Added QOI reading

Author: radarhere

Tests/images/hopper.qoi

@@ -0,0 +1,28 @@
+import pytest
+
+from PIL import Image, QoiImagePlugin
+
+from .helper import assert_image_equal_tofile, assert_image_similar_tofile
+
+
+class TestFileQOI:
+    def test_sanity(self):
+        with Image.open("Tests/images/hopper.qoi") as im:
+            assert im.mode == "RGB"
+            assert im.size == (128, 128)
+            assert im.format == "QOI"
+
+            assert_image_equal_tofile(im, "Tests/images/hopper.png")
+
+        with Image.open("Tests/images/pil123rgba.qoi") as im:
+            assert im.mode == "RGBA"
+            assert im.size == (162, 150)
+            assert im.format == "QOI"
+
+            assert_image_similar_tofile(im, "Tests/images/pil123rgba.png", 0.03)
+
+    def test_invalid_file(self):
+        invalid_file = "Tests/images/flower.jpg"
+
+        with pytest.raises(SyntaxError):
+            QoiImagePlugin.QoiImageFile(invalid_file)

Tests/images/pil123rgba.qoi

@@ -1544,6 +1544,13 @@ The :py:meth:`~PIL.Image.Image.save` method can take the following keyword argum
 
     .. versionadded:: 5.3.0
 
+QOI
+^^^
+
+.. versionadded:: 9.5.0
+
+Pillow identifies and reads QOI images.
+
 XV Thumbnails
 ^^^^^^^^^^^^^
 

Tests/test_file_qoi.py

@@ -28,6 +28,11 @@ TODO
 API Additions
 =============
 
+QOI file format
+^^^^^^^^^^^^^^^
+
+Pillow can now read QOI images.
+
 Added ``dpi`` argument when saving PDFs
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

docs/handbook/image-file-formats.rst

@@ -0,0 +1,106 @@
+#
+# The Python Imaging Library.
+# $Id$
+#
+# QOI support for PIL
+#
+# See the README file for information on usage and redistribution.
+#
+
+import os
+
+from . import Image, ImageFile
+from ._binary import i32be as i32
+from ._binary import o8
+
+
+def _accept(prefix):
+    return prefix[:4] == b"qoif"
+
+
+class QoiImageFile(ImageFile.ImageFile):
+    format = "QOI"
+    format_description = "Quite OK Image"
+
+    def _open(self):
+        if not _accept(self.fp.read(4)):
+            msg = "not a QOI file"
+            raise SyntaxError(msg)
+
+        self._size = tuple(i32(self.fp.read(4)) for i in range(2))
+
+        channels = self.fp.read(1)[0]
+        self.mode = "RGB" if channels == 3 else "RGBA"
+
+        self.fp.seek(1, os.SEEK_CUR)  # colorspace
+        self.tile = [("qoi", (0, 0) + self._size, self.fp.tell(), None)]
+
+
+class QoiDecoder(ImageFile.PyDecoder):
+    _pulls_fd = True
+
+    def _add_to_previous_pixels(self, value):
+        self._previous_pixel = value
+
+        r, g, b, a = value
+        hash_value = (r * 3 + g * 5 + b * 7 + a * 11) % 64
+        self._previously_seen_pixels[hash_value] = value
+
+    def decode(self, buffer):
+        self._previously_seen_pixels = {}
+        self._previous_pixel = None
+        self._add_to_previous_pixels(b"".join(o8(i) for i in (0, 0, 0, 255)))
+
+        data = bytearray()
+        bands = Image.getmodebands(self.mode)
+        while len(data) < self.state.xsize * self.state.ysize * bands:
+            byte = self.fd.read(1)[0]
+            if byte == 0b11111110:  # QOI_OP_RGB
+                value = self.fd.read(3) + o8(255)
+            elif byte == 0b11111111:  # QOI_OP_RGBA
+                value = self.fd.read(4)
+            else:
+                op = byte >> 6
+                if op == 0:  # QOI_OP_INDEX
+                    op_index = byte & 0b00111111
+                    value = self._previously_seen_pixels.get(op_index, (0, 0, 0, 0))
+                elif op == 1:  # QOI_OP_DIFF
+                    value = (
+                        (self._previous_pixel[0] + ((byte & 0b00110000) >> 4) - 2)
+                        % 256,
+                        (self._previous_pixel[1] + ((byte & 0b00001100) >> 2) - 2)
+                        % 256,
+                        (self._previous_pixel[2] + (byte & 0b00000011) - 2) % 256,
+                    )
+                    value += (self._previous_pixel[3],)
+                elif op == 2:  # QOI_OP_LUMA
+                    second_byte = self.fd.read(1)[0]
+                    diff_green = (byte & 0b00111111) - 32
+                    diff_red = ((second_byte & 0b11110000) >> 4) - 8
+                    diff_blue = (second_byte & 0b00001111) - 8
+
+                    value = tuple(
+                        (self._previous_pixel[i] + diff_green + diff) % 256
+                        for i, diff in enumerate((diff_red, 0, diff_blue))
+                    )
+                    value += (self._previous_pixel[3],)
+                elif op == 3:  # QOI_OP_RUN
+                    run_length = (byte & 0b00111111) + 1
+                    value = self._previous_pixel
+                    if bands == 3:
+                        value = value[:3]
+                    data += value * run_length
+                    continue
+                value = b"".join(o8(i) for i in value)
+            self._add_to_previous_pixels(value)
+
+            if bands == 3:
+                value = value[:3]
+            data += value
+        self.set_as_raw(bytes(data))
+        return -1, 0
+
+
+Image.register_open(QoiImageFile.format, QoiImageFile, _accept)
+Image.register_decoder("qoi", QoiDecoder)
+Image.register_extension(QoiImageFile.format, ".qoi")

docs/releasenotes/9.5.0.rst

@@ -59,6 +59,7 @@
     "PngImagePlugin",
     "PpmImagePlugin",
     "PsdImagePlugin",
+    "QoiImagePlugin",
     "SgiImagePlugin",
     "SpiderImagePlugin",
     "SunImagePlugin",