from contextlib import ExitStack
from copy import copy
import io
import os
import sys
from pathlib import Path
import platform
import urllib.request
import warnings

import numpy as np
from numpy import ma
from numpy.testing import assert_array_equal

from matplotlib import (
    colors, image as mimage, patches, pyplot as plt, style,
    rc_context, rcParams)
from matplotlib.cbook import MatplotlibDeprecationWarning
from matplotlib.image import (AxesImage, BboxImage, FigureImage,
                              NonUniformImage, PcolorImage)
from matplotlib.testing.decorators import check_figures_equal, image_comparison
from matplotlib.transforms import Bbox, Affine2D, TransformedBbox

import pytest


@image_comparison(baseline_images=['image_interps'], style='mpl20')
def test_image_interps():
    'make the basic nearest, bilinear and bicubic interps'
    X = np.arange(100)
    X = X.reshape(5, 20)

    fig = plt.figure()
    ax1 = fig.add_subplot(311)
    ax1.imshow(X, interpolation='nearest')
    ax1.set_title('three interpolations')
    ax1.set_ylabel('nearest')

    ax2 = fig.add_subplot(312)
    ax2.imshow(X, interpolation='bilinear')
    ax2.set_ylabel('bilinear')

    ax3 = fig.add_subplot(313)
    ax3.imshow(X, interpolation='bicubic')
    ax3.set_ylabel('bicubic')


@image_comparison(baseline_images=['interp_alpha'],
                  extensions=['png'], remove_text=True)
def test_alpha_interp():
    'Test the interpolation of the alpha channel on RGBA images'
    fig, (axl, axr) = plt.subplots(1, 2)
    # full green image
    img = np.zeros((5, 5, 4))
    img[..., 1] = np.ones((5, 5))
    # transparent under main diagonal
    img[..., 3] = np.tril(np.ones((5, 5), dtype=np.uint8))
    axl.imshow(img, interpolation="none")
    axr.imshow(img, interpolation="bilinear")


@image_comparison(baseline_images=['interp_nearest_vs_none'],
                  extensions=['pdf', 'svg'], remove_text=True)
def test_interp_nearest_vs_none():
    'Test the effect of "nearest" and "none" interpolation'
    # Setting dpi to something really small makes the difference very
    # visible. This works fine with pdf, since the dpi setting doesn't
    # affect anything but images, but the agg output becomes unusably
    # small.
    rcParams['savefig.dpi'] = 3
    X = np.array([[[218, 165, 32], [122, 103, 238]],
                  [[127, 255, 0], [255, 99, 71]]], dtype=np.uint8)
    fig = plt.figure()
    ax1 = fig.add_subplot(121)
    ax1.imshow(X, interpolation='none')
    ax1.set_title('interpolation none')
    ax2 = fig.add_subplot(122)
    ax2.imshow(X, interpolation='nearest')
    ax2.set_title('interpolation nearest')


def do_figimage(suppressComposite):
    """Helper for the next two tests."""
    fig = plt.figure(figsize=(2, 2), dpi=100)
    fig.suppressComposite = suppressComposite
    x, y = np.ix_(np.arange(100) / 100.0, np.arange(100) / 100)
    z = np.sin(x**2 + y**2 - x*y)
    c = np.sin(20*x**2 + 50*y**2)
    img = z + c/5

    fig.figimage(img, xo=0, yo=0, origin='lower')
    fig.figimage(img[::-1, :], xo=0, yo=100, origin='lower')
    fig.figimage(img[:, ::-1], xo=100, yo=0, origin='lower')
    fig.figimage(img[::-1, ::-1], xo=100, yo=100, origin='lower')


@image_comparison(baseline_images=['figimage-0'], extensions=['png', 'pdf'])
def test_figimage0():
    suppressComposite = False
    do_figimage(suppressComposite)


@image_comparison(baseline_images=['figimage-1'], extensions=['png', 'pdf'])
def test_figimage1():
    suppressComposite = True
    do_figimage(suppressComposite)


def test_image_python_io():
    fig, ax = plt.subplots()
    ax.plot([1, 2, 3])
    buffer = io.BytesIO()
    fig.savefig(buffer)
    buffer.seek(0)
    plt.imread(buffer)


@check_figures_equal()
def test_imshow_pil(fig_test, fig_ref):
    style.use("default")
    PIL = pytest.importorskip("PIL")
    png_path = Path(__file__).parent / "baseline_images/pngsuite/basn3p04.png"
    tiff_path = Path(__file__).parent / "baseline_images/test_image/uint16.tif"
    axs = fig_test.subplots(2)
    axs[0].imshow(PIL.Image.open(png_path))
    axs[1].imshow(PIL.Image.open(tiff_path))
    axs = fig_ref.subplots(2)
    axs[0].imshow(plt.imread(str(png_path)))
    axs[1].imshow(plt.imread(tiff_path))


def test_imread_pil_uint16():
    pytest.importorskip("PIL")
    img = plt.imread(os.path.join(os.path.dirname(__file__),
                     'baseline_images', 'test_image', 'uint16.tif'))
    assert img.dtype == np.uint16
    assert np.sum(img) == 134184960


def test_imread_fspath():
    pytest.importorskip("PIL")
    img = plt.imread(
        Path(__file__).parent / 'baseline_images/test_image/uint16.tif')
    assert img.dtype == np.uint16
    assert np.sum(img) == 134184960


@pytest.mark.parametrize("fmt", ["png", "jpg", "jpeg", "tiff"])
def test_imsave(fmt):
    if fmt in ["jpg", "jpeg", "tiff"]:
        pytest.importorskip("PIL")
    has_alpha = fmt not in ["jpg", "jpeg"]

    # The goal here is that the user can specify an output logical DPI
    # for the image, but this will not actually add any extra pixels
    # to the image, it will merely be used for metadata purposes.

    # So we do the traditional case (dpi == 1), and the new case (dpi
    # == 100) and read the resulting PNG files back in and make sure
    # the data is 100% identical.
    np.random.seed(1)
    # The height of 1856 pixels was selected because going through creating an
    # actual dpi=100 figure to save the image to a Pillow-provided format would
    # cause a rounding error resulting in a final image of shape 1855.
    data = np.random.rand(1856, 2)

    buff_dpi1 = io.BytesIO()
    plt.imsave(buff_dpi1, data, format=fmt, dpi=1)

    buff_dpi100 = io.BytesIO()
    plt.imsave(buff_dpi100, data, format=fmt, dpi=100)

    buff_dpi1.seek(0)
    arr_dpi1 = plt.imread(buff_dpi1, format=fmt)

    buff_dpi100.seek(0)
    arr_dpi100 = plt.imread(buff_dpi100, format=fmt)

    assert arr_dpi1.shape == (1856, 2, 3 + has_alpha)
    assert arr_dpi100.shape == (1856, 2, 3 + has_alpha)

    assert_array_equal(arr_dpi1, arr_dpi100)


@pytest.mark.parametrize("fmt", ["png", "pdf", "ps", "eps", "svg"])
def test_imsave_fspath(fmt):
    plt.imsave(Path(os.devnull), np.array([[0, 1]]), format=fmt)


def test_imsave_color_alpha():
    # Test that imsave accept arrays with ndim=3 where the third dimension is
    # color and alpha without raising any exceptions, and that the data is
    # acceptably preserved through a save/read roundtrip.
    np.random.seed(1)

    for origin in ['lower', 'upper']:
        data = np.random.rand(16, 16, 4)
        buff = io.BytesIO()
        plt.imsave(buff, data, origin=origin, format="png")

        buff.seek(0)
        arr_buf = plt.imread(buff)

        # Recreate the float -> uint8 conversion of the data
        # We can only expect to be the same with 8 bits of precision,
        # since that's what the PNG file used.
        data = (255*data).astype('uint8')
        if origin == 'lower':
            data = data[::-1]
        arr_buf = (255*arr_buf).astype('uint8')

        assert_array_equal(data, arr_buf)


@image_comparison(baseline_images=['image_alpha'], remove_text=True)
def test_image_alpha():
    plt.figure()

    np.random.seed(0)
    Z = np.random.rand(6, 6)

    plt.subplot(131)
    plt.imshow(Z, alpha=1.0, interpolation='none')

    plt.subplot(132)
    plt.imshow(Z, alpha=0.5, interpolation='none')

    plt.subplot(133)
    plt.imshow(Z, alpha=0.5, interpolation='nearest')


def test_cursor_data():
    from matplotlib.backend_bases import MouseEvent

    fig, ax = plt.subplots()
    im = ax.imshow(np.arange(100).reshape(10, 10), origin='upper')

    x, y = 4, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) == 44

    # Now try for a point outside the image
    # Tests issue #4957
    x, y = 10.1, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) is None

    # Hmm, something is wrong here... I get 0, not None...
    # But, this works further down in the tests with extents flipped
    #x, y = 0.1, -0.1
    #xdisp, ydisp = ax.transData.transform_point([x, y])
    #event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    #z = im.get_cursor_data(event)
    #assert z is None, "Did not get None, got %d" % z

    ax.clear()
    # Now try with the extents flipped.
    im = ax.imshow(np.arange(100).reshape(10, 10), origin='lower')

    x, y = 4, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) == 44

    fig, ax = plt.subplots()
    im = ax.imshow(np.arange(100).reshape(10, 10), extent=[0, 0.5, 0, 0.5])

    x, y = 0.25, 0.25
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) == 55

    # Now try for a point outside the image
    # Tests issue #4957
    x, y = 0.75, 0.25
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) is None

    x, y = 0.01, -0.01
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) is None


@pytest.mark.parametrize(
    "data, text_without_colorbar, text_with_colorbar", [
        ([[10001, 10000]], "[1e+04]", "[10001]"),
        ([[.123, .987]], "[0.123]", "[0.123]"),
])
def test_format_cursor_data(data, text_without_colorbar, text_with_colorbar):
    from matplotlib.backend_bases import MouseEvent

    fig, ax = plt.subplots()
    im = ax.imshow(data)

    xdisp, ydisp = ax.transData.transform_point([0, 0])
    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    assert im.get_cursor_data(event) == data[0][0]
    assert im.format_cursor_data(im.get_cursor_data(event)) \
        == text_without_colorbar

    fig.colorbar(im)
    fig.canvas.draw()  # This is necessary to set up the colorbar formatter.

    assert im.get_cursor_data(event) == data[0][0]
    assert im.format_cursor_data(im.get_cursor_data(event)) \
        == text_with_colorbar


@image_comparison(baseline_images=['image_clip'], style='mpl20')
def test_image_clip():
    d = [[1, 2], [3, 4]]

    fig, ax = plt.subplots()
    im = ax.imshow(d)
    patch = patches.Circle((0, 0), radius=1, transform=ax.transData)
    im.set_clip_path(patch)


@image_comparison(baseline_images=['image_cliprect'], style='mpl20')
def test_image_cliprect():
    import matplotlib.patches as patches

    fig, ax = plt.subplots()
    d = [[1, 2], [3, 4]]

    im = ax.imshow(d, extent=(0, 5, 0, 5))

    rect = patches.Rectangle(
        xy=(1, 1), width=2, height=2, transform=im.axes.transData)
    im.set_clip_path(rect)


@image_comparison(baseline_images=['imshow'], remove_text=True, style='mpl20')
def test_imshow():
    fig, ax = plt.subplots()
    arr = np.arange(100).reshape((10, 10))
    ax.imshow(arr, interpolation="bilinear", extent=(1, 2, 1, 2))
    ax.set_xlim(0, 3)
    ax.set_ylim(0, 3)


@image_comparison(baseline_images=['no_interpolation_origin'],
                  remove_text=True)
def test_no_interpolation_origin():
    fig, axs = plt.subplots(2)
    axs[0].imshow(np.arange(100).reshape((2, 50)), origin="lower",
                  interpolation='none')
    axs[1].imshow(np.arange(100).reshape((2, 50)), interpolation='none')


@image_comparison(baseline_images=['image_shift'], remove_text=True,
                  extensions=['pdf', 'svg'])
def test_image_shift():
    from matplotlib.colors import LogNorm

    imgData = [[1 / x + 1 / y for x in range(1, 100)] for y in range(1, 100)]
    tMin = 734717.945208
    tMax = 734717.946366

    fig, ax = plt.subplots()
    ax.imshow(imgData, norm=LogNorm(), interpolation='none',
              extent=(tMin, tMax, 1, 100))
    ax.set_aspect('auto')


def test_image_edges():
    f = plt.figure(figsize=[1, 1])
    ax = f.add_axes([0, 0, 1, 1], frameon=False)

    data = np.tile(np.arange(12), 15).reshape(20, 9)

    im = ax.imshow(data, origin='upper', extent=[-10, 10, -10, 10],
                   interpolation='none', cmap='gray')

    x = y = 2
    ax.set_xlim([-x, x])
    ax.set_ylim([-y, y])

    ax.set_xticks([])
    ax.set_yticks([])

    buf = io.BytesIO()
    f.savefig(buf, facecolor=(0, 1, 0))

    buf.seek(0)

    im = plt.imread(buf)
    r, g, b, a = sum(im[:, 0])
    r, g, b, a = sum(im[:, -1])

    assert g != 100, 'Expected a non-green edge - but sadly, it was.'


@image_comparison(baseline_images=['image_composite_background'],
                  remove_text=True,
                  style='mpl20')
def test_image_composite_background():
    fig, ax = plt.subplots()
    arr = np.arange(12).reshape(4, 3)
    ax.imshow(arr, extent=[0, 2, 15, 0])
    ax.imshow(arr, extent=[4, 6, 15, 0])
    ax.set_facecolor((1, 0, 0, 0.5))
    ax.set_xlim([0, 12])


@image_comparison(baseline_images=['image_composite_alpha'],
                  remove_text=True)
def test_image_composite_alpha():
    """
    Tests that the alpha value is recognized and correctly applied in the
    process of compositing images together.
    """
    fig, ax = plt.subplots()
    arr = np.zeros((11, 21, 4))
    arr[:, :, 0] = 1
    arr[:, :, 3] = np.concatenate(
        (np.arange(0, 1.1, 0.1), np.arange(0, 1, 0.1)[::-1]))
    arr2 = np.zeros((21, 11, 4))
    arr2[:, :, 0] = 1
    arr2[:, :, 1] = 1
    arr2[:, :, 3] = np.concatenate(
        (np.arange(0, 1.1, 0.1), np.arange(0, 1, 0.1)[::-1]))[:, np.newaxis]
    ax.imshow(arr, extent=[1, 2, 5, 0], alpha=0.3)
    ax.imshow(arr, extent=[2, 3, 5, 0], alpha=0.6)
    ax.imshow(arr, extent=[3, 4, 5, 0])
    ax.imshow(arr2, extent=[0, 5, 1, 2])
    ax.imshow(arr2, extent=[0, 5, 2, 3], alpha=0.6)
    ax.imshow(arr2, extent=[0, 5, 3, 4], alpha=0.3)
    ax.set_facecolor((0, 0.5, 0, 1))
    ax.set_xlim([0, 5])
    ax.set_ylim([5, 0])


@image_comparison(baseline_images=['rasterize_10dpi'],
                  extensions=['pdf', 'svg'],
                  remove_text=True, style='mpl20')
def test_rasterize_dpi():
    # This test should check rasterized rendering with high output resolution.
    # It plots a rasterized line and a normal image with imshow.  So it will
    # catch when images end up in the wrong place in case of non-standard dpi
    # setting.  Instead of high-res rasterization I use low-res.  Therefore
    # the fact that the resolution is non-standard is easily checked by
    # image_comparison.
    img = np.asarray([[1, 2], [3, 4]])

    fig, axes = plt.subplots(1, 3, figsize=(3, 1))

    axes[0].imshow(img)

    axes[1].plot([0, 1], [0, 1], linewidth=20., rasterized=True)
    axes[1].set(xlim=(0, 1), ylim=(-1, 2))

    axes[2].plot([0, 1], [0, 1], linewidth=20.)
    axes[2].set(xlim=(0, 1), ylim=(-1, 2))

    # Low-dpi PDF rasterization errors prevent proper image comparison tests.
    # Hide detailed structures like the axes spines.
    for ax in axes:
        ax.set_xticks([])
        ax.set_yticks([])
        for spine in ax.spines.values():
            spine.set_visible(False)

    rcParams['savefig.dpi'] = 10


@image_comparison(baseline_images=['bbox_image_inverted'], remove_text=True,
                  style='mpl20')
def test_bbox_image_inverted():
    # This is just used to produce an image to feed to BboxImage
    image = np.arange(100).reshape((10, 10))

    fig, ax = plt.subplots()
    bbox_im = BboxImage(
        TransformedBbox(Bbox([[100, 100], [0, 0]]), ax.transData))
    bbox_im.set_data(image)
    bbox_im.set_clip_on(False)
    ax.set_xlim(0, 100)
    ax.set_ylim(0, 100)
    ax.add_artist(bbox_im)

    image = np.identity(10)

    bbox_im = BboxImage(TransformedBbox(Bbox([[0.1, 0.2], [0.3, 0.25]]),
                                        ax.figure.transFigure))
    bbox_im.set_data(image)
    bbox_im.set_clip_on(False)
    ax.add_artist(bbox_im)


def test_get_window_extent_for_AxisImage():
    # Create a figure of known size (1000x1000 pixels), place an image
    # object at a given location and check that get_window_extent()
    # returns the correct bounding box values (in pixels).

    im = np.array([[0.25, 0.75, 1.0, 0.75], [0.1, 0.65, 0.5, 0.4],
                   [0.6, 0.3, 0.0, 0.2], [0.7, 0.9, 0.4, 0.6]])
    fig, ax = plt.subplots(figsize=(10, 10), dpi=100)
    ax.set_position([0, 0, 1, 1])
    ax.set_xlim(0, 1)
    ax.set_ylim(0, 1)
    im_obj = ax.imshow(
        im, extent=[0.4, 0.7, 0.2, 0.9], interpolation='nearest')

    fig.canvas.draw()
    renderer = fig.canvas.renderer
    im_bbox = im_obj.get_window_extent(renderer)

    assert_array_equal(im_bbox.get_points(), [[400, 200], [700, 900]])


@image_comparison(baseline_images=['zoom_and_clip_upper_origin'],
                  remove_text=True,
                  extensions=['png'],
                  style='mpl20')
def test_zoom_and_clip_upper_origin():
    image = np.arange(100)
    image = image.reshape((10, 10))

    fig, ax = plt.subplots()
    ax.imshow(image)
    ax.set_ylim(2.0, -0.5)
    ax.set_xlim(-0.5, 2.0)


def test_nonuniformimage_setcmap():
    ax = plt.gca()
    im = NonUniformImage(ax)
    im.set_cmap('Blues')


def test_nonuniformimage_setnorm():
    ax = plt.gca()
    im = NonUniformImage(ax)
    im.set_norm(plt.Normalize())


def test_jpeg_2d():
    Image = pytest.importorskip('PIL.Image')
    # smoke test that mode-L pillow images work.
    imd = np.ones((10, 10), dtype='uint8')
    for i in range(10):
        imd[i, :] = np.linspace(0.0, 1.0, 10) * 255
    im = Image.new('L', (10, 10))
    im.putdata(imd.flatten())
    fig, ax = plt.subplots()
    ax.imshow(im)


def test_jpeg_alpha():
    Image = pytest.importorskip('PIL.Image')

    plt.figure(figsize=(1, 1), dpi=300)
    # Create an image that is all black, with a gradient from 0-1 in
    # the alpha channel from left to right.
    im = np.zeros((300, 300, 4), dtype=float)
    im[..., 3] = np.linspace(0.0, 1.0, 300)

    plt.figimage(im)

    buff = io.BytesIO()
    with rc_context({'savefig.facecolor': 'red'}):
        plt.savefig(buff, transparent=True, format='jpg', dpi=300)

    buff.seek(0)
    image = Image.open(buff)

    # If this fails, there will be only one color (all black). If this
    # is working, we should have all 256 shades of grey represented.
    num_colors = len(image.getcolors(256))
    assert 175 <= num_colors <= 185
    # The fully transparent part should be red.
    corner_pixel = image.getpixel((0, 0))
    assert corner_pixel == (254, 0, 0)


def test_nonuniformimage_setdata():
    ax = plt.gca()
    im = NonUniformImage(ax)
    x = np.arange(3, dtype=float)
    y = np.arange(4, dtype=float)
    z = np.arange(12, dtype=float).reshape((4, 3))
    im.set_data(x, y, z)
    x[0] = y[0] = z[0, 0] = 9.9
    assert im._A[0, 0] == im._Ax[0] == im._Ay[0] == 0, 'value changed'


def test_axesimage_setdata():
    ax = plt.gca()
    im = AxesImage(ax)
    z = np.arange(12, dtype=float).reshape((4, 3))
    im.set_data(z)
    z[0, 0] = 9.9
    assert im._A[0, 0] == 0, 'value changed'


def test_figureimage_setdata():
    fig = plt.gcf()
    im = FigureImage(fig)
    z = np.arange(12, dtype=float).reshape((4, 3))
    im.set_data(z)
    z[0, 0] = 9.9
    assert im._A[0, 0] == 0, 'value changed'


def test_pcolorimage_setdata():
    ax = plt.gca()
    im = PcolorImage(ax)
    x = np.arange(3, dtype=float)
    y = np.arange(4, dtype=float)
    z = np.arange(6, dtype=float).reshape((3, 2))
    im.set_data(x, y, z)
    x[0] = y[0] = z[0, 0] = 9.9
    assert im._A[0, 0] == im._Ax[0] == im._Ay[0] == 0, 'value changed'


def test_minimized_rasterized():
    # This ensures that the rasterized content in the colorbars is
    # only as thick as the colorbar, and doesn't extend to other parts
    # of the image.  See #5814.  While the original bug exists only
    # in Postscript, the best way to detect it is to generate SVG
    # and then parse the output to make sure the two colorbar images
    # are the same size.
    from xml.etree import ElementTree

    np.random.seed(0)
    data = np.random.rand(10, 10)

    fig, ax = plt.subplots(1, 2)
    p1 = ax[0].pcolormesh(data)
    p2 = ax[1].pcolormesh(data)

    plt.colorbar(p1, ax=ax[0])
    plt.colorbar(p2, ax=ax[1])

    buff = io.BytesIO()
    plt.savefig(buff, format='svg')

    buff = io.BytesIO(buff.getvalue())
    tree = ElementTree.parse(buff)
    width = None
    for image in tree.iter('image'):
        if width is None:
            width = image['width']
        else:
            if image['width'] != width:
                assert False


@pytest.mark.network
def test_load_from_url():
    url = "http://matplotlib.org/_static/logo_sidebar_horiz.png"
    plt.imread(url)
    plt.imread(urllib.request.urlopen(url))


@image_comparison(baseline_images=['log_scale_image'],
                  remove_text=True)
# The recwarn fixture captures a warning in image_comparison.
def test_log_scale_image(recwarn):
    Z = np.zeros((10, 10))
    Z[::2] = 1

    fig, ax = plt.subplots()
    ax.imshow(Z, extent=[1, 100, 1, 100], cmap='viridis',
              vmax=1, vmin=-1)
    ax.set_yscale('log')


@image_comparison(baseline_images=['rotate_image'],
                  remove_text=True)
def test_rotate_image():
    delta = 0.25
    x = y = np.arange(-3.0, 3.0, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = np.exp(-(X**2 + Y**2) / 2) / (2 * np.pi)
    Z2 = (np.exp(-(((X - 1) / 1.5)**2 + ((Y - 1) / 0.5)**2) / 2) /
          (2 * np.pi * 0.5 * 1.5))
    Z = Z2 - Z1  # difference of Gaussians

    fig, ax1 = plt.subplots(1, 1)
    im1 = ax1.imshow(Z, interpolation='none', cmap='viridis',
                     origin='lower',
                     extent=[-2, 4, -3, 2], clip_on=True)

    trans_data2 = Affine2D().rotate_deg(30) + ax1.transData
    im1.set_transform(trans_data2)

    # display intended extent of the image
    x1, x2, y1, y2 = im1.get_extent()

    ax1.plot([x1, x2, x2, x1, x1], [y1, y1, y2, y2, y1], "r--", lw=3,
             transform=trans_data2)

    ax1.set_xlim(2, 5)
    ax1.set_ylim(0, 4)


def test_image_preserve_size():
    buff = io.BytesIO()

    im = np.zeros((481, 321))
    plt.imsave(buff, im, format="png")

    buff.seek(0)
    img = plt.imread(buff)

    assert img.shape[:2] == im.shape


def test_image_preserve_size2():
    n = 7
    data = np.identity(n, float)

    fig = plt.figure(figsize=(n, n), frameon=False)

    ax = plt.Axes(fig, [0.0, 0.0, 1.0, 1.0])
    ax.set_axis_off()
    fig.add_axes(ax)
    ax.imshow(data, interpolation='nearest', origin='lower', aspect='auto')
    buff = io.BytesIO()
    fig.savefig(buff, dpi=1)

    buff.seek(0)
    img = plt.imread(buff)

    assert img.shape == (7, 7, 4)

    assert_array_equal(np.asarray(img[:, :, 0], bool),
                       np.identity(n, bool)[::-1])


@image_comparison(baseline_images=['mask_image_over_under'],
                  remove_text=True, extensions=['png'])
def test_mask_image_over_under():
    delta = 0.025
    x = y = np.arange(-3.0, 3.0, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = np.exp(-(X**2 + Y**2) / 2) / (2 * np.pi)
    Z2 = (np.exp(-(((X - 1) / 1.5)**2 + ((Y - 1) / 0.5)**2) / 2) /
          (2 * np.pi * 0.5 * 1.5))
    Z = 10*(Z2 - Z1)  # difference of Gaussians

    palette = copy(plt.cm.gray)
    palette.set_over('r', 1.0)
    palette.set_under('g', 1.0)
    palette.set_bad('b', 1.0)
    Zm = ma.masked_where(Z > 1.2, Z)
    fig, (ax1, ax2) = plt.subplots(1, 2)
    im = ax1.imshow(Zm, interpolation='bilinear',
                    cmap=palette,
                    norm=colors.Normalize(vmin=-1.0, vmax=1.0, clip=False),
                    origin='lower', extent=[-3, 3, -3, 3])
    ax1.set_title('Green=low, Red=high, Blue=bad')
    fig.colorbar(im, extend='both', orientation='horizontal',
                 ax=ax1, aspect=10)

    im = ax2.imshow(Zm, interpolation='nearest',
                    cmap=palette,
                    norm=colors.BoundaryNorm([-1, -0.5, -0.2, 0, 0.2, 0.5, 1],
                                             ncolors=256, clip=False),
                    origin='lower', extent=[-3, 3, -3, 3])
    ax2.set_title('With BoundaryNorm')
    fig.colorbar(im, extend='both', spacing='proportional',
                 orientation='horizontal', ax=ax2, aspect=10)


@image_comparison(baseline_images=['mask_image'],
                  remove_text=True)
def test_mask_image():
    # Test mask image two ways: Using nans and using a masked array.

    fig, (ax1, ax2) = plt.subplots(1, 2)

    A = np.ones((5, 5))
    A[1:2, 1:2] = np.nan

    ax1.imshow(A, interpolation='nearest')

    A = np.zeros((5, 5), dtype=bool)
    A[1:2, 1:2] = True
    A = np.ma.masked_array(np.ones((5, 5), dtype=np.uint16), A)

    ax2.imshow(A, interpolation='nearest')


@image_comparison(baseline_images=['imshow_endianess'],
                  remove_text=True, extensions=['png'])
def test_imshow_endianess():
    x = np.arange(10)
    X, Y = np.meshgrid(x, x)
    Z = np.hypot(X - 5, Y - 5)

    fig, (ax1, ax2) = plt.subplots(1, 2)

    kwargs = dict(origin="lower", interpolation='nearest', cmap='viridis')

    ax1.imshow(Z.astype('<f8'), **kwargs)
    ax2.imshow(Z.astype('>f8'), **kwargs)


@image_comparison(baseline_images=['imshow_masked_interpolation'],
                  tol={'aarch64': 0.02}.get(platform.machine(), 0.0),
                  remove_text=True, style='mpl20')
def test_imshow_masked_interpolation():

    cm = copy(plt.get_cmap('viridis'))
    cm.set_over('r')
    cm.set_under('b')
    cm.set_bad('k')

    N = 20
    n = colors.Normalize(vmin=0, vmax=N*N-1)

    data = np.arange(N*N, dtype='float').reshape(N, N)

    data[5, 5] = -1
    # This will cause crazy ringing for the higher-order
    # interpolations
    data[15, 5] = 1e5

    # data[3, 3] = np.nan

    data[15, 15] = np.inf

    mask = np.zeros_like(data).astype('bool')
    mask[5, 15] = True

    data = np.ma.masked_array(data, mask)

    fig, ax_grid = plt.subplots(3, 6)

    for interp, ax in zip(sorted(mimage._interpd_), ax_grid.ravel()):
        ax.set_title(interp)
        ax.imshow(data, norm=n, cmap=cm, interpolation=interp)
        ax.axis('off')


def test_imshow_no_warn_invalid():
    with warnings.catch_warnings(record=True) as warns:
        warnings.simplefilter("always")
        plt.imshow([[1, 2], [3, np.nan]])
    assert len(warns) == 0


@pytest.mark.parametrize(
    'dtype', [np.dtype(s) for s in 'u2 u4 i2 i4 i8 f4 f8'.split()])
def test_imshow_clips_rgb_to_valid_range(dtype):
    arr = np.arange(300, dtype=dtype).reshape((10, 10, 3))
    if dtype.kind != 'u':
        arr -= 10
    too_low = arr < 0
    too_high = arr > 255
    if dtype.kind == 'f':
        arr = arr / 255
    _, ax = plt.subplots()
    out = ax.imshow(arr).get_array()
    assert (out[too_low] == 0).all()
    if dtype.kind == 'f':
        assert (out[too_high] == 1).all()
        assert out.dtype.kind == 'f'
    else:
        assert (out[too_high] == 255).all()
        assert out.dtype == np.uint8


@image_comparison(baseline_images=['imshow_flatfield'],
                  remove_text=True, style='mpl20',
                  extensions=['png'])
def test_imshow_flatfield():
    fig, ax = plt.subplots()
    im = ax.imshow(np.ones((5, 5)))
    im.set_clim(.5, 1.5)


@image_comparison(baseline_images=['imshow_bignumbers'],
                  remove_text=True, style='mpl20',
                  extensions=['png'])
def test_imshow_bignumbers():
    # putting a big number in an array of integers shouldn't
    # ruin the dynamic range of the resolved bits.
    fig, ax = plt.subplots()
    img = np.array([[1, 2, 1e12], [3, 1, 4]], dtype=np.uint64)
    pc = ax.imshow(img)
    pc.set_clim(0, 5)


@image_comparison(baseline_images=['imshow_bignumbers_real'],
                  remove_text=True, style='mpl20',
                  extensions=['png'])
def test_imshow_bignumbers_real():
    # putting a big number in an array of integers shouldn't
    # ruin the dynamic range of the resolved bits.
    fig, ax = plt.subplots()
    img = np.array([[2., 1., 1.e22], [4., 1., 3.]])
    pc = ax.imshow(img)
    pc.set_clim(0, 5)


@pytest.mark.parametrize(
    "make_norm",
    [colors.Normalize,
     colors.LogNorm,
     lambda: colors.SymLogNorm(1),
     lambda: colors.PowerNorm(1)])
def test_empty_imshow(make_norm):
    fig, ax = plt.subplots()
    with warnings.catch_warnings():
        warnings.filterwarnings(
            "ignore", "Attempting to set identical left==right")
        im = ax.imshow([[]], norm=make_norm())
    im.set_extent([-5, 5, -5, 5])
    fig.canvas.draw()

    with pytest.raises(RuntimeError):
        im.make_image(fig._cachedRenderer)


def test_imshow_float128():
    fig, ax = plt.subplots()
    ax.imshow(np.zeros((3, 3), dtype=np.longdouble))
    with (ExitStack() if np.can_cast(np.longdouble, np.float64, "equiv")
          else pytest.warns(UserWarning)):
        # Ensure that drawing doesn't cause crash.
        fig.canvas.draw()


def test_imshow_bool():
    fig, ax = plt.subplots()
    ax.imshow(np.array([[True, False], [False, True]], dtype=bool))


def test_full_invalid():
    x = np.ones((10, 10))
    x[:] = np.nan

    f, ax = plt.subplots()
    ax.imshow(x)

    f.canvas.draw()


@pytest.mark.parametrize("fmt,counted",
                         [("ps", b" colorimage"), ("svg", b"<image")])
@pytest.mark.parametrize("composite_image,count", [(True, 1), (False, 2)])
def test_composite(fmt, counted, composite_image, count):
    # Test that figures can be saved with and without combining multiple images
    # (on a single set of axes) into a single composite image.
    X, Y = np.meshgrid(np.arange(-5, 5, 1), np.arange(-5, 5, 1))
    Z = np.sin(Y ** 2)

    fig, ax = plt.subplots()
    ax.set_xlim(0, 3)
    ax.imshow(Z, extent=[0, 1, 0, 1])
    ax.imshow(Z[::-1], extent=[2, 3, 0, 1])
    plt.rcParams['image.composite_image'] = composite_image
    buf = io.BytesIO()
    fig.savefig(buf, format=fmt)
    assert buf.getvalue().count(counted) == count


def test_relim():
    fig, ax = plt.subplots()
    ax.imshow([[0]], extent=(0, 1, 0, 1))
    ax.relim()
    ax.autoscale()
    assert ax.get_xlim() == ax.get_ylim() == (0, 1)


def test_deprecation():
    data = [[1, 2], [3, 4]]
    ax = plt.figure().subplots()
    for obj in [ax, plt]:
        with pytest.warns(None) as record:
            obj.imshow(data)
            assert len(record) == 0
        with pytest.warns(MatplotlibDeprecationWarning):
            obj.imshow(data, shape=None)
        with pytest.warns(MatplotlibDeprecationWarning):
            # Enough arguments to pass "shape" positionally.
            obj.imshow(data, *[None] * 10)


def test_image_cursor_formatting():
    fig, ax = plt.subplots()
    # Create a dummy image to be able to call format_cursor_data
    im = ax.imshow(np.zeros((4, 4)))

    data = np.ma.masked_array([0], mask=[True])
    assert im.format_cursor_data(data) == '[]'

    data = np.ma.masked_array([0], mask=[False])
    assert im.format_cursor_data(data) == '[0]'

    data = np.nan
    assert im.format_cursor_data(data) == '[nan]'
