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document PngImagePlugin constants

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nulano 2020-07-09 22:16:25 +02:00 committed by Andrew Murray
parent 4046e1c921
commit 9c277f5c49
3 changed files with 42 additions and 17 deletions
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8
docs/handbook/image-file-formats.rst
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@ -501,12 +501,14 @@ The :py:meth:`~PIL.Image.Image.open` method sets the following
This key is omitted if the image is not a transparent palette image.
.. _png-text:
``open`` also sets ``Image.text`` to a dictionary of the values of the
``tEXt``, ``zTXt``, and ``iTXt`` chunks of the PNG image. Individual
compressed chunks are limited to a decompressed size of
``PngImagePlugin.MAX_TEXT_CHUNK``, by default 1MB, to prevent
:data:`.PngImagePlugin.MAX_TEXT_CHUNK`, by default 1MB, to prevent
decompression bombs. Additionally, the total size of all of the text
chunks is limited to ``PngImagePlugin.MAX_TEXT_MEMORY``, defaulting to
chunks is limited to :data:`.PngImagePlugin.MAX_TEXT_MEMORY`, defaulting to
64MB.
The :py:meth:`~PIL.Image.Image.save` method supports the following options:
@ -611,6 +613,8 @@ where applicable:
Any APNG file containing sequence errors is treated as an invalid image. The APNG
loader will not attempt to repair and reorder files containing sequence errors.
.. _apng-saving:
Saving
~~~~~~

16
docs/reference/plugins.rst
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@ -229,20 +229,12 @@ Plugin reference
---------------------------------
.. automodule:: PIL.PngImagePlugin
:members: ChunkStream, PngStream, getchunks, is_cid, putchunk
:show-inheritance:
.. autoclass:: PIL.PngImagePlugin.ChunkStream
:members:
:undoc-members:
:show-inheritance:
.. autoclass:: PIL.PngImagePlugin.PngImageFile
:members:
:undoc-members:
:show-inheritance:
.. autoclass:: PIL.PngImagePlugin.PngStream
:members:
:members: ChunkStream, PngImageFile, PngStream, getchunks, is_cid, putchunk,
MAX_TEXT_CHUNK, MAX_TEXT_MEMORY, APNG_BLEND_OP_SOURCE, APNG_BLEND_OP_OVER,
APNG_DISPOSE_OP_NONE, APNG_DISPOSE_OP_BACKGROUND, APNG_DISPOSE_OP_PREVIOUS
:undoc-members:
:show-inheritance:
:member-order: groupwise
:mod:`~PIL.PpmImagePlugin` Module

35
src/PIL/PngImagePlugin.py
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@ -76,21 +76,50 @@ _MODES = {
_simple_palette = re.compile(b"^\xff*\x00\xff*$")
# Maximum decompressed size for a iTXt or zTXt chunk.
# Eliminates decompression bombs where compressed chunks can expand 1000x
MAX_TEXT_CHUNK = ImageFile.SAFEBLOCK
# Set the maximum total text chunk size.
"""
Maximum decompressed size for a iTXt or zTXt chunk.
Eliminates decompression bombs where compressed chunks can expand 1000x
See :ref:`Text in PNG File Format<png-text>`.
"""
MAX_TEXT_MEMORY = 64 * MAX_TEXT_CHUNK
"""
Set the maximum total text chunk size.
See :ref:`Text in PNG File Format<png-text>`.
"""
# APNG frame disposal modes
APNG_DISPOSE_OP_NONE = 0
"""
No disposal is done on this frame before rendering the next frame.
See :ref:`Saving APNG sequences<apng-saving>`.
"""
APNG_DISPOSE_OP_BACKGROUND = 1
"""
This frame’s modified region is cleared to fully transparent black before rendering
the next frame.
See :ref:`Saving APNG sequences<apng-saving>`.
"""
APNG_DISPOSE_OP_PREVIOUS = 2
"""
This frame’s modified region is reverted to the previous frame’s contents before
rendering the next frame.
See :ref:`Saving APNG sequences<apng-saving>`.
"""
# APNG frame blend modes
APNG_BLEND_OP_SOURCE = 0
"""
All color components of this frame, including alpha, overwrite the previous output
image contents.
See :ref:`Saving APNG sequences<apng-saving>`.
"""
APNG_BLEND_OP_OVER = 1
"""
This frame should be alpha composited with the previous output image contents.
See :ref:`Saving APNG sequences<apng-saving>`.
"""
def _safe_zlib_decompress(s):