Add leather with dashed lines until PR is merged

wireservice/leather#89

leather/__init__.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+
+from leather.axis import Axis
+from leather.data_types import Number, Text
+from leather.chart import Chart
+from leather.grid import Grid
+from leather.lattice import Lattice
+from leather.scales import Scale, Linear, Ordinal, Temporal
+from leather.series import Series, CategorySeries, key_function
+from leather.shapes import Shape, Bars, Columns, Dots, Line, style_function
+from leather.testcase import LeatherTestCase
+from leather import theme

leather/axis.py

@@ -0,0 +1,193 @@
+#!/usr/bin/env python
+
+import xml.etree.ElementTree as ET
+
+import six
+
+from leather import svg
+from leather import theme
+
+
+class Axis(object):
+    """
+    A horizontal or vertical chart axis.
+
+    :param ticks:
+        Instead of inferring tick values from the data, use exactly this
+        sequence of ticks values. These will still be passed to the
+        :code:`tick_formatter`.
+    :param tick_formatter:
+        An optional :func:`.tick_format_function`.
+    """
+    def __init__(self, ticks=None, tick_formatter=None, name=None):
+        self._ticks = ticks
+        self._tick_formatter = tick_formatter
+        self._name = six.text_type(name) if name is not None else None
+
+    def _estimate_left_tick_width(self, scale):
+        """
+        Estimate the y axis space used by tick labels.
+        """
+        tick_values = self._ticks or scale.ticks()
+        tick_count = len(tick_values)
+        tick_formatter = self._tick_formatter or scale.format_tick
+        max_len = 0
+
+        for i, value in enumerate(tick_values):
+            max_len = max(max_len, len(tick_formatter(value, i, tick_count)))
+
+        return max_len * theme.tick_font_char_width
+
+    def estimate_label_margin(self, scale, orient):
+        """
+        Estimate the space needed for the tick labels.
+        """
+        margin = 0
+
+        if orient == 'left':
+            margin += self._estimate_left_tick_width(scale) + (theme.tick_size * 2)
+        elif orient == 'bottom':
+            margin += theme.tick_font_char_height + (theme.tick_size * 2)
+
+        if self._name:
+            margin += theme.axis_title_font_char_height + theme.axis_title_gap
+
+        return margin
+
+    def to_svg(self, width, height, scale, orient):
+        """
+        Render this axis to SVG elements.
+        """
+        group = ET.Element('g')
+        group.set('class', 'axis ' + orient)
+
+        # Axis title
+        if self._name is not None:
+            if orient == 'left':
+                title_x = -(self._estimate_left_tick_width(scale) + theme.axis_title_gap)
+                title_y = height / 2
+                dy=''
+                transform = svg.rotate(270, title_x, title_y)
+            elif orient == 'bottom':
+                title_x = width / 2
+                title_y = height + theme.tick_font_char_height + (theme.tick_size * 2) + theme.axis_title_gap
+                dy='1em'
+                transform = ''
+
+            title = ET.Element('text',
+                x=six.text_type(title_x),
+                y=six.text_type(title_y),
+                dy=dy,
+                fill=theme.axis_title_color,
+                transform=transform
+            )
+            title.set('text-anchor', 'middle')
+            title.set('font-family', theme.axis_title_font_family)
+            title.text = self._name
+
+            group.append(title)
+
+        # Ticks
+        if orient == 'left':
+            label_x = -(theme.tick_size * 2)
+            x1 = -theme.tick_size
+            x2 = width
+            range_min = height
+            range_max = 0
+        elif orient == 'bottom':
+            label_y = height + (theme.tick_size * 2)
+            y1 = 0
+            y2 = height + theme.tick_size
+            range_min = 0
+            range_max = width
+
+        tick_values = self._ticks or scale.ticks()
+        tick_count = len(tick_values)
+        tick_formatter = self._tick_formatter or scale.format_tick
+
+        zero_tick_group = None
+
+        for i, value in enumerate(tick_values):
+            # Tick group
+            tick_group = ET.Element('g')
+            tick_group.set('class', 'tick')
+
+            if value == 0:
+                zero_tick_group = tick_group
+            else:
+                group.append(tick_group)
+
+            # Tick line
+            projected_value = scale.project(value, range_min, range_max)
+
+            if value == 0:
+                tick_color = theme.zero_color
+            else:
+                tick_color = theme.tick_color
+
+            if orient == 'left':
+                y1 = projected_value
+                y2 = projected_value
+
+            elif orient == 'bottom':
+                x1 = projected_value
+                x2 = projected_value
+
+            tick = ET.Element('line',
+                x1=six.text_type(x1),
+                y1=six.text_type(y1),
+                x2=six.text_type(x2),
+                y2=six.text_type(y2),
+                stroke=tick_color
+            )
+            tick.set('stroke-width', six.text_type(theme.tick_width))
+
+            tick_group.append(tick)
+
+            # Tick label
+            if orient == 'left':
+                x = label_x
+                y = projected_value
+                dy = '0.32em'
+                text_anchor = 'end'
+            elif orient == 'bottom':
+                x = projected_value
+                y = label_y
+                dy = '1em'
+                text_anchor = 'middle'
+
+            label = ET.Element('text',
+                x=six.text_type(x),
+                y=six.text_type(y),
+                dy=dy,
+                fill=theme.label_color
+            )
+            label.set('text-anchor', text_anchor)
+            label.set('font-family', theme.tick_font_family)
+
+            value = tick_formatter(value, i, tick_count)
+            label.text = six.text_type(value)
+
+            tick_group.append(label)
+
+        if zero_tick_group is not None:
+            group.append(zero_tick_group)
+
+        return group
+
+
+def tick_format_function(value, index, tick_count):
+    """
+    This example shows how to define a function to format tick values for
+    display.
+
+    :param x:
+        The value to be formatted.
+    :param index:
+        The index of the tick.
+    :param tick_count:
+        The total number of ticks being displayed.
+    :returns:
+        A stringified tick value for display.
+    """
+    return six.text_type(value)