Pillow/Tests/test_imagefont.py

import copy
import distutils.version
import os
import re
import shutil
import sys
import unittest
from io import BytesIO

from PIL import Image, ImageDraw, ImageFont, features

from .helper import PillowTestCase, is_pypy, is_win32

FONT_PATH = "Tests/fonts/FreeMono.ttf"
FONT_SIZE = 20

TEST_TEXT = "hey you\nyou are awesome\nthis looks awkward"

HAS_FREETYPE = features.check("freetype2")
HAS_RAQM = features.check("raqm")


class SimplePatcher:
    def __init__(self, parent_obj, attr_name, value):
        self._parent_obj = parent_obj
        self._attr_name = attr_name
        self._saved = None
        self._is_saved = False
        self._value = value

    def __enter__(self):
        # Patch the attr on the object
        if hasattr(self._parent_obj, self._attr_name):
            self._saved = getattr(self._parent_obj, self._attr_name)
            setattr(self._parent_obj, self._attr_name, self._value)
            self._is_saved = True
        else:
            setattr(self._parent_obj, self._attr_name, self._value)
            self._is_saved = False

    def __exit__(self, type, value, traceback):
        # Restore the original value
        if self._is_saved:
            setattr(self._parent_obj, self._attr_name, self._saved)
        else:
            delattr(self._parent_obj, self._attr_name)


@unittest.skipUnless(HAS_FREETYPE, "ImageFont not available")
class TestImageFont(PillowTestCase):
    LAYOUT_ENGINE = ImageFont.LAYOUT_BASIC

    # Freetype has different metrics depending on the version.
    # (and, other things, but first things first)
    METRICS = {
        (">=2.3", "<2.4"): {"multiline": 30, "textsize": 12, "getters": (13, 16)},
        (">=2.7",): {"multiline": 6.2, "textsize": 2.5, "getters": (12, 16)},
        "Default": {"multiline": 0.5, "textsize": 0.5, "getters": (12, 16)},
    }

    def setUp(self):
        freetype = distutils.version.StrictVersion(ImageFont.core.freetype2_version)

        self.metrics = self.METRICS["Default"]
        for conditions, metrics in self.METRICS.items():
            if not isinstance(conditions, tuple):
                continue

            for condition in conditions:
                version = re.sub("[<=>]", "", condition)
                if (condition.startswith(">=") and freetype >= version) or (
                    condition.startswith("<") and freetype < version
                ):
                    # Condition was met
                    continue

                # Condition failed
                break
            else:
                # All conditions were met
                self.metrics = metrics

    def get_font(self):
        return ImageFont.truetype(
            FONT_PATH, FONT_SIZE, layout_engine=self.LAYOUT_ENGINE
        )

    def test_sanity(self):
        self.assertRegex(ImageFont.core.freetype2_version, r"\d+\.\d+\.\d+$")

    def test_font_properties(self):
        ttf = self.get_font()
        self.assertEqual(ttf.path, FONT_PATH)
        self.assertEqual(ttf.size, FONT_SIZE)

        ttf_copy = ttf.font_variant()
        self.assertEqual(ttf_copy.path, FONT_PATH)
        self.assertEqual(ttf_copy.size, FONT_SIZE)

        ttf_copy = ttf.font_variant(size=FONT_SIZE + 1)
        self.assertEqual(ttf_copy.size, FONT_SIZE + 1)

        second_font_path = "Tests/fonts/DejaVuSans.ttf"
        ttf_copy = ttf.font_variant(font=second_font_path)
        self.assertEqual(ttf_copy.path, second_font_path)

    def test_font_with_name(self):
        self.get_font()
        self._render(FONT_PATH)

    def _font_as_bytes(self):
        with open(FONT_PATH, "rb") as f:
            font_bytes = BytesIO(f.read())
        return font_bytes

    def test_font_with_filelike(self):
        ImageFont.truetype(
            self._font_as_bytes(), FONT_SIZE, layout_engine=self.LAYOUT_ENGINE
        )
        self._render(self._font_as_bytes())
        # Usage note:  making two fonts from the same buffer fails.
        # shared_bytes = self._font_as_bytes()
        # self._render(shared_bytes)
        # self.assertRaises(Exception, _render, shared_bytes)

    def test_font_with_open_file(self):
        with open(FONT_PATH, "rb") as f:
            self._render(f)

    def test_non_unicode_path(self):
        try:
            tempfile = self.tempfile("temp_" + chr(128) + ".ttf")
        except UnicodeEncodeError:
            self.skipTest("Unicode path could not be created")
        shutil.copy(FONT_PATH, tempfile)

        ImageFont.truetype(tempfile, FONT_SIZE)

    def test_unavailable_layout_engine(self):
        have_raqm = ImageFont.core.HAVE_RAQM
        ImageFont.core.HAVE_RAQM = False

        try:
            ttf = ImageFont.truetype(
                FONT_PATH, FONT_SIZE, layout_engine=ImageFont.LAYOUT_RAQM
            )
        finally:
            ImageFont.core.HAVE_RAQM = have_raqm

        self.assertEqual(ttf.layout_engine, ImageFont.LAYOUT_BASIC)

    def _render(self, font):
        txt = "Hello World!"
        ttf = ImageFont.truetype(font, FONT_SIZE, layout_engine=self.LAYOUT_ENGINE)
        ttf.getsize(txt)

        img = Image.new("RGB", (256, 64), "white")
        d = ImageDraw.Draw(img)
        d.text((10, 10), txt, font=ttf, fill="black")

        return img

    def test_render_equal(self):
        img_path = self._render(FONT_PATH)
        with open(FONT_PATH, "rb") as f:
            font_filelike = BytesIO(f.read())
        img_filelike = self._render(font_filelike)

        self.assert_image_equal(img_path, img_filelike)

    def test_textsize_equal(self):
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)
        ttf = self.get_font()

        txt = "Hello World!"
        size = draw.textsize(txt, ttf)
        draw.text((10, 10), txt, font=ttf)
        draw.rectangle((10, 10, 10 + size[0], 10 + size[1]))

        target = "Tests/images/rectangle_surrounding_text.png"
        with Image.open(target) as target_img:

            # Epsilon ~.5 fails with FreeType 2.7
            self.assert_image_similar(im, target_img, self.metrics["textsize"])

    def test_render_multiline(self):
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)
        ttf = self.get_font()
        line_spacing = draw.textsize("A", font=ttf)[1] + 4
        lines = TEST_TEXT.split("\n")
        y = 0
        for line in lines:
            draw.text((0, y), line, font=ttf)
            y += line_spacing

        target = "Tests/images/multiline_text.png"
        with Image.open(target) as target_img:

            # some versions of freetype have different horizontal spacing.
            # setting a tight epsilon, I'm showing the original test failure
            # at epsilon = ~38.
            self.assert_image_similar(im, target_img, self.metrics["multiline"])

    def test_render_multiline_text(self):
        ttf = self.get_font()

        # Test that text() correctly connects to multiline_text()
        # and that align defaults to left
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)
        draw.text((0, 0), TEST_TEXT, font=ttf)

        target = "Tests/images/multiline_text.png"
        with Image.open(target) as target_img:

            # Epsilon ~.5 fails with FreeType 2.7
            self.assert_image_similar(im, target_img, self.metrics["multiline"])

        # Test that text() can pass on additional arguments
        # to multiline_text()
        draw.text(
            (0, 0), TEST_TEXT, fill=None, font=ttf, anchor=None, spacing=4, align="left"
        )
        draw.text((0, 0), TEST_TEXT, None, ttf, None, 4, "left")

        # Test align center and right
        for align, ext in {"center": "_center", "right": "_right"}.items():
            im = Image.new(mode="RGB", size=(300, 100))
            draw = ImageDraw.Draw(im)
            draw.multiline_text((0, 0), TEST_TEXT, font=ttf, align=align)

            target = "Tests/images/multiline_text" + ext + ".png"
            with Image.open(target) as target_img:

                # Epsilon ~.5 fails with FreeType 2.7
                self.assert_image_similar(im, target_img, self.metrics["multiline"])

    def test_unknown_align(self):
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)
        ttf = self.get_font()

        # Act/Assert
        self.assertRaises(
            ValueError,
            draw.multiline_text,
            (0, 0),
            TEST_TEXT,
            font=ttf,
            align="unknown",
        )

    def test_draw_align(self):
        im = Image.new("RGB", (300, 100), "white")
        draw = ImageDraw.Draw(im)
        ttf = self.get_font()
        line = "some text"
        draw.text((100, 40), line, (0, 0, 0), font=ttf, align="left")

    def test_multiline_size(self):
        ttf = self.get_font()
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)

        # Test that textsize() correctly connects to multiline_textsize()
        self.assertEqual(
            draw.textsize(TEST_TEXT, font=ttf),
            draw.multiline_textsize(TEST_TEXT, font=ttf),
        )

        # Test that multiline_textsize corresponds to ImageFont.textsize()
        # for single line text
        self.assertEqual(ttf.getsize("A"), draw.multiline_textsize("A", font=ttf))

        # Test that textsize() can pass on additional arguments
        # to multiline_textsize()
        draw.textsize(TEST_TEXT, font=ttf, spacing=4)
        draw.textsize(TEST_TEXT, ttf, 4)

    def test_multiline_width(self):
        ttf = self.get_font()
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)

        self.assertEqual(
            draw.textsize("longest line", font=ttf)[0],
            draw.multiline_textsize("longest line\nline", font=ttf)[0],
        )

    def test_multiline_spacing(self):
        ttf = self.get_font()

        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)
        draw.multiline_text((0, 0), TEST_TEXT, font=ttf, spacing=10)

        target = "Tests/images/multiline_text_spacing.png"
        with Image.open(target) as target_img:

            # Epsilon ~.5 fails with FreeType 2.7
            self.assert_image_similar(im, target_img, self.metrics["multiline"])

    def test_rotated_transposed_font(self):
        img_grey = Image.new("L", (100, 100))
        draw = ImageDraw.Draw(img_grey)
        word = "testing"
        font = self.get_font()

        orientation = Image.ROTATE_90
        transposed_font = ImageFont.TransposedFont(font, orientation=orientation)

        # Original font
        draw.font = font
        box_size_a = draw.textsize(word)

        # Rotated font
        draw.font = transposed_font
        box_size_b = draw.textsize(word)

        # Check (w,h) of box a is (h,w) of box b
        self.assertEqual(box_size_a[0], box_size_b[1])
        self.assertEqual(box_size_a[1], box_size_b[0])

    def test_unrotated_transposed_font(self):
        img_grey = Image.new("L", (100, 100))
        draw = ImageDraw.Draw(img_grey)
        word = "testing"
        font = self.get_font()

        orientation = None
        transposed_font = ImageFont.TransposedFont(font, orientation=orientation)

        # Original font
        draw.font = font
        box_size_a = draw.textsize(word)

        # Rotated font
        draw.font = transposed_font
        box_size_b = draw.textsize(word)

        # Check boxes a and b are same size
        self.assertEqual(box_size_a, box_size_b)

    def test_rotated_transposed_font_get_mask(self):
        # Arrange
        text = "mask this"
        font = self.get_font()
        orientation = Image.ROTATE_90
        transposed_font = ImageFont.TransposedFont(font, orientation=orientation)

        # Act
        mask = transposed_font.getmask(text)

        # Assert
        self.assertEqual(mask.size, (13, 108))

    def test_unrotated_transposed_font_get_mask(self):
        # Arrange
        text = "mask this"
        font = self.get_font()
        orientation = None
        transposed_font = ImageFont.TransposedFont(font, orientation=orientation)

        # Act
        mask = transposed_font.getmask(text)

        # Assert
        self.assertEqual(mask.size, (108, 13))

    def test_free_type_font_get_name(self):
        # Arrange
        font = self.get_font()

        # Act
        name = font.getname()

        # Assert
        self.assertEqual(("FreeMono", "Regular"), name)

    def test_free_type_font_get_metrics(self):
        # Arrange
        font = self.get_font()

        # Act
        ascent, descent = font.getmetrics()

        # Assert
        self.assertIsInstance(ascent, int)
        self.assertIsInstance(descent, int)
        self.assertEqual((ascent, descent), (16, 4))  # too exact check?

    def test_free_type_font_get_offset(self):
        # Arrange
        font = self.get_font()
        text = "offset this"

        # Act
        offset = font.getoffset(text)

        # Assert
        self.assertEqual(offset, (0, 3))

    def test_free_type_font_get_mask(self):
        # Arrange
        font = self.get_font()
        text = "mask this"

        # Act
        mask = font.getmask(text)

        # Assert
        self.assertEqual(mask.size, (108, 13))

    def test_load_path_not_found(self):
        # Arrange
        filename = "somefilenamethatdoesntexist.ttf"

        # Act/Assert
        self.assertRaises(IOError, ImageFont.load_path, filename)
        self.assertRaises(IOError, ImageFont.truetype, filename)

    def test_load_non_font_bytes(self):
        with open("Tests/images/hopper.jpg", "rb") as f:
            self.assertRaises(IOError, ImageFont.truetype, f)

    def test_default_font(self):
        # Arrange
        txt = 'This is a "better than nothing" default font.'
        im = Image.new(mode="RGB", size=(300, 100))
        draw = ImageDraw.Draw(im)

        target = "Tests/images/default_font.png"
        with Image.open(target) as target_img:

            # Act
            default_font = ImageFont.load_default()
            draw.text((10, 10), txt, font=default_font)

            # Assert
            self.assert_image_equal(im, target_img)

    def test_getsize_empty(self):
        # issue #2614
        font = self.get_font()
        # should not crash.
        self.assertEqual((0, 0), font.getsize(""))

    def test_render_empty(self):
        # issue 2666
        font = self.get_font()
        im = Image.new(mode="RGB", size=(300, 100))
        target = im.copy()
        draw = ImageDraw.Draw(im)
        # should not crash here.
        draw.text((10, 10), "", font=font)
        self.assert_image_equal(im, target)

    def test_unicode_pilfont(self):
        # should not segfault, should return UnicodeDecodeError
        # issue #2826
        font = ImageFont.load_default()
        with self.assertRaises(UnicodeEncodeError):
            font.getsize("’")

    @unittest.skipIf(is_pypy(), "failing on PyPy")
    def test_unicode_extended(self):
        # issue #3777
        text = "A\u278A\U0001F12B"
        target = "Tests/images/unicode_extended.png"

        ttf = ImageFont.truetype(
            "Tests/fonts/NotoSansSymbols-Regular.ttf",
            FONT_SIZE,
            layout_engine=self.LAYOUT_ENGINE,
        )
        img = Image.new("RGB", (100, 60))
        d = ImageDraw.Draw(img)
        d.text((10, 10), text, font=ttf)

        self.assert_image_similar_tofile(img, target, self.metrics["multiline"])

    def _test_fake_loading_font(self, path_to_fake, fontname):
        # Make a copy of FreeTypeFont so we can patch the original
        free_type_font = copy.deepcopy(ImageFont.FreeTypeFont)
        with SimplePatcher(ImageFont, "_FreeTypeFont", free_type_font):

            def loadable_font(filepath, size, index, encoding, *args, **kwargs):
                if filepath == path_to_fake:
                    return ImageFont._FreeTypeFont(
                        FONT_PATH, size, index, encoding, *args, **kwargs
                    )
                return ImageFont._FreeTypeFont(
                    filepath, size, index, encoding, *args, **kwargs
                )

            with SimplePatcher(ImageFont, "FreeTypeFont", loadable_font):
                font = ImageFont.truetype(fontname)
                # Make sure it's loaded
                name = font.getname()
                self.assertEqual(("FreeMono", "Regular"), name)

    @unittest.skipIf(is_win32(), "requires Unix or macOS")
    def test_find_linux_font(self):
        # A lot of mocking here - this is more for hitting code and
        # catching syntax like errors
        font_directory = "/usr/local/share/fonts"
        with SimplePatcher(sys, "platform", "linux"):
            patched_env = copy.deepcopy(os.environ)
            patched_env["XDG_DATA_DIRS"] = "/usr/share/:/usr/local/share/"
            with SimplePatcher(os, "environ", patched_env):

                def fake_walker(path):
                    if path == font_directory:
                        return [
                            (
                                path,
                                [],
                                [
                                    "Arial.ttf",
                                    "Single.otf",
                                    "Duplicate.otf",
                                    "Duplicate.ttf",
                                ],
                            )
                        ]
                    return [(path, [], ["some_random_font.ttf"])]

                with SimplePatcher(os, "walk", fake_walker):
                    # Test that the font loads both with and without the
                    # extension
                    self._test_fake_loading_font(
                        font_directory + "/Arial.ttf", "Arial.ttf"
                    )
                    self._test_fake_loading_font(font_directory + "/Arial.ttf", "Arial")

                    # Test that non-ttf fonts can be found without the
                    # extension
                    self._test_fake_loading_font(
                        font_directory + "/Single.otf", "Single"
                    )

                    # Test that ttf fonts are preferred if the extension is
                    # not specified
                    self._test_fake_loading_font(
                        font_directory + "/Duplicate.ttf", "Duplicate"
                    )

    @unittest.skipIf(is_win32(), "requires Unix or macOS")
    def test_find_macos_font(self):
        # Like the linux test, more cover hitting code rather than testing
        # correctness.
        font_directory = "/System/Library/Fonts"
        with SimplePatcher(sys, "platform", "darwin"):

            def fake_walker(path):
                if path == font_directory:
                    return [
                        (
                            path,
                            [],
                            [
                                "Arial.ttf",
                                "Single.otf",
                                "Duplicate.otf",
                                "Duplicate.ttf",
                            ],
                        )
                    ]
                return [(path, [], ["some_random_font.ttf"])]

            with SimplePatcher(os, "walk", fake_walker):
                self._test_fake_loading_font(font_directory + "/Arial.ttf", "Arial.ttf")
                self._test_fake_loading_font(font_directory + "/Arial.ttf", "Arial")
                self._test_fake_loading_font(font_directory + "/Single.otf", "Single")
                self._test_fake_loading_font(
                    font_directory + "/Duplicate.ttf", "Duplicate"
                )

    def test_imagefont_getters(self):
        # Arrange
        t = self.get_font()

        # Act / Assert
        self.assertEqual(t.getmetrics(), (16, 4))
        self.assertEqual(t.font.ascent, 16)
        self.assertEqual(t.font.descent, 4)
        self.assertEqual(t.font.height, 20)
        self.assertEqual(t.font.x_ppem, 20)
        self.assertEqual(t.font.y_ppem, 20)
        self.assertEqual(t.font.glyphs, 4177)
        self.assertEqual(t.getsize("A"), (12, 16))
        self.assertEqual(t.getsize("AB"), (24, 16))
        self.assertEqual(t.getsize("M"), self.metrics["getters"])
        self.assertEqual(t.getsize("y"), (12, 20))
        self.assertEqual(t.getsize("a"), (12, 16))
        self.assertEqual(t.getsize_multiline("A"), (12, 16))
        self.assertEqual(t.getsize_multiline("AB"), (24, 16))
        self.assertEqual(t.getsize_multiline("a"), (12, 16))
        self.assertEqual(t.getsize_multiline("ABC\n"), (36, 36))
        self.assertEqual(t.getsize_multiline("ABC\nA"), (36, 36))
        self.assertEqual(t.getsize_multiline("ABC\nAaaa"), (48, 36))

    def test_getsize_stroke(self):
        # Arrange
        t = self.get_font()

        # Act / Assert
        for stroke_width in [0, 2]:
            self.assertEqual(
                t.getsize("A", stroke_width=stroke_width),
                (12 + stroke_width * 2, 16 + stroke_width * 2),
            )
            self.assertEqual(
                t.getsize_multiline("ABC\nAaaa", stroke_width=stroke_width),
                (48 + stroke_width * 2, 36 + stroke_width * 4),
            )

    def test_complex_font_settings(self):
        # Arrange
        t = self.get_font()
        # Act / Assert
        if t.layout_engine == ImageFont.LAYOUT_BASIC:
            self.assertRaises(KeyError, t.getmask, "абвг", direction="rtl")
            self.assertRaises(KeyError, t.getmask, "абвг", features=["-kern"])
            self.assertRaises(KeyError, t.getmask, "абвг", language="sr")

    def test_variation_get(self):
        font = self.get_font()

        freetype = distutils.version.StrictVersion(ImageFont.core.freetype2_version)
        if freetype < "2.9.1":
            self.assertRaises(NotImplementedError, font.get_variation_names)
            self.assertRaises(NotImplementedError, font.get_variation_axes)
            return

        self.assertRaises(IOError, font.get_variation_names)
        self.assertRaises(IOError, font.get_variation_axes)

        font = ImageFont.truetype("Tests/fonts/AdobeVFPrototype.ttf")
        self.assertEqual(
            font.get_variation_names(),
            [
                b"ExtraLight",
                b"Light",
                b"Regular",
                b"Semibold",
                b"Bold",
                b"Black",
                b"Black Medium Contrast",
                b"Black High Contrast",
                b"Default",
            ],
        )
        self.assertEqual(
            font.get_variation_axes(),
            [
                {"name": b"Weight", "minimum": 200, "maximum": 900, "default": 389},
                {"name": b"Contrast", "minimum": 0, "maximum": 100, "default": 0},
            ],
        )

        font = ImageFont.truetype("Tests/fonts/TINY5x3GX.ttf")
        self.assertEqual(
            font.get_variation_names(),
            [
                b"20",
                b"40",
                b"60",
                b"80",
                b"100",
                b"120",
                b"140",
                b"160",
                b"180",
                b"200",
                b"220",
                b"240",
                b"260",
                b"280",
                b"300",
                b"Regular",
            ],
        )
        self.assertEqual(
            font.get_variation_axes(),
            [{"name": b"Size", "minimum": 0, "maximum": 300, "default": 0}],
        )

    def test_variation_set_by_name(self):
        font = self.get_font()

        freetype = distutils.version.StrictVersion(ImageFont.core.freetype2_version)
        if freetype < "2.9.1":
            self.assertRaises(NotImplementedError, font.set_variation_by_name, "Bold")
            return

        self.assertRaises(IOError, font.set_variation_by_name, "Bold")

        def _check_text(font, path, epsilon):
            im = Image.new("RGB", (100, 75), "white")
            d = ImageDraw.Draw(im)
            d.text((10, 10), "Text", font=font, fill="black")

            with Image.open(path) as expected:
                self.assert_image_similar(im, expected, epsilon)

        font = ImageFont.truetype("Tests/fonts/AdobeVFPrototype.ttf", 36)
        _check_text(font, "Tests/images/variation_adobe.png", 11)
        for name in ["Bold", b"Bold"]:
            font.set_variation_by_name(name)
        _check_text(font, "Tests/images/variation_adobe_name.png", 11)

        font = ImageFont.truetype("Tests/fonts/TINY5x3GX.ttf", 36)
        _check_text(font, "Tests/images/variation_tiny.png", 40)
        for name in ["200", b"200"]:
            font.set_variation_by_name(name)
        _check_text(font, "Tests/images/variation_tiny_name.png", 40)

    def test_variation_set_by_axes(self):
        font = self.get_font()

        freetype = distutils.version.StrictVersion(ImageFont.core.freetype2_version)
        if freetype < "2.9.1":
            self.assertRaises(NotImplementedError, font.set_variation_by_axes, [100])
            return

        self.assertRaises(IOError, font.set_variation_by_axes, [500, 50])

        def _check_text(font, path, epsilon):
            im = Image.new("RGB", (100, 75), "white")
            d = ImageDraw.Draw(im)
            d.text((10, 10), "Text", font=font, fill="black")

            with Image.open(path) as expected:
                self.assert_image_similar(im, expected, epsilon)

        font = ImageFont.truetype("Tests/fonts/AdobeVFPrototype.ttf", 36)
        font.set_variation_by_axes([500, 50])
        _check_text(font, "Tests/images/variation_adobe_axes.png", 5.1)

        font = ImageFont.truetype("Tests/fonts/TINY5x3GX.ttf", 36)
        font.set_variation_by_axes([100])
        _check_text(font, "Tests/images/variation_tiny_axes.png", 32.5)


@unittest.skipUnless(HAS_RAQM, "Raqm not Available")
class TestImageFont_RaqmLayout(TestImageFont):
    LAYOUT_ENGINE = ImageFont.LAYOUT_RAQM