Speed up rectangle, polygon and line drawing

Tests/test_imagedraw.py

@@ -625,18 +625,6 @@ def test_point(points: Coords) -> None:
     assert_image_equal_tofile(im, "Tests/images/imagedraw_point.png")
 
 
-def test_point_I16() -> None:
-    # Arrange
-    im = Image.new("I;16", (1, 1))
-    draw = ImageDraw.Draw(im)
-
-    # Act
-    draw.point((0, 0), fill=0x1234)
-
-    # Assert
-    assert im.getpixel((0, 0)) == 0x1234
-
-
 @pytest.mark.parametrize("points", POINTS)
 def test_polygon(points: Coords) -> None:
     # Arrange
@@ -650,19 +638,6 @@ def test_polygon(points: Coords) -> None:
     assert_image_equal_tofile(im, "Tests/images/imagedraw_polygon.png")
 
 
-@pytest.mark.parametrize("points", POINTS)
-def test_polygon_width_I16(points: Coords) -> None:
-    # Arrange
-    im = Image.new("I;16", (W, H))
-    draw = ImageDraw.Draw(im)
-
-    # Act
-    draw.polygon(points, outline=0xFFFF, width=2)
-
-    # Assert
-    assert_image_equal_tofile(im, "Tests/images/imagedraw_polygon_width_I.tiff")
-
-
 @pytest.mark.parametrize("mode", ("RGB", "L"))
 @pytest.mark.parametrize("kite_points", KITE_POINTS)
 def test_polygon_kite(
@@ -791,20 +766,6 @@ def test_rectangle_zero_width(bbox: Coords) -> None:
     assert_image_equal_tofile(im, "Tests/images/imagedraw_rectangle_zero_width.png")
 
 
-@pytest.mark.parametrize("bbox", BBOX)
-def test_rectangle_I16(bbox: Coords) -> None:
-    # Arrange
-    im = Image.new("I;16", (W, H))
-    draw = ImageDraw.Draw(im)
-
-    # Act
-    draw.rectangle(bbox, outline=0xCDEF)
-
-    # Assert
-    assert im.getpixel((X0, Y0)) == 0xCDEF
-    assert_image_equal_tofile(im, "Tests/images/imagedraw_rectangle_I.tiff")
-
-
 @pytest.mark.parametrize("bbox", BBOX)
 def test_rectangle_translucent_outline(bbox: Coords) -> None:
     # Arrange
@@ -1169,6 +1130,29 @@ def test_line_horizontal() -> None:
     )
 
 
+def test_line_horizontal_w1px_direction() -> None:
+    # Drawing right-to-left must paint the same pixels as left-to-right.
+    im_lr = Image.new("L", (20, 3))
+    ImageDraw.Draw(im_lr).line((2, 1, 17, 1), fill=255)
+    assert [im_lr.getpixel((x, 1)) for x in range(20)] == [
+        255 if 2 <= x <= 17 else 0 for x in range(20)
+    ]
+
+    im_rl = Image.new("L", (20, 3))
+    ImageDraw.Draw(im_rl).line((17, 1, 2, 1), fill=255)
+    assert_image_equal(im_rl, im_lr)
+
+
+def test_line_joints_blend_once() -> None:
+    # Pixels shared by consecutive polyline segments
+    # (and the final endpoint, which is drawn separately)
+    # must be blended exactly once.
+    im = Image.new("RGB", (20, 3))
+    draw = ImageDraw.Draw(im, "RGBA")
+    draw.line([(0, 1), (10, 1), (19, 1)], fill=(255, 255, 255, 128))
+    assert {im.getpixel((x, 1)) for x in range(20)} == {(128, 128, 128)}
+
+
 @pytest.mark.xfail(reason="failing test")
 def test_line_h_s1_w2() -> None:
     img, draw = create_base_image_draw((20, 20))

Tests/test_imagedraw_i16.py

@@ -0,0 +1,104 @@
+from __future__ import annotations
+
+import pytest
+
+from PIL import Image, ImageDraw
+from Tests.helper import assert_image_equal_tofile
+from Tests.test_imagedraw import BBOX, POINTS, X0, Y0, H, W
+
+TYPE_CHECKING = False
+
+if TYPE_CHECKING:
+    from PIL._typing import Coords
+
+I16_MODES = ("I;16", "I;16L", "I;16B", "I;16N")
+I16_INK = 0x1234
+
+
+def create_I16_image_draw(mode: str) -> tuple[Image.Image, ImageDraw.ImageDraw]:
+    img = Image.new(mode, (8, 8))
+    return img, ImageDraw.Draw(img)
+
+
+@pytest.mark.parametrize("points", POINTS)
+def test_polygon_width_I16(points: Coords) -> None:
+    # Arrange
+    im = Image.new("I;16", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.polygon(points, outline=0xFFFF, width=2)
+
+    # Assert
+    assert_image_equal_tofile(im, "Tests/images/imagedraw_polygon_width_I.tiff")
+
+
+@pytest.mark.parametrize("bbox", BBOX)
+def test_rectangle_I16(bbox: Coords) -> None:
+    # Arrange
+    im = Image.new("I;16", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.rectangle(bbox, outline=0xCDEF)
+
+    # Assert
+    assert im.getpixel((X0, Y0)) == 0xCDEF
+    assert_image_equal_tofile(im, "Tests/images/imagedraw_rectangle_I.tiff")
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_point_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.point((4, 4), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_horizontal_line_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.line((0, 4, 7, 4), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_vertical_line_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.line((4, 0, 4, 7), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_diagonal_line_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.line((0, 0, 7, 7), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_rectangle_fill_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.rectangle((0, 0, 7, 7), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_polygon_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.polygon([(0, 0), (7, 0), (7, 7), (0, 7)], fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_masked_polygon_I16(mode: str) -> None:
+    # A polygon outline wider than one pixel is drawn through a mask.
+    img, draw = create_I16_image_draw(mode)
+    draw.polygon([(0, 0), (7, 0), (7, 7), (0, 7)], outline=I16_INK, width=8)
+    assert img.getpixel((4, 4)) == I16_INK
+
+
+@pytest.mark.parametrize("mode", I16_MODES)
+def test_ellipse_I16(mode: str) -> None:
+    img, draw = create_I16_image_draw(mode)
+    draw.ellipse((0, 0, 7, 7), fill=I16_INK)
+    assert img.getpixel((4, 4)) == I16_INK

docs/releasenotes/13.0.0.rst

@@ -119,6 +119,12 @@ Two new filters are available for :py:meth:`~PIL.Image.Image.resize` and
 Other changes
 =============
 
+Drawing on I;16B images
+^^^^^^^^^^^^^^^^^^^^^^^
+
+When drawing on an ``I;16B`` image, some drawing methods wrote in the wrong byte order.
+All drawing operations now use the byte order of the image mode.
+
 Python 3.15
 ^^^^^^^^^^^