272 lines
11 KiB
Python
272 lines
11 KiB
Python
# https://en.wikipedia.org/wiki/ICO_(file_format)
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# All values in ICO/CUR files are represented in little-endian byte order.
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# Broad file structure:
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# _______________________
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# | ICO header |
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# |-----------------------|
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# | Icon directories 1..n |
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# |-----------------------|
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# | Image data 1..n |
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# |_______________________|
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# ICO header:
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# _______________________________________________________________________________
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# | Offset | Size (bytes) | Purpose |
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# |--------|--------------|-------------------------------------------------------|
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# | 0 | 2 | Reserved. Must always be 0. |
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# |--------|--------------|-------------------------------------------------------|
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# | 2 | 2 | Specifies image type: 1 for icon (.ICO) image, |
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# | | | 2 for cursor (.CUR) image. Other values are invalid. |
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# |--------|--------------|-------------------------------------------------------|
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# | 4 | 2 | Specifies number of images in the file. |
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# |________|______________|_______________________________________________________|
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# Icon directory structure:
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# _______________________________________________________________________________
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# | Offset | Size (bytes) | Purpose |
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# |--------|--------------|-------------------------------------------------------|
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# | 0 | 1 | Specifies image width in pixels. Can be any number |
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# | | | between 0 and 255. Value 0 means image width is 256 |
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# | | | pixels. |
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# |--------|--------------|-------------------------------------------------------|
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# | 1 | 1 | Specifies image height in pixels. Can be any number |
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# | | | between 0 and 255. Value 0 means image height is 256 |
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# | | | pixels. |
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# |--------|--------------|-------------------------------------------------------|
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# | 2 | 1 | Specifies number of colors in the color palette. |
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# | | | Should be 0 if the image does not use a color palette |
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# |--------|--------------|-------------------------------------------------------|
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# | 3 | 1 | Reserved. Should be 0. |
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# |--------|--------------|-------------------------------------------------------|
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# | 4 | 2 | In ICO format: Specifies color planes. |
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# | | | Should be 0 or 1. |
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# | | | In CUR format: Specifies the horizontal coordinates |
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# | | | of the hotspot in number of pixels from the left. |
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# |--------|--------------|-------------------------------------------------------|
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# | 6 | 2 | In ICO format: Specifies bits per pixel. |
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# | | | In CUR format: Specifies the vertical coordinates of |
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# | | | the hotspot in number of pixels from the top. |
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# |--------|--------------|-------------------------------------------------------|
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# | 8 | 4 | Specifies the size of the image's data in bytes |
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# |--------|--------------|-------------------------------------------------------|
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# | 12 | 4 | Specifies the offset of BMP or PNG data from the |
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# | | | beginning of the ICO/CUR file |
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# |________|______________|_______________________________________________________|
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# Image data structure
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# BMP, starting from the BITMAPINFOHEADER, ignoring normal file header:
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# _______________________________________________________________________________
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# | Offset | Size (bytes) | Purpose |
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# |--------|--------------|-------------------------------------------------------|
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# | 0 | 4 | The size of this header. Always 40. |
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# |--------|--------------|-------------------------------------------------------|
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# | 4 | 4 | Image width in pixels, signed. |
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# |--------|--------------|-------------------------------------------------------|
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# | 8 | 4 | Image height in pixels, signed. |
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# |--------|--------------|-------------------------------------------------------|
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# | 12 | 2 | Number of color planes. Always 1. |
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# |--------|--------------|-------------------------------------------------------|
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# | 14 | 2 | Bits per pixel aka color depth. |
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# |--------|--------------|-------------------------------------------------------|
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# | 16 | 4 | Compression method. 0 for None aka BI_RGB. |
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# |--------|--------------|-------------------------------------------------------|
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# | 20 | 4 | Image bytes length. 0 for BI_RGB because inferred. |
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# |--------|--------------|-------------------------------------------------------|
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# | 24 | 4 | Horizontal print resolution. |
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# |--------|--------------|-------------------------------------------------------|
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# | 28 | 4 | Vertical print resolution |
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# |--------|--------------|-------------------------------------------------------|
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# | 32 | 4 | Number of colors in palette. 0 for 2^n. |
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# |--------|--------------|-------------------------------------------------------|
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# | 36 | 4 | Number of important colors. 0 for all. |
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# |--------|--------------|-------------------------------------------------------|
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# | 40 | n | Pixel bytes, r, g, b, a. |
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# |________|______________|_______________________________________________________|
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import argparse
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import os
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import PIL.Image
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import sys
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from voussoirkit import betterhelp
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from voussoirkit import imagetools
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from voussoirkit import pipeable
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from voussoirkit import vlogging
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log = vlogging.get_logger(__name__, 'icoconvert')
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ICO_HEADER_LENGTH = 6
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ICON_DIRECTORY_ENTRY_LENGTH = 16
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BMP_HEADER_LENGTH = 40
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def chunk_sequence(sequence, chunk_length, allow_incomplete=True):
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'''
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Given a sequence, divide it into sequences of length `chunk_length`.
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allow_incomplete:
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If True, allow the final chunk to be shorter if the
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given sequence is not an exact multiple of `chunk_length`.
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If False, the incomplete chunk will be discarded.
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'''
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(complete, leftover) = divmod(len(sequence), chunk_length)
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if not allow_incomplete:
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leftover = 0
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chunk_count = complete + min(leftover, 1)
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chunks = []
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for x in range(chunk_count):
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left = chunk_length * x
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right = left + chunk_length
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chunks.append(sequence[left:right])
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return chunks
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def little(x, length):
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return x.to_bytes(length, byteorder='little')
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def load_image(filename):
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image = PIL.Image.open(filename)
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(w, h) = image.size
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(new_w, new_h) = imagetools.fit_into_bounds(w, h, 256, 256, only_shrink=True)
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image = image.resize((new_w, new_h), resample=PIL.Image.LANCZOS)
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image = image.convert('RGBA')
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image = imagetools.pad_to_square(image)
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return image
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def build_ico_header_blob(image_count):
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datablob = b''.join([
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# reserved
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little(0, 2),
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# 1 = ico type
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little(1, 2),
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little(image_count, 2),
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])
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return datablob
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def build_icon_directory_blob(image, offset_from_start):
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(width, height) = image.size
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datablob = b''.join([
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little(width if width < 256 else 0, 1),
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little(height if height < 256 else 0, 1),
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# colors in palette
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little(0, 1),
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# reserved
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little(0, 1),
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# color planes
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little(1, 2),
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# bit depth
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little(32, 2),
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# image bytes length
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little((width * height * 4) + BMP_HEADER_LENGTH, 4),
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little(offset_from_start, 4),
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])
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return datablob
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def build_image_data_blob(image):
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datablob = b''.join([
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# header size
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little(40, 4),
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little(image.size[0], 4),
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# "Even if the AND mask is not supplied, if the image is in Windows BMP
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# format, the BMP header must still specify a doubled height." - wikipedia
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little(image.size[1] * 2, 4),
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# color planes
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little(1, 2),
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# bit depth
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little(32, 2),
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# no compression
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little(0, 4),
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# bytes length, inferred
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little(0, 4),
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# hor print
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little(0, 4),
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# ver print
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little(0, 4),
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# palette
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little(0, 4),
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# important palette
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little(0, 4),
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])
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pixeldata = []
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# Image.getdata() is a list of (r, g, b, a) channels
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# But the BMP are written (b, g, r, a)
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# Also they are written from bottom to top.
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pixels = list(image.getdata())
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pixels = reversed(chunk_sequence(pixels, image.size[0]))
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pixels = [line for chunk in pixels for line in chunk]
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for pixel in pixels:
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(r, g, b, a) = pixel
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pixeldata.extend((b, g, r, a))
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datablob += bytes(pixeldata)
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return datablob
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def images_to_ico(images):
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# For some reason Windows reads the icons in reverse order.
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images.reverse()
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# The directory entries need to know their image's address, so therefore
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# we must know the lengths of all the image binaries before we can write
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# any directory entries.
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# We will calculate the image blobs first, store them separately,
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# and then put them after the directory blobs.
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datablobs = []
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imageblobs = []
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ico_header_blob = build_ico_header_blob(image_count=len(images))
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datablobs.append(ico_header_blob)
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for (index, image) in enumerate(images):
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imageblob = build_image_data_blob(image)
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imageblobs.append(imageblob)
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# Since the ICO header and directory entries are of fixed length, we know
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# the location of the first image.
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# After that, the offset just gains the size of the previous image.
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offset_from_start = ICO_HEADER_LENGTH + (len(images) * ICON_DIRECTORY_ENTRY_LENGTH)
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for (index, (image, imageblob)) in enumerate(zip(images, imageblobs)):
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directoryblob = build_icon_directory_blob(image, offset_from_start=offset_from_start)
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datablobs.append(directoryblob)
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offset_from_start += len(imageblob)
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datablobs.extend(imageblobs)
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final_data = b''.join(datablobs)
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return final_data
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def icoconvert_argparse(args):
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log.info('Iconifying %s', args.files)
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images = [load_image(filename) for filename in args.files]
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final_data = images_to_ico(images)
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iconame = os.path.splitext(args.files[0])[0] + '.ico'
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output_file = open(iconame, 'wb')
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output_file.write(final_data)
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output_file.close()
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pipeable.stderr(iconame)
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return 0
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@vlogging.main_decorator
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def main(argv):
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parser = argparse.ArgumentParser(
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description='''
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Create a Windows .ico icon file from one or more images.
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''',
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)
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parser.add_argument(
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'files',
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nargs='+',
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help='''
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One or more image files to put into the ico.
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''',
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)
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parser.set_defaults(func=icoconvert_argparse)
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return betterhelp.go(parser, argv)
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if __name__ == '__main__':
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raise SystemExit(main(sys.argv[1:]))
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