pygal/svg/charts/graph.py

#!python
# -*- coding: UTF-8 -*-

from operator import itemgetter
from itertools import islice
import pkg_resources
import functools

import cssutils
from lxml import etree

from svg.charts import css # causes the SVG profile to be loaded

try:
	import zlib
except ImportError:
	zlib = None

def sort_multiple(arrays):
	"sort multiple lists (of equal size) using the first list for the sort keys"
	tuples = zip(*arrays)
	tuples.sort()
	return zip(*tuples)

class Graph(object):
	"""
	Base object for generating SVG Graphs
	
	Synopsis

		This class is only used as a superclass of specialized charts.  Do not
		attempt to use this class directly, unless creating a new chart type.

		For examples of how to subclass this class, see the existing specific
		subclasses, such as svn.charts.Pie.

	* svg.charts.bar
	* svg.charts.line
	* svg.charts.pie
	* svg.charts.plot
	* svg.charts.time_series

	"""
	width=                500
	height=               300
	show_x_guidelines=    False
	show_y_guidelines=    True
	show_data_values=     True
	min_scale_value=      None
	show_x_labels=        True
	stagger_x_labels=     False
	rotate_x_labels=      False
	step_x_labels=        1
	step_include_first_x_label= True
	show_y_labels=        True
	rotate_y_labels=      False
	stagger_y_labels=     False
	step_include_first_y_label= True
	step_y_labels=        1
	scale_integers=       False
	show_x_title=         False
	x_title=              'X Field names'
	show_y_title=         False
	y_title_text_direction= 'bt' # 'bt' for bottom to top; 'tb' for top to bottom
	y_title=              'Y Scale'
	show_graph_title=     False
	graph_title=          'Graph Title'
	show_graph_subtitle=  False
	graph_subtitle=       'Graph Subtitle'
	key=                  True
	key_position=         'right' # 'bottom' or 'right',
	
	font_size=            12
	title_font_size=      16
	subtitle_font_size=   14
	x_label_font_size=    12
	x_title_font_size=    14
	y_label_font_size=    12
	y_title_font_size=    14
	key_font_size=        10
	
	css_inline=           False
	add_popups=           False

	top_align = top_font = right_align = right_font = 0
	
	compress = False
	
	stylesheet_names = ['graph.css']

	def __init__(self, config = {}):
		"""Initialize the graph object with the graph settings."""
		if self.__class__ is Graph:
			raise NotImplementedError("Graph is an abstract base class")
		self.load_config(config)
		self.clear_data()
		self.style = {}

	def load_config(self, config):
		self.__dict__.update(config)
		
	def add_data(self, conf):
		"""
		Add data to the graph object. May be called several times to add
		additional data sets.
		
		>>> data_sales_02 = [12, 45, 21] # doctest: +SKIP
		>>> graph.add_data({ # doctest: +SKIP
		...  'data': data_sales_02,
		...  'title': 'Sales 2002'
		... }) # doctest: +SKIP
		"""
		self.validate_data(conf)
		self.process_data(conf)
		self.data.append(conf)

	def validate_data(self, conf):
		try:
			assert(isinstance(conf['data'], (tuple, list)))
		except TypeError, e:
			raise TypeError, "conf should be dictionary with 'data' and other items"
		except AssertionError:
			if not hasattr(conf['data'], '__iter__'):
				raise TypeError, "conf['data'] should be tuple or list or iterable"

	def process_data(self, data): pass
	
	def clear_data(self):
		"""
		This method removes all data from the object so that you can
		reuse it to create a new graph but with the same config options.
		
		>>> graph.clear_data() # doctest: +SKIP
		"""
		self.data = []
		
	def burn(self):
		"""
		Process the template with the data and
		config which has been set and return the resulting SVG.
		
		Raises ValueError when no data set has
		been added to the graph object.
		"""
		if not self.data: raise ValueError("No data available")
		
		if hasattr(self, 'calculations'): self.calculations()
		
		self.start_svg()
		self.calculate_graph_dimensions()
		self.foreground = etree.Element("g")
		self.draw_graph()
		self.draw_titles()
		self.draw_legend()
		self.draw_data()
		self.graph.append(self.foreground)
		self.render_inline_styles()
		
		return self._burn_compressed()

	def _burn_compressed(self):
		if self.compress and not zlib:
			self.root.addprevious(etree.Comment('Python zlib not available for SVGZ'))
		
		data = etree.tostring(self.root, pretty_print=True, xml_declaration=True, encoding='utf-8')
		
		if self.compress and zlib:
			data = zlib.compress(data)

		return data
	
	KEY_BOX_SIZE = 12
	
	def calculate_left_margin(self):
		"""
		Calculates the margin to the left of the plot area, setting
		border_left.
		"""
		bl = 7
		# Check for Y labels
		if self.rotate_y_labels:
			max_y_label_height_px = self.y_label_font_size
		else:
			label_lengths = map(len, self.get_y_labels())
			max_y_label_len = max(label_lengths)
			max_y_label_height_px = 0.6 * max_y_label_len * self.y_label_font_size
		if self.show_y_labels: bl += max_y_label_height_px
		if self.stagger_y_labels: bl += max_y_label_height_px + 10
		if self.show_y_title: bl += self.y_title_font_size + 5
		self.border_left = bl
		
	def max_y_label_width_px(self):
		"""
		Calculate the width of the widest Y label.  This will be the
		character height if the Y labels are rotated.
		"""
		if self.rotate_y_labels:
			return self.font_size
		
	def calculate_right_margin(self):
		"""
		Calculate the margin in pixels to the right of the plot area,
		setting border_right.
		"""
		br = 7
		if self.key and self.key_position == 'right':
			max_key_len = max(map(len, self.keys()))
			br += max_key_len * self.key_font_size * 0.6
			br += self.KEY_BOX_SIZE
			br += 10		# Some padding around the box
		self.border_right = br
		
	def calculate_top_margin(self):
		"""
		Calculate the margin in pixels above the plot area, setting
		border_top.
		"""
		self.border_top = 5
		if self.show_graph_title: self.border_top += self.title_font_size
		self.border_top += 5
		if self.show_graph_subtitle: self.border_top += self.subtitle_font_size
		
	def add_popup(self, x, y, label):
		"""
		Add pop-up information to a point on the graph.
		"""
		txt_width = len(label) * self.font_size * 0.6 + 10
		tx = x + [5,-5][int(x+txt_width > self.width)]
		anchor = ['start', 'end'][x+txt_width > self.width]
		style = 'fill: #000; text-anchor: %s;' % anchor
		id = 'label-%s' % label
		t = etree.SubElement(self.foreground, 'text', {
			'x': str(tx),
			'y': str(y - self.font_size),
			'visibility': 'hidden',
			'style': style,
			'text': label,
			'id': id
			})

		# add the circle element to the foreground
		visibility = "document.getElementById('%s').setAttribute('visibility', %%s)" % id
		t = etree.SubElement(self.foreground, 'circle', {
			'cx': str(x),
			'cy': str(y),
			'r': str(10),
			'style': 'opacity: 0;',
			'onmouseover': visibility % 'visible',
			'onmouseout': visibility % 'hidden',
			})

	def calculate_bottom_margin(self):
		"""
		Calculate the margin in pixels below the plot area, setting
		border_bottom.
		"""
		bb = 7
		if self.key and self.key_position == 'bottom':
			bb += len(self.data) * (self.font_size + 5)
			bb += 10
		if self.show_x_labels:
			max_x_label_height_px = self.x_label_font_size
			if self.rotate_x_labels:
				label_lengths = map(len, self.get_x_labels())
				max_x_label_len = reduce(max, label_lengths)
				max_x_label_height_px *= 0.6 * max_x_label_len
			bb += max_x_label_height_px
			if self.stagger_x_labels: bb += max_x_label_height_px + 10
		if self.show_x_title: bb += self.x_title_font_size + 5
		self.border_bottom = bb
		
	def draw_graph(self):
		"""
		The central logic for drawing the graph.

		Sets self.graph (the 'g' element in the SVG root)
		"""
		transform = 'translate (%s %s)' % (self.border_left, self.border_top)
		self.graph = etree.SubElement(self.root, 'g', transform=transform)
		
		etree.SubElement(self.graph, 'rect', {
			'x': '0',
			'y': '0',
			'width': str(self.graph_width),
			'height': str(self.graph_height),
			'class': 'graphBackground'
			})
		
		#Axis
		etree.SubElement(self.graph, 'path', {
			'd': 'M 0 0 v%s' % self.graph_height,
			'class': 'axis',
			'id': 'xAxis'
		})
		etree.SubElement(self.graph, 'path', {
			'd': 'M 0 %s h%s' % (self.graph_height, self.graph_width),
			'class': 'axis',
			'id': 'yAxis'
		})
		
		self.draw_x_labels()
		self.draw_y_labels()
	
	def x_label_offset(self, width):
		"""
		Return an offset for drawing the x label. Currently returns 0.
		"""
		# consider width/2 for centering the labels
		return 0

	def make_datapoint_text(self, x, y, value, style=None):
		"""
		Add text for a datapoint
		"""
		if not self.show_data_values:
			# do nothing
			return
		# first lay down the text in a wide white stroke to
		#  differentiate it from the background
		e = etree.SubElement(self.foreground, 'text', {
			'x': str(x),
			'y': str(y),
			'class': 'dataPointLabel',
			'style': '%(style)s stroke: #fff; stroke-width: 2;' % vars(),
		})
		e.text = str(value)
		# then lay down the text in the specified style
		e = etree.SubElement(self.foreground, 'text', {
			'x': str(x),
			'y': str(y),
			'class': 'dataPointLabel'})
		e.text = str(value)
		if style: e.set('style', style)

	def draw_x_labels(self):
		"Draw the X axis labels"
		if self.show_x_labels:
			labels = self.get_x_labels()
			count = len(labels)
			
			labels = enumerate(iter(labels))
			start = int(not self.step_include_first_x_label)
			labels = islice(labels, start, None, self.step_x_labels)
			map(self.draw_x_label, labels)
			self.draw_x_guidelines(self.field_width(), count)
	
	def draw_x_label(self, label):
		label_width = self.field_width()
		index, label = label
		text = etree.SubElement(self.graph, 'text', {'class': 'xAxisLabels'})
		text.text = label
		
		x = index * label_width + self.x_label_offset(label_width)
		y = self.graph_height + self.x_label_font_size + 3
		t = 0 - (self.font_size / 2)
		
		if self.stagger_x_labels and  (index % 2):
			stagger = self.x_label_font_size + 5
			y += stagger
			graph_height = self.graph_height
			path = etree.SubElement(self.graph, 'path', {
				'd': 'M%(x)f %(graph_height)f v%(stagger)d' % vars(),
				'class': 'staggerGuideLine'
			})
			
		text.set('x', str(x))
		text.set('y', str(y))
		
		if self.rotate_x_labels:
			transform = 'rotate(90 %d %d) translate(0 -%d)' % \
				(x, y-self.x_label_font_size, self.x_label_font_size/4)
			text.set('transform', transform)
			text.set('style', 'text-anchor: start')
		else:
			text.set('style', 'text-anchor: middle')
			
	def y_label_offset(self, height):
		"""
		Return an offset for drawing the y label. Currently returns 0.
		"""
		# Consider height/2 to center within the field.
		return 0
	
	def get_field_width(self):
		return float(self.graph_width - self.font_size*2*self.right_font) / \
			(len(self.get_x_labels()) - self.right_align)
	field_width = get_field_width
	
	def get_field_height(self):
		return float(self.graph_height - self.font_size*2*self.top_font) / \
			(len(self.get_y_labels()) - self.top_align)
	field_height = get_field_height

	def draw_y_labels(self):
		"Draw the Y axis labels"
		if not self.show_y_labels:
			# do nothing
			return

		labels = self.get_y_labels()
		count = len(labels)
		
		labels = enumerate(iter(labels))
		start = int(not self.step_include_first_y_label)
		labels = islice(labels, start, None, self.step_y_labels)
		map(self.draw_y_label, labels)
		self.draw_y_guidelines(self.field_height(), count)

	def get_y_offset(self):
		result = self.graph_height + self.y_label_offset(self.field_height())
		if not self.rotate_y_labels: result += self.font_size/1.2
		return result
	y_offset = property(get_y_offset)
	
	def draw_y_label(self, label):
		label_height = self.field_height()
		index, label = label
		text = etree.SubElement(self.graph, 'text', {'class': 'yAxisLabels'})
		text.text = label
		
		y = self.y_offset - (label_height * index)
		x = {True: 0, False:-3}[self.rotate_y_labels]
		
		if self.stagger_y_labels and  (index % 2):
			stagger = self.y_label_font_size + 5
			x -= stagger
			path = etree.SubElement(self.graph, 'path', {
				'd': 'M%(x)f %(y)f h%(stagger)d' % vars(),
				'class': 'staggerGuideLine'
			})
			
		text.set('x', str(x))
		text.set('y', str(y))
		
		if self.rotate_y_labels:
			transform = 'translate(-%d 0) rotate (90 %d %d)' % \
				(self.font_size, x, y)
			text.set('transform', transform)
			text.set('style', 'text-anchor: middle')
		else:
			text.set('y', str(y - self.y_label_font_size/2))
			text.set('style', 'text-anchor: end')
		
	def draw_x_guidelines(self, label_height, count):
		"Draw the X-axis guidelines"
		if not self.show_x_guidelines: return
		# skip the first one
		for count in range(1,count):
			start = label_height*count
			stop = self.graph_height
			path = etree.SubElement(self.graph, 'path', {
				'd': 'M %(start)s 0 v%(stop)s' % vars(),
				'class': 'guideLines'})

	def draw_y_guidelines(self, label_height, count):
		"Draw the Y-axis guidelines"
		if not self.show_y_guidelines: return
		for count in range(1, count):
			start = self.graph_height - label_height*count
			stop = self.graph_width
			path = etree.SubElement(self.graph, 'path', {
				'd': 'M 0 %(start)s h%(stop)s' % vars(),
				'class': 'guideLines'})

	def draw_titles(self):
		"Draws the graph title and subtitle"
		if self.show_graph_title: self.draw_graph_title()
		if self.show_graph_subtitle: self.draw_graph_subtitle()
		if self.show_x_title: self.draw_x_title()
		if self.show_y_title: self.draw_y_title()

	def draw_graph_title(self):
		text = etree.SubElement(self.root, 'text', {
			'x': str(self.width / 2),
			'y': str(self.title_font_size),
			'class': 'mainTitle'})
		text.text = self.graph_title

	def draw_graph_subtitle(self):
		y_subtitle_options = [subtitle_font_size, title_font_size+10]
		y_subtitle = y_subtitle_options[self.show_graph_title]
		text = etree.SubElement(self.root, 'text', {
			'x': str(self.width/2),
			'y': str(y_subtitle),
			'class': 'subTitle',
			})
		text.text = self.graph_title

	def draw_x_title(self):
		y = self.graph_height + self.border_top + self.x_title_font_size
		if self.show_x_labels:
			y_size = self.x_label_font_size+5
			if self.stagger_x_labels: y_size*=2
			y += y_size
		x = self.width / 2
		
		text = etree.SubElement(self.root, 'text', {
			'x': str(x),
			'y': str(y),
			'class': 'xAxisTitle',
			})
		text.text = self.x_title

	def draw_y_title(self):
		x = self.y_title_font_size
		if self.y_title_text_direction=='bt':
				x += 3
				rotate = -90
		else:
				x -= 3
				rotate = 90
		y = self.height / 2
		text = etree.SubElement(self.root, 'text', {
				'x': str(x),
				'y': str(y),
				'class': 'yAxisTitle',
				})
		text.text = self.y_title
		text.set('transform', 'rotate(%(rotate)d, %(x)s, %(y)s)' % vars())

	def keys(self):
		return map(itemgetter('title'), self.data)
	
	def draw_legend(self):
		if not self.key:
			# do nothing
			return

		group = etree.SubElement(self.root, 'g')
		
		for key_count, key_name in enumerate(self.keys()):
			y_offset = (self.KEY_BOX_SIZE * key_count) + (key_count * 5)
			etree.SubElement(group, 'rect', {
				'x': '0',
				'y': str(y_offset),
				'width': str(self.KEY_BOX_SIZE),
				'height': str(self.KEY_BOX_SIZE),
				'class': 'key%s' % (key_count + 1),
			})
			text = etree.SubElement(group, 'text', {
				'x': str(self.KEY_BOX_SIZE + 5),
				'y': str(y_offset + self.KEY_BOX_SIZE),
				'class': 'keyText'})
			text.text = key_name
		
		if self.key_position == 'right':
			x_offset = self.graph_width + self.border_left + 10
			y_offset = self.border_top + 20
		if self.key_position == 'bottom':
			x_offset, y_offset = self.calculate_offsets_bottom()
		group.set('transform', 'translate(%(x_offset)d %(y_offset)d)' % vars())

	def calculate_offsets_bottom(self):
		x_offset = self.border_left + 20
		y_offset = self.border_top + self.graph_height + 5
		if self.show_x_labels:
			max_x_label_height_px = x_label_font_size
			if self.rotate_x_labels:
				longest_label_length = max(map(len, self.get_x_labels()))
				# note: I think 0.6 is the ratio of width to height of characters
				max_x_label_height_px *= longest_label_length * 0.6
			y_offset += max_x_label_height_px
			if self.stagger_x_labels:
				y_offset += max_x_label_height_px + 5
		if self.show_x_title:
			y_offset += x_title_font_size + 5
		return x_offset, y_offset
			
	def render_inline_styles(self):
		"Hard-code the styles into the SVG XML if style sheets are not used."
		if not self.css_inline:
			# do nothing
			return

		styles = self.parse_css()
		for node in xpath.Evaluate('//*[@class]', self.root):
			cl = node.getAttribute('class')
			style = styles[cl]
			if node.hasAttribute('style'):
				style += node.getAttribute('style')
			node.setAttribute('style', style)

	def parse_css(self):
		"""
		Take a .css file (classes only please) and parse it into a dictionary
		of class/style pairs.
		"""
		# todo: save the prefs for use later
		#orig_prefs = cssutils.ser.prefs
		cssutils.ser.prefs.useMinified()
		get_pair = lambda r: (r.selectorText, r.style.cssText)
		result = dict(map(get_pair, self.get_stylesheet()))
		return result

	def add_defs(self, defs):
		"""
		Override and place code to add defs here. TODO: what are defs?
		"""
	
	def start_svg(self):
		"Base SVG Document Creation"
		SVG_NAMESPACE = 'http://www.w3.org/2000/svg'
		SVG = '{%s}' % SVG_NAMESPACE
		NSMAP = {
			None: SVG_NAMESPACE,
			'xlink': 'http://www.w3.org/1999/xlink',
			'a3': 'http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/',
			}
		self.root = etree.Element(SVG+"svg", attrib={
			'width': str(self.width),
			'height': str(self.height),
			'viewBox': '0 0 %s %s' % (self.width, self.height),
			'{http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/}scriptImplementation': 'Adobe',
			}, nsmap=NSMAP)
		if hasattr(self, 'style_sheet_href'):
			pi = etree.ProcessingInstruction(
				'xml-stylesheet',
				'href="%s" type="text/css"' % self.style_sheet_href
				)
			self.root.addprevious(pi)
		
		comment_strings = (
			' Created with SVG.Graph ',
			' SVG.Graph by Jason R. Coombs ',
			' Based on SVG::Graph by Sean E. Russel ',
			' Based on Perl SVG:TT:Graph by Leo Lapworth & Stephan Morgan ',
			' '+'/'*66,
			)
		map(self.root.append, map(etree.Comment, comment_strings))

		defs = etree.SubElement(self.root, 'defs')
		self.add_defs(defs)
		
		if not hasattr(self, 'style_sheet_href') and not self.css_inline:
			self.root.append(etree.Comment(' include default stylesheet if none specified '))
			style = etree.SubElement(defs, 'style', type='text/css')
			# TODO: the text was previously escaped in a CDATA declaration... how
			#  to do that with etree?
			style.text = self.get_stylesheet().cssText
		
		self.root.append(etree.Comment('SVG Background'))
		rect = etree.SubElement(self.root, 'rect', {
			'width': str(self.width),
			'height': str(self.height),
			'x': '0',
			'y': '0',
			'class': 'svgBackground'})
		
	def calculate_graph_dimensions(self):
		self.calculate_left_margin()
		self.calculate_right_margin()
		self.calculate_bottom_margin()
		self.calculate_top_margin()
		self.graph_width = self.width - self.border_left - self.border_right
		self.graph_height = self.height - self.border_top - self.border_bottom

	@staticmethod
	def load_resource_stylesheet(name, subs=dict()):
		css_stream = pkg_resources.resource_stream('svg.charts', name)
		css_string = css_stream.read()
		css_string = css_string % subs
		sheet = cssutils.parseString(css_string)
		return sheet

	def get_stylesheet_resources(self):
		"Get the stylesheets for this instance"
		# allow css to include class variables
		class_vars = class_dict(self)
		loader = functools.partial(self.load_resource_stylesheet,
			subs=class_vars)
		sheets = map(loader, self.stylesheet_names)
		return sheets

	def get_stylesheet(self):
		cssutils.log.setLevel(30) # disable INFO log messages
		def merge_sheets(s1, s2):
			map(s1.add, s2)
			return s1
		return reduce(merge_sheets, self.get_stylesheet_resources())

class class_dict(object):
	"Emulates a dictionary, but retrieves class attributes"
	def __init__(self, obj):
		self.__obj__ = obj

	def __getitem__(self, item):
		return getattr(self.__obj__, item)

	def keys(self):
		# dir returns a good guess of what attributes might be available
		return dir(self.__obj__)