easy. It will not replace *ImageGenerator*, nor will it ever be for the faint-of-heart. I think generating a *python* image-generation script from *cheetah* has the advantage, though, of abstracting image generation from the database structure, reporting cycles, and *weeWX* implementation details. It would promote *weeWX* extensibility. Also, it opens the possibility of using plotting packages other than PIL. My inclination is to use *matplotlib* instead. Would those who have used both recommend something else? > If you can looke into the Seedes of Time, > And say, which Graine will grow, and which will not, > Speake then to me, who neyther begge, nor feare > Your fauors, nor your hate. I'd like my development not to conflict with previous or future *weeWX* development. Are there things that have been tried and abandoned that would impact image templating? Are there things in the works that would conflict with using *matplotlib*? Are there better options for image templating? -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/20200622123641.08a30e2c%40quixote.LacusVeris.com.
