nuttx-apps/tools/bitmap_converter.py

#!/usr/bin/env python

"""This script converts from any image type supported by
Python imaging library to the RLE-encoded format used by
NxWidgets.
"""

from PIL import Image


def get_palette(img, maxcolors=255):
    """Returns a list of colors. If there are too many colors in the image,
    the least used are removed.
    """
    img = img.convert("RGB")
    colors = img.getcolors(65536)
    colors.sort(key=lambda c: -c[0])
    return [c[1] for c in colors[:maxcolors]]


def write_palette(outfile, palette):
    """Write the palette (normal and highlight) to the output file."""

    outfile.write(
        "static const NXWidgets::nxwidget_pixel_t palette[BITMAP_PALETTESIZE] =\n"
    )
    outfile.write("{\n")

    for i in range(0, len(palette), 4):
        outfile.write("  ")
        for r, g, b in palette[i : i + 4]:
            outfile.write("MKRGB(%3d,%3d,%3d), " % (r, g, b))
        outfile.write("\n")

    outfile.write("};\n\n")

    outfile.write(
        "static const NXWidgets::nxwidget_pixel_t hilight_palette[BITMAP_PALETTESIZE] =\n"
    )
    outfile.write("{\n")

    for i in range(0, len(palette), 4):
        outfile.write("  ")
        for r, g, b in palette[i : i + 4]:
            r = min(255, r + 50)
            g = min(255, g + 50)
            b = min(255, b + 50)
            outfile.write("MKRGB(%3d,%3d,%3d), " % (r, g, b))
        outfile.write("\n")

    outfile.write("};\n\n")


def quantize(color, palette):
    """Return the color index to closest match in the palette."""
    try:
        return palette.index(color)
    except ValueError:
        # No exact match, search for the closest
        def distance(color2):
            return sum([(a - b) ** 2 for a, b in zip(color, color2)])

        return palette.index(min(palette, key=distance))


def encode_row(img, palette, y):
    """RLE-encode one row of image data."""
    entries = []
    color = None
    repeats = 0

    for x in range(0, img.size[0]):
        c = quantize(img.getpixel((x, y)), palette)
        if c == color and repeats < 255:
            repeats += 1
        else:
            if color is not None:
                entries.append((repeats, color))

            repeats = 1
            color = c

    if color is not None:
        entries.append((repeats, color))

    return entries


def write_image(outfile, img, palette):
    """Write the image contents to the output file."""

    outfile.write("static const NXWidgets::SRlePaletteBitmapEntry bitmap[] =\n")
    outfile.write("{\n")

    for y in range(0, img.size[1]):
        entries = encode_row(img, palette, y)
        row = ""
        for r, c in entries:
            if len(row) > 60:
                outfile.write("  " + row + "\n")
                row = ""

            row += "{%3d, %3d}, " % (r, c)

        row += " " * (73 - len(row))
        outfile.write("  " + row + "/* Row %d */\n" % y)

    outfile.write("};\n\n")


def write_descriptor(outfile, name):
    """Write the public descriptor structure for the image."""

    outfile.write("extern const struct NXWidgets::SRlePaletteBitmap g_%s =\n" % name)
    outfile.write("{\n")
    outfile.write("  CONFIG_NXWIDGETS_BPP,\n")
    outfile.write("  CONFIG_NXWIDGETS_FMT,\n")
    outfile.write("  BITMAP_PALETTESIZE,\n")
    outfile.write("  BITMAP_WIDTH,\n")
    outfile.write("  BITMAP_HEIGHT,\n")
    outfile.write("  {palette, hilight_palette},\n")
    outfile.write("  bitmap\n")
    outfile.write("};\n")


if __name__ == "__main__":
    import os.path
    import sys

    if len(sys.argv) != 3:
        print("Usage: bitmap_converter.py source.png output.cxx")
        sys.exit(1)

    img = Image.open(sys.argv[1]).convert("RGB")
    outfile = open(sys.argv[2], "w")
    palette = get_palette(img)

    outfile.write(
        """
/* Automatically NuttX bitmap file. */
/* Generated from %(src)s by bitmap_converter.py. */

#include <nxconfig.hxx>
#include <crlepalettebitmap.hxx>

#define BITMAP_WIDTH %(width)s
#define BITMAP_HEIGHT %(height)s
#define BITMAP_PALETTESIZE %(palettesize)s

"""
        % {
            "src": sys.argv[1],
            "width": img.size[0],
            "height": img.size[1],
            "palettesize": len(palette),
        }
    )

    name = os.path.splitext(os.path.basename(sys.argv[1]))[0]

    write_palette(outfile, palette)
    write_image(outfile, img, palette)
    write_descriptor(outfile, name)