text: """
  
  Conventions:
  
  "constrain_x" means to constrain the variable with either
  another kiwisolver variable, or a float.  i.e. `constrain_width(0.2)`
  will set a constraint that the width has to be 0.2 and this constraint is
  permanent - i.e. it will not be removed if it becomes obsolete.
  
  "edit_x" means to set x to a value (just a float), and that this value can
  change.  So `edit_width(0.2)` will set width to be 0.2, but `edit_width(0.3)`
  will allow it to change to 0.3 later.  Note that these values are still just
  "suggestions" in `kiwisolver` parlance, and could be over-ridden by
  other constrains.
  
  """
  
  import itertools
  import kiwisolver as kiwi
  import logging
  import numpy as np
  import warnings
  
  import matplotlib
  
  _log = logging.getLogger(__name__)
  
  
  # renderers can be complicated
  def get_renderer(fig):
      if fig._cachedRenderer:
          renderer = fig._cachedRenderer
      else:
          canvas = fig.canvas
          if canvas and hasattr(canvas, "get_renderer"):
              renderer = canvas.get_renderer()
          else:
              # not sure if this can happen
              # seems to with PDF...
              _log.info("constrained_layout : falling back to Agg renderer")
              from matplotlib.backends.backend_agg import FigureCanvasAgg
              canvas = FigureCanvasAgg(fig)
              renderer = canvas.get_renderer()
  
      return renderer
  
  
  class LayoutBox(object):
      """
      Basic rectangle representation using kiwi solver variables
      """
  
      def __init__(self, parent=None, name='', tightwidth=False,
                   tightheight=False, artist=None,
                   lower_left=(0, 0), upper_right=(1, 1), pos=False,
                   subplot=False, h_pad=None, w_pad=None):
          Variable = kiwi.Variable
          self.parent = parent
          self.name = name
          sn = self.name + '_'
          if parent is None:
              self.solver = kiwi.Solver()
              self.constrained_layout_called = 0
          else:
              self.solver = parent.solver
              self.constrained_layout_called = None
              # parent wants to know about this child!
              parent.add_child(self)
          # keep track of artist associated w/ this layout.  Can be none
          self.artist = artist
          # keep track if this box is supposed to be a pos that is constrained
          # by the parent.
          self.pos = pos
          # keep track of whether we need to match this subplot up with others.
          self.subplot = subplot
  
          # we need the str below for Py 2 which complains the string is unicode
          self.top = Variable(str(sn + 'top'))
          self.bottom = Variable(str(sn + 'bottom'))
          self.left = Variable(str(sn + 'left'))
          self.right = Variable(str(sn + 'right'))
  
          self.width = Variable(str(sn + 'width'))
          self.height = Variable(str(sn + 'height'))
          self.h_center = Variable(str(sn + 'h_center'))
          self.v_center = Variable(str(sn + 'v_center'))
  
          self.min_width = Variable(str(sn + 'min_width'))
          self.min_height = Variable(str(sn + 'min_height'))
          self.pref_width = Variable(str(sn + 'pref_width'))
          self.pref_height = Variable(str(sn + 'pref_height'))
          # margis are only used for axes-position layout boxes.  maybe should
          # be a separate subclass:
          self.left_margin = Variable(str(sn + 'left_margin'))
          self.right_margin = Variable(str(sn + 'right_margin'))
          self.bottom_margin = Variable(str(sn + 'bottom_margin'))
          self.top_margin = Variable(str(sn + 'top_margin'))
          # mins
          self.left_margin_min = Variable(str(sn + 'left_margin_min'))
          self.right_margin_min = Variable(str(sn + 'right_margin_min'))
          self.bottom_margin_min = Variable(str(sn + 'bottom_margin_min'))
          self.top_margin_min = Variable(str(sn + 'top_margin_min'))
  
          right, top = upper_right
          left, bottom = lower_left
          self.tightheight = tightheight
          self.tightwidth = tightwidth
          self.add_constraints()
          self.children = []
          self.subplotspec = None
          if self.pos:
              self.constrain_margins()
          self.h_pad = h_pad
          self.w_pad = w_pad
  
      def constrain_margins(self):
          """
          Only do this for pos.  This sets a variable distance
          margin between the position of the axes and the outer edge of
          the axes.
  
          Margins are variable because they change with the fogure size.
  
          Margin minimums are set to make room for axes decorations.  However,
          the margins can be larger if we are mathicng the position size to
          otehr axes.
          """
          sol = self.solver
  
          # left
          if not sol.hasEditVariable(self.left_margin_min):
              sol.addEditVariable(self.left_margin_min, 'strong')
              sol.suggestValue(self.left_margin_min, 0.0001)
          c = (self.left_margin == self.left - self.parent.left)
          self.solver.addConstraint(c | 'required')
          c = (self.left_margin >= self.left_margin_min)
          self.solver.addConstraint(c | 'strong')
  
          # right
          if not sol.hasEditVariable(self.right_margin_min):
              sol.addEditVariable(self.right_margin_min, 'strong')
              sol.suggestValue(self.right_margin_min, 0.0001)
          c = (self.right_margin == self.parent.right - self.right)
          self.solver.addConstraint(c | 'required')
          c = (self.right_margin >= self.right_margin_min)
          self.solver.addConstraint(c | 'required')
          # bottom
          if not sol.hasEditVariable(self.bottom_margin_min):
              sol.addEditVariable(self.bottom_margin_min, 'strong')
              sol.suggestValue(self.bottom_margin_min, 0.0001)
          c = (self.bottom_margin == self.bottom - self.parent.bottom)
          self.solver.addConstraint(c | 'required')
          c = (self.bottom_margin >= self.bottom_margin_min)
          self.solver.addConstraint(c | 'required')
          # top
          if not sol.hasEditVariable(self.top_margin_min):
              sol.addEditVariable(self.top_margin_min, 'strong')
              sol.suggestValue(self.top_margin_min, 0.0001)
          c = (self.top_margin == self.parent.top - self.top)
          self.solver.addConstraint(c | 'required')
          c = (self.top_margin >= self.top_margin_min)
          self.solver.addConstraint(c | 'required')
  
      def add_child(self, child):
          self.children += [child]
  
      def remove_child(self, child):
          try:
              self.children.remove(child)
          except ValueError:
              _log.info("Tried to remove child that doesn't belong to parent")
  
      def add_constraints(self):
          sol = self.solver
          # never let width and height go negative.
          for i in [self.min_width, self.min_height]:
              sol.addEditVariable(i, 1e9)
              sol.suggestValue(i, 0.0)
          # define relation ships between things thing width and right and left
          self.hard_constraints()
          # self.soft_constraints()
          if self.parent:
              self.parent_constrain()
          # sol.updateVariables()
  
      def parent_constrain(self):
          parent = self.parent
          hc = [self.left >= parent.left,
                self.bottom >= parent.bottom,
                self.top <= parent.top,
                self.right <= parent.right]
          for c in hc:
              self.solver.addConstraint(c | 'required')
  
      def hard_constraints(self):
          hc = [self.width == self.right - self.left,
                self.height == self.top - self.bottom,
                self.h_center == (self.left + self.right) * 0.5,
                self.v_center == (self.top + self.bottom) * 0.5,
                self.width >= self.min_width,
                self.height >= self.min_height]
          for c in hc:
              self.solver.addConstraint(c | 'required')
  
      def soft_constraints(self):
          sol = self.solver
          if self.tightwidth:
              suggest = 0.
          else:
              suggest = 20.
          c = (self.pref_width == suggest)
          for i in c:
              sol.addConstraint(i | 'required')
          if self.tightheight:
              suggest = 0.
          else:
              suggest = 20.
          c = (self.pref_height == suggest)
          for i in c:
              sol.addConstraint(i | 'required')
  
          c = [(self.width >= suggest),
               (self.height >= suggest)]
          for i in c:
              sol.addConstraint(i | 150000)
  
      def set_parent(self, parent):
          ''' replace the parent of this with the new parent
          '''
          self.parent = parent
          self.parent_constrain()
  
      def constrain_geometry(self, left, bottom, right, top, strength='strong'):
          hc = [self.left == left,
                self.right == right,
                self.bottom == bottom,
                self.top == top]
          for c in hc:
              self.solver.addConstraint((c | strength))
          # self.solver.updateVariables()
  
      def constrain_same(self, other, strength='strong'):
          """
          Make the layoutbox have same position as other layoutbox
          """
          hc = [self.left == other.left,
                self.right == other.right,
                self.bottom == other.bottom,
                self.top == other.top]
          for c in hc:
              self.solver.addConstraint((c | strength))
  
      def constrain_left_margin(self, margin, strength='strong'):
          c = (self.left == self.parent.left + margin)
          self.solver.addConstraint(c | strength)
  
      def edit_left_margin_min(self, margin):
          self.solver.suggestValue(self.left_margin_min, margin)
  
      def constrain_right_margin(self, margin, strength='strong'):
          c = (self.right == self.parent.right - margin)
          self.solver.addConstraint(c | strength)
  
      def edit_right_margin_min(self, margin):
          self.solver.suggestValue(self.right_margin_min, margin)
  
      def constrain_bottom_margin(self, margin, strength='strong'):
          c = (self.bottom == self.parent.bottom + margin)
          self.solver.addConstraint(c | strength)
  
      def edit_bottom_margin_min(self, margin):
          self.solver.suggestValue(self.bottom_margin_min, margin)
  
      def constrain_top_margin(self, margin, strength='strong'):
          c = (self.top == self.parent.top - margin)
          self.solver.addConstraint(c | strength)
  
      def edit_top_margin_min(self, margin):
          self.solver.suggestValue(self.top_margin_min, margin)
  
      def get_rect(self):
          return (self.left.value(), self.bottom.value(),
                  self.width.value(), self.height.value())
  
      def update_variables(self):
          '''
          Update *all* the variables that are part of the solver this LayoutBox
          is created with
          '''
          self.solver.updateVariables()
  
      def edit_height(self, height, strength='strong'):
          '''
          Set the height of the layout box.
  
          This is done as an editable variable so that the value can change
          due to resizing.
          '''
          sol = self.solver
          for i in [self.height]:
              if not sol.hasEditVariable(i):
                  sol.addEditVariable(i, strength)
          sol.suggestValue(self.height, height)
  
      def constrain_height(self, height, strength='strong'):
          '''
          Constrain the height of the layout box.  height is
          either a float or a layoutbox.height.
          '''
          c = (self.height == height)
          self.solver.addConstraint(c | strength)
  
      def constrain_height_min(self, height, strength='strong'):
          c = (self.height >= height)
          self.solver.addConstraint(c | strength)
  
      def edit_width(self, width, strength='strong'):
          sol = self.solver
          for i in [self.width]:
              if not sol.hasEditVariable(i):
                  sol.addEditVariable(i, strength)
          sol.suggestValue(self.width, width)
  
      def constrain_width(self, width, strength='strong'):
          '''
          Constrain the width of the layout box.  `width` is
          either a float or a layoutbox.width.
          '''
          c = (self.width == width)
          self.solver.addConstraint(c | strength)
  
      def constrain_width_min(self, width, strength='strong'):
          c = (self.width >= width)
          self.solver.addConstraint(c | strength)
  
      def constrain_left(self, left,  strength='strong'):
          c = (self.left == left)
          self.solver.addConstraint(c | strength)
  
      def constrain_bottom(self, bottom, strength='strong'):
          c = (self.bottom == bottom)
          self.solver.addConstraint(c | strength)
  
      def constrain_right(self, right, strength='strong'):
          c = (self.right == right)
          self.solver.addConstraint(c | strength)
  
      def constrain_top(self, top, strength='strong'):
          c = (self.top == top)
          self.solver.addConstraint(c | strength)
  
      def _is_subplotspec_layoutbox(self):
          '''
          Helper to check if this layoutbox is the layoutbox of a
          subplotspec
          '''
          name = (self.name).split('.')[-1]
          return name[:2] == 'ss'
  
      def _is_gridspec_layoutbox(self):
          '''
          Helper to check if this layoutbox is the layoutbox of a
          gridspec
          '''
          name = (self.name).split('.')[-1]
          return name[:8] == 'gridspec'
  
      def find_child_subplots(self):
          '''
          Find children of this layout box that are subplots.  We want to line
          poss up, and this is an easy way to find them all.
          '''
          if self.subplot:
              subplots = [self]
          else:
              subplots = []
          for child in self.children:
              subplots += child.find_child_subplots()
          return subplots
  
      def layout_from_subplotspec(self, subspec,
                                  name='', artist=None, pos=False):
          '''  Make a layout box from a subplotspec. The layout box is
          constrained to be a fraction of the width/height of the parent,
          and be a fraction of the parent width/height from the left/bottom
          of the parent.  Therefore the parent can move around and the
          layout for the subplot spec should move with it.
  
          The parent is *usually* the gridspec that made the subplotspec.??
          '''
          lb = LayoutBox(parent=self, name=name, artist=artist, pos=pos)
          gs = subspec.get_gridspec()
          nrows, ncols = gs.get_geometry()
          parent = self.parent
  
          # OK, now, we want to set the position of this subplotspec
          # based on its subplotspec parameters.  The new gridspec will inherit.
  
          # from gridspec.  prob should be new method in gridspec
          left = 0.0
          right = 1.0
          bottom = 0.0
          top = 1.0
          totWidth = right-left
          totHeight = top-bottom
          hspace = 0.
          wspace = 0.
  
          # calculate accumulated heights of columns
          cellH = totHeight / (nrows + hspace * (nrows - 1))
          sepH = hspace*cellH
  
          if gs._row_height_ratios is not None:
              netHeight = cellH * nrows
              tr = float(sum(gs._row_height_ratios))
              cellHeights = [netHeight*r/tr for r in gs._row_height_ratios]
          else:
              cellHeights = [cellH] * nrows
  
          sepHeights = [0] + ([sepH] * (nrows - 1))
          cellHs = np.add.accumulate(np.ravel(
                  list(zip(sepHeights, cellHeights))))
  
          # calculate accumulated widths of rows
          cellW = totWidth/(ncols + wspace * (ncols - 1))
          sepW = wspace*cellW
  
          if gs._col_width_ratios is not None:
              netWidth = cellW * ncols
              tr = float(sum(gs._col_width_ratios))
              cellWidths = [netWidth * r / tr for r in gs._col_width_ratios]
          else:
              cellWidths = [cellW] * ncols
  
          sepWidths = [0] + ([sepW] * (ncols - 1))
          cellWs = np.add.accumulate(np.ravel(list(zip(sepWidths, cellWidths))))
  
          figTops = [top - cellHs[2 * rowNum] for rowNum in range(nrows)]
          figBottoms = [top - cellHs[2 * rowNum + 1] for rowNum in range(nrows)]
          figLefts = [left + cellWs[2 * colNum] for colNum in range(ncols)]
          figRights = [left + cellWs[2 * colNum + 1] for colNum in range(ncols)]
  
          rowNum, colNum = divmod(subspec.num1, ncols)
          figBottom = figBottoms[rowNum]
          figTop = figTops[rowNum]
          figLeft = figLefts[colNum]
          figRight = figRights[colNum]
  
          if subspec.num2 is not None:
  
              rowNum2, colNum2 = divmod(subspec.num2, ncols)
              figBottom2 = figBottoms[rowNum2]
              figTop2 = figTops[rowNum2]
              figLeft2 = figLefts[colNum2]
              figRight2 = figRights[colNum2]
  
              figBottom = min(figBottom, figBottom2)
              figLeft = min(figLeft, figLeft2)
              figTop = max(figTop, figTop2)
              figRight = max(figRight, figRight2)
          # These are numbers relative to 0,0,1,1.  Need to constrain
          # relative to parent.
  
          width = figRight - figLeft
          height = figTop - figBottom
          parent = self.parent
          cs = [self.left == parent.left + parent.width * figLeft,
                self.bottom == parent.bottom + parent.height * figBottom,
                self.width == parent.width * width,
                self.height == parent.height * height]
          for c in cs:
              self.solver.addConstraint((c | 'required'))
  
          return lb
  
      def __repr__(self):
          args = (self.name, self.left.value(), self.bottom.value(),
                  self.right.value(), self.top.value())
          return ('LayoutBox: %25s, (left: %1.3f) (bot: %1.3f) '
                 '(right: %1.3f)  (top: %1.3f) ') % args
  
  
  # Utility functions that act on layoutboxes...
  def hstack(boxes, padding=0, strength='strong'):
      '''
      Stack LayoutBox instances from left to right.
      `padding` is in figure-relative units.
      '''
  
      for i in range(1, len(boxes)):
          c = (boxes[i-1].right + padding <= boxes[i].left)
          boxes[i].solver.addConstraint(c | strength)
  
  
  def hpack(boxes, padding=0, strength='strong'):
      '''
      Stack LayoutBox instances from left to right.
      '''
  
      for i in range(1, len(boxes)):
          c = (boxes[i-1].right + padding == boxes[i].left)
          boxes[i].solver.addConstraint(c | strength)
  
  
  def vstack(boxes, padding=0, strength='strong'):
      '''
      Stack LayoutBox instances from top to bottom
      '''
  
      for i in range(1, len(boxes)):
          c = (boxes[i-1].bottom - padding >= boxes[i].top)
          boxes[i].solver.addConstraint(c | strength)
  
  
  def vpack(boxes, padding=0, strength='strong'):
      '''
      Stack LayoutBox instances from top to bottom
      '''
  
      for i in range(1, len(boxes)):
          c = (boxes[i-1].bottom - padding >= boxes[i].top)
          boxes[i].solver.addConstraint(c | strength)
  
  
  def match_heights(boxes, height_ratios=None, strength='medium'):
      '''
      Stack LayoutBox instances from top to bottom
      '''
  
      if height_ratios is None:
          height_ratios = np.ones(len(boxes))
      for i in range(1, len(boxes)):
          c = (boxes[i-1].height ==
               boxes[i].height*height_ratios[i-1]/height_ratios[i])
          boxes[i].solver.addConstraint(c | strength)
  
  
  def match_widths(boxes, width_ratios=None, strength='medium'):
      '''
      Stack LayoutBox instances from top to bottom
      '''
  
      if width_ratios is None:
          width_ratios = np.ones(len(boxes))
      for i in range(1, len(boxes)):
          c = (boxes[i-1].width ==
               boxes[i].width*width_ratios[i-1]/width_ratios[i])
          boxes[i].solver.addConstraint(c | strength)
  
  
  def vstackeq(boxes, padding=0, height_ratios=None):
      vstack(boxes, padding=padding)
      match_heights(boxes, height_ratios=height_ratios)
  
  
  def hstackeq(boxes, padding=0, width_ratios=None):
      hstack(boxes, padding=padding)
      match_widths(boxes, width_ratios=width_ratios)
  
  
  def align(boxes, attr, strength='strong'):
      cons = []
      for box in boxes[1:]:
          cons = (getattr(boxes[0], attr) == getattr(box, attr))
          boxes[0].solver.addConstraint(cons | strength)
  
  
  def match_top_margins(boxes, levels=1):
      box0 = boxes[0]
      top0 = box0
      for n in range(levels):
          top0 = top0.parent
      for box in boxes[1:]:
          topb = box
          for n in range(levels):
              topb = topb.parent
          c = (box0.top-top0.top == box.top-topb.top)
          box0.solver.addConstraint(c | 'strong')
  
  
  def match_bottom_margins(boxes, levels=1):
      box0 = boxes[0]
      top0 = box0
      for n in range(levels):
          top0 = top0.parent
      for box in boxes[1:]:
          topb = box
          for n in range(levels):
              topb = topb.parent
          c = (box0.bottom-top0.bottom == box.bottom-topb.bottom)
          box0.solver.addConstraint(c | 'strong')
  
  
  def match_left_margins(boxes, levels=1):
      box0 = boxes[0]
      top0 = box0
      for n in range(levels):
          top0 = top0.parent
      for box in boxes[1:]:
          topb = box
          for n in range(levels):
              topb = topb.parent
          c = (box0.left-top0.left == box.left-topb.left)
          box0.solver.addConstraint(c | 'strong')
  
  
  def match_right_margins(boxes, levels=1):
      box0 = boxes[0]
      top0 = box0
      for n in range(levels):
          top0 = top0.parent
      for box in boxes[1:]:
          topb = box
          for n in range(levels):
              topb = topb.parent
          c = (box0.right-top0.right == box.right-topb.right)
          box0.solver.addConstraint(c | 'strong')
  
  
  def match_width_margins(boxes, levels=1):
      match_left_margins(boxes, levels=levels)
      match_right_margins(boxes, levels=levels)
  
  
  def match_height_margins(boxes, levels=1):
      match_top_margins(boxes, levels=levels)
      match_bottom_margins(boxes, levels=levels)
  
  
  def match_margins(boxes, levels=1):
      match_width_margins(boxes, levels=levels)
      match_height_margins(boxes, levels=levels)
  
  
  _layoutboxobjnum = itertools.count()
  
  
  def seq_id():
      '''
      Generate a short sequential id for layoutbox objects...
      '''
  
      global _layoutboxobjnum
  
      return ('%06d' % (next(_layoutboxobjnum)))
  
  
  def print_children(lb):
      '''
      Print the children of the layoutbox
      '''
      print(lb)
      for child in lb.children:
          print_children(child)
  
  
  def nonetree(lb):
      '''
      Make all elements in this tree none...  This signals not to do any more
      layout.
      '''
      if lb is not None:
          if lb.parent is None:
              # Clear the solver.  Hopefully this garbage collects.
              lb.solver.reset()
              nonechildren(lb)
          else:
              nonetree(lb.parent)
  
  
  def nonechildren(lb):
      for child in lb.children:
          nonechildren(child)
      lb.artist._layoutbox = None
      lb = None
  
  
  def print_tree(lb):
      '''
      Print the tree of layoutboxes
      '''
  
      if lb.parent is None:
          print('LayoutBox Tree\n')
          print('==============\n')
          print_children(lb)
          print('\n')
      else:
          print_tree(lb.parent)
  
  
  def plot_children(fig, box, level=0, printit=True):
      '''
      Simple plotting to show where boxes are
      '''
      import matplotlib
      import matplotlib.pyplot as plt
  
      if isinstance(fig, matplotlib.figure.Figure):
          ax = fig.add_axes([0., 0., 1., 1.])
          ax.set_facecolor([1., 1., 1., 0.7])
          ax.set_alpha(0.3)
          fig.draw(fig.canvas.get_renderer())
      else:
          ax = fig
  
      import matplotlib.patches as patches
      colors = plt.rcParams["axes.prop_cycle"].by_key()["color"]
      if printit:
          print("Level:", level)
      for child in box.children:
          rect = child.get_rect()
          if printit:
              print(child)
          ax.add_patch(
              patches.Rectangle(
                  (child.left.value(), child.bottom.value()),   # (x,y)
                  child.width.value(),          # width
                  child.height.value(),          # height
                  fc='none',
                  alpha=0.8,
                  ec=colors[level]
              )
          )
          if level > 0:
              name = child.name.split('.')[-1]
              if level % 2 == 0:
                  ax.text(child.left.value(), child.bottom.value(), name,
                          size=12-level, color=colors[level])
              else:
                  ax.text(child.right.value(), child.top.value(), name,
                          ha='right', va='top', size=12-level,
                          color=colors[level])
  
          plot_children(ax, child, level=level+1, printit=printit)
  