Add wallpaper switch

2026-07-03 19:14:45 +02:00
parent 6f2598ef52
commit 873bec97fc
6 changed files with 306 additions and 30 deletions
@@ -0,0 +1,131 @@
+# shellcheck shell=bash
+# wallpaper-pick — print a random wallpaper from $wallpapersDir whose palette
+# best matches the given theme variant. Per-image palettes are extracted once
+# (ImageMagick) and cached, keyed by the (immutable) source path so a rebuild
+# that changes the wallpaper set reindexes automatically.
+#
+# Matching uses several key colors on both sides: the variant's base16
+# base00–base05 (the background→foreground neutral range) are each matched to
+# their nearest wallpaper dominant color; the sum of those nearest distances
+# is the score. A random image is picked from the lowest-score tier.
+#
+# Env (injected by the Nix wrapper):
+#   wallpapersDir    directory of wallpaper images (~/Wallpapers, a git clone)
+#   wallpaperRepo    git URL cloned into wallpapersDir on first use
+#   variantSchemes   space-separated `variant:schemeFile` pairs (base16 YAML)
+#   MAGICK           path to the ImageMagick `magick` binary
+#   GIT              path to the `git` binary
+# Arg: variant name (e.g. gruvbox-dark)
+
+: "${wallpapersDir:?wallpaper-pick: wallpapersDir not set}"
+: "${wallpaperRepo:?wallpaper-pick: wallpaperRepo not set}"
+: "${variantSchemes:?wallpaper-pick: variantSchemes not set}"
+: "${MAGICK:?wallpaper-pick: MAGICK not set}"
+: "${GIT:?wallpaper-pick: GIT not set}"
+set -euo pipefail
+
+variant="${1:?usage: wallpaper-pick <variant>}"
+
+# Ensure the wallpaper repo is cloned locally. The clone is a one-time cost
+# paid on first use (not at build time), keeping `nix build` fast.
+if [ ! -d "$wallpapersDir/.git" ]; then
+  log_info "cloning wallpaper repo (one-time, may take a few minutes)..."
+  mkdir -p "$(dirname "$wallpapersDir")"
+  "$GIT" clone --depth=1 --single-branch "$wallpaperRepo" "$wallpapersDir" >&2
+  log_info "clone ready"
+fi
+
+cache_dir="${XDG_CACHE_HOME:-$HOME/.cache}/wallpaper-pick"
+palettes="$cache_dir/palettes.tsv"
+stamp_file="$cache_dir/source"
+
+# Cache key: the clone's current commit, so a `git pull` reindexes. Falls back
+# to the resolved path if git fails for some reason.
+src_stamp="$("$GIT" -C "$wallpapersDir" rev-parse HEAD 2>/dev/null || readlink -f "$wallpapersDir")"
+
+rebuild_cache() {
+  img_count="$(find "$wallpapersDir" -type f \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.webp' \) -printf . 2>/dev/null | wc -c)"
+  log_info "indexing ${img_count} wallpapers (one-time, building palette cache)..."
+  mkdir -p "$cache_dir"
+  tmp="$palettes.tmp"
+  : > "$tmp"
+  jobs="$(nproc 2>/dev/null || echo 4)"
+
+  # For each image: top dominant colors (by pixel count) as space-separated #hex.
+  find "$wallpapersDir" -type f \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.webp' \) -print0 \
+    | xargs -0 -P "$jobs" -n1 sh -c '
+        MAGICK="$0" img="$1"
+        "$MAGICK" "$img" -resize 128x128^ -gravity center -extent 128x128 +dither -colors 8 -format "%c" histogram:info: 2>/dev/null \
+          | grep -E "^[[:space:]]*[0-9]+:" | sort -rn | grep -oE "#[0-9A-Fa-f]{6}" | head -6 | paste -sd" " - \
+          | { read -r hex; [ -n "$hex" ] && printf "%s\t%s\n" "$img" "$hex"; }
+      ' "$MAGICK" >> "$tmp" || true
+
+  mv "$tmp" "$palettes"
+  printf '%s\n' "$src_stamp" > "$stamp_file"
+}
+
+if [ ! -f "$palettes" ] || [ ! -f "$stamp_file" ] || [ "$(cat "$stamp_file")" != "$src_stamp" ]; then
+  rebuild_cache
+fi
+
+# Resolve the base16 scheme file for the requested variant.
+scheme=""
+for pair in $variantSchemes; do
+  case "$pair" in
+    "${variant}":*) scheme="${pair#*:}"; break ;;
+  esac
+done
+[ -n "$scheme" ] || { log_error "no scheme mapped for variant '$variant'"; exit 2; }
+
+# Theme key colors: base00–base05 hex (one per line, with leading #).
+theme_colors="$(grep -E '^[[:space:]]*base0[0-5]:' "$scheme" | grep -oE '#[0-9A-Fa-f]{6}')"
+[ -n "$theme_colors" ] || { log_error "could not parse base00–05 from $scheme"; exit 2; }
+
+# hex (no #) -> decimal rgb on stdout
+hex2dec() { printf '%d %d %d\n' "$((16#${1:0:2}))" "$((16#${1:2:2}))" "$((16#${1:4:2}))"; }
+
+# Theme colors as parallel arrays.
+t_r=(); t_g=(); t_b=()
+while read -r h; do
+  read -r r g b < <(hex2dec "${h#\#}")
+  t_r+=("$r"); t_g+=("$g"); t_b+=("$b")
+done <<< "$theme_colors"
+
+# Score every indexed wallpaper: sum over theme colors of nearest wallpaper color.
+scores="$cache_dir/scores.tmp"
+: > "$scores"
+while IFS=$'\t' read -r path whexes; do
+  w_r=(); w_g=(); w_b=()
+  for wh in $whexes; do
+    read -r wr wg wb < <(hex2dec "${wh#\#}")
+    w_r+=("$wr"); w_g+=("$wg"); w_b+=("$wb")
+  done
+  if [ "${#w_r[@]}" -eq 0 ]; then continue; fi
+  total=0
+  for i in "${!t_r[@]}"; do
+    mind=1000000000
+    for j in "${!w_r[@]}"; do
+      dr=$(( t_r[i] - w_r[j] )); dg=$(( t_g[i] - w_g[j] )); db=$(( t_b[i] - w_b[j] ))
+      cd=$(( dr*dr + dg*dg + db*db ))
+      if [ "$cd" -lt "$mind" ]; then mind=$cd; fi
+    done
+    total=$(( total + mind ))
+  done
+  printf '%s\t%s\n' "$total" "$path"
+done < "$palettes" | sort -n -k1 > "$scores"
+
+[ -s "$scores" ] || { log_error "no wallpapers indexed"; exit 3; }
+
+# Matched tier: within 1.4x of the best score (fall back to closest 20).
+best="$(head -n1 "$scores" | cut -f1)"
+threshold=$(( best * 14 / 10 ))
+matched="$(awk -F'\t' -v t="$threshold" '$1 <= t {print $2}' "$scores")"
+if [ "$(printf '%s\n' "$matched" | grep -c .)" -lt 5 ]; then
+  matched="$(head -n20 "$scores" | cut -f2)"
+fi
+
+# Print the chosen PATH on stdout (data channel for callers) and log the
+# human-readable choice on stderr.
+chosen="$(printf '%s\n' "$matched" | shuf -n1)"
+log_info "picked $(basename "$chosen") for ${variant}"
+printf '%s\n' "$chosen"