Band names for arrow exported images

Tests/test_arro3.py

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+from __future__ import annotations
+
+import json
+from typing import Any, NamedTuple
+
+import pytest
+
+from PIL import Image
+
+from .helper import (
+    assert_deep_equal,
+    assert_image_equal,
+    hopper,
+    is_big_endian,
+)
+
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from arro3 import compute  #  type: ignore [import-not-found]
+    from arro3.core import (  #  type: ignore [import-not-found]
+        Array,
+        DataType,
+        Field,
+        fixed_size_list_array,
+    )
+else:
+    arro3 = pytest.importorskip("arro3", reason="Arro3 not installed")
+    from arro3 import compute
+    from arro3.core import Array, DataType, Field, fixed_size_list_array
+
+TEST_IMAGE_SIZE = (10, 10)
+
+
+def _test_img_equals_pyarray(
+    img: Image.Image, arr: Any, mask: list[int] | None, elts_per_pixel: int = 1
+) -> None:
+    assert img.height * img.width * elts_per_pixel == len(arr)
+    px = img.load()
+    assert px is not None
+    if elts_per_pixel > 1 and mask is None:
+        # have to do element-wise comparison when we're comparing
+        # flattened r,g,b,a to a pixel.
+        mask = list(range(elts_per_pixel))
+    for x in range(0, img.size[0], int(img.size[0] / 10)):
+        for y in range(0, img.size[1], int(img.size[1] / 10)):
+            if mask:
+                pixel = px[x, y]
+                assert isinstance(pixel, tuple)
+                for ix, elt in enumerate(mask):
+                    if elts_per_pixel == 1:
+                        assert pixel[ix] == arr[y * img.width + x].as_py()[elt]
+                    else:
+                        assert (
+                            pixel[ix]
+                            == arr[(y * img.width + x) * elts_per_pixel + elt].as_py()
+                        )
+            else:
+                assert_deep_equal(px[x, y], arr[y * img.width + x].as_py())
+
+
+def _test_img_equals_int32_pyarray(
+    img: Image.Image, arr: Any, mask: list[int] | None, elts_per_pixel: int = 1
+) -> None:
+    assert img.height * img.width * elts_per_pixel == len(arr)
+    px = img.load()
+    assert px is not None
+    if mask is None:
+        # have to do element-wise comparison when we're comparing
+        # flattened rgba in an uint32 to a pixel.
+        mask = list(range(elts_per_pixel))
+    for x in range(0, img.size[0], int(img.size[0] / 10)):
+        for y in range(0, img.size[1], int(img.size[1] / 10)):
+            pixel = px[x, y]
+            assert isinstance(pixel, tuple)
+            arr_pixel_int = arr[y * img.width + x].as_py()
+            arr_pixel_tuple = (
+                arr_pixel_int % 256,
+                (arr_pixel_int // 256) % 256,
+                (arr_pixel_int // 256**2) % 256,
+                (arr_pixel_int // 256**3),
+            )
+            if is_big_endian():
+                arr_pixel_tuple = arr_pixel_tuple[::-1]
+
+            for ix, elt in enumerate(mask):
+                assert pixel[ix] == arr_pixel_tuple[elt]
+
+
+fl_uint8_4_type = DataType.list(Field("_", DataType.uint8()).with_nullable(False), 4)
+
+
+@pytest.mark.parametrize(
+    "mode, dtype, mask",
+    (
+        ("L", DataType.uint8(), None),
+        ("I", DataType.int32(), None),
+        ("F", DataType.float32(), None),
+        ("LA", fl_uint8_4_type, [0, 3]),
+        ("RGB", fl_uint8_4_type, [0, 1, 2]),
+        ("RGBA", fl_uint8_4_type, None),
+        ("RGBX", fl_uint8_4_type, None),
+        ("CMYK", fl_uint8_4_type, None),
+        ("YCbCr", fl_uint8_4_type, [0, 1, 2]),
+        ("HSV", fl_uint8_4_type, [0, 1, 2]),
+    ),
+)
+def test_to_array(mode: str, dtype: DataType, mask: list[int] | None) -> None:
+    img = hopper(mode)
+
+    # Resize to non-square
+    img = img.crop((3, 0, 124, 127))
+    assert img.size == (121, 127)
+
+    arr = Array(img)
+    _test_img_equals_pyarray(img, arr, mask)
+    assert arr.type == dtype
+
+    reloaded = Image.fromarrow(arr, mode, img.size)
+    assert_image_equal(img, reloaded)
+
+
+def test_lifetime() -> None:
+    # valgrind shouldn't error out here.
+    # arrays should be accessible after the image is deleted.
+
+    img = hopper("L")
+
+    arr_1 = Array(img)
+    arr_2 = Array(img)
+
+    del img
+
+    assert compute.sum(arr_1).as_py() > 0
+    del arr_1
+
+    assert compute.sum(arr_2).as_py() > 0
+    del arr_2
+
+
+def test_lifetime2() -> None:
+    # valgrind shouldn't error out here.
+    # img should remain after the arrays are collected.
+
+    img = hopper("L")
+
+    arr_1 = Array(img)
+    arr_2 = Array(img)
+
+    assert compute.sum(arr_1).as_py() > 0
+    del arr_1
+
+    assert compute.sum(arr_2).as_py() > 0
+    del arr_2
+
+    img2 = img.copy()
+    px = img2.load()
+    assert px  # make mypy happy
+    assert isinstance(px[0, 0], int)
+
+
+class DataShape(NamedTuple):
+    dtype: DataType
+    # Strictly speaking, elt should be a pixel or pixel component, so
+    # list[uint8][4], float, int, uint32, uint8, etc.  But more
+    # correctly, it should be exactly the dtype from the line above.
+    elt: Any
+    elts_per_pixel: int
+
+
+UINT_ARR = DataShape(
+    dtype=fl_uint8_4_type,
+    elt=[1, 2, 3, 4],  # array of 4 uint8 per pixel
+    elts_per_pixel=1,  # only one array per pixel
+)
+
+UINT = DataShape(
+    dtype=DataType.uint8(),
+    elt=3,  # one uint8,
+    elts_per_pixel=4,  # but repeated 4x per pixel
+)
+
+UINT32 = DataShape(
+    dtype=DataType.uint32(),
+    elt=0xABCDEF45,  # one packed int, doesn't fit in a int32 > 0x80000000
+    elts_per_pixel=1,  # one per pixel
+)
+
+INT32 = DataShape(
+    dtype=DataType.uint32(),
+    elt=0x12CDEF45,  # one packed int
+    elts_per_pixel=1,  # one per pixel
+)
+
+
+@pytest.mark.parametrize(
+    "mode, data_tp, mask",
+    (
+        ("L", DataShape(DataType.uint8(), 3, 1), None),
+        ("I", DataShape(DataType.int32(), 1 << 24, 1), None),
+        ("F", DataShape(DataType.float32(), 3.14159, 1), None),
+        ("LA", UINT_ARR, [0, 3]),
+        ("LA", UINT, [0, 3]),
+        ("RGB", UINT_ARR, [0, 1, 2]),
+        ("RGBA", UINT_ARR, None),
+        ("CMYK", UINT_ARR, None),
+        ("YCbCr", UINT_ARR, [0, 1, 2]),
+        ("HSV", UINT_ARR, [0, 1, 2]),
+        ("RGB", UINT, [0, 1, 2]),
+        ("RGBA", UINT, None),
+        ("CMYK", UINT, None),
+        ("YCbCr", UINT, [0, 1, 2]),
+        ("HSV", UINT, [0, 1, 2]),
+    ),
+)
+def test_fromarray(mode: str, data_tp: DataShape, mask: list[int] | None) -> None:
+    (dtype, elt, elts_per_pixel) = data_tp
+
+    ct_pixels = TEST_IMAGE_SIZE[0] * TEST_IMAGE_SIZE[1]
+    if dtype == fl_uint8_4_type:
+        tmp_arr = Array(elt * (ct_pixels * elts_per_pixel), type=DataType.uint8())
+        arr = fixed_size_list_array(tmp_arr, 4)
+    else:
+        arr = Array([elt] * (ct_pixels * elts_per_pixel), type=dtype)
+    img = Image.fromarrow(arr, mode, TEST_IMAGE_SIZE)
+
+    _test_img_equals_pyarray(img, arr, mask, elts_per_pixel)
+
+
+@pytest.mark.parametrize(
+    "mode, mask",
+    (
+        ("LA", [0, 3]),
+        ("RGB", [0, 1, 2]),
+        ("RGBA", None),
+        ("CMYK", None),
+        ("YCbCr", [0, 1, 2]),
+        ("HSV", [0, 1, 2]),
+    ),
+)
+@pytest.mark.parametrize("data_tp", (UINT32, INT32))
+def test_from_int32array(mode: str, mask: list[int] | None, data_tp: DataShape) -> None:
+    (dtype, elt, elts_per_pixel) = data_tp
+
+    ct_pixels = TEST_IMAGE_SIZE[0] * TEST_IMAGE_SIZE[1]
+    arr = Array([elt] * (ct_pixels * elts_per_pixel), type=dtype)
+    img = Image.fromarrow(arr, mode, TEST_IMAGE_SIZE)
+
+    _test_img_equals_int32_pyarray(img, arr, mask, elts_per_pixel)
+
+
+@pytest.mark.parametrize(
+    "mode, metadata",
+    (
+        ("LA", ["L", "X", "X", "A"]),
+        ("RGB", ["R", "G", "B", "X"]),
+        ("RGBX", ["R", "G", "B", "X"]),
+        ("RGBA", ["R", "G", "B", "A"]),
+        ("CMYK", ["C", "M", "Y", "K"]),
+        ("YCbCr", ["Y", "Cb", "Cr", "X"]),
+        ("HSV", ["H", "S", "V", "X"]),
+    ),
+)
+def test_image_metadata(mode: str, metadata: list[str]) -> None:
+    img = hopper(mode)
+
+    arr = Array(img)
+
+    assert arr.type.value_field
+    assert arr.type.value_field.metadata
+    assert arr.type.value_field.metadata[b"image"]
+
+    parsed_metadata = json.loads(arr.type.value_field.metadata[b"image"].decode("utf8"))
+
+    assert "bands" in parsed_metadata
+    assert parsed_metadata["bands"] == metadata