KDE Klipper/Clipboard copy event checks -> turns copied JXL files into more-compatible formats (PNG, JPEG, WebP or AVIF); adds seamlessly to clipboard, convenient for sharing online. Created with much help using Gemini 3 Pro Preview. Requirements are found in script comments. ISSUES: Anim & multilayer JXL untested; Metadata likely not respected

jxl-clipboard-watcher-autoconvert.sh

#!/bin/bash

# ==============================================================================
# JPEG-XL CLIPBOARD AUTOCONVERT WATCHDOG (KDE/Wayland)
# ==============================================================================
# Description:
#   Made for and tested with Arch Linux/KDE/Wayland/Klipper (KDE built-in clipboard)
#   Animation, multi layer, etc not tested. Only still images (screenshots, web images, renders) were tested
#   Automatically detects copied JXL files and converts them to compatible
#   formats (JPEG/PNG/WebP/AVIF) for pasting into apps like Discord.
#
# Dependencies:
#   - libjxl (djxl, jxlinfo)
#   - imagemagick (magick)
#   - xclip (IMPORTANT: used for background clipboard writing to bypass wl-paste focus steal)
#   - python3 (used for URI parsing)
#   - qdbus & dbus-monitor (standard in KDE)
#
# Usage:
#   1. Make executable: chmod +x jxl-clipboard-watcher-autoconvert.sh
#   2. Run in terminal: ./jxl-clipboard-watcher-autoconvert.sh
#   3. (Optional) Add to Autostart to run on login.
# ==============================================================================

# --- CONFIGURATION ---
# Syntax: "FORMAT;VALUE"
# Formats: JPEG (Quality 0-100), PNG (Compression 0-9), WEBP (Quality 0-100)
#          WEBP_LOSSLESS (Effort 0-6), AVIF (Quality 0-100, 100=lossless)

# 1. Target for Lossless JXLs (e.g. Art/Screenshots)
CFG_LOSSLESS="PNG;6"

# 2. Target for Lossy JXLs (e.g. Photos)
CFG_LOSSY="JPEG;90"

# 3. Reconstruction Behavior
# true  = If the JXL contains an original JPEG bitstream, restore that exact JPEG.
# false = Ignore hidden JPEG data and re-encode using CFG_LOSSLESS/LOSSY rules.
CFG_PREFER_RECONSTRUCTION=true

# Temporary directory for converted files
TMP_DIR="/tmp/jxl_transcode"

# ==============================================================================

# --- INITIALIZATION ---
rm -rf "$TMP_DIR"
mkdir -p "$TMP_DIR"

echo "--- JPEG-XL Clipboard Autoconvert Watchdog ---"
echo " [Cfg] Lossless Target:  $CFG_LOSSLESS"
echo " [Cfg] Lossy Target:     $CFG_LOSSY"
echo " [Cfg] Reconstruct JPEG: $CFG_PREFER_RECONSTRUCTION"
echo " [Msg] Waiting for copy events..."

# Check dependencies
for cmd in xclip qdbus dbus-monitor magick djxl jxlinfo python3; do
    if ! command -v $cmd &> /dev/null; then
        echo " [Err] Missing dependency: '$cmd'. Please install it."
        exit 1
    fi
done

# Internal state to prevent loop-backs
LAST_SEEN_TEXT=""

# --- HELPER: Python URI Parser ---
# Handles URL encoding/decoding (e.g. "%20" -> " ") reliably
PY_PARSER=$(cat <<EOF
import sys, urllib.parse, pathlib
action = sys.argv[1]
data = sys.stdin.read().strip().splitlines()
if action == 'decode':
    for line in data:
        print(urllib.parse.unquote(line).replace('file://', '').strip())
elif action == 'encode':
    for line in data:
        if line.strip():
            print(pathlib.Path(line).as_uri())
EOF
)

# --- HELPER: Image Converter ---
convert_with_config() {
    local IN="$1"; local BASE="$2"; local CFG="$3"
    local FMT="${CFG%;*}"; local VAL="${CFG#*;}"
    local ARGS=(); local EXT=""

    case "${FMT^^}" in
        JPEG|JPG) EXT=".jpg"; ARGS=(-quality "$VAL") ;;
        PNG)      EXT=".png"; ARGS=(-define png:compression-level="$VAL") ;;
        WEBP)     EXT=".webp"; ARGS=(-quality "$VAL") ;;
        WEBP_LOSSLESS) EXT=".webp"; ARGS=(-define webp:lossless=true -quality "$VAL") ;;
        AVIF)     EXT=".avif"; ARGS=(-quality "$VAL") ;;
        AVIF_LOSSLESS) EXT=".avif"; ARGS=(-define heic:lossless=true -quality "$VAL") ;;
        *)        EXT=".jpg"; ARGS=(-quality 90) ;;
    esac

    local OUT="$BASE$EXT"
    magick "$IN" "${ARGS[@]}" "$OUT"
    if [[ -f "$OUT" ]]; then echo "$OUT"; fi
}

# --- MAIN LOOP ---
# Listens to KDE's clipboard signal without polling
dbus-monitor "interface='org.kde.klipper.klipper',member='clipboardHistoryUpdated'" 2>/dev/null | while read -r line; do
    if echo "$line" | grep -q "clipboardHistoryUpdated"; then

        # 1. READ (Invisible)
        # Check clipboard content via IPC. Does NOT create a Wayland surface.
        CLIP_TEXT=$(qdbus org.kde.klipper /klipper getClipboardContents 2>/dev/null)

        # 2. ANTI-ECHO
        # If this content matches what we just wrote, ignore it.
        if [[ "$CLIP_TEXT" == "$LAST_SEEN_TEXT" ]]; then
            continue
        fi

        # 3. PARSE
        # Quick string check before doing heavy lifting
        if echo "$CLIP_TEXT" | grep -iq "\.jxl"; then

            # Short sleep to ensure file locks are released by the source app
            sleep 0.2

            FILE_PATHS=$(echo "$CLIP_TEXT" | python3 -c "$PY_PARSER" "decode")
            NEW_FILE_LIST=""
            DID_CONVERT=0
            HAS_JXL=0

            while IFS= read -r FILE_PATH; do
                if [[ -z "$FILE_PATH" ]]; then continue; fi

                # Verify file exists and is JXL
                if [[ "${FILE_PATH,,}" == *.jxl ]] && [[ -f "$FILE_PATH" ]]; then
                    HAS_JXL=1

                    FILENAME=$(basename -- "$FILE_PATH")
                    NAME_NO_EXT="${FILENAME%.*}"
                    BASE_OUT="$TMP_DIR/$NAME_NO_EXT"
                    RESULT_FILE=""

                    echo "   [+] Processing: $FILENAME"

                    # Analyze Metadata
                    INFO=$(jxlinfo "$FILE_PATH" 2>/dev/null)

                    # LOGIC A: JPEG Bitstream Reconstruction
                    if $CFG_PREFER_RECONSTRUCTION && echo "$INFO" | grep -Fq "JPEG bitstream reconstruction data available"; then
                        if djxl "$FILE_PATH" "$BASE_OUT.jpg" >/dev/null 2>&1; then
                            RESULT_FILE="$BASE_OUT.jpg"
                            echo "       -> [Bitstream] Reconstructed original JPEG."
                        fi
                    fi

                    # LOGIC B: Transcode (if A failed or skipped)
                    if [[ -z "$RESULT_FILE" ]]; then
                        if echo "$INFO" | grep -Fq "lossless"; then
                            # Lossless JXL -> PNG (or configured lossless format)
                            echo "       -> [Lossless]  Converting to $CFG_LOSSLESS..."
                            RESULT_FILE=$(convert_with_config "$FILE_PATH" "$BASE_OUT" "$CFG_LOSSLESS")
                        else
                            # Lossy JXL -> JPEG (or configured lossy format)
                            echo "       -> [Lossy]     Converting to $CFG_LOSSY..."
                            RESULT_FILE=$(convert_with_config "$FILE_PATH" "$BASE_OUT" "$CFG_LOSSY")
                        fi
                    fi

                    # Success Check
                    if [[ -f "$RESULT_FILE" ]]; then
                        NEW_FILE_LIST+="$RESULT_FILE"$'\n'
                        ((DID_CONVERT++))
                    else
                        echo "       -> [Error] Conversion failed. Keeping original."
                        NEW_FILE_LIST+="$FILE_PATH"$'\n'
                    fi
                else
                    # Not a JXL, keep in the list
                    NEW_FILE_LIST+="$FILE_PATH"$'\n'
                fi
            done <<< "$FILE_PATHS"

            # 4. WRITE (Stealth)
            if [[ $DID_CONVERT -gt 0 ]]; then
                FINAL_URIS=$(echo -n "$NEW_FILE_LIST" | python3 -c "$PY_PARSER" "encode")

                # Update memory BEFORE writing to prevent loop
                LAST_SEEN_TEXT="$FINAL_URIS"

                echo " > Batch finished: $DID_CONVERT file(s) converted."
                echo " > Updating clipboard via XWayland bridge..."

                # Use xclip to update clipboard via X11 background bridge.
                # This bypasses Wayland focus stealing logic.
                echo -n "$FINAL_URIS" | xclip -selection clipboard -t text/uri-list
            else
                # Found JXLs but failed to convert, or text just contained ".jxl" string
                LAST_SEEN_TEXT="$CLIP_TEXT"
            fi
        else
            # Not relevant content, update memory to avoid re-scanning
            LAST_SEEN_TEXT="$CLIP_TEXT"
        fi
    fi
done