Improve desktop branding and NSIS assets
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Esdras Renan
parent
9439890488
commit
78030dbcdb
5 changed files with 253 additions and 12 deletions
231
apps/desktop/scripts/png_to_bmp.py
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231
apps/desktop/scripts/png_to_bmp.py
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#!/usr/bin/env python3
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"""
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Utility script to convert a PNG file (non-interlaced, 8-bit RGBA/RGB)
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into a 24-bit BMP with optional letterboxing resize.
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The script is intentionally lightweight and relies only on Python's
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standard library so it can run in constrained build environments.
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"""
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from __future__ import annotations
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import argparse
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import struct
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import sys
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import zlib
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from pathlib import Path
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PNG_SIGNATURE = b"\x89PNG\r\n\x1a\n"
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def parse_png(path: Path):
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data = path.read_bytes()
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if not data.startswith(PNG_SIGNATURE):
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raise ValueError("Input is not a PNG file")
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idx = len(PNG_SIGNATURE)
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width = height = bit_depth = color_type = None
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compressed = bytearray()
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interlaced = False
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while idx < len(data):
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if idx + 8 > len(data):
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raise ValueError("Corrupted PNG (unexpected EOF)")
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length = struct.unpack(">I", data[idx : idx + 4])[0]
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idx += 4
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chunk_type = data[idx : idx + 4]
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idx += 4
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chunk_data = data[idx : idx + length]
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idx += length
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crc = data[idx : idx + 4] # noqa: F841 - crc skipped (validated by reader)
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idx += 4
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if chunk_type == b"IHDR":
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width, height, bit_depth, color_type, compression, filter_method, interlace = struct.unpack(
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">IIBBBBB", chunk_data
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)
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if compression != 0 or filter_method != 0:
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raise ValueError("Unsupported PNG compression/filter method")
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interlaced = interlace != 0
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elif chunk_type == b"IDAT":
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compressed.extend(chunk_data)
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elif chunk_type == b"IEND":
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break
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if interlaced:
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raise ValueError("Interlaced PNGs are not supported by this script")
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if bit_depth != 8:
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raise ValueError(f"Unsupported bit depth: {bit_depth}")
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if color_type not in (2, 6):
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raise ValueError(f"Unsupported color type: {color_type}")
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raw = zlib.decompress(bytes(compressed))
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bytes_per_pixel = 3 if color_type == 2 else 4
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stride = width * bytes_per_pixel
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expected = (stride + 1) * height
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if len(raw) != expected:
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raise ValueError("Corrupted PNG data")
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# Apply PNG scanline filters
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image = bytearray(width * height * 4) # Force RGBA output
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prev_row = [0] * (stride)
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def paeth(a, b, c):
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p = a + b - c
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pa = abs(p - a)
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pb = abs(p - b)
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pc = abs(p - c)
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if pa <= pb and pa <= pc:
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return a
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if pb <= pc:
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return b
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return c
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out_idx = 0
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for y in range(height):
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offset = y * (stride + 1)
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filter_type = raw[offset]
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row = bytearray(raw[offset + 1 : offset + 1 + stride])
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if filter_type == 1: # Sub
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for i in range(stride):
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left = row[i - bytes_per_pixel] if i >= bytes_per_pixel else 0
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row[i] = (row[i] + left) & 0xFF
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elif filter_type == 2: # Up
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for i in range(stride):
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row[i] = (row[i] + prev_row[i]) & 0xFF
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elif filter_type == 3: # Average
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for i in range(stride):
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left = row[i - bytes_per_pixel] if i >= bytes_per_pixel else 0
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up = prev_row[i]
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row[i] = (row[i] + ((left + up) >> 1)) & 0xFF
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elif filter_type == 4: # Paeth
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for i in range(stride):
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left = row[i - bytes_per_pixel] if i >= bytes_per_pixel else 0
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up = prev_row[i]
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up_left = prev_row[i - bytes_per_pixel] if i >= bytes_per_pixel else 0
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row[i] = (row[i] + paeth(left, up, up_left)) & 0xFF
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elif filter_type != 0:
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raise ValueError(f"Unsupported PNG filter type: {filter_type}")
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# Convert to RGBA
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for x in range(width):
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if color_type == 2:
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r, g, b = row[x * 3 : x * 3 + 3]
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a = 255
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else:
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r, g, b, a = row[x * 4 : x * 4 + 4]
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image[out_idx : out_idx + 4] = bytes((r, g, b, a))
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out_idx += 4
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prev_row = list(row)
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return width, height, image
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def resize_with_letterbox(image, width, height, target_w, target_h, background):
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if width == target_w and height == target_h:
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return image, width, height
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bg_r, bg_g, bg_b = background
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scale = min(target_w / width, target_h / height)
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scale = max(scale, 1 / max(width, height)) # avoid zero
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scaled_w = max(1, int(round(width * scale)))
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scaled_h = max(1, int(round(height * scale)))
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output = bytearray(target_w * target_h * 4)
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# Fill background
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for i in range(0, len(output), 4):
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output[i : i + 4] = bytes((bg_r, bg_g, bg_b, 255))
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offset_x = (target_w - scaled_w) // 2
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offset_y = (target_h - scaled_h) // 2
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for y in range(scaled_h):
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src_y = min(height - 1, int(round(y / scale)))
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for x in range(scaled_w):
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src_x = min(width - 1, int(round(x / scale)))
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src_idx = (src_y * width + src_x) * 4
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dst_idx = ((y + offset_y) * target_w + (x + offset_x)) * 4
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output[dst_idx : dst_idx + 4] = image[src_idx : src_idx + 4]
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return output, target_w, target_h
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def blend_to_rgb(image):
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rgb = bytearray(len(image) // 4 * 3)
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for i in range(0, len(image), 4):
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r, g, b, a = image[i : i + 4]
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if a == 255:
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rgb[(i // 4) * 3 : (i // 4) * 3 + 3] = bytes((b, g, r)) # BMP stores BGR
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else:
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alpha = a / 255.0
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bg = (255, 255, 255)
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rr = int(round(r * alpha + bg[0] * (1 - alpha)))
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gg = int(round(g * alpha + bg[1] * (1 - alpha)))
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bb = int(round(b * alpha + bg[2] * (1 - alpha)))
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rgb[(i // 4) * 3 : (i // 4) * 3 + 3] = bytes((bb, gg, rr))
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return rgb
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def write_bmp(path: Path, width: int, height: int, rgb: bytearray):
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row_stride = (width * 3 + 3) & ~3 # align to 4 bytes
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padding = row_stride - width * 3
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pixel_data = bytearray()
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for y in range(height - 1, -1, -1):
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start = y * width * 3
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end = start + width * 3
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pixel_data.extend(rgb[start:end])
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if padding:
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pixel_data.extend(b"\0" * padding)
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file_size = 14 + 40 + len(pixel_data)
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header = struct.pack("<2sIHHI", b"BM", file_size, 0, 0, 14 + 40)
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dib_header = struct.pack(
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"<IIIHHIIIIII",
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40, # header size
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width,
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height,
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1, # planes
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24, # bits per pixel
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0, # compression
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len(pixel_data),
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2835, # horizontal resolution (px/m ~72dpi)
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2835, # vertical resolution
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0,
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0,
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)
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path.write_bytes(header + dib_header + pixel_data)
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def main():
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parser = argparse.ArgumentParser(description=__doc__)
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parser.add_argument("input", type=Path)
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parser.add_argument("output", type=Path)
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parser.add_argument("--width", type=int, help="Target width (px)")
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parser.add_argument("--height", type=int, help="Target height (px)")
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parser.add_argument(
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"--background",
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type=str,
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default="FFFFFF",
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help="Background hex color used for transparent pixels (default: FFFFFF)",
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)
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args = parser.parse_args()
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try:
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width, height, image = parse_png(args.input)
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if args.width and args.height:
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bg = tuple(int(args.background[i : i + 2], 16) for i in (0, 2, 4))
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image, width, height = resize_with_letterbox(image, width, height, args.width, args.height, bg)
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rgb = blend_to_rgb(image)
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write_bmp(args.output, width, height, rgb)
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except Exception as exc: # noqa: BLE001
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print(f"Error: {exc}", file=sys.stderr)
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sys.exit(1)
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if __name__ == "__main__":
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main()
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