python-pillow/Pillow
1
1
Fork 0
mirror of https://github.com/python-pillow/Pillow.git synced 2024-12-24 17:06:16 +03:00
Code Issues Packages Projects Releases Wiki Activity

BMP: Add 4-bit RLE decoder

Browse Source
This commit is contained in:
Nathanael Gentry 2022-10-21 19:44:48 -04:00
parent 79b3b000c1
commit 70e3e4fb10
1 changed files with 69 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
src/PIL/BmpImagePlugin.py
View File

@ -212,7 +212,9 @@ class BmpImageFile(ImageFile.ImageFile):
if file_info["bits"] == 32 and header == 22: # 32-bit .cur offset
raw_mode, self.mode = "BGRA", "RGBA"
elif file_info["compression"] == self.RLE8:
decoder_name = "bmp_rle"
decoder_name = "bmp_rle8"
elif file_info["compression"] == self.RLE4:
decoder_name = "bmp_rle4"
else:
raise OSError(f"Unsupported BMP compression ({file_info['compression']})")
@ -227,7 +229,7 @@ class BmpImageFile(ImageFile.ImageFile):
palette = read(padding * file_info["colors"])
greyscale = True
indices = (
(0, 255)
(0, file_info["colors"])
if file_info["colors"] == 2
else list(range(file_info["colors"]))
)
@ -276,7 +278,7 @@ class BmpImageFile(ImageFile.ImageFile):
self._bitmap(offset=offset)
class BmpRleDecoder(ImageFile.PyDecoder):
class BmpRle8Decoder(ImageFile.PyDecoder):
_pulls_fd = True
def decode(self, buffer):
@ -328,6 +330,68 @@ class BmpRleDecoder(ImageFile.PyDecoder):
return -1, 0
class BmpRle4Decoder(ImageFile.PyDecoder):
_pulls_fd = True
def decode(self, buffer):
data = bytearray()
x = 0
while len(data) < self.state.xsize * self.state.ysize:
pixels = self.fd.read(1)
byte = self.fd.read(1)
if not pixels or not byte:
break
num_pixels = pixels[0]
if num_pixels:
# encoded mode
if x + num_pixels > self.state.xsize:
# Too much data for row
num_pixels = max(0, self.state.xsize - x)
first_pixel = o8(byte[0] >> 4)
second_pixel = o8(byte[0] & 0x0f)
for index in range(num_pixels):
if index % 2 == 0:
data += first_pixel
else:
data += second_pixel
x += num_pixels
else:
if byte[0] == 0:
# end of line
while len(data) % self.state.xsize != 0:
data += b"\x00"
x = 0
elif byte[0] == 1:
# end of bitmap
break
elif byte[0] == 2:
# delta
bytes_read = self.fd.read(2)
if len(bytes_read) < 2:
break
right, up = self.fd.read(2)
data += b"\x00" * (right + up * self.state.xsize)
x = len(data) % self.state.xsize
else:
# absolute mode (2 pixels per byte)
total_bytes_to_read = byte[0] // 2
bytes_read = self.fd.read(total_bytes_to_read)
for byte_read in bytes_read:
first_pixel = o8(byte_read >> 4)
data += first_pixel
second_pixel = o8(byte_read & 0x0f)
data += second_pixel
if len(bytes_read) < total_bytes_to_read:
break
x += byte[0]
# align to 16-bit word boundary
if self.fd.tell() % 2 != 0:
self.fd.seek(1, os.SEEK_CUR)
rawmode = "L" if self.mode == "L" else "P"
self.set_as_raw(bytes(data), (rawmode, 0, self.args[-1]))
return -1, 0
# =============================================================================
# Image plugin for the DIB format (BMP alias)
# =============================================================================
@ -433,7 +497,8 @@ Image.register_extension(BmpImageFile.format, ".bmp")
Image.register_mime(BmpImageFile.format, "image/bmp")
Image.register_decoder("bmp_rle", BmpRleDecoder)
Image.register_decoder("bmp_rle8", BmpRle8Decoder)
Image.register_decoder("bmp_rle4", BmpRle4Decoder)
Image.register_open(DibImageFile.format, DibImageFile, _dib_accept)
Image.register_save(DibImageFile.format, _dib_save)