bg-cycle.py

#!/usr/bin/env python3
#
# Create backgrounds for applications.
#

import raehutils
import sys, os, argparse, logging

import random
import glob

class BGCycler(raehutils.RaehBaseClass):
    BACKGROUNDS = ["desktop", "grub"]
    VALID_IMG_EXTS = ["png", "jpg"]
    GRUB_BG_IMG = "/boot/grub/background-image.png"

    DEF_BG_DIR = os.path.join(os.environ.get("HOME"), ".assets", "backgrounds")
    DEF_WIDTH = "1366"
    DEF_HEIGHT = "768"
    DEF_BRIGHTNESS = "-81"
    DEF_CONTRAST = "-91"

    ERR_IMG_CONVERSION = 1

    ## CLI-related {{{
    def _parse_args(self):
        self.parser = argparse.ArgumentParser(
                description="Create backgrounds for applications.",
                epilog="I use a rule of contrast = brightness-10 for a nice image.")
        self.parser.add_argument("-v", "--verbose", help="be verbose", action="count", default=0)
        self.parser.add_argument("-q", "--quiet", help="be quiet (overrides -v)", action="count", default=0)
        self.parser.add_argument("-d", "--bg-dir",
                help="directory to read for images",
                default=BGCycler.DEF_BG_DIR)
        self.parser.add_argument("-w", "--width",
                help="width to resize images to (when required)",
                default=BGCycler.DEF_WIDTH)
        self.parser.add_argument("-u", "--height",
                help="height to resize images to (when required)",
                default=BGCycler.DEF_HEIGHT)
        self.parser.add_argument("-b", "--brightness",
                help="converted image brightness",
                default=BGCycler.DEF_BRIGHTNESS)
        self.parser.add_argument("-c", "--contrast",
                help="converted image contrast",
                default=BGCycler.DEF_CONTRAST)
        self.parser.add_argument("images", nargs="*",
                help="images to use (instead of picking randomly)")

        self.args = self.parser.parse_args()

        self.args.verbose += 1 # force some verbosity
        self._parse_verbosity()
    ## }}}

    def main(self):
        """Main entrypoint after program setup."""
        imgs = self.get_shuffled_images(self.args.bg_dir)

        if len(BGCycler.BACKGROUNDS) > len(imgs):
            self.fail("not enough images for the backgrounds required", BGCycler.ERR_IMG_CONVERSION)

        for bg, img in zip(BGCycler.BACKGROUNDS, imgs):
            # get outfile
            img_converted = os.path.join(
                self.args.bg_dir,
                "converted",
                os.path.basename(os.path.splitext(img)[0]) + ".png")

            # convert
            self.logger.info(os.path.basename(img))
            if bg == "grub":
                # special override: resize, copy to GRUB background image
                self.convert_image(img, img_converted, self.args.brightness,
                    self.args.contrast, self.args.width, self.args.height)
                raehutils.drop_to_shell(["sudo", "cp", img_converted, BGCycler.GRUB_BG_IMG])
            else:
                self.convert_image(img, img_converted, self.args.brightness,
                    self.args.contrast)

            # make symlink
            bg_out_symlink = os.path.join(self.args.bg_dir, bg)
            try:
                # remove symlink if it already exists
                os.remove(bg_out_symlink)
            except FileNotFoundError:
                pass
            os.symlink(
                os.path.join("converted", os.path.basename(img_converted)),
                bg_out_symlink)

        # now set the background
        raehutils.drop_to_shell([os.path.join(self.args.bg_dir, "set-desktop-background")])

    def get_shuffled_images(self, d):
        """Fills an array with images in a specified directory, shuffles it,
        then prepends user-provided images."""
        imgs = []

        # get all backgrounds
        for ext in BGCycler.VALID_IMG_EXTS:
            imgs.extend(glob.glob(os.path.join(d, "original", "*." + ext)))

        random.shuffle(imgs)

        # now insert user images at the start of the list
        if self.args.images:
            # reverse since we're inserting at index 0 every time
            for img in reversed(self.args.images):
                if img == "":
                    # not giving file for this background: skip
                    continue
                else:
                    # assume images are provided relative to the given dir
                    imgs.insert(0, os.path.join(d, "original", img))
        return imgs

    def convert_image(self, img, img_converted, brightness, contrast, width="0", height="0"):
        cmd_convert_img = [
                "convert", img,
                "-brightness-contrast", "{}x{}".format(brightness, contrast)]
        if width == "0" or height == "0":
            pass
        else:
            cmd_convert_img += [
                    "-crop", "{}x{}+0+0".format(width, height),
                    "-gravity", "center"]
        cmd_convert_img.append(img_converted)
        ret = raehutils.drop_to_shell(cmd_convert_img)
        if ret != 0:
            self.fail("couldn't convert image {}".format(img), BGCycler.ERR_IMG_CONVERSION)

if __name__ == "__main__":
    program = BGCycler()
    program.run()