+
−import os
+
−
+
−from logilab.common import flatten
+
−
+
−from cubicweb.vregistry import objectify_selector
+
−from cubicweb.web.views import baseviews
+
−
+
−@objectify_selector
+
−def plot_selector(cls, req, rset, *args, **kwargs):
+
−    """accept result set with at least one line and two columns of result
+
−    all columns after second must be of numerical types"""
+
−    if rset is None:
+
−        return 0
+
−    if not len(rset):
+
−        return 0
+
−    if len(rset.rows[0]) < 2:
+
−        return 0
+
−    for etype in rset.description[0]:
+
−        if etype not in ('Int', 'Float'):
+
−            return 0
+
−    return 1
+
−
+
−try:
+
−    import matplotlib
+
−    import sys
+
−    if 'matplotlib.backends' not in sys.modules:
+
−        matplotlib.use('Agg')
+
−    from pylab import figure
+
−except ImportError:
+
−    pass
+
−else:
+
−    class PlotView(baseviews.AnyRsetView):
+
−        id = 'plot'
+
−        title = _('generic plot')
+
−        binary = True
+
−        content_type = 'image/png'
+
−        _plot_count = 0
+
−        __select__ = plot_selector()
+
−
+
−        def call(self, width=None, height=None):
+
−            # compute dimensions
+
−            if width is None:
+
−                if 'width' in self.req.form:
+
−                    width = int(self.req.form['width'])
+
−                else:
+
−                    width = 500
+
−
+
−            if height is None:
+
−                if 'height' in self.req.form:
+
−                    height = int(self.req.form['height'])
+
−                else:
+
−                    height = 400
+
−            dpi = 100.
+
−
+
−            # compute data
+
−            abscisses = [row[0] for row in self.rset]
+
−            courbes = []
+
−            nbcols = len(self.rset.rows[0])
+
−            for col in xrange(1, nbcols):
+
−                courbe = [row[col] for row in self.rset]
+
−                courbes.append(courbe)
+
−            if not courbes:
+
−                raise Exception('no data')
+
−            # plot data
+
−            fig = figure(figsize=(width/dpi, height/dpi), dpi=dpi)
+
−            ax = fig.add_subplot(111)
+
−            colors = 'brgybrgy'
+
−            try:
+
−                float(abscisses[0])
+
−                xlabels = None
+
−            except ValueError:
+
−                xlabels = abscisses
+
−                abscisses = range(len(xlabels))
+
−            for idx, courbe in enumerate(courbes):
+
−                ax.plot(abscisses, courbe, '%sv-' % colors[idx], label=self.rset.description[0][idx+1])
+
−            ax.autoscale_view()
+
−            alldata = flatten(courbes)
+
−            m, M = min(alldata or [0]), max(alldata or [1])
+
−            if m is None: m = 0
+
−            if M is None: M = 0
+
−            margin = float(M-m)/10
+
−            ax.set_ylim(m-margin, M+margin)
+
−            ax.grid(True)
+
−            ax.legend(loc='best')
+
−            if xlabels is not None:
+
−                ax.set_xticks(abscisses)
+
−                ax.set_xticklabels(xlabels)
+
−            try:
+
−                fig.autofmt_xdate()
+
−            except AttributeError:
+
−                # XXX too old version of matplotlib. Ignore safely.
+
−                pass
+
−
+
−            # save plot
+
−            filename = self.build_figname()
+
−            fig.savefig(filename, dpi=100)
+
−            img = open(filename, 'rb')
+
−            self.w(img.read())
+
−            img.close()
+
−            os.remove(filename)
+
−
+
−        def build_figname(self):
+
−            self.__class__._plot_count += 1
+
−            return '/tmp/burndown_chart_%s_%d.png' % (self.config.appid, self.__class__._plot_count)