Hi, > Hi, > > I am starting to use mapnik with python and I have two questions: > > 1. Is there any datasource for mysql? > 2. Does exist a way to implement a datasource from python? >
The short answer is no to both, the longer one: 1. No, but you can implement MySQL data source in c++ . postgis,input can be a good starting point. 2. No, not at the moment. I agree it would be nice to be able to create Features/Geometries in Python. \ Cheers Artem > Thanks > > > El sáb, 14-06-2008 a las 02:25 +0200, Frederik Ramm escribió: >> Hi, >> >>>> Fred, Image32 does appear to be a pretty basic type >>>> (yes it's a mapnik class). If you're using C++ at all (or have >>>> the option to) I'd highly suggest you take a look at CImg... >>> >>> I'm using C++ and tend to stick what I already know (which is >>> GD and ImageMagick) but will check out CImg as well. >> >> Ok here's an update on what I've achieved so far. >> >> I have successfully used the cairo_renderer to draw onto a cairo >> surface >> which I subsequently rendered onto a new surface with scaling >> applied. >> This gives the desired result, with good quality, but unfortunately >> it >> is very slow (full execution time for rendering a 2° by 2° OSM styled >> map onto an 800x600 canvas - 15 seconds with cairo compared to 7 >> seconds >> with AGG). >> >> Actually applying the scaling to the cairo context used internally by >> the cairo_renderer, instead of scaling the resulting surface like I >> do, >> gains you a second but still the performance makes this unsuitable >> for >> my task. >> >> So I went back to the idea of using the original AGG render result >> and >> somehow scale that bitmap before returning it. Unfortunately, >> neither GD >> nor ImageMagick nor CImg have a convenient method to work with the >> kind >> of interleaved data store that backs the Image32 type (GD stores an >> array of interleaved three-byte pixels and the alpha value is >> elsewhere; >> ImageMagick has 64bit pixels; CImg uses a non-interlaved four byte >> store, while Image32 is an interleaved four byte store). Somewhat >> exasperated, I did the ugliest thing and had Mapnik write the image >> to >> disk for me, then called ImageMagick externally to scale the PNG >> file, >> then read it back in - which adds an extra half second to >> processing but >> at least works for testing. >> >> Since I don't need top-notch image quality for this corner case where >> the WMS client requests non-matching width/height, I will perhaps try >> the homebrew way of simply duplicating or dropping full lines in >> the PNG >> output to achieve the desired height. I have to roll my own PNG >> output >> from Image32 anyway because (unlike cairo which supports callback >> output) the existing Mapnik code will only create PNG files on disk >> and >> not in memory, where I need them if I want to return them to the >> user. >> >> If anyone in the know reads this and has some insight to share, do >> speak up. >> >> Bye >> Frederik >> > _______________________________________________ > Mapnik-users mailing list > [email protected] > https://lists.berlios.de/mailman/listinfo/mapnik-users _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
