Pillow/Tests/test_file_webp_animated.py

from PIL import Image

from .helper import PillowTestCase

try:
    from PIL import _webp

    HAVE_WEBP = True
except ImportError:
    HAVE_WEBP = False


class TestFileWebpAnimation(PillowTestCase):
    def setUp(self):
        if not HAVE_WEBP:
            self.skipTest("WebP support not installed")
            return

        if not _webp.HAVE_WEBPANIM:
            self.skipTest(
                "WebP library does not contain animation support, "
                "not testing animation"
            )

    def test_n_frames(self):
        """
        Ensure that WebP format sets n_frames and is_animated
        attributes correctly.
        """

        with Image.open("Tests/images/hopper.webp") as im:
            self.assertEqual(im.n_frames, 1)
            self.assertFalse(im.is_animated)

        with Image.open("Tests/images/iss634.webp") as im:
            self.assertEqual(im.n_frames, 42)
            self.assertTrue(im.is_animated)

    def test_write_animation_L(self):
        """
        Convert an animated GIF to animated WebP, then compare the
        frame count, and first and last frames to ensure they're
        visually similar.
        """

        with Image.open("Tests/images/iss634.gif") as orig:
            self.assertGreater(orig.n_frames, 1)

            temp_file = self.tempfile("temp.webp")
            orig.save(temp_file, save_all=True)
            im = Image.open(temp_file)
            self.assertEqual(im.n_frames, orig.n_frames)

            # Compare first and last frames to the original animated GIF
            orig.load()
            im.load()
            self.assert_image_similar(im, orig.convert("RGBA"), 25.0)
            orig.seek(orig.n_frames - 1)
            im.seek(im.n_frames - 1)
            orig.load()
            im.load()
            self.assert_image_similar(im, orig.convert("RGBA"), 25.0)

    def test_write_animation_RGB(self):
        """
        Write an animated WebP from RGB frames, and ensure the frames
        are visually similar to the originals.
        """

        def check(temp_file):
            im = Image.open(temp_file)
            self.assertEqual(im.n_frames, 2)

            # Compare first frame to original
            im.load()
            self.assert_image_equal(im, frame1.convert("RGBA"))

            # Compare second frame to original
            im.seek(1)
            im.load()
            self.assert_image_equal(im, frame2.convert("RGBA"))

        frame1 = Image.open("Tests/images/anim_frame1.webp")
        frame2 = Image.open("Tests/images/anim_frame2.webp")

        temp_file1 = self.tempfile("temp.webp")
        frame1.copy().save(
            temp_file1, save_all=True, append_images=[frame2], lossless=True
        )
        check(temp_file1)

        # Tests appending using a generator
        def imGenerator(ims):
            yield from ims

        temp_file2 = self.tempfile("temp_generator.webp")
        frame1.copy().save(
            temp_file2,
            save_all=True,
            append_images=imGenerator([frame2]),
            lossless=True,
        )
        check(temp_file2)

    def test_timestamp_and_duration(self):
        """
        Try passing a list of durations, and make sure the encoded
        timestamps and durations are correct.
        """

        durations = [0, 10, 20, 30, 40]
        temp_file = self.tempfile("temp.webp")
        frame1 = Image.open("Tests/images/anim_frame1.webp")
        frame2 = Image.open("Tests/images/anim_frame2.webp")
        frame1.save(
            temp_file,
            save_all=True,
            append_images=[frame2, frame1, frame2, frame1],
            duration=durations,
        )

        im = Image.open(temp_file)
        self.assertEqual(im.n_frames, 5)
        self.assertTrue(im.is_animated)

        # Check that timestamps and durations match original values specified
        ts = 0
        for frame in range(im.n_frames):
            im.seek(frame)
            im.load()
            self.assertEqual(im.info["duration"], durations[frame])
            self.assertEqual(im.info["timestamp"], ts)
            ts += durations[frame]

    def test_seeking(self):
        """
        Create an animated WebP file, and then try seeking through
        frames in reverse-order, verifying the timestamps and durations
        are correct.
        """

        dur = 33
        temp_file = self.tempfile("temp.webp")
        frame1 = Image.open("Tests/images/anim_frame1.webp")
        frame2 = Image.open("Tests/images/anim_frame2.webp")
        frame1.save(
            temp_file,
            save_all=True,
            append_images=[frame2, frame1, frame2, frame1],
            duration=dur,
        )

        im = Image.open(temp_file)
        self.assertEqual(im.n_frames, 5)
        self.assertTrue(im.is_animated)

        # Traverse frames in reverse, checking timestamps and durations
        ts = dur * (im.n_frames - 1)
        for frame in reversed(range(im.n_frames)):
            im.seek(frame)
            im.load()
            self.assertEqual(im.info["duration"], dur)
            self.assertEqual(im.info["timestamp"], ts)
            ts -= dur