Pillow

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from __future__ import annotations
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from io import BytesIO
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from pathlib import Path
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from PIL import Image, ImageWin
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from .helper import hopper, is_win32
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# see https://github.com/python-pillow/Pillow/pull/1431#issuecomment-144692652
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if is_win32():
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    import ctypes
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    import ctypes.wintypes
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    class BITMAPFILEHEADER(ctypes.Structure):
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        _pack_ = 2
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        _fields_ = [
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            ("bfType", ctypes.wintypes.WORD),
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            ("bfSize", ctypes.wintypes.DWORD),
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            ("bfReserved1", ctypes.wintypes.WORD),
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            ("bfReserved2", ctypes.wintypes.WORD),
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            ("bfOffBits", ctypes.wintypes.DWORD),
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        ]
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    class BITMAPINFOHEADER(ctypes.Structure):
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        _pack_ = 2
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        _fields_ = [
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            ("biSize", ctypes.wintypes.DWORD),
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            ("biWidth", ctypes.wintypes.LONG),
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            ("biHeight", ctypes.wintypes.LONG),
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            ("biPlanes", ctypes.wintypes.WORD),
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            ("biBitCount", ctypes.wintypes.WORD),
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            ("biCompression", ctypes.wintypes.DWORD),
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            ("biSizeImage", ctypes.wintypes.DWORD),
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            ("biXPelsPerMeter", ctypes.wintypes.LONG),
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            ("biYPelsPerMeter", ctypes.wintypes.LONG),
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            ("biClrUsed", ctypes.wintypes.DWORD),
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            ("biClrImportant", ctypes.wintypes.DWORD),
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        ]
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    BI_RGB = 0
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    DIB_RGB_COLORS = 0
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    memcpy = ctypes.cdll.msvcrt.memcpy
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    memcpy.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_size_t]
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    windll = getattr(ctypes, "windll")
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    CreateCompatibleDC = windll.gdi32.CreateCompatibleDC
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    CreateCompatibleDC.argtypes = [ctypes.wintypes.HDC]
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    CreateCompatibleDC.restype = ctypes.wintypes.HDC
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    DeleteDC = windll.gdi32.DeleteDC
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    DeleteDC.argtypes = [ctypes.wintypes.HDC]
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    SelectObject = windll.gdi32.SelectObject
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    SelectObject.argtypes = [ctypes.wintypes.HDC, ctypes.wintypes.HGDIOBJ]
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    SelectObject.restype = ctypes.wintypes.HGDIOBJ
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    DeleteObject = windll.gdi32.DeleteObject
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    DeleteObject.argtypes = [ctypes.wintypes.HGDIOBJ]
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    CreateDIBSection = windll.gdi32.CreateDIBSection
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    CreateDIBSection.argtypes = [
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        ctypes.wintypes.HDC,
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        ctypes.c_void_p,
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        ctypes.c_uint,
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        ctypes.POINTER(ctypes.c_void_p),
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        ctypes.wintypes.HANDLE,
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        ctypes.wintypes.DWORD,
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    ]
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    CreateDIBSection.restype = ctypes.wintypes.HBITMAP
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    def serialize_dib(bi: BITMAPINFOHEADER, pixels: ctypes.c_void_p) -> bytearray:
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        bf = BITMAPFILEHEADER()
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        bf.bfType = 0x4D42
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        bf.bfOffBits = ctypes.sizeof(bf) + bi.biSize
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        bf.bfSize = bf.bfOffBits + bi.biSizeImage
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        bf.bfReserved1 = bf.bfReserved2 = 0
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        buf = (ctypes.c_byte * bf.bfSize)()
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        bp = ctypes.addressof(buf)
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        memcpy(bp, ctypes.byref(bf), ctypes.sizeof(bf))
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        memcpy(bp + ctypes.sizeof(bf), ctypes.byref(bi), bi.biSize)
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        memcpy(bp + bf.bfOffBits, pixels, bi.biSizeImage)
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        return bytearray(buf)
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    def test_pointer(tmp_path: Path) -> None:
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        im = hopper()
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        (width, height) = im.size
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        opath = str(tmp_path / "temp.png")
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        imdib = ImageWin.Dib(im)
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        hdr = BITMAPINFOHEADER()
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        hdr.biSize = ctypes.sizeof(hdr)
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        hdr.biWidth = width
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        hdr.biHeight = height
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        hdr.biPlanes = 1
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        hdr.biBitCount = 32
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        hdr.biCompression = BI_RGB
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        hdr.biSizeImage = width * height * 4
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        hdr.biClrUsed = 0
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        hdr.biClrImportant = 0
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        hdc = CreateCompatibleDC(None)
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        pixels = ctypes.c_void_p()
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        dib = CreateDIBSection(
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            hdc, ctypes.byref(hdr), DIB_RGB_COLORS, ctypes.byref(pixels), None, 0
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        )
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        SelectObject(hdc, dib)
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        imdib.expose(hdc)
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        bitmap = serialize_dib(hdr, pixels)
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        DeleteObject(dib)
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        DeleteDC(hdc)
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        with Image.open(BytesIO(bitmap)) as im:
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            im.save(opath)
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