Pillow/Tests/test_imagewin_pointers.py

from helper import unittest, PillowTestCase, hopper

from PIL import Image, ImageWin
import sys
import ctypes
import ctypes.wintypes
from io import BytesIO

# see https://github.com/python-pillow/Pillow/pull/1431#issuecomment-144692652

if not sys.platform.startswith('win32'):
	unittest.skip("Win32 only test")

class BITMAPFILEHEADER(ctypes.Structure):
    _pack_ = 2
    _fields_ = [
        ('bfType', ctypes.wintypes.WORD),
        ('bfSize', ctypes.wintypes.DWORD),
        ('bfReserved1', ctypes.wintypes.WORD),
        ('bfReserved2', ctypes.wintypes.WORD),
        ('bfOffBits', ctypes.wintypes.DWORD),
    ]

class BITMAPINFOHEADER(ctypes.Structure):
    _pack_ = 2
    _fields_ = [
        ('biSize', ctypes.wintypes.DWORD),
        ('biWidth', ctypes.wintypes.LONG),
        ('biHeight', ctypes.wintypes.LONG),
        ('biPlanes', ctypes.wintypes.WORD),
        ('biBitCount', ctypes.wintypes.WORD),
        ('biCompression', ctypes.wintypes.DWORD),
        ('biSizeImage', ctypes.wintypes.DWORD),
        ('biXPelsPerMeter', ctypes.wintypes.LONG),
        ('biYPelsPerMeter', ctypes.wintypes.LONG),
        ('biClrUsed', ctypes.wintypes.DWORD),
        ('biClrImportant', ctypes.wintypes.DWORD),
    ]

BI_RGB = 0
DIB_RGB_COLORS = 0

memcpy = ctypes.cdll.msvcrt.memcpy
memcpy.argtypes = [ ctypes.c_void_p, ctypes.c_void_p, ctypes.c_size_t ]

CreateCompatibleDC = ctypes.windll.gdi32.CreateCompatibleDC
CreateCompatibleDC.argtypes = [ ctypes.wintypes.HDC ]
CreateCompatibleDC.restype = ctypes.wintypes.HDC

DeleteDC = ctypes.windll.gdi32.DeleteDC
DeleteDC.argtypes = [ ctypes.wintypes.HDC ]

SelectObject = ctypes.windll.gdi32.SelectObject
SelectObject.argtypes = [ ctypes.wintypes.HDC, ctypes.wintypes.HGDIOBJ ]
SelectObject.restype = ctypes.wintypes.HGDIOBJ

DeleteObject = ctypes.windll.gdi32.DeleteObject
DeleteObject.argtypes = [ ctypes.wintypes.HGDIOBJ ]

CreateDIBSection = ctypes.windll.gdi32.CreateDIBSection
CreateDIBSection.argtypes = [ ctypes.wintypes.HDC, ctypes.c_void_p, ctypes.c_uint, ctypes.POINTER(ctypes.c_void_p), ctypes.wintypes.HANDLE, ctypes.wintypes.DWORD ]
CreateDIBSection.restype = ctypes.wintypes.HBITMAP


def serialize_dib(bi, pixels):
    bf = BITMAPFILEHEADER()
    bf.bfType = 0x4d42
    bf.bfOffBits = ctypes.sizeof(bf) + bi.biSize
    bf.bfSize = bf.bfOffBits + bi.biSizeImage
    bf.bfReserved1 = bf.bfReserved2 = 0

    buf = (ctypes.c_byte * bf.bfSize)()
    bp = ctypes.addressof(buf)
    memcpy(bp, ctypes.byref(bf), ctypes.sizeof(bf))
    memcpy(bp + ctypes.sizeof(bf), ctypes.byref(bi), bi.biSize)
    memcpy(bp + bf.bfOffBits, pixels, bi.biSizeImage)
    return bytes(buf)

class TestImageWinPointers(PillowTestCase):
	def test_pointer(self):
		im = hopper()
		(width, height) =im.size
		opath = self.tempfile('temp.png')
		imdib = ImageWin.Dib(im)

		hdr = BITMAPINFOHEADER()
		hdr.biSize = ctypes.sizeof(hdr)
		hdr.biWidth = width
		hdr.biHeight = height
		hdr.biPlanes = 1
		hdr.biBitCount = 32
		hdr.biCompression = BI_RGB
		hdr.biSizeImage = width * height * 4
		hdr.biClrUsed = 0
		hdr.biClrImportant = 0

		hdc = CreateCompatibleDC(None)
		print('hdc:',hex(hdc))
		pixels = ctypes.c_void_p()
		dib = CreateDIBSection(hdc, ctypes.byref(hdr), DIB_RGB_COLORS, ctypes.byref(pixels), None, 0)
		SelectObject(hdc, dib)

		imdib.expose(hdc)
		bitmap = serialize_dib(hdr, pixels)
		DeleteObject(dib)
		DeleteDC(hdc)

		reloaded = Image.open(BytesIO(bitmap)).save(opath)

if __name__ == '__main__':
    unittest.main()

# End of file