in infrastructure/pillow-layer/python/PIL/BmpImagePlugin.py [0:0]
def _bitmap(self, header=0, offset=0):
""" Read relevant info about the BMP """
read, seek = self.fp.read, self.fp.seek
if header:
seek(header)
file_info = {}
# read bmp header size @offset 14 (this is part of the header size)
file_info["header_size"] = i32(read(4))
file_info["direction"] = -1
# -------------------- If requested, read header at a specific position
# read the rest of the bmp header, without its size
header_data = ImageFile._safe_read(self.fp, file_info["header_size"] - 4)
# -------------------------------------------------- IBM OS/2 Bitmap v1
# ----- This format has different offsets because of width/height types
if file_info["header_size"] == 12:
file_info["width"] = i16(header_data[0:2])
file_info["height"] = i16(header_data[2:4])
file_info["planes"] = i16(header_data[4:6])
file_info["bits"] = i16(header_data[6:8])
file_info["compression"] = self.RAW
file_info["palette_padding"] = 3
# --------------------------------------------- Windows Bitmap v2 to v5
# v3, OS/2 v2, v4, v5
elif file_info["header_size"] in (40, 64, 108, 124):
file_info["y_flip"] = i8(header_data[7]) == 0xFF
file_info["direction"] = 1 if file_info["y_flip"] else -1
file_info["width"] = i32(header_data[0:4])
file_info["height"] = (
i32(header_data[4:8])
if not file_info["y_flip"]
else 2 ** 32 - i32(header_data[4:8])
)
file_info["planes"] = i16(header_data[8:10])
file_info["bits"] = i16(header_data[10:12])
file_info["compression"] = i32(header_data[12:16])
# byte size of pixel data
file_info["data_size"] = i32(header_data[16:20])
file_info["pixels_per_meter"] = (
i32(header_data[20:24]),
i32(header_data[24:28]),
)
file_info["colors"] = i32(header_data[28:32])
file_info["palette_padding"] = 4
self.info["dpi"] = tuple(
int(x / 39.3701 + 0.5) for x in file_info["pixels_per_meter"]
)
if file_info["compression"] == self.BITFIELDS:
if len(header_data) >= 52:
for idx, mask in enumerate(
["r_mask", "g_mask", "b_mask", "a_mask"]
):
file_info[mask] = i32(header_data[36 + idx * 4 : 40 + idx * 4])
else:
# 40 byte headers only have the three components in the
# bitfields masks, ref:
# https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
# See also
# https://github.com/python-pillow/Pillow/issues/1293
# There is a 4th component in the RGBQuad, in the alpha
# location, but it is listed as a reserved component,
# and it is not generally an alpha channel
file_info["a_mask"] = 0x0
for mask in ["r_mask", "g_mask", "b_mask"]:
file_info[mask] = i32(read(4))
file_info["rgb_mask"] = (
file_info["r_mask"],
file_info["g_mask"],
file_info["b_mask"],
)
file_info["rgba_mask"] = (
file_info["r_mask"],
file_info["g_mask"],
file_info["b_mask"],
file_info["a_mask"],
)
else:
raise OSError(f"Unsupported BMP header type ({file_info['header_size']})")
# ------------------ Special case : header is reported 40, which
# ---------------------- is shorter than real size for bpp >= 16
self._size = file_info["width"], file_info["height"]
# ------- If color count was not found in the header, compute from bits
file_info["colors"] = (
file_info["colors"]
if file_info.get("colors", 0)
else (1 << file_info["bits"])
)
# ---------------------- Check bit depth for unusual unsupported values
self.mode, raw_mode = BIT2MODE.get(file_info["bits"], (None, None))
if self.mode is None:
raise OSError(f"Unsupported BMP pixel depth ({file_info['bits']})")
# ---------------- Process BMP with Bitfields compression (not palette)
if file_info["compression"] == self.BITFIELDS:
SUPPORTED = {
32: [
(0xFF0000, 0xFF00, 0xFF, 0x0),
(0xFF0000, 0xFF00, 0xFF, 0xFF000000),
(0xFF, 0xFF00, 0xFF0000, 0xFF000000),
(0x0, 0x0, 0x0, 0x0),
(0xFF000000, 0xFF0000, 0xFF00, 0x0),
],
24: [(0xFF0000, 0xFF00, 0xFF)],
16: [(0xF800, 0x7E0, 0x1F), (0x7C00, 0x3E0, 0x1F)],
}
MASK_MODES = {
(32, (0xFF0000, 0xFF00, 0xFF, 0x0)): "BGRX",
(32, (0xFF000000, 0xFF0000, 0xFF00, 0x0)): "XBGR",
(32, (0xFF, 0xFF00, 0xFF0000, 0xFF000000)): "RGBA",
(32, (0xFF0000, 0xFF00, 0xFF, 0xFF000000)): "BGRA",
(32, (0x0, 0x0, 0x0, 0x0)): "BGRA",
(24, (0xFF0000, 0xFF00, 0xFF)): "BGR",
(16, (0xF800, 0x7E0, 0x1F)): "BGR;16",
(16, (0x7C00, 0x3E0, 0x1F)): "BGR;15",
}
if file_info["bits"] in SUPPORTED:
if (
file_info["bits"] == 32
and file_info["rgba_mask"] in SUPPORTED[file_info["bits"]]
):
raw_mode = MASK_MODES[(file_info["bits"], file_info["rgba_mask"])]
self.mode = "RGBA" if "A" in raw_mode else self.mode
elif (
file_info["bits"] in (24, 16)
and file_info["rgb_mask"] in SUPPORTED[file_info["bits"]]
):
raw_mode = MASK_MODES[(file_info["bits"], file_info["rgb_mask"])]
else:
raise OSError("Unsupported BMP bitfields layout")
else:
raise OSError("Unsupported BMP bitfields layout")
elif file_info["compression"] == self.RAW:
if file_info["bits"] == 32 and header == 22: # 32-bit .cur offset
raw_mode, self.mode = "BGRA", "RGBA"
else:
raise OSError(f"Unsupported BMP compression ({file_info['compression']})")
# --------------- Once the header is processed, process the palette/LUT
if self.mode == "P": # Paletted for 1, 4 and 8 bit images
# ---------------------------------------------------- 1-bit images
if not (0 < file_info["colors"] <= 65536):
raise OSError(f"Unsupported BMP Palette size ({file_info['colors']})")
else:
padding = file_info["palette_padding"]
palette = read(padding * file_info["colors"])
greyscale = True
indices = (
(0, 255)
if file_info["colors"] == 2
else list(range(file_info["colors"]))
)
# ----------------- Check if greyscale and ignore palette if so
for ind, val in enumerate(indices):
rgb = palette[ind * padding : ind * padding + 3]
if rgb != o8(val) * 3:
greyscale = False
# ------- If all colors are grey, white or black, ditch palette
if greyscale:
self.mode = "1" if file_info["colors"] == 2 else "L"
raw_mode = self.mode
else:
self.mode = "P"
self.palette = ImagePalette.raw(
"BGRX" if padding == 4 else "BGR", palette
)
# ---------------------------- Finally set the tile data for the plugin
self.info["compression"] = file_info["compression"]
self.tile = [
(
"raw",
(0, 0, file_info["width"], file_info["height"]),
offset or self.fp.tell(),
(
raw_mode,
((file_info["width"] * file_info["bits"] + 31) >> 3) & (~3),
file_info["direction"],
),
)
]