Hi Michael,
On 29.06.06, Michael J Gruber wrote:
> That code worked around the time of PyX 0.6.3 but not much longer, I
> guess. Back then there was only PS which is why getting the PS fragment
> in translate_pt() worked that way. Now the canvas doesn't know whether
> it's going to be output as PS or PDF (or SVG...).
>
> I couldn't resist taking a shot at this. The attached code derives an
> insertstyle from graph.style.symbol which can be used in exactly the
> same way (this is different from the original code you mention) but
> inserts references in the PS instead of repeating the paths (following
> Andre's ideas). The savings are only on the PS side, not in python
> (there are canvas instances for each symbol being drawn).
Indeed.
> P.S.: Works with PyX 0.9 and SVN, not with 0.8.1
> P.P.S.: Code is not optimal, I know... I said "shot" ;)
Hey, not bad for a "shot".
> import cStringIO
> from pyx import *
> from pyx import pswriter
>
>
> class ref(canvas.canvasitem):
> """a stupid object insertable into a canvas; it needs to get all the
> information in the constructor"""
>
> def __init__(self, bbox, output, insertcanvas):
> self._bbox = bbox
> self._output = output
> self._insertcanvas = insertcanvas
>
> def bbox(self):
> return self._bbox
>
> def processPS(self, file, writer, context, registry, bbox):
You also have to update the bounding box, i.e.
bbox += self._bbox
> stringfile = cStringIO.StringIO()
> canvas._canvas.processPS(self._insertcanvas, stringfile, writer,
> context, registry, bbox)
> canvasproc = "gsave\nmatrix translate concat\n%sgrestore\n" %
> stringfile.getvalue()
> stringfile.close()
> registry.add(pswriter.PSdefinition(self._insertcanvas._id, "{\n" +
> canvasproc + "}"))
> file.write(self._output)
>
> # need help here
> def processPDF(self, file, writer, context, registry, bbox):
> raise NotImplementedError("ref canvasitem not implemented for PDF")
This goes along the lines of the PS case.
> class translateablecanvas(canvas._canvas):
> "a canvas which is efficiently translateable"
>
> def __init__(self, *args, **kwargs):
> canvas._canvas.__init__(self, *args, **kwargs)
> self._id = "symbol%d" % id(self)
>
> def translate_pt(self, x_pt, y_pt):
> """returns an insertable object which stores only the position and
> a reference to a prolog definition"""
> return ref(self.bbox().transformed(trafo.translate_pt(x_pt, y_pt)),
> "%g %g %s\n" % (x_pt, y_pt, self._id), self)
>
> class insertstyle(graph.style.symbol):
> """a graph style which calls a translate_pt method of the symbol to insert
> the result instead of calling the symbol to get a path to be drawn"""
>
> def selectstyle(self, privatedata, sharedata, graph, selectindex,
> selecttotal):
> privatedata.symbol = attr.selectattr(self.symbol, selectindex,
> selecttotal)
> privatedata.size_pt = unit.topt(attr.selectattr(self.size,
> selectindex, selecttotal))
> privatedata.insertcanvas = translateablecanvas()
> if self.symbolattrs is not None:
> privatedata.symbolattrs =
> attr.selectattrs(self.defaultsymbolattrs + self.symbolattrs, selectindex,
> selecttotal)
> else:
> privatedata.symbolattrs = None
> # stroke symbol on insertcanvas instead of symbolcanvas
> privatedata.symbol(privatedata.insertcanvas, 0, 0,
> privatedata.size_pt, privatedata.symbolattrs)
>
> def drawpoint(self, privatedata, sharedata, graph, point):
> if sharedata.vposvalid and privatedata.symbolattrs is not None:
> x_pt, y_pt = graph.vpos_pt(*sharedata.vpos)
> # use more efficient version of
> privatedata.symbolcanvas.insert(privatedata.insertcanvas,[trafo.translate_pt(x_pt,
> y_pt)])
>
> privatedata.symbolcanvas.insert(privatedata.insertcanvas.translate_pt(x_pt,
> y_pt))
>
> # key_pt is inherited from graph.style.symbol because reimplementing
> would save only one instance
Looks good.
Jörg
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