launcher-menu: detect missing icon fallbacks on switch (iconFallbacks.enable/extra)

modules/launcher-menu/icon-fallbacks.sh

@@ -0,0 +1,125 @@
+# Hicolor fallbacks for desktop entry icons that only Breeze has.
+#
+# Usage: steam-frame-icon-fallbacks [EXTRA_NAME...]
+#   BREEZE_APPS=<breeze-icons>/share/icons/breeze/apps: link the Icon= names
+#     of the desktop entries Steam sees (plus EXTRA_NAMEs) that no hicolor
+#     theme dir has but Breeze does, as
+#     $XDG_DATA_HOME/icons/hicolor/scalable/apps/<name>.svg -> Breeze's SVG.
+#   BREEZE_APPS unset: remove all links made before (disabled).
+# Links made are listed in a manifest; only those, and only while they still
+# point into a breeze-icons store path, are ever removed. Nothing else in the
+# icon dir is touched.
+
+data_home=${XDG_DATA_HOME:-$HOME/.local/share}
+dest=$data_home/icons/hicolor/scalable/apps
+manifest=${XDG_STATE_HOME:-$HOME/.local/state}/steam-frame-nix/icon-fallbacks
+# Steam's data dirs (XDG_DATA_HOME, then its XDG_DATA_DIRS on SteamOS), not
+# the caller's: switches usually run from the nested desktop session.
+data_dirs=(
+  "$data_home"
+  "$HOME/.local/share/flatpak/exports/share"
+  /var/lib/flatpak/exports/share
+  /usr/local/share
+  /usr/share
+  "$HOME/.nix-profile/share"
+  /nix/var/nix/profiles/default/share
+)
+shopt -s nullglob
+
+ours() { [[ -L $1 && $(readlink "$1") == /nix/store/*-breeze-icons-*/* ]]; }
+
+# Does Steam already find <name> (hicolor in any data dir, or pixmaps)?
+# Our own links don't count.
+resolves() {
+  local d f
+  for d in "$HOME/.icons" "${data_dirs[@]/%//icons}"; do
+    for f in "$d"/hicolor/*/*/"$1".{png,svg,xpm}; do
+      ours "$f" || return 0
+    done
+  done
+  for d in "${data_dirs[@]}"; do
+    for f in "$d"/pixmaps/"$1".{png,svg,xpm}; do [[ ! -e $f ]] || return 0; done
+  done
+  return 1
+}
+
+# Largest Breeze app icon for <name> (Breeze's app icons are all SVG).
+breeze() {
+  local size
+  for size in 64 48 32 24 22 16; do
+    if [[ -e $BREEZE_APPS/$size/$1.svg ]]; then echo "$BREEZE_APPS/$size/$1.svg"; return; fi
+  done
+  return 1
+}
+
+# Icon= of a desktop entry, unless it is Hidden/NoDisplay or not a plain icon
+# name (e.g. an absolute path).
+entry_icon() {
+  awk -F= '
+    /^\[/ { group = ($0 ~ /^\[Desktop Entry\][[:space:]]*$/); next }
+    !group { next }
+    { key = $1; sub(/[[:space:]]+$/, "", key); val = substr($0, index($0, "=") + 1)
+      gsub(/^[[:space:]]+|[[:space:]\r]+$/, "", val) }
+    (key == "Hidden" || key == "NoDisplay") && val == "true" { skip = 1 }
+    key == "Icon" { icon = val }
+    END { if (!skip && icon ~ /^[A-Za-z0-9._+-]+$/) print icon }
+  ' "$1"
+}
+
+# Wanted: extra names, and the icons of the entries Steam sees (the first
+# entry with a given desktop-file ID wins, like in the menu).
+declare -A wanted=() seen=()
+if [[ -n ${BREEZE_APPS:-} ]]; then
+  for name in "$@"; do wanted[$name]=extra; done
+  for d in "${data_dirs[@]}"; do
+    [[ -d $d/applications ]] || continue
+    while IFS= read -r -d '' f; do
+      id=${f#"$d/applications/"}; id=${id//\//-}
+      [[ -z ${seen[$id]:-} ]] || continue
+      seen[$id]=1
+      icon=$(entry_icon "$f")
+      [[ -z $icon ]] || wanted[$icon]=${wanted[$icon]:-$id}
+    done < <(find -L "$d/applications" -name '*.desktop' -print0 2>/dev/null)
+  done
+fi
+
+changed=
+linked=()
+for name in "${!wanted[@]}"; do
+  resolves "$name" && continue
+  if ! src=$(breeze "$name"); then
+    [[ ${wanted[$name]} != extra ]] || echo "icon fallbacks: Breeze has no app icon \"$name\" (extra)" >&2
+    continue
+  fi
+  link=$dest/$name.svg
+  if [[ -e $link || -L $link ]] && ! ours "$link"; then continue; fi   # not ours
+  linked+=("$name")
+  [[ $(readlink "$link") == "$src" ]] && continue
+  mkdir -p "$dest"
+  ln -sfn "$src" "$link"
+  echo "icon fallbacks: linked $name (${wanted[$name]})"
+  changed=1
+done
+
+# Remove links from earlier runs that are no longer wanted.
+if [[ -f $manifest ]]; then
+  while IFS= read -r name; do
+    [[ -n $name && " ${linked[*]} " != *" $name "* ]] || continue
+    if ours "$dest/$name.svg"; then
+      rm -f "$dest/$name.svg"
+      echo "icon fallbacks: removed $name"
+      changed=1
+    fi
+  done < "$manifest"
+fi
+
+if (( ${#linked[@]} )); then
+  mkdir -p "${manifest%/*}"
+  printf '%s\n' "${linked[@]}" | sort > "$manifest"
+else
+  rm -f "$manifest"
+fi
+
+# GTK rescans an icon theme only when a theme dir's mtime changes; bump it
+# so a running Steam sees the change.
+if [[ -n $changed && -d $data_home/icons/hicolor ]]; then touch "$data_home/icons/hicolor"; fi