API_CHANGES

    Added ax kwarg to pyplot.colorbar and Figure.colorbar so that
    one can specify the axes object from which space for the colorbar
    is to be taken, if one does not want to make the colorbar axes
    manually.

    Changed cbook.reversed so it yields a tuple rather than a
    (index, tuple). This agrees with the python reversed builtin,
    and cbook only defines reversed if python doesnt provide the
    builtin.

    Made skiprows=1 the default on csv2rec

    The gd and paint backends have been deleted.

    The errorbar method and function now accept additional kwargs
    so that upper and lower limits can be indicated by capping the
    bar with a caret instead of a straight line segment.

    The dviread.py file now has a parser for files like psfonts.map
    and pdftex.map, to map TeX font names to external files.

    The file type1font.py contains a new class for Type 1 fonts.
    Currently it simply reads pfa and pfb format files and stores the
    data in a way that is suitable for embedding in pdf files. In the
    future the class might actually parse the font to allow e.g.
    subsetting.

    FT2Font now supports FT_Attach_File. In practice this can be used
    to read an afm file in addition to a pfa/pfb file, to get metrics
    and kerning information for a Type 1 font.

    The AFM class now supports querying CapHeight and stem widths. The
    get_name_char method now has an isord kwarg like get_width_char.

    Changed pcolor default to shading='flat'; but as noted now in the
    docstring, it is preferable to simply use the edgecolor kwarg.

    The mathtext font commands (\cal, \rm, \it, \tt) now behave as TeX
    does: they are in effect until the next font change command or the
    end of the grouping.  Therefore uses of $\cal{R}$ should be
    changed to ${\cal R}$.  Alternatively, you may use the new
    LaTeX-style font commands (\mathcal, \mathrm, \mathit, \mathtt)
    which do affect the following group, eg. $\mathcal{R}$.

    Text creation commands have a new default linespacing and
    a new linespacing kwarg, which is a multiple of the maximum
    vertical extent of a line of ordinary text.  The default is
    1.2; linespacing=2 would be like ordinary double spacing, for
    example.

    Changed default kwarg in colors.Normalize.__init__ to clip=False;
    clipping silently defeats the purpose of the special over, under,
    and bad values in the colormap, thereby leading to unexpected
    behavior.  The new default should reduce such surprises.

    Made the emit property of set_xlim and set_ylim true by default;
    removed the Axes custom callback handling into a 'callbacks'
    attribute which is a cbook.CallbackRegistry instance.  This now
    supports the xlim_changed and ylim_changed Axes events.

0.90.1 released

    The file dviread.py has a (very limited and fragile) dvi reader
    for usetex support. The API might change in the future so don't
    depend on it yet.

    Removed deprecated support for a float value as a gray-scale;
    now it must be a string, like '0.5'.  Added alpha kwarg to
    ColorConverter.to_rgba_list.

    New method set_bounds(vmin, vmax) for formatters, locators sets
    the viewInterval and dataInterval from floats.

    Removed deprecated colorbar_classic.

    Line2D.get_xdata and get_ydata valid_only=False kwarg is replaced
    by orig=True.  When True, it returns the original data, otherwise
    the processed data (masked, converted)

    Some modifications to the units interface.
    units.ConversionInterface.tickers renamed to
    units.ConversionInterface.axisinfo and it now returns a
    units.AxisInfo object rather than a tuple.  This will make it
    easier to add axis info functionality (eg I added a default label
    on this iteration) w/o having to change the tuple length and hence
    the API of the client code everytime new functionality is added.
    Also, units.ConversionInterface.convert_to_value is now simply
    named units.ConversionInterface.convert.

    Axes.errorbar uses Axes.vlines and Axes.hlines to draw its error
    limits int he vertical and horizontal direction.  As you'll see
    in the changes below, these funcs now return a LineCollection
    rather than a list of lines.  The new return signature for
    errorbar is  ylins, caplines, errorcollections where
    errorcollections is a xerrcollection, yerrcollection

    Axes.vlines and Axes.hlines now create and returns a LineCollection, not a list
    of lines.  This is much faster.  The kwarg signature has changed,
    so consult the docs

    MaxNLocator accepts a new Boolean kwarg ('integer') to force
    ticks to integer locations.

    Commands that pass an argument to the Text constructor or to
    Text.set_text() now accept any object that can be converted
    with '%s'.  This affects xlabel(), title(), etc.

    Barh now takes a **kwargs dict instead of most of the old
    arguments. This helps ensure that bar and barh are kept in sync,
    but as a side effect you can no longer pass e.g. color as a
    positional argument.

    ft2font.get_charmap() now returns a dict that maps character codes
    to glyph indices (until now it was reversed)

    Moved data files into lib/matplotlib so that setuptools' develop
    mode works. Re-organized the mpl-data layout so that this source
    structure is maintained in the installation. (I.e. the 'fonts' and
    'images' sub-directories are maintained in site-packages.).
    Suggest removing site-packages/matplotlib/mpl-data and
    ~/.matplotlib/ttffont.cache before installing

0.90.0 released

    All artists now implement a "pick" method which users should not
    call.  Rather, set the "picker" property of any artist you want to
    pick on (the epsilon distance in points for a hit test) and
    register with the "pick_event" callback.  See
    examples/pick_event_demo.py for details

    Bar, barh, and hist have "log" binary kwarg: log=True
    sets the ordinate to a log scale.

    Boxplot can handle a list of vectors instead of just
    an array, so vectors can have different lengths.

    Plot can handle 2-D x and/or y; it plots the columns.

    Added linewidth kwarg to bar and barh.

    Made the default Artist._transform None (rather than invoking
    identity_transform for each artist only to have it overridden
    later).  Use artist.get_transform() rather than artist._transform,
    even in derived classes, so that the default transform will be
    created lazily as needed

    New LogNorm subclass of Normalize added to colors.py.
    All Normalize subclasses have new inverse() method, and
    the __call__() method has a new clip kwarg.

    Changed class names in colors.py to match convention:
    normalize -> Normalize, no_norm -> NoNorm.  Old names
    are still available for now.

    Removed obsolete pcolor_classic command and method.

    Removed lineprops and markerprops from the Annotation code and
    replaced them with an arrow configurable with kwarg arrowprops.
    See examples/annotation_demo.py - JDH

0.87.7 released

    Completely reworked the annotations API because I found the old
    API cumbersome.  The new design is much more legible and easy to
    read.  See matplotlib.text.Annotation and
    examples/annotation_demo.py

    markeredgecolor and markerfacecolor cannot be configured in
    matplotlibrc any more. Instead, markers are generally colored
    automatically based on the color of the line, unless marker colors
    are explicitely set as kwargs - NN

    Changed default comment character for load to '#' - JDH

    math_parse_s_ft2font_svg from mathtext.py & mathtext2.py now returns
    width, height, svg_elements. svg_elements is an instance of Bunch (
    cmbook.py) and has the attributes svg_glyphs and svg_lines, which are both
    lists.

    Renderer.draw_arc now takes an additional parameter, rotation.
    It specifies to draw the artist rotated in degrees anti-
    clockwise.  It was added for rotated ellipses.

    Renamed Figure.set_figsize_inches to Figure.set_size_inches to
    better match the get method, Figure.get_size_inches.

    Removed the copy_bbox_transform from transforms.py; added
    shallowcopy methods to all transforms.  All transforms already
    had deepcopy methods.

    FigureManager.resize(width, height): resize the window
    specified in pixels

    barh: x and y args have been renamed to width and bottom
    respectively, and their order has been swapped to maintain
    a (position, value) order.

    bar and barh: now accept kwarg 'edgecolor'.

    bar and barh: The left, height, width and bottom args can
    now all be scalars or sequences; see docstring.

    barh: now defaults to edge aligned instead of center
    aligned bars

    bar, barh and hist: Added a keyword arg 'align' that
    controls between edge or center bar alignment.

    Collections: PolyCollection and LineCollection now accept
    vertices or segments either in the original form [(x,y),
    (x,y), ...] or as a 2D numerix array, with X as the first column
    and Y as the second. Contour and quiver output the numerix
    form.  The transforms methods Bbox.update() and
    Transformation.seq_xy_tups() now accept either form.

    Collections: LineCollection is now a ScalarMappable like
    PolyCollection, etc.

    Specifying a grayscale color as a float is deprecated; use
    a string instead, e.g., 0.75 -> '0.75'.

    Collections: initializers now accept any mpl color arg, or
    sequence of such args; previously only a sequence of rgba
    tuples was accepted.

    Colorbar: completely new version and api; see docstring.  The
    original version is still accessible as colorbar_classic, but
    is deprecated.

    Contourf: "extend" kwarg replaces "clip_ends"; see docstring.
    Masked array support added to pcolormesh.

    Modified aspect-ratio handling:
        Removed aspect kwarg from imshow
        Axes methods:
            set_aspect(self, aspect, adjustable=None, anchor=None)
            set_adjustable(self, adjustable)
            set_anchor(self, anchor)
        Pylab interface:
            axis('image')

     Backend developers: ft2font's load_char now takes a flags
     argument, which you can OR together from the LOAD_XXX
     constants.

API Changes in matplotlib-0.86

     Matplotlib data is installed into the matplotlib module.
     This is similar to package_data.  This should get rid of
     having to check for many possibilities in _get_data_path().
     The MATPLOTLIBDATA env key is still checked first to allow
     for flexibility.

     1) Separated the color table data from cm.py out into
     a new file, _cm.py, to make it easier to find the actual
     code in cm.py and to add new colormaps. Everything
     from _cm.py is imported by cm.py, so the split should be
     transparent.
     2) Enabled automatic generation of a colormap from
     a list of colors in contour; see modified
     examples/contour_demo.py.
     3) Support for imshow of a masked array, with the
     ability to specify colors (or no color at all) for
     masked regions, and for regions that are above or
     below the normally mapped region.  See
     examples/image_masked.py.
     4) In support of the above, added two new classes,
     ListedColormap, and no_norm, to colors.py, and modified
     the Colormap class to include common functionality. Added
     a clip kwarg to the normalize class.


API Changes in matplotlib-0.85

    Made xtick and ytick separate props in rc

    made pos=None the default for tick formatters rather than 0 to
    indicate "not supplied"

    Removed "feature" of minor ticks which prevents them from
    overlapping major ticks.  Often you want major and minor ticks at
    the same place, and can offset the major ticks with the pad.  This
    could be made configurable

    Changed the internal structure of contour.py to a more OO style.
    Calls to contour or contourf in axes.py or pylab.py now return
    a ContourSet object which contains references to the
    LineCollections or PolyCollections created by the call,
    as well as the configuration variables that were used.
    The ContourSet object is a "mappable" if a colormap was used.

    Added a clip_ends kwarg to contourf. From the docstring:
             * clip_ends = True
               If False, the limits for color scaling are set to the
               minimum and maximum contour levels.
               True (default) clips the scaling limits.  Example:
               if the contour boundaries are V = [-100, 2, 1, 0, 1, 2, 100],
               then the scaling limits will be [-100, 100] if clip_ends
               is False, and [-3, 3] if clip_ends is True.
    Added kwargs linewidths, antialiased, and nchunk to contourf.  These
    are experimental; see the docstring.

    Changed Figure.colorbar():
        kw argument order changed;
        if mappable arg is a non-filled ContourSet, colorbar() shows
                lines instead hof polygons.
        if mappable arg is a filled ContourSet with clip_ends=True,
                the endpoints are not labelled, so as to give the
                correct impression of open-endedness.

    Changed LineCollection.get_linewidths to get_linewidth, for
    consistency.


API Changes in matplotlib-0.84

    Unified argument handling between hlines and vlines.  Both now
    take optionally a fmt argument (as in plot) and a keyword args
    that can be passed onto Line2D.

    Removed all references to "data clipping" in rc and lines.py since
    these were not used and not optimized.  I'm sure they'll be
    resurrected later with a better implementation when needed.

    'set' removed - no more deprecation warnings.  Use 'setp' instead.

    Backend developers: Added flipud method to image and removed it
    from to_str.  Removed origin kwarg from backend.draw_image.
    origin is handled entirely by the frontend now.

API Changes in matplotlib-0.83

  - Made HOME/.matplotlib the new config dir where the matplotlibrc
    file, the ttf.cache, and the tex.cache live.  The new default
    filenames in .matplotlib have no leading dot and are not hidden.
    Eg, the new names are matplotlibrc, tex.cache, and ttffont.cache.
    This is how ipython does it so it must be right.

    If old files are found, a warning is issued and they are moved to
    the new location.

  - backends/__init__.py no longer imports new_figure_manager,
    draw_if_interactive and show from the default backend, but puts
    these imports into a call to pylab_setup.  Also, the Toolbar is no
    longer imported from WX/WXAgg.  New usage:

      from backends import pylab_setup
      new_figure_manager, draw_if_interactive, show = pylab_setup()

  - Moved Figure.get_width_height() to FigureCanvasBase. It now
    returns int instead of float.

API Changes in matplotlib-0.82

  - toolbar import change in GTKAgg, GTKCairo and WXAgg

  - Added subplot config tool to GTK* backends -- note you must now
    import the NavigationToolbar2 from your backend of choice rather
    than from backend_gtk because it needs to know about the backend
    specific canvas -- see examples/embedding_in_gtk2.py.  Ditto for
    wx backend -- see examples/embedding_in_wxagg.py


  - hist bin change

      Sean Richards notes there was a problem in the way we created
      the binning for histogram, which made the last bin
      underrepresented.  From his post:

        I see that hist uses the linspace function to create the bins
        and then uses searchsorted to put the values in their correct
        bin. Thats all good but I am confused over the use of linspace
        for the bin creation. I wouldn't have thought that it does
        what is needed, to quote the docstring it creates a "Linear
        spaced array from min to max". For it to work correctly
        shouldn't the values in the bins array be the same bound for
        each bin? (i.e. each value should be the lower bound of a
        bin). To provide the correct bins for hist would it not be
        something like

        def bins(xmin, xmax, N):
          if N==1: return xmax
          dx = (xmax-xmin)/N # instead of N-1
          return xmin + dx*arange(N)


       This suggestion is implemented in 0.81.  My test script with these
       changes does not reveal any bias in the binning

        from matplotlib.numerix.mlab import randn, rand, zeros, Float
        from matplotlib.mlab import hist, mean

        Nbins = 50
        Ntests = 200
        results = zeros((Ntests,Nbins), typecode=Float)
        for i in range(Ntests):
            print 'computing', i
            x = rand(10000)
            n, bins = hist(x, Nbins)
            results[i] = n
        print mean(results)


API CHANGES in matplotlib-0.81

  - pylab and artist "set" functions renamed to setp to avoid clash
    with python2.4 built-in set.  Current version will issue a
    deprecation warning which will be removed in future versions

  - imshow interpolation arguments changes for advanced interpolation
    schemes.  See help imshow, particularly the interpolation,
    filternorm and filterrad kwargs

  - Support for masked arrays has been added to the plot command and
    to the Line2D object.  Only the valid points are plotted.  A
    "valid_only" kwarg was added to the get_xdata() and get_ydata()
    methods of Line2D; by default it is False, so that the original
    data arrays are returned. Setting it to True returns the plottable
    points.

  - contour changes:

    Masked arrays: contour and contourf now accept masked arrays as
      the variable to be contoured.  Masking works correctly for
      contour, but a bug remains to be fixed before it will work for
      contourf.  The "badmask" kwarg has been removed from both
      functions.

     Level argument changes:

       Old version: a list of levels as one of the positional
       arguments specified the lower bound of each filled region; the
       upper bound of the last region was taken as a very large
       number.  Hence, it was not possible to specify that z values
       between 0 and 1, for example, be filled, and that values
       outside that range remain unfilled.

       New version: a list of N levels is taken as specifying the
       boundaries of N-1 z ranges.  Now the user has more control over
       what is colored and what is not.  Repeated calls to contourf
       (with different colormaps or color specifications, for example)
       can be used to color different ranges of z.  Values of z
       outside an expected range are left uncolored.

       Example:
         Old: contourf(z, [0, 1, 2]) would yield 3 regions: 0-1, 1-2, and >2.
         New: it would yield 2 regions: 0-1, 1-2.  If the same 3 regions were
         desired, the equivalent list of levels would be [0, 1, 2,
         1e38].


API CHANGES in matplotlib-0.80

  - xlim/ylim/axis always return the new limits regardless of
    arguments.  They now take kwargs which allow you to selectively
    change the upper or lower limits while leaving unnamed limits
    unchanged.  See help(xlim) for example

API CHANGES in matplotlib-0.73

  - Removed deprecated ColormapJet and friends

  - Removed all error handling from the verbose object

  - figure num of zero is now allowed

API CHANGES in matplotlib-0.72

  - Line2D, Text, and Patch copy_properties renamed update_from and
    moved into artist base class

  - LineCollecitons.color renamed to LineCollections.set_color for
    consistency with set/get introspection mechanism,

  - pylab figure now defaults to num=None, which creates a new figure
    with a guaranteed unique number

  - contour method syntax changed - now it is matlab compatible

      unchanged: contour(Z)
      old: contour(Z, x=Y, y=Y)
      new: contour(X, Y, Z)

    see http://matplotlib.sf.net/matplotlib.pylab.html#-contour


   - Increased the default resolution for save command.

   - Renamed the base attribute of the ticker classes to _base to avoid conflict
     with the base method.  Sitt for subs

   - subs=none now does autosubbing in the tick locator.

   - New subplots that overlap old will delete the old axes.  If you
     do not want this behavior, use fig.add_subplot or the axes
     command

API CHANGES in matplotlib-0.71

   Significant numerix namespace changes, introduced to resolve
   namespace clashes between python built-ins and mlab names.
   Refactored numerix to maintain separate modules, rather than
   folding all these names into a single namespace.  See the following
   mailing list threads for more information and background

     http://sourceforge.net/mailarchive/forum.php?thread_id=6398890&forum_id=36187
     http://sourceforge.net/mailarchive/forum.php?thread_id=6323208&forum_id=36187


  OLD usage

   from matplotlib.numerix import array, mean, fft

  NEW usage

   from matplotlib.numerix import array
   from matplotlib.numerix.mlab import mean
   from matplotlib.numerix.fft import fft

  numerix dir structure mirrors numarray (though it is an incomplete
  implementation)

    numerix
    numerix/mlab
    numerix/linear_algebra
    numerix/fft
    numerix/random_array

  but of course you can use 'numerix : Numeric' and still get the
  symbols.

  pylab still imports most of the symbols from Numerix, MLab, fft,
  etc, but is more cautious.  For names that clash with python names
  (min, max, sum), pylab keeps the builtins and provides the numeric
  versions with an a* prefix, eg (amin, amax, asum)



API CHANGES in matplotlib-0.70

   MplEvent factored into a base class Event and derived classes
   MouseEvent and KeyEvent

   Removed definct set_measurement in wx toolbar

API CHANGES in matplotlib-0.65.1

  removed add_axes and add_subplot from backend_bases.  Use
  figure.add_axes and add_subplot instead.  The figure now manages the
  current axes with gca and sca for get and set current axe.  If you
  have code you are porting which called, eg, figmanager.add_axes, you
  can now simply do figmanager.canvas.figure.add_axes.

API CHANGES in matplotlib-0.65

  mpl_connect and mpl_disconnect in the matlab interface renamed to
  connect and disconnect

  Did away with the text methods for angle since they were ambiguous.
  fontangle could mean fontstyle (obligue, etc) or the rotation of the
  text.  Use style and rotation instead.


API CHANGES in matplotlib-0.63

  Dates are now represented internally as float days since 0001-01-01,
  UTC.

  All date tickers and formatters are now in matplotlib.dates, rather
  than matplotlib.tickers

  converters have been abolished from all functions and classes.
  num2date and date2num are now the converter functions for all date
  plots

  Most of the date tick locators have a different meaning in their
  constructors.  In the prior implementation, the first argument was a
  base and multiples of the base were ticked.  Eg

    HourLocator(5)  # old: tick every 5 minutes

  In the new implementation, the explicit points you want to tick are
  provided as a number or sequence

     HourLocator(range(0,5,61))  # new: tick every 5 minutes

  This gives much greater flexibility.  I have tried to make the
  default constructors (no args) behave similarly, where possible.

  Note that YearLocator still works under the base/multiple scheme.
  The difference between the YearLocator and the other locators is
  that years are not recurrent.


  Financial functions:

    matplotlib.finance.quotes_historical_yahoo(ticker, date1, date2)

     date1, date2 are now datetime instances.  Return value is a list
     of quotes where the quote time is a float - days since gregorian
     start, as returned by date2num

     See examples/finance_demo.py for example usage of new API


API CHANGES in matplotlib-0.61

  canvas.connect is now deprecated for event handling.  use
  mpl_connect and mpl_disconnect instead.  The callback signature is
  func(event) rather than func(widget, evet)

API CHANGES in matplotlib-0.60

ColormapJet and Grayscale are deprecated.  For backwards
compatibility, they can be obtained either by doing

  from matplotlib.cm import ColormapJet

or

  from matplotlib.matlab import *

They are replaced by cm.jet and cm.grey


API CHANGES in matplotlib-0.54.3

removed the set_default_font / get_default_font scheme from the
font_manager to unify customization of font defaults with the rest of
the rc scheme.  See examples/font_properties_demo.py and help(rc) in
matplotlib.matlab.


API CHANGES in matplotlib-0.54

matlab interface
================

dpi
---

Several of the backends used a PIXELS_PER_INCH hack that I added to
try and make images render consistently across backends.  This just
complicated matters.  So you may find that some font sizes and line
widths appear different than before.  Apologies for the
inconvenience. You should set the dpi to an accurate value for your
screen to get true sizes.


pcolor and scatter
------------------

There are two changes to the matlab interface API, both involving the
patch drawing commands.  For efficiency, pcolor and scatter have been
rewritten to use polygon collections, which are a new set of objects
from matplotlib.collections designed to enable efficient handling of
large collections of objects.  These new collections make it possible
to build large scatter plots or pcolor plots with no loops at the
python level, and are significantly faster than their predecessors.
The original pcolor and scatter functions are retained as
pcolor_classic and scatter_classic.

The return value from pcolor is a PolyCollection.  Most of the
propertes that are available on rectangles or other patches are also
available on PolyCollections, eg you can say

  c = scatter(blah, blah)
  c.set_linewidth(1.0)
  c.set_facecolor('r')
  c.set_alpha(0.5)

or

  c = scatter(blah, blah)
  set(c, 'linewidth', 1.0, 'facecolor', 'r', 'alpha', 0.5)


Because the collection is a single object, you no longer need to loop
over the return value of scatter or pcolor to set properties for the
entire list.

If you want the different elements of a collection to vary on a
property, eg to have different line widths, see matplotlib.collections
for a discussion on how to set the properties as a sequence.

For scatter, the size argument is now in points^2 (the area of the
symbol in points) as in matlab and is not in data coords as before.
Using sizes in data coords caused several problems.  So you will need
to adjust your size arguments accordingly or use scatter_classic.

mathtext spacing
----------------

For reasons not clear to me (and which I'll eventually fix) spacing no
longer works in font groups.  However, I added three new spacing
commands which compensate for this '\ ' (regular space), '\/' (small
space) and '\hspace{frac}' where frac is a fraction of fontsize in
points.  You will need to quote spaces in font strings, is

  title(r'$\rm{Histogram\ of\ IQ:}\ \mu=100,\ \sigma=15$')



Object interface - Application programmers
==========================================

Autoscaling
------------

  The x and y axis instances no longer have autoscale view.  These are
  handled by axes.autoscale_view

Axes creation
--------------

    You should not instantiate your own Axes any more using the OO API.
    Rather, create a Figure as before and in place of

      f = Figure(figsize=(5,4), dpi=100)
      a = Subplot(f, 111)
      f.add_axis(a)

    use

      f = Figure(figsize=(5,4), dpi=100)
      a = f.add_subplot(111)

    That is, add_axis no longer exists and is replaced by

      add_axes(rect, axisbg=defaultcolor, frameon=True)
      add_subplot(num, axisbg=defaultcolor, frameon=True)

Artist methods
---------------

  If you define your own Artists, you need to rename the _draw method
  to draw

Bounding boxes
--------------

   matplotlib.transforms.Bound2D is replaced by
   matplotlib.transforms.Bbox.  If you want to construct a bbox from
   left, bottom, width, height (the signature for Bound2D), use
   matplotlib.transforms.lbwh_to_bbox, as in

    bbox = clickBBox = lbwh_to_bbox(left, bottom, width, height)

   The Bbox has a different API than the Bound2D.  Eg, if you want to
   get the width and height of the bbox

     OLD
        width  = fig.bbox.x.interval()
        height = fig.bbox.y.interval()

     New
        width  = fig.bbox.width()
        height = fig.bbox.height()




Object constructors
-------------------

  You no longer pass the bbox, dpi, or transforms to the various
  Artist constructors.  The old way or creating lines and rectangles
  was cumbersome because you had to pass so many attributes to the
  Line2D and Rectangle classes not related directly to the gemoetry
  and properties of the object.  Now default values are added to the
  object when you call axes.add_line or axes.add_patch, so they are
  hidden from the user.

  If you want to define a custom transformation on these objects, call
  o.set_transform(trans) where trans is a Transformation instance.

  In prior versions of you wanted to add a custom line in data coords,
  you would have to do

        l =  Line2D(dpi, bbox, x, y,
                    color = color,
                    transx = transx,
                    transy = transy,
                    )

  now all you need is

        l =  Line2D(x, y, color=color)

  and the axes will set the transformation for you (unless you have
  set your own already, in which case it will eave it unchanged)

Transformations
---------------

  The entire transformation architecture has been rewritten.
  Previously the x and y transformations where stored in the xaxis and
  yaxis insstances.  The problem with this approach is it only allows
  for separable transforms (where the x and y transformations don't
  depend on one another).  But for cases like polar, they do.  Now
  transformations operate on x,y together.  There is a new base class
  matplotlib.transforms.Transformation and two concrete
  implemetations, matplotlib.transforms.SeparableTransformation and
  matplotlib.transforms.Affine.  The SeparableTransformation is
  constructed with the bounding box of the input (this determines the
  rectangular coordinate system of the input, ie the x and y view
  limits), the bounding box of the display, and possibily nonlinear
  transformations of x and y.  The 2 most frequently used
  transformations, data cordinates -> display and axes coordinates ->
  display are available as ax.transData and ax.transAxes.  See
  alignment_demo.py which uses axes coords.

  Also, the transformations should be much faster now, for two reasons

   * they are written entirely in extension code

   * because they operate on x and y together, they can do the entire
     transformation in one loop.  Earlier I did something along the
     lines of

       xt = sx*func(x) + tx
       yt = sy*func(y) + ty

     Although this was done in numerix, it still involves 6 length(x)
     for-loops (the multiply, add, and function evaluation each for x
     and y).  Now all of that is done in a single pass.


  If you are using transformations and bounding boxes to get the
  cursor position in data coordinates, the method calls are a little
  different now.  See the updated examples/coords_demo.py which shows
  you how to do this.

  Likewise, if you are using the artist bounding boxes to pick items
  on the canvas with the GUI, the bbox methods are somewhat
  different.  You will need to see the updated
  examples/object_picker.py.

  See unit/transforms_unit.py for many examples using the new
  transformations.



API changes at 0.50

  * refactored Figure class so it is no longer backend dependent.
    FigureCanvasBackend takes over the backend specific duties of the
    Figure.  matplotlib.backend_bases.FigureBase moved to
    matplotlib.figure.Figure.

  * backends must implement FigureCanvasBackend (the thing that
    controls the figure and handles the events if any) and
    FigureManagerBackend (wraps the canvas and the window for matlab
    interface).  FigureCanvasBase implements a backend switching
    mechanism

  * Figure is now an Artist (like everything else in the figure) and
    is totally backend independent

  * GDFONTPATH renamed to TTFPATH

  * backend faceColor argument changed to rgbFace

  * colormap stuff moved to colors.py

  * arg_to_rgb in backend_bases moved to class ColorConverter in
    colors.py

  * GD users must upgrade to gd-2.0.22 and gdmodule-0.52 since new gd
    features (clipping, antialiased lines) are now used.

  * Renderer must implement points_to_pixels

Migrating code:

  Matlab interface:

    The only API change for those using the matlab interface is in how
    you call figure redraws for dynamically updating figures.  In the
    old API, you did

      fig.draw()

    In the new API, you do

      manager = get_current_fig_manager()
      manager.canvas.draw()

    See the examples system_monitor.py, dynamic_demo.py, and anim.py

  API

    There is one important API change for application developers.
    Figure instances used subclass GUI widgets that enabled them to be
    placed directly into figures.  Eg, FigureGTK subclassed
    gtk.DrawingArea.  Now the Figure class is independent of the
    backend, and FigureCanvas takes over the functionality formerly
    handled by Figure.  In order to include figures into your apps,
    you now need to do, for example

      # gtk example
      fig = Figure(figsize=(5,4), dpi=100)
      canvas = FigureCanvasGTK(fig)  # a gtk.DrawingArea
      canvas.show()
      vbox.pack_start(canvas)

    If you use the NavigationToolbar, this in now intialized with a
    FigureCanvas, not a Figure.  The examples embedding_in_gtk.py,
    embedding_in_gtk2.py, and mpl_with_glade.py all reflect the new
    API so use these as a guide.

    All prior calls to

     figure.draw()  and
     figure.print_figure(args)

    should now be

     canvas.draw()  and
     canvas.print_figure(args)

    Apologies for the inconvenience.  This refactorization brings
    significant more freedom in developing matplotlib and should bring
    better plotting capabilities, so I hope the inconvenience is worth
    it.



API changes at 0.42

  * Refactoring AxisText to be backend independent.  Text drawing and
    get_window_extent functionality will be moved to the Renderer.

  * backend_bases.AxisTextBase is now text.Text module

  * All the erase and reset functionality removed frmo AxisText - not
    needed with double buffered drawing.  Ditto with state change.
    Text instances have a get_prop_tup method that returns a hashable
    tuple of text properties which you can use to see if text props
    have changed, eg by caching a font or layout instance in a dict
    with the prop tup as a key -- see RendererGTK.get_pango_layout in
    backend_gtk for an example.

  * Text._get_xy_display renamed Text.get_xy_display

  * Artist set_renderer and wash_brushes methods removed

  * Moved Legend class from matplotlib.axes into matplotlib.legend

  * Moved Tick, XTick, YTick, Axis, XAxis, YAxis from matplotlib.axes
    to matplotlib.axis

  * moved process_text_args to matplotlib.text

  * After getting Text handled in a backend independent fashion, the
    import process is much cleaner since there are no longer cyclic
    dependencies

  * matplotlib.matlab._get_current_fig_manager renamed to
    matplotlib.matlab.get_current_fig_manager to allow user access to
    the GUI window attribute, eg figManager.window for GTK and
    figManager.frame for wx





API changes at 0.40

- Artist
    * __init__ takes a DPI instance and a Bound2D instance which is
      the bounding box of the artist in display coords
    * get_window_extent returns a Bound2D instance
    * set_size is removed; replaced by bbox and dpi
    * the clip_gc method is removed.  Artists now clip themselves with
      their box
    * added _clipOn boolean attribute.  If True, gc clip to bbox.

- AxisTextBase
    * Initialized with a transx, transy which are Transform instances
    * set_drawing_area removed
    * get_left_right and get_top_bottom are replaced by get_window_extent

- Line2D Patches now take transx, transy
    * Initialized with a transx, transy which are Transform instances

- Patches
   * Initialized with a transx, transy which are Transform instances

- FigureBase attributes dpi is a DPI intance rather than scalar and
  new attribute bbox is a Bound2D in display coords, and I got rid of
  the left, width, height, etc... attributes.  These are now
  accessible as, for example, bbox.x.min is left, bbox.x.interval() is
  width, bbox.y.max is top, etc...

- GcfBase attribute pagesize renamed to figsize

- Axes
    * removed figbg attribute
    * added fig instance to __init__
    * resizing is handled by figure call to resize.

- Subplot
    * added fig instance to __init__

- Renderer methods for patches now take gcEdge and gcFace instances.
  gcFace=None takes the place of filled=False

- True and False symbols provided by cbook in a python2.3 compatible
  way

- new module transforms supplies Bound1D, Bound2D and Transform
  instances and more

- Changes to the matlab helpers API

  * _matlab_helpers.GcfBase is renamed by Gcf.  Backends no longer
    need to derive from this class.  Instead, they provide a factory
    function new_figure_manager(num, figsize, dpi).  The destroy
    method of the GcfDerived from the backends is moved to the derived
    FigureManager.

  * FigureManagerBase moved to backend_bases

  * Gcf.get_all_figwins renamed to Gcf.get_all_fig_managers

Jeremy:

  Make sure to self._reset = False in AxisTextWX._set_font.  This was
  something missing in my backend code.