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Merge pull request #5564 from radarhere/getcolor

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Do not use background or transparency index for new color
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Andrew Murray 2021-06-30 21:45:21 +10:00 committed by GitHub
commit 1b74bddfde
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2 changed files with 32 additions and 1 deletions
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23
Tests/test_imagepalette.py
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@ -49,6 +49,29 @@ def test_getcolor():
palette.getcolor("unknown")
@pytest.mark.parametrize(
"index, palette",
[
# Test when the palette is not full
(0, ImagePalette.ImagePalette()),
# Test when the palette is full
(255, ImagePalette.ImagePalette("RGB", list(range(256)) * 3)),
],
)
def test_getcolor_not_special(index, palette):
im = Image.new("P", (1, 1))
# Do not use transparency index as a new color
im.info["transparency"] = index
index1 = palette.getcolor((0, 0, 0), im)
assert index1 != index
# Do not use background index as a new color
im.info["background"] = index1
index2 = palette.getcolor((0, 0, 1), im)
assert index2 not in (index, index1)
def test_file(tmp_path):
palette = ImagePalette.ImagePalette("RGB", list(range(256)) * 3)

10
src/PIL/ImagePalette.py
View File

@ -118,11 +118,19 @@ class ImagePalette:
if not isinstance(self.palette, bytearray):
self._palette = bytearray(self.palette)
index = len(self.palette) // 3
special_colors = ()
if image:
special_colors = (
image.info.get("background"),
image.info.get("transparency"),
)
while index in special_colors:
index += 1
if index >= 256:
if image:
# Search for an unused index
for i, count in reversed(list(enumerate(image.histogram()))):
if count == 0:
if count == 0 and i not in special_colors:
index = i
break
if index >= 256: