"""
Classes for including text in a figure.
"""

import contextlib
import logging
import math
import weakref

import numpy as np

from . import artist, cbook, docstring, rcParams
from .artist import Artist
from .font_manager import FontProperties
from .patches import FancyArrowPatch, FancyBboxPatch, Rectangle
from .textpath import TextPath  # Unused, but imported by others.
from .transforms import (
    Affine2D, Bbox, BboxBase, BboxTransformTo, IdentityTransform, Transform)


_log = logging.getLogger(__name__)


@contextlib.contextmanager
def _wrap_text(textobj):
    """Temporarily inserts newlines if the wrap option is enabled."""
    if textobj.get_wrap():
        old_text = textobj.get_text()
        try:
            textobj.set_text(textobj._get_wrapped_text())
            yield textobj
        finally:
            textobj.set_text(old_text)
    else:
        yield textobj


# Extracted from Text's method to serve as a function
def get_rotation(rotation):
    """
    Return *rotation* normalized to an angle between 0 and 360 degrees.

    Parameters
    ----------
    rotation : float or {None, 'horizontal', 'vertical'}
        Rotation angle in degrees. *None* and 'horizontal' equal 0,
        'vertical' equals 90.

    Returns
    -------
    float
    """
    try:
        return float(rotation) % 360
    except (ValueError, TypeError) as err:
        if cbook._str_equal(rotation, 'horizontal') or rotation is None:
            return 0.
        elif cbook._str_equal(rotation, 'vertical'):
            return 90.
        else:
            raise ValueError("rotation is {!r}; expected either 'horizontal', "
                             "'vertical', numeric value, or None"
                             .format(rotation)) from err


def _get_textbox(text, renderer):
    """
    Calculate the bounding box of the text. Unlike
    :meth:`matplotlib.text.Text.get_extents` method, The bbox size of
    the text before the rotation is calculated.
    """
    # TODO : This function may move into the Text class as a method. As a
    # matter of fact, The information from the _get_textbox function
    # should be available during the Text._get_layout() call, which is
    # called within the _get_textbox. So, it would better to move this
    # function as a method with some refactoring of _get_layout method.

    projected_xs = []
    projected_ys = []

    theta = np.deg2rad(text.get_rotation())
    tr = Affine2D().rotate(-theta)

    _, parts, d = text._get_layout(renderer)

    for t, wh, x, y in parts:
        w, h = wh

        xt1, yt1 = tr.transform((x, y))
        yt1 -= d
        xt2, yt2 = xt1 + w, yt1 + h

        projected_xs.extend([xt1, xt2])
        projected_ys.extend([yt1, yt2])

    xt_box, yt_box = min(projected_xs), min(projected_ys)
    w_box, h_box = max(projected_xs) - xt_box, max(projected_ys) - yt_box

    x_box, y_box = Affine2D().rotate(theta).transform((xt_box, yt_box))

    return x_box, y_box, w_box, h_box


@cbook._define_aliases({
    "color": ["c"],
    "fontfamily": ["family"],
    "fontproperties": ["font", "font_properties"],
    "horizontalalignment": ["ha"],
    "multialignment": ["ma"],
    "fontname": ["name"],
    "fontsize": ["size"],
    "fontstretch": ["stretch"],
    "fontstyle": ["style"],
    "fontvariant": ["variant"],
    "verticalalignment": ["va"],
    "fontweight": ["weight"],
})
class Text(Artist):
    """Handle storing and drawing of text in window or data coordinates."""

    zorder = 3
    _cached = cbook.maxdict(50)

    def __repr__(self):
        return "Text(%s, %s, %s)" % (self._x, self._y, repr(self._text))

    def __init__(self,
                 x=0, y=0, text='',
                 color=None,           # defaults to rc params
                 verticalalignment='baseline',
                 horizontalalignment='left',
                 multialignment=None,
                 fontproperties=None,  # defaults to FontProperties()
                 rotation=None,
                 linespacing=None,
                 rotation_mode=None,
                 usetex=None,          # defaults to rcParams['text.usetex']
                 wrap=False,
                 **kwargs
                 ):
        """
        Create a `.Text` instance at *x*, *y* with string *text*.

        Valid keyword arguments are:

        %(Text)s
        """
        Artist.__init__(self)
        self._x, self._y = x, y
        self._text = ''
        self.set_text(text)
        self.set_color(color if color is not None else rcParams["text.color"])
        self.set_fontproperties(fontproperties)
        self.set_usetex(usetex)
        self.set_wrap(wrap)
        self.set_verticalalignment(verticalalignment)
        self.set_horizontalalignment(horizontalalignment)
        self._multialignment = multialignment
        self._rotation = rotation
        self._bbox_patch = None  # a FancyBboxPatch instance
        self._renderer = None
        if linespacing is None:
            linespacing = 1.2   # Maybe use rcParam later.
        self._linespacing = linespacing
        self.set_rotation_mode(rotation_mode)
        self.update(kwargs)

    def update(self, kwargs):
        # docstring inherited
        # make a copy so we do not mutate user input!
        kwargs = dict(kwargs)
        sentinel = object()  # bbox can be None, so use another sentinel.
        # Update fontproperties first, as it has lowest priority.
        fontproperties = kwargs.pop("fontproperties", sentinel)
        if fontproperties is not sentinel:
            self.set_fontproperties(fontproperties)
        # Update bbox last, as it depends on font properties.
        bbox = kwargs.pop("bbox", sentinel)
        super().update(kwargs)
        if bbox is not sentinel:
            self.set_bbox(bbox)

    def __getstate__(self):
        d = super().__getstate__()
        # remove the cached _renderer (if it exists)
        d['_renderer'] = None
        return d

    def contains(self, mouseevent):
        """
        Return whether the mouse event occurred inside the axis-aligned
        bounding-box of the text.
        """
        inside, info = self._default_contains(mouseevent)
        if inside is not None:
            return inside, info

        if not self.get_visible() or self._renderer is None:
            return False, {}

        # Explicitly use Text.get_window_extent(self) and not
        # self.get_window_extent() so that Annotation.contains does not
        # accidentally cover the entire annotation bounding box.
        bbox = Text.get_window_extent(self)
        inside = (bbox.x0 <= mouseevent.x <= bbox.x1
                  and bbox.y0 <= mouseevent.y <= bbox.y1)

        cattr = {}
        # if the text has a surrounding patch, also check containment for it,
        # and merge the results with the results for the text.
        if self._bbox_patch:
            patch_inside, patch_cattr = self._bbox_patch.contains(mouseevent)
            inside = inside or patch_inside
            cattr["bbox_patch"] = patch_cattr

        return inside, cattr

    def _get_xy_display(self):
        """
        Get the (possibly unit converted) transformed x, y in display coords.
        """
        x, y = self.get_unitless_position()
        return self.get_transform().transform((x, y))

    def _get_multialignment(self):
        if self._multialignment is not None:
            return self._multialignment
        else:
            return self._horizontalalignment

    def get_rotation(self):
        """Return the text angle in degrees between 0 and 360."""
        return get_rotation(self._rotation)  # string_or_number -> number

    def set_rotation_mode(self, m):
        """
        Set text rotation mode.

        Parameters
        ----------
        m : {None, 'default', 'anchor'}
            If ``None`` or ``"default"``, the text will be first rotated, then
            aligned according to their horizontal and vertical alignments.  If
            ``"anchor"``, then alignment occurs before rotation.
        """
        cbook._check_in_list(["anchor", "default", None], rotation_mode=m)
        self._rotation_mode = m
        self.stale = True

    def get_rotation_mode(self):
        """Return the text rotation mode."""
        return self._rotation_mode

    def update_from(self, other):
        # docstring inherited
        Artist.update_from(self, other)
        self._color = other._color
        self._multialignment = other._multialignment
        self._verticalalignment = other._verticalalignment
        self._horizontalalignment = other._horizontalalignment
        self._fontproperties = other._fontproperties.copy()
        self._usetex = other._usetex
        self._rotation = other._rotation
        self._picker = other._picker
        self._linespacing = other._linespacing
        self.stale = True

    def _get_layout(self, renderer):
        """
        Return the extent (bbox) of the text together with
        multiple-alignment information. Note that it returns an extent
        of a rotated text when necessary.
        """
        key = self.get_prop_tup(renderer=renderer)
        if key in self._cached:
            return self._cached[key]

        thisx, thisy = 0.0, 0.0
        lines = self.get_text().split("\n")  # Ensures lines is not empty.

        ws = []
        hs = []
        xs = []
        ys = []

        # Full vertical extent of font, including ascenders and descenders:
        _, lp_h, lp_d = renderer.get_text_width_height_descent(
            "lp", self._fontproperties,
            ismath="TeX" if self.get_usetex() else False)
        min_dy = (lp_h - lp_d) * self._linespacing

        for i, line in enumerate(lines):
            clean_line, ismath = self._preprocess_math(line)
            if clean_line:
                w, h, d = renderer.get_text_width_height_descent(
                    clean_line, self._fontproperties, ismath=ismath)
            else:
                w = h = d = 0

            # For multiline text, increase the line spacing when the text
            # net-height (excluding baseline) is larger than that of a "l"
            # (e.g., use of superscripts), which seems what TeX does.
            h = max(h, lp_h)
            d = max(d, lp_d)

            ws.append(w)
            hs.append(h)

            # Metrics of the last line that are needed later:
            baseline = (h - d) - thisy

            if i == 0:
                # position at baseline
                thisy = -(h - d)
            else:
                # put baseline a good distance from bottom of previous line
                thisy -= max(min_dy, (h - d) * self._linespacing)

            xs.append(thisx)  # == 0.
            ys.append(thisy)

            thisy -= d

        # Metrics of the last line that are needed later:
        descent = d

        # Bounding box definition:
        width = max(ws)
        xmin = 0
        xmax = width
        ymax = 0
        ymin = ys[-1] - descent  # baseline of last line minus its descent
        height = ymax - ymin

        # get the rotation matrix
        M = Affine2D().rotate_deg(self.get_rotation())

        # now offset the individual text lines within the box
        malign = self._get_multialignment()
        if malign == 'left':
            offset_layout = [(x, y) for x, y in zip(xs, ys)]
        elif malign == 'center':
            offset_layout = [(x + width / 2 - w / 2, y)
                             for x, y, w in zip(xs, ys, ws)]
        elif malign == 'right':
            offset_layout = [(x + width - w, y)
                             for x, y, w in zip(xs, ys, ws)]

        # the corners of the unrotated bounding box
        corners_horiz = np.array(
            [(xmin, ymin), (xmin, ymax), (xmax, ymax), (xmax, ymin)])

        # now rotate the bbox
        corners_rotated = M.transform(corners_horiz)
        # compute the bounds of the rotated box
        xmin = corners_rotated[:, 0].min()
        xmax = corners_rotated[:, 0].max()
        ymin = corners_rotated[:, 1].min()
        ymax = corners_rotated[:, 1].max()
        width = xmax - xmin
        height = ymax - ymin

        # Now move the box to the target position offset the display
        # bbox by alignment
        halign = self._horizontalalignment
        valign = self._verticalalignment

        rotation_mode = self.get_rotation_mode()
        if rotation_mode != "anchor":
            # compute the text location in display coords and the offsets
            # necessary to align the bbox with that location
            if halign == 'center':
                offsetx = (xmin + xmax) / 2
            elif halign == 'right':
                offsetx = xmax
            else:
                offsetx = xmin

            if valign == 'center':
                offsety = (ymin + ymax) / 2
            elif valign == 'top':
                offsety = ymax
            elif valign == 'baseline':
                offsety = ymin + descent
            elif valign == 'center_baseline':
                offsety = ymin + height - baseline / 2.0
            else:
                offsety = ymin
        else:
            xmin1, ymin1 = corners_horiz[0]
            xmax1, ymax1 = corners_horiz[2]

            if halign == 'center':
                offsetx = (xmin1 + xmax1) / 2.0
            elif halign == 'right':
                offsetx = xmax1
            else:
                offsetx = xmin1

            if valign == 'center':
                offsety = (ymin1 + ymax1) / 2.0
            elif valign == 'top':
                offsety = ymax1
            elif valign == 'baseline':
                offsety = ymax1 - baseline
            elif valign == 'center_baseline':
                offsety = ymax1 - baseline / 2.0
            else:
                offsety = ymin1

            offsetx, offsety = M.transform((offsetx, offsety))

        xmin -= offsetx
        ymin -= offsety

        bbox = Bbox.from_bounds(xmin, ymin, width, height)

        # now rotate the positions around the first (x, y) position
        xys = M.transform(offset_layout) - (offsetx, offsety)

        ret = bbox, list(zip(lines, zip(ws, hs), *xys.T)), descent
        self._cached[key] = ret
        return ret

    def set_bbox(self, rectprops):
        """
        Draw a bounding box around self.

        Parameters
        ----------
        rectprops : dict with properties for `.patches.FancyBboxPatch`
             The default boxstyle is 'square'. The mutation
             scale of the `.patches.FancyBboxPatch` is set to the fontsize.

        Examples
        --------
        ::

            t.set_bbox(dict(facecolor='red', alpha=0.5))
        """

        if rectprops is not None:
            props = rectprops.copy()
            boxstyle = props.pop("boxstyle", None)
            pad = props.pop("pad", None)
            if boxstyle is None:
                boxstyle = "square"
                if pad is None:
                    pad = 4  # points
                pad /= self.get_size()  # to fraction of font size
            else:
                if pad is None:
                    pad = 0.3

            # boxstyle could be a callable or a string
            if isinstance(boxstyle, str) and "pad" not in boxstyle:
                boxstyle += ",pad=%0.2f" % pad

            bbox_transmuter = props.pop("bbox_transmuter", None)

            self._bbox_patch = FancyBboxPatch(
                                    (0., 0.),
                                    1., 1.,
                                    boxstyle=boxstyle,
                                    bbox_transmuter=bbox_transmuter,
                                    transform=IdentityTransform(),
                                    **props)
        else:
            self._bbox_patch = None

        self._update_clip_properties()

    def get_bbox_patch(self):
        """
        Return the bbox Patch, or None if the `.patches.FancyBboxPatch`
        is not made.
        """
        return self._bbox_patch

    def update_bbox_position_size(self, renderer):
        """
        Update the location and the size of the bbox.

        This method should be used when the position and size of the bbox needs
        to be updated before actually drawing the bbox.
        """

        if self._bbox_patch:

            trans = self.get_transform()

            # don't use self.get_unitless_position here, which refers to text
            # position in Text:
            posx = float(self.convert_xunits(self._x))
            posy = float(self.convert_yunits(self._y))

            posx, posy = trans.transform((posx, posy))

            x_box, y_box, w_box, h_box = _get_textbox(self, renderer)
            self._bbox_patch.set_bounds(0., 0., w_box, h_box)
            self._bbox_patch.set_transform(
                Affine2D()
                .rotate_deg(self.get_rotation())
                .translate(posx + x_box, posy + y_box))
            fontsize_in_pixel = renderer.points_to_pixels(self.get_size())
            self._bbox_patch.set_mutation_scale(fontsize_in_pixel)

    def _draw_bbox(self, renderer, posx, posy):
        """
        Update the location and size of the bbox (`.patches.FancyBboxPatch`),
        and draw.
        """

        x_box, y_box, w_box, h_box = _get_textbox(self, renderer)
        self._bbox_patch.set_bounds(0., 0., w_box, h_box)
        theta = np.deg2rad(self.get_rotation())
        tr = Affine2D().rotate(theta)
        tr = tr.translate(posx + x_box, posy + y_box)
        self._bbox_patch.set_transform(tr)
        fontsize_in_pixel = renderer.points_to_pixels(self.get_size())
        self._bbox_patch.set_mutation_scale(fontsize_in_pixel)
        self._bbox_patch.draw(renderer)

    def _update_clip_properties(self):
        clipprops = dict(clip_box=self.clipbox,
                         clip_path=self._clippath,
                         clip_on=self._clipon)
        if self._bbox_patch:
            self._bbox_patch.update(clipprops)

    def set_clip_box(self, clipbox):
        # docstring inherited.
        super().set_clip_box(clipbox)
        self._update_clip_properties()

    def set_clip_path(self, path, transform=None):
        # docstring inherited.
        super().set_clip_path(path, transform)
        self._update_clip_properties()

    def set_clip_on(self, b):
        # docstring inherited.
        super().set_clip_on(b)
        self._update_clip_properties()

    def get_wrap(self):
        """Return whether the text can be wrapped."""
        return self._wrap

    def set_wrap(self, wrap):
        """
        Set whether the text can be wrapped.

        Parameters
        ----------
        wrap : bool
        """
        self._wrap = wrap

    def _get_wrap_line_width(self):
        """
        Return the maximum line width for wrapping text based on the current
        orientation.
        """
        x0, y0 = self.get_transform().transform(self.get_position())
        figure_box = self.get_figure().get_window_extent()

        # Calculate available width based on text alignment
        alignment = self.get_horizontalalignment()
        self.set_rotation_mode('anchor')
        rotation = self.get_rotation()

        left = self._get_dist_to_box(rotation, x0, y0, figure_box)
        right = self._get_dist_to_box(
            (180 + rotation) % 360, x0, y0, figure_box)

        if alignment == 'left':
            line_width = left
        elif alignment == 'right':
            line_width = right
        else:
            line_width = 2 * min(left, right)

        return line_width

    def _get_dist_to_box(self, rotation, x0, y0, figure_box):
        """
        Return the distance from the given points to the boundaries of a
        rotated box, in pixels.
        """
        if rotation > 270:
            quad = rotation - 270
            h1 = y0 / math.cos(math.radians(quad))
            h2 = (figure_box.x1 - x0) / math.cos(math.radians(90 - quad))
        elif rotation > 180:
            quad = rotation - 180
            h1 = x0 / math.cos(math.radians(quad))
            h2 = y0 / math.cos(math.radians(90 - quad))
        elif rotation > 90:
            quad = rotation - 90
            h1 = (figure_box.y1 - y0) / math.cos(math.radians(quad))
            h2 = x0 / math.cos(math.radians(90 - quad))
        else:
            h1 = (figure_box.x1 - x0) / math.cos(math.radians(rotation))
            h2 = (figure_box.y1 - y0) / math.cos(math.radians(90 - rotation))

        return min(h1, h2)

    def _get_rendered_text_width(self, text):
        """
        Return the width of a given text string, in pixels.
        """
        w, h, d = self._renderer.get_text_width_height_descent(
            text,
            self.get_fontproperties(),
            False)
        return math.ceil(w)

    def _get_wrapped_text(self):
        """
        Return a copy of the text with new lines added, so that
        the text is wrapped relative to the parent figure.
        """
        # Not fit to handle breaking up latex syntax correctly, so
        # ignore latex for now.
        if self.get_usetex():
            return self.get_text()

        # Build the line incrementally, for a more accurate measure of length
        line_width = self._get_wrap_line_width()
        wrapped_lines = []

        # New lines in the user's text force a split
        unwrapped_lines = self.get_text().split('\n')

        # Now wrap each individual unwrapped line
        for unwrapped_line in unwrapped_lines:

            sub_words = unwrapped_line.split(' ')
            # Remove items from sub_words as we go, so stop when empty
            while len(sub_words) > 0:
                if len(sub_words) == 1:
                    # Only one word, so just add it to the end
                    wrapped_lines.append(sub_words.pop(0))
                    continue

                for i in range(2, len(sub_words) + 1):
                    # Get width of all words up to and including here
                    line = ' '.join(sub_words[:i])
                    current_width = self._get_rendered_text_width(line)

                    # If all these words are too wide, append all not including
                    # last word
                    if current_width > line_width:
                        wrapped_lines.append(' '.join(sub_words[:i - 1]))
                        sub_words = sub_words[i - 1:]
                        break

                    # Otherwise if all words fit in the width, append them all
                    elif i == len(sub_words):
                        wrapped_lines.append(' '.join(sub_words[:i]))
                        sub_words = []
                        break

        return '\n'.join(wrapped_lines)

    @artist.allow_rasterization
    def draw(self, renderer):
        # docstring inherited

        if renderer is not None:
            self._renderer = renderer
        if not self.get_visible():
            return
        if self.get_text() == '':
            return

        renderer.open_group('text', self.get_gid())

        with _wrap_text(self) as textobj:
            bbox, info, descent = textobj._get_layout(renderer)
            trans = textobj.get_transform()

            # don't use textobj.get_position here, which refers to text
            # position in Text:
            posx = float(textobj.convert_xunits(textobj._x))
            posy = float(textobj.convert_yunits(textobj._y))
            posx, posy = trans.transform((posx, posy))
            if not np.isfinite(posx) or not np.isfinite(posy):
                _log.warning("posx and posy should be finite values")
                return
            canvasw, canvash = renderer.get_canvas_width_height()

            # draw the FancyBboxPatch
            if textobj._bbox_patch:
                textobj._draw_bbox(renderer, posx, posy)

            gc = renderer.new_gc()
            gc.set_foreground(textobj.get_color())
            gc.set_alpha(textobj.get_alpha())
            gc.set_url(textobj._url)
            textobj._set_gc_clip(gc)

            angle = textobj.get_rotation()

            for line, wh, x, y in info:

                mtext = textobj if len(info) == 1 else None
                x = x + posx
                y = y + posy
                if renderer.flipy():
                    y = canvash - y
                clean_line, ismath = textobj._preprocess_math(line)

                if textobj.get_path_effects():
                    from matplotlib.patheffects import PathEffectRenderer
                    textrenderer = PathEffectRenderer(
                                        textobj.get_path_effects(), renderer)
                else:
                    textrenderer = renderer

                if textobj.get_usetex():
                    textrenderer.draw_tex(gc, x, y, clean_line,
                                          textobj._fontproperties, angle,
                                          mtext=mtext)
                else:
                    textrenderer.draw_text(gc, x, y, clean_line,
                                           textobj._fontproperties, angle,
                                           ismath=ismath, mtext=mtext)

        gc.restore()
        renderer.close_group('text')
        self.stale = False

    def get_color(self):
        """Return the color of the text."""
        return self._color

    def get_fontproperties(self):
        """Return the `.font_manager.FontProperties`."""
        return self._fontproperties

    def get_fontfamily(self):
        """
        Return the list of font families used for font lookup.

        See Also
        --------
        .font_manager.FontProperties.get_family
        """
        return self._fontproperties.get_family()

    def get_fontname(self):
        """
        Return the font name as a string.

        See Also
        --------
        .font_manager.FontProperties.get_name
        """
        return self._fontproperties.get_name()

    def get_fontstyle(self):
        """
        Return the font style as a string.

        See Also
        --------
        .font_manager.FontProperties.get_style
        """
        return self._fontproperties.get_style()

    def get_fontsize(self):
        """
        Return the font size as an integer.

        See Also
        --------
        .font_manager.FontProperties.get_size_in_points
        """
        return self._fontproperties.get_size_in_points()

    def get_fontvariant(self):
        """
        Return the font variant as a string.

        See Also
        --------
        .font_manager.FontProperties.get_variant
        """
        return self._fontproperties.get_variant()

    def get_fontweight(self):
        """
        Return the font weight as a string or a number.

        See Also
        --------
        .font_manager.FontProperties.get_weight
        """
        return self._fontproperties.get_weight()

    def get_stretch(self):
        """
        Return the font stretch as a string or a number.

        See Also
        --------
        .font_manager.FontProperties.get_stretch
        """
        return self._fontproperties.get_stretch()

    def get_horizontalalignment(self):
        """
        Return the horizontal alignment as a string.  Will be one of
        'left', 'center' or 'right'.
        """
        return self._horizontalalignment

    def get_unitless_position(self):
        """Return the (x, y) unitless position of the text."""
        # This will get the position with all unit information stripped away.
        # This is here for convenience since it is done in several locations.
        x = float(self.convert_xunits(self._x))
        y = float(self.convert_yunits(self._y))
        return x, y

    def get_position(self):
        """Return the (x, y) position of the text."""
        # This should return the same data (possible unitized) as was
        # specified with 'set_x' and 'set_y'.
        return self._x, self._y

    def get_prop_tup(self, renderer=None):
        """
        Return a hashable tuple of properties.

        Not intended to be human readable, but useful for backends who
        want to cache derived information about text (e.g., layouts) and
        need to know if the text has changed.
        """
        x, y = self.get_unitless_position()
        renderer = renderer or self._renderer
        return (x, y, self.get_text(), self._color,
                self._verticalalignment, self._horizontalalignment,
                hash(self._fontproperties),
                self._rotation, self._rotation_mode,
                self.figure.dpi, weakref.ref(renderer),
                self._linespacing
                )

    def get_text(self):
        """Return the text string."""
        return self._text

    def get_verticalalignment(self):
        """
        Return the vertical alignment as a string.  Will be one of
        'top', 'center', 'bottom' or 'baseline'.
        """
        return self._verticalalignment

    def get_window_extent(self, renderer=None, dpi=None):
        """
        Return the `.Bbox` bounding the text, in display units.

        In addition to being used internally, this is useful for specifying
        clickable regions in a png file on a web page.

        Parameters
        ----------
        renderer : Renderer, optional
            A renderer is needed to compute the bounding box.  If the artist
            has already been drawn, the renderer is cached; thus, it is only
            necessary to pass this argument when calling `get_window_extent`
            before the first `draw`.  In practice, it is usually easier to
            trigger a draw first (e.g. by saving the figure).

        dpi : float, optional
            The dpi value for computing the bbox, defaults to
            ``self.figure.dpi`` (*not* the renderer dpi); should be set e.g. if
            to match regions with a figure saved with a custom dpi value.
        """
        #return _unit_box
        if not self.get_visible():
            return Bbox.unit()
        if dpi is None:
            dpi = self.figure.dpi
        if self.get_text() == '':
            with cbook._setattr_cm(self.figure, dpi=dpi):
                tx, ty = self._get_xy_display()
                return Bbox.from_bounds(tx, ty, 0, 0)

        if renderer is not None:
            self._renderer = renderer
        if self._renderer is None:
            self._renderer = self.figure._cachedRenderer
        if self._renderer is None:
            raise RuntimeError('Cannot get window extent w/o renderer')

        with cbook._setattr_cm(self.figure, dpi=dpi):
            bbox, info, descent = self._get_layout(self._renderer)
            x, y = self.get_unitless_position()
            x, y = self.get_transform().transform((x, y))
            bbox = bbox.translated(x, y)
            return bbox

    def set_backgroundcolor(self, color):
        """
        Set the background color of the text by updating the bbox.

        Parameters
        ----------
        color : color

        See Also
        --------
        .set_bbox : To change the position of the bounding box
        """
        if self._bbox_patch is None:
            self.set_bbox(dict(facecolor=color, edgecolor=color))
        else:
            self._bbox_patch.update(dict(facecolor=color))

        self._update_clip_properties()
        self.stale = True

    def set_color(self, color):
        """
        Set the foreground color of the text

        Parameters
        ----------
        color : color
        """
        # Make sure it is hashable, or get_prop_tup will fail.
        try:
            hash(color)
        except TypeError:
            color = tuple(color)
        self._color = color
        self.stale = True

    def set_horizontalalignment(self, align):
        """
        Set the horizontal alignment to one of

        Parameters
        ----------
        align : {'center', 'right', 'left'}
        """
        cbook._check_in_list(['center', 'right', 'left'], align=align)
        self._horizontalalignment = align
        self.stale = True

    def set_multialignment(self, align):
        """
        Set the text alignment for multiline texts.

        The layout of the bounding box of all the lines is determined by the
        horizontalalignment and verticalalignment properties. This property
        controls the alignment of the text lines within that box.

        Parameters
        ----------
        align : {'left', 'right', 'center'}
        """
        cbook._check_in_list(['center', 'right', 'left'], align=align)
        self._multialignment = align
        self.stale = True

    def set_linespacing(self, spacing):
        """
        Set the line spacing as a multiple of the font size.

        The default line spacing is 1.2.

        Parameters
        ----------
        spacing : float (multiple of font size)
        """
        self._linespacing = spacing
        self.stale = True

    def set_fontfamily(self, fontname):
        """
        Set the font family.  May be either a single string, or a list of
        strings in decreasing priority.  Each string may be either a real font
        name or a generic font class name.  If the latter, the specific font
        names will be looked up in the corresponding rcParams.

        If a `Text` instance is constructed with ``fontfamily=None``, then the
        font is set to :rc:`font.family`, and the
        same is done when `set_fontfamily()` is called on an existing
        `Text` instance.

        Parameters
        ----------
        fontname : {FONTNAME, 'serif', 'sans-serif', 'cursive', 'fantasy', \
'monospace'}

        See Also
        --------
        .font_manager.FontProperties.set_family
        """
        self._fontproperties.set_family(fontname)
        self.stale = True

    def set_fontvariant(self, variant):
        """
        Set the font variant.

        Parameters
        ----------
        variant : {'normal', 'small-caps'}

        See Also
        --------
        .font_manager.FontProperties.set_variant
        """
        self._fontproperties.set_variant(variant)
        self.stale = True

    def set_fontstyle(self, fontstyle):
        """
        Set the font style.

        Parameters
        ----------
        fontstyle : {'normal', 'italic', 'oblique'}

        See Also
        --------
        .font_manager.FontProperties.set_style
        """
        self._fontproperties.set_style(fontstyle)
        self.stale = True

    def set_fontsize(self, fontsize):
        """
        Set the font size.

        Parameters
        ----------
        fontsize : float or {'xx-small', 'x-small', 'small', 'medium', \
'large', 'x-large', 'xx-large'}
            If float, the fontsize in points. The string values denote sizes
            relative to the default font size.

        See Also
        --------
        .font_manager.FontProperties.set_size
        """
        self._fontproperties.set_size(fontsize)
        self.stale = True

    def set_fontweight(self, weight):
        """
        Set the font weight.

        Parameters
        ----------
        weight : {a numeric value in range 0-1000, 'ultralight', 'light', \
'normal', 'regular', 'book', 'medium', 'roman', 'semibold', 'demibold', \
'demi', 'bold', 'heavy', 'extra bold', 'black'}

        See Also
        --------
        .font_manager.FontProperties.set_weight
        """
        self._fontproperties.set_weight(weight)
        self.stale = True

    def set_fontstretch(self, stretch):
        """
        Set the font stretch (horizontal condensation or expansion).

        Parameters
        ----------
        stretch : {a numeric value in range 0-1000, 'ultra-condensed', \
'extra-condensed', 'condensed', 'semi-condensed', 'normal', 'semi-expanded', \
'expanded', 'extra-expanded', 'ultra-expanded'}

        See Also
        --------
        .font_manager.FontProperties.set_stretch
        """
        self._fontproperties.set_stretch(stretch)
        self.stale = True

    def set_position(self, xy):
        """
        Set the (*x*, *y*) position of the text.

        Parameters
        ----------
        xy : (float, float)
        """
        self.set_x(xy[0])
        self.set_y(xy[1])

    def set_x(self, x):
        """
        Set the *x* position of the text.

        Parameters
        ----------
        x : float
        """
        self._x = x
        self.stale = True

    def set_y(self, y):
        """
        Set the *y* position of the text.

        Parameters
        ----------
        y : float
        """
        self._y = y
        self.stale = True

    def set_rotation(self, s):
        """
        Set the rotation of the text.

        Parameters
        ----------
        s : float or {'vertical', 'horizontal'}
            The rotation angle in degrees in mathematically positive direction
            (counterclockwise). 'horizontal' equals 0, 'vertical' equals 90.
        """
        self._rotation = s
        self.stale = True

    def set_verticalalignment(self, align):
        """
        Set the vertical alignment.

        Parameters
        ----------
        align : {'center', 'top', 'bottom', 'baseline', 'center_baseline'}
        """
        cbook._check_in_list(
            ['top', 'bottom', 'center', 'baseline', 'center_baseline'],
            align=align)
        self._verticalalignment = align
        self.stale = True

    def set_text(self, s):
        r"""
        Set the text string *s*.

        It may contain newlines (``\n``) or math in LaTeX syntax.

        Parameters
        ----------
        s : object
            Any object gets converted to its `str` representation, except for
            ``None`` which is converted to an empty string.
        """
        if s is None:
            s = ''
        if s != self._text:
            self._text = str(s)
            self.stale = True

    def _preprocess_math(self, s):
        """
        Return the string *s* after mathtext preprocessing, and the kind of
        mathtext support needed.

        - If *self* is configured to use TeX, return *s* unchanged except that
          a single space gets escaped, and the flag "TeX".
        - Otherwise, if *s* is mathtext (has an even number of unescaped dollar
          signs), return *s* and the flag True.
        - Otherwise, return *s* with dollar signs unescaped, and the flag
          False.
        """
        if self.get_usetex():
            if s == " ":
                s = r"\ "
            return s, "TeX"
        elif cbook.is_math_text(s):
            return s, True
        else:
            return s.replace(r"\$", "$"), False

    def set_fontproperties(self, fp):
        """
        Set the font properties that control the text.

        Parameters
        ----------
        fp : `.font_manager.FontProperties` or `str` or `pathlib.Path`
            If a `str`, it is interpreted as a fontconfig pattern parsed by
            `.FontProperties`.  If a `pathlib.Path`, it is interpreted as the
            absolute path to a font file.
        """
        self._fontproperties = FontProperties._from_any(fp).copy()
        self.stale = True

    def set_usetex(self, usetex):
        """
        Parameters
        ----------
        usetex : bool or None
            Whether to render using TeX, ``None`` means to use
            :rc:`text.usetex`.
        """
        if usetex is None:
            self._usetex = rcParams['text.usetex']
        else:
            self._usetex = bool(usetex)
        self.stale = True

    def get_usetex(self):
        """Return whether this `Text` object uses TeX for rendering."""
        return self._usetex

    def set_fontname(self, fontname):
        """
        Alias for `set_family`.

        One-way alias only: the getter differs.

        Parameters
        ----------
        fontname : {FONTNAME, 'serif', 'sans-serif', 'cursive', 'fantasy', \
'monospace'}

        See Also
        --------
        .font_manager.FontProperties.set_family

        """
        return self.set_family(fontname)


docstring.interpd.update(Text=artist.kwdoc(Text))
docstring.dedent_interpd(Text.__init__)


class OffsetFrom:
    """Callable helper class for working with `Annotation`."""

    def __init__(self, artist, ref_coord, unit="points"):
        """
        Parameters
        ----------
        artist : `.Artist` or `.BboxBase` or `.Transform`
            The object to compute the offset from.

        ref_coord : (float, float)
            If *artist* is an `.Artist` or `.BboxBase`, this values is
            the location to of the offset origin in fractions of the
            *artist* bounding box.

            If *artist* is a transform, the offset origin is the
            transform applied to this value.

        unit : {'points, 'pixels'}, default: 'points'
            The screen units to use (pixels or points) for the offset input.
        """
        self._artist = artist
        self._ref_coord = ref_coord
        self.set_unit(unit)

    def set_unit(self, unit):
        """
        Set the unit for input to the transform used by ``__call__``.

        Parameters
        ----------
        unit : {'points', 'pixels'}
        """
        cbook._check_in_list(["points", "pixels"], unit=unit)
        self._unit = unit

    def get_unit(self):
        """Return the unit for input to the transform used by ``__call__``."""
        return self._unit

    def _get_scale(self, renderer):
        unit = self.get_unit()
        if unit == "pixels":
            return 1.
        else:
            return renderer.points_to_pixels(1.)

    def __call__(self, renderer):
        """
        Return the offset transform.

        Parameters
        ----------
        renderer : `RendererBase`
            The renderer to use to compute the offset

        Returns
        -------
        `Transform`
            Maps (x, y) in pixel or point units to screen units
            relative to the given artist.
        """
        if isinstance(self._artist, Artist):
            bbox = self._artist.get_window_extent(renderer)
            xf, yf = self._ref_coord
            x = bbox.x0 + bbox.width * xf
            y = bbox.y0 + bbox.height * yf
        elif isinstance(self._artist, BboxBase):
            bbox = self._artist
            xf, yf = self._ref_coord
            x = bbox.x0 + bbox.width * xf
            y = bbox.y0 + bbox.height * yf
        elif isinstance(self._artist, Transform):
            x, y = self._artist.transform(self._ref_coord)
        else:
            raise RuntimeError("unknown type")

        sc = self._get_scale(renderer)
        tr = Affine2D().scale(sc).translate(x, y)

        return tr


class _AnnotationBase:
    def __init__(self,
                 xy,
                 xycoords='data',
                 annotation_clip=None):

        self.xy = xy
        self.xycoords = xycoords
        self.set_annotation_clip(annotation_clip)

        self._draggable = None

    def _get_xy(self, renderer, x, y, s):
        if isinstance(s, tuple):
            s1, s2 = s
        else:
            s1, s2 = s, s
        if s1 == 'data':
            x = float(self.convert_xunits(x))
        if s2 == 'data':
            y = float(self.convert_yunits(y))
        return self._get_xy_transform(renderer, s).transform((x, y))

    def _get_xy_transform(self, renderer, s):

        if isinstance(s, tuple):
            s1, s2 = s
            from matplotlib.transforms import blended_transform_factory
            tr1 = self._get_xy_transform(renderer, s1)
            tr2 = self._get_xy_transform(renderer, s2)
            tr = blended_transform_factory(tr1, tr2)
            return tr
        elif callable(s):
            tr = s(renderer)
            if isinstance(tr, BboxBase):
                return BboxTransformTo(tr)
            elif isinstance(tr, Transform):
                return tr
            else:
                raise RuntimeError("unknown return type ...")
        elif isinstance(s, Artist):
            bbox = s.get_window_extent(renderer)
            return BboxTransformTo(bbox)
        elif isinstance(s, BboxBase):
            return BboxTransformTo(s)
        elif isinstance(s, Transform):
            return s
        elif not isinstance(s, str):
            raise RuntimeError("unknown coordinate type : %s" % s)

        if s == 'data':
            return self.axes.transData
        elif s == 'polar':
            from matplotlib.projections import PolarAxes
            tr = PolarAxes.PolarTransform()
            trans = tr + self.axes.transData
            return trans

        s_ = s.split()
        if len(s_) != 2:
            raise ValueError("%s is not a recognized coordinate" % s)

        bbox0, xy0 = None, None

        bbox_name, unit = s_
        # if unit is offset-like
        if bbox_name == "figure":
            bbox0 = self.figure.bbox
        elif bbox_name == "axes":
            bbox0 = self.axes.bbox
        # elif bbox_name == "bbox":
        #     if bbox is None:
        #         raise RuntimeError("bbox is specified as a coordinate but "
        #                            "never set")
        #     bbox0 = self._get_bbox(renderer, bbox)

        if bbox0 is not None:
            xy0 = bbox0.p0
        elif bbox_name == "offset":
            xy0 = self._get_ref_xy(renderer)

        if xy0 is not None:
            # reference x, y in display coordinate
            ref_x, ref_y = xy0
            from matplotlib.transforms import Affine2D
            if unit == "points":
                # dots per points
                dpp = self.figure.get_dpi() / 72.
                tr = Affine2D().scale(dpp)
            elif unit == "pixels":
                tr = Affine2D()
            elif unit == "fontsize":
                fontsize = self.get_size()
                dpp = fontsize * self.figure.get_dpi() / 72.
                tr = Affine2D().scale(dpp)
            elif unit == "fraction":
                w, h = bbox0.size
                tr = Affine2D().scale(w, h)
            else:
                raise ValueError("%s is not a recognized coordinate" % s)

            return tr.translate(ref_x, ref_y)

        else:
            raise ValueError("%s is not a recognized coordinate" % s)

    def _get_ref_xy(self, renderer):
        """
        Return x, y (in display coordinates) that is to be used for a reference
        of any offset coordinate.
        """
        return self._get_xy(renderer, *self.xy, self.xycoords)

    # def _get_bbox(self, renderer):
    #     if hasattr(bbox, "bounds"):
    #         return bbox
    #     elif hasattr(bbox, "get_window_extent"):
    #         bbox = bbox.get_window_extent()
    #         return bbox
    #     else:
    #         raise ValueError("A bbox instance is expected but got %s" %
    #                          str(bbox))

    def set_annotation_clip(self, b):
        """
        Set the annotation's clipping behavior.

        Parameters
        ----------
        b : bool or None
            - True: the annotation will only be drawn when ``self.xy`` is
              inside the axes.
            - False: the annotation will always be drawn regardless of its
              position.
            - None: the ``self.xy`` will be checked only if *xycoords* is
              "data".
        """
        self._annotation_clip = b

    def get_annotation_clip(self):
        """
        Return the annotation's clipping behavior.

        See `set_annotation_clip` for the meaning of return values.
        """
        return self._annotation_clip

    def _get_position_xy(self, renderer):
        """Return the pixel position of the annotated point."""
        x, y = self.xy
        return self._get_xy(renderer, x, y, self.xycoords)

    def _check_xy(self, renderer):
        """Check whether the annotation at *xy_pixel* should be drawn."""
        b = self.get_annotation_clip()
        if b or (b is None and self.xycoords == "data"):
            # check if self.xy is inside the axes.
            xy_pixel = self._get_position_xy(renderer)
            return self.axes.contains_point(xy_pixel)
        return True

    def draggable(self, state=None, use_blit=False):
        """
        Set whether the annotation is draggable with the mouse.

        Parameters
        ----------
        state : bool or None
            - True or False: set the draggability.
            - None: toggle the draggability.

        Returns
        -------
        DraggableAnnotation or None
            If the annotation is draggable, the corresponding
            `.DraggableAnnotation` helper is returned.
        """
        from matplotlib.offsetbox import DraggableAnnotation
        is_draggable = self._draggable is not None

        # if state is None we'll toggle
        if state is None:
            state = not is_draggable

        if state:
            if self._draggable is None:
                self._draggable = DraggableAnnotation(self, use_blit)
        else:
            if self._draggable is not None:
                self._draggable.disconnect()
            self._draggable = None

        return self._draggable


class Annotation(Text, _AnnotationBase):
    """
    An `.Annotation` is a `.Text` that can refer to a specific position *xy*.
    Optionally an arrow pointing from the text to *xy* can be drawn.

    Attributes
    ----------
    xy
        The annotated position.
    xycoords
        The coordinate system for *xy*.
    arrow_patch
        A `.FancyArrowPatch` to point from *xytext* to *xy*.
    """

    def __str__(self):
        return "Annotation(%g, %g, %r)" % (self.xy[0], self.xy[1], self._text)

    def __init__(self, text, xy,
                 xytext=None,
                 xycoords='data',
                 textcoords=None,
                 arrowprops=None,
                 annotation_clip=None,
                 **kwargs):
        """
        Annotate the point *xy* with text *text*.

        In the simplest form, the text is placed at *xy*.

        Optionally, the text can be displayed in another position *xytext*.
        An arrow pointing from the text to the annotated point *xy* can then
        be added by defining *arrowprops*.

        Parameters
        ----------
        text : str
            The text of the annotation.  *s* is a deprecated synonym for this
            parameter.

        xy : (float, float)
            The point *(x, y)* to annotate. The coordinate system is determined
            by *xycoords*.

        xytext : (float, float), default: *xy*
            The position *(x, y)* to place the text at. The coordinate system
            is determined by *textcoords*.

        xycoords : str or `.Artist` or `.Transform` or callable or \
(float, float), default: 'data'

            The coordinate system that *xy* is given in. The following types
            of values are supported:

            - One of the following strings:

              =================   =============================================
              Value               Description
              =================   =============================================
              'figure points'     Points from the lower left of the figure
              'figure pixels'     Pixels from the lower left of the figure
              'figure fraction'   Fraction of figure from lower left
              'axes points'       Points from lower left corner of axes
              'axes pixels'       Pixels from lower left corner of axes
              'axes fraction'     Fraction of axes from lower left
              'data'              Use the coordinate system of the object being
                                  annotated (default)
              'polar'             *(theta, r)* if not native 'data' coordinates
              =================   =============================================

            - An `.Artist`: *xy* is interpreted as a fraction of the artist's
              `~matplotlib.transforms.Bbox`. E.g. *(0, 0)* would be the lower
              left corner of the bounding box and *(0.5, 1)* would be the
              center top of the bounding box.

            - A `.Transform` to transform *xy* to screen coordinates.

            - A function with one of the following signatures::

                def transform(renderer) -> Bbox
                def transform(renderer) -> Transform

              where *renderer* is a `.RendererBase` subclass.

              The result of the function is interpreted like the `.Artist` and
              `.Transform` cases above.

            - A tuple *(xcoords, ycoords)* specifying separate coordinate
              systems for *x* and *y*. *xcoords* and *ycoords* must each be
              of one of the above described types.

            See :ref:`plotting-guide-annotation` for more details.

        textcoords : str or `.Artist` or `.Transform` or callable or \
(float, float), default: value of *xycoords*
            The coordinate system that *xytext* is given in.

            All *xycoords* values are valid as well as the following
            strings:

            =================   =========================================
            Value               Description
            =================   =========================================
            'offset points'     Offset (in points) from the *xy* value
            'offset pixels'     Offset (in pixels) from the *xy* value
            =================   =========================================

        arrowprops : dict, optional
            The properties used to draw a `.FancyArrowPatch` arrow between the
            positions *xy* and *xytext*.

            If *arrowprops* does not contain the key 'arrowstyle' the
            allowed keys are:

            ==========   ======================================================
            Key          Description
            ==========   ======================================================
            width        The width of the arrow in points
            headwidth    The width of the base of the arrow head in points
            headlength   The length of the arrow head in points
            shrink       Fraction of total length to shrink from both ends
            ?            Any key to :class:`matplotlib.patches.FancyArrowPatch`
            ==========   ======================================================

            If *arrowprops* contains the key 'arrowstyle' the
            above keys are forbidden.  The allowed values of
            ``'arrowstyle'`` are:

            ============   =============================================
            Name           Attrs
            ============   =============================================
            ``'-'``        None
            ``'->'``       head_length=0.4,head_width=0.2
            ``'-['``       widthB=1.0,lengthB=0.2,angleB=None
            ``'|-|'``      widthA=1.0,widthB=1.0
            ``'-|>'``      head_length=0.4,head_width=0.2
            ``'<-'``       head_length=0.4,head_width=0.2
            ``'<->'``      head_length=0.4,head_width=0.2
            ``'<|-'``      head_length=0.4,head_width=0.2
            ``'<|-|>'``    head_length=0.4,head_width=0.2
            ``'fancy'``    head_length=0.4,head_width=0.4,tail_width=0.4
            ``'simple'``   head_length=0.5,head_width=0.5,tail_width=0.2
            ``'wedge'``    tail_width=0.3,shrink_factor=0.5
            ============   =============================================

            Valid keys for `~matplotlib.patches.FancyArrowPatch` are:

            ===============  ==================================================
            Key              Description
            ===============  ==================================================
            arrowstyle       the arrow style
            connectionstyle  the connection style
            relpos           default is (0.5, 0.5)
            patchA           default is bounding box of the text
            patchB           default is None
            shrinkA          default is 2 points
            shrinkB          default is 2 points
            mutation_scale   default is text size (in points)
            mutation_aspect  default is 1.
            ?                any key for :class:`matplotlib.patches.PathPatch`
            ===============  ==================================================

            Defaults to None, i.e. no arrow is drawn.

        annotation_clip : bool or None, default: None
            Whether to draw the annotation when the annotation point *xy* is
            outside the axes area.

            - If *True*, the annotation will only be drawn when *xy* is
              within the axes.
            - If *False*, the annotation will always be drawn.
            - If *None*, the annotation will only be drawn when *xy* is
              within the axes and *xycoords* is 'data'.

        **kwargs
            Additional kwargs are passed to `~matplotlib.text.Text`.

        Returns
        -------
        `.Annotation`

        See Also
        --------
        :ref:`plotting-guide-annotation`

        """
        _AnnotationBase.__init__(self,
                                 xy,
                                 xycoords=xycoords,
                                 annotation_clip=annotation_clip)
        # warn about wonky input data
        if (xytext is None and
                textcoords is not None and
                textcoords != xycoords):
            cbook._warn_external("You have used the `textcoords` kwarg, but "
                                 "not the `xytext` kwarg.  This can lead to "
                                 "surprising results.")

        # clean up textcoords and assign default
        if textcoords is None:
            textcoords = self.xycoords
        self._textcoords = textcoords

        # cleanup xytext defaults
        if xytext is None:
            xytext = self.xy
        x, y = xytext

        self.arrowprops = arrowprops
        if arrowprops is not None:
            arrowprops = arrowprops.copy()
            if "arrowstyle" in arrowprops:
                self._arrow_relpos = arrowprops.pop("relpos", (0.5, 0.5))
            else:
                # modified YAArrow API to be used with FancyArrowPatch
                for key in [
                        'width', 'headwidth', 'headlength', 'shrink', 'frac']:
                    arrowprops.pop(key, None)
            self.arrow_patch = FancyArrowPatch((0, 0), (1, 1), **arrowprops)
        else:
            self.arrow_patch = None

        # Must come last, as some kwargs may be propagated to arrow_patch.
        Text.__init__(self, x, y, text, **kwargs)

    def contains(self, event):
        inside, info = self._default_contains(event)
        if inside is not None:
            return inside, info
        contains, tinfo = Text.contains(self, event)
        if self.arrow_patch is not None:
            in_patch, _ = self.arrow_patch.contains(event)
            contains = contains or in_patch
        return contains, tinfo

    @property
    def xycoords(self):
        return self._xycoords

    @xycoords.setter
    def xycoords(self, xycoords):
        def is_offset(s):
            return isinstance(s, str) and s.startswith("offset")

        if (isinstance(xycoords, tuple) and any(map(is_offset, xycoords))
                or is_offset(xycoords)):
            raise ValueError("xycoords cannot be an offset coordinate")
        self._xycoords = xycoords

    @property
    def xyann(self):
        """
        The text position.

        See also *xytext* in `.Annotation`.
        """
        return self.get_position()

    @xyann.setter
    def xyann(self, xytext):
        self.set_position(xytext)

    def get_anncoords(self):
        """
        Return the coordinate system to use for `.Annotation.xyann`.

        See also *xycoords* in `.Annotation`.
        """
        return self._textcoords

    def set_anncoords(self, coords):
        """
        Set the coordinate system to use for `.Annotation.xyann`.

        See also *xycoords* in `.Annotation`.
        """
        self._textcoords = coords

    anncoords = property(get_anncoords, set_anncoords, doc="""
        The coordinate system to use for `.Annotation.xyann`.""")

    def set_figure(self, fig):
        # docstring inherited
        if self.arrow_patch is not None:
            self.arrow_patch.set_figure(fig)
        Artist.set_figure(self, fig)

    def update_positions(self, renderer):
        """
        Update the pixel positions of the annotation text and the arrow patch.
        """
        x1, y1 = self._get_position_xy(renderer)  # Annotated position.
        # generate transformation,
        self.set_transform(self._get_xy_transform(renderer, self.anncoords))

        if self.arrowprops is None:
            return

        bbox = Text.get_window_extent(self, renderer)

        d = self.arrowprops.copy()
        ms = d.pop("mutation_scale", self.get_size())
        self.arrow_patch.set_mutation_scale(ms)

        if "arrowstyle" not in d:
            # Approximately simulate the YAArrow.
            # Pop its kwargs:
            shrink = d.pop('shrink', 0.0)
            width = d.pop('width', 4)
            headwidth = d.pop('headwidth', 12)
            # Ignore frac--it is useless.
            frac = d.pop('frac', None)
            if frac is not None:
                cbook._warn_external(
                    "'frac' option in 'arrowprops' is no longer supported;"
                    " use 'headlength' to set the head length in points.")
            headlength = d.pop('headlength', 12)

            # NB: ms is in pts
            stylekw = dict(head_length=headlength / ms,
                           head_width=headwidth / ms,
                           tail_width=width / ms)

            self.arrow_patch.set_arrowstyle('simple', **stylekw)

            # using YAArrow style:
            # pick the corner of the text bbox closest to annotated point.
            xpos = [(bbox.x0, 0), ((bbox.x0 + bbox.x1) / 2, 0.5), (bbox.x1, 1)]
            ypos = [(bbox.y0, 0), ((bbox.y0 + bbox.y1) / 2, 0.5), (bbox.y1, 1)]
            x, relposx = min(xpos, key=lambda v: abs(v[0] - x1))
            y, relposy = min(ypos, key=lambda v: abs(v[0] - y1))
            self._arrow_relpos = (relposx, relposy)
            r = np.hypot(y - y1, x - x1)
            shrink_pts = shrink * r / renderer.points_to_pixels(1)
            self.arrow_patch.shrinkA = self.arrow_patch.shrinkB = shrink_pts

        # adjust the starting point of the arrow relative to the textbox.
        # TODO : Rotation needs to be accounted.
        relposx, relposy = self._arrow_relpos
        x0 = bbox.x0 + bbox.width * relposx
        y0 = bbox.y0 + bbox.height * relposy

        # The arrow will be drawn from (x0, y0) to (x1, y1). It will be first
        # clipped by patchA and patchB.  Then it will be shrunk by shrinkA and
        # shrinkB (in points).  If patch A is not set, self.bbox_patch is used.
        self.arrow_patch.set_positions((x0, y0), (x1, y1))

        if "patchA" in d:
            self.arrow_patch.set_patchA(d.pop("patchA"))
        else:
            if self._bbox_patch:
                self.arrow_patch.set_patchA(self._bbox_patch)
            else:
                if self.get_text() == "":
                    self.arrow_patch.set_patchA(None)
                    return
                pad = renderer.points_to_pixels(4)
                r = Rectangle(xy=(bbox.x0 - pad / 2, bbox.y0 - pad / 2),
                              width=bbox.width + pad, height=bbox.height + pad,
                              transform=IdentityTransform(), clip_on=False)
                self.arrow_patch.set_patchA(r)

    @artist.allow_rasterization
    def draw(self, renderer):
        # docstring inherited
        if renderer is not None:
            self._renderer = renderer
        if not self.get_visible() or not self._check_xy(renderer):
            return
        self.update_positions(renderer)
        self.update_bbox_position_size(renderer)
        if self.arrow_patch is not None:   # FancyArrowPatch
            if self.arrow_patch.figure is None and self.figure is not None:
                self.arrow_patch.figure = self.figure
            self.arrow_patch.draw(renderer)
        # Draw text, including FancyBboxPatch, after FancyArrowPatch.
        # Otherwise, a wedge arrowstyle can land partly on top of the Bbox.
        Text.draw(self, renderer)

    def get_window_extent(self, renderer=None):
        """
        Return the `.Bbox` bounding the text and arrow, in display units.

        Parameters
        ----------
        renderer : Renderer, optional
            A renderer is needed to compute the bounding box.  If the artist
            has already been drawn, the renderer is cached; thus, it is only
            necessary to pass this argument when calling `get_window_extent`
            before the first `draw`.  In practice, it is usually easier to
            trigger a draw first (e.g. by saving the figure).
        """
        # This block is the same as in Text.get_window_extent, but we need to
        # set the renderer before calling update_positions().
        if not self.get_visible():
            return Bbox.unit()
        if renderer is not None:
            self._renderer = renderer
        if self._renderer is None:
            self._renderer = self.figure._cachedRenderer
        if self._renderer is None:
            raise RuntimeError('Cannot get window extent w/o renderer')

        self.update_positions(self._renderer)

        text_bbox = Text.get_window_extent(self)
        bboxes = [text_bbox]

        if self.arrow_patch is not None:
            bboxes.append(self.arrow_patch.get_window_extent())

        return Bbox.union(bboxes)


docstring.interpd.update(Annotation=Annotation.__init__.__doc__)