#! /bin/zsh
#
# this file:
#   https://dataswamp.org/~incal/conf/.zsh/gfx-resize

upscale () {
    local src=$1
    local dst=${src:r}-4k.${src:e}
    local w=2048
    local h=$w
    convert                                             \
      $src                                              \
      -alpha on                                         \
      -virtual-pixel transparent                        \
      -filter Triangle                                  \
      +distort Affine "0,0 0,0 %w,0 ${w},0 0,%h 0,${h}" \
      -alpha off                                        \
      -crop ${w}x${h}+0+0                               \
        $dst
}

rs () {
    local fs=($@)

    local w=1080
    local h=720
    local gm=${w}x${h}

    for src in $fs; do
        local ext=${src:e}
        local nom=${src:r}
        local dst=${nom}-rs.${ext}

        convert -resize $gm $src $dst
        pad-to-size $dst $w $h
    done
}

pad-to-size () {
    local src=$1
    local nom=${src:r}
    local ext=${src:e}

    local w=$2
    local h=$3

    local col=${4:-#000001}
    local rect=rect.${ext}

    draw-rect $w $h $col $rect

    composite -gravity center $src $rect ${nom}-pad.${ext}

    rm $rect
}

draw-rect () {
    local w=$1
    local h=$2
    local dim=${w}x${h}

    local col=${3:-black}

    local dst=${4:-${col}-${dim}.jpg}

    convert \
        -draw "rectangle 0,0,${w},${h}" \
        -fill $col                      \
        -size $dim                      \
        xc:none                         \
                                        $dst
}