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ZPLify/cmd/web/main.go

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package main
import (
"bytes"
"fmt"
"image"
"image/color"
_ "image/gif"
_ "image/jpeg"
_ "image/png"
"io"
"log"
"math"
"net/http"
"strconv"
"strings"
"time"
"github.com/anthonynsimon/bild/blur"
"github.com/anthonynsimon/bild/effect"
"github.com/anthonynsimon/bild/segment"
"github.com/nfnt/resize"
"simonwaldherr.de/go/zplgfa"
)
const maxUploadSize = 20 << 20 // 20 MB
func getGraphicType(t string) zplgfa.GraphicType {
switch strings.ToUpper(t) {
case "ASCII":
return zplgfa.ASCII
case "BINARY":
return zplgfa.Binary
default:
return zplgfa.CompressedASCII
}
}
func invertImage(img image.Image) image.Image {
b := img.Bounds()
out := image.NewNRGBA(b)
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
r, g, bv, a := img.At(x, y).RGBA()
out.Set(x, y, color.RGBA{
R: uint8((65535 - r) >> 8),
G: uint8((65535 - g) >> 8),
B: uint8((65535 - bv) >> 8),
A: uint8(a >> 8),
})
}
}
return out
}
func monochromeImage(img image.Image) image.Image {
b := img.Bounds()
out := image.NewNRGBA(b)
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
r, g, bv, a := img.At(x, y).RGBA()
var v uint8
if r > math.MaxUint16/2 || g > math.MaxUint16/2 || bv > math.MaxUint16/2 {
v = 255
}
out.Set(x, y, color.RGBA{R: v, G: v, B: v, A: uint8(a >> 8)})
}
}
return out
}
func processImage(img image.Image, editFlag string, width, height uint) image.Image {
if strings.Contains(editFlag, "monochrome") {
img = monochromeImage(img)
}
bounds := img.Bounds()
if strings.Contains(editFlag, "blur") {
img = blur.Gaussian(img, float64(bounds.Dx())/300)
}
if strings.Contains(editFlag, "edge") {
img = effect.Sobel(img)
}
if strings.Contains(editFlag, "segment") {
img = segment.Threshold(img, 128)
}
if strings.Contains(editFlag, "invert") {
img = invertImage(img)
}
if width > 0 || height > 0 {
img = resize.Resize(width, height, img, resize.MitchellNetravali)
}
return img
}
func convertHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
if err := r.ParseMultipartForm(maxUploadSize); err != nil {
http.Error(w, "file too large", http.StatusBadRequest)
return
}
file, _, err := r.FormFile("file")
if err != nil {
http.Error(w, "missing file", http.StatusBadRequest)
return
}
defer file.Close()
img, _, err := image.Decode(file)
if err != nil {
http.Error(w, fmt.Sprintf("cannot decode image: %s", err), http.StatusBadRequest)
return
}
var w2, h2 uint
if v, err := strconv.ParseUint(r.FormValue("width"), 10, 32); err == nil {
w2 = uint(v)
}
if v, err := strconv.ParseUint(r.FormValue("height"), 10, 32); err == nil {
h2 = uint(v)
}
editFlag := r.FormValue("edit")
graphicType := getGraphicType(r.FormValue("type"))
img = processImage(img, editFlag, w2, h2)
flat := zplgfa.FlattenImage(img)
zpl := zplgfa.ConvertToZPL(flat, graphicType)
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
w.Header().Set("Content-Disposition", `attachment; filename="label.zpl"`)
fmt.Fprint(w, zpl)
}
func previewHandler(w http.ResponseWriter, r *http.Request) {
// Returns image info (dimensions) before conversion
if r.Method != http.MethodPost {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
if err := r.ParseMultipartForm(maxUploadSize); err != nil {
http.Error(w, "file too large", http.StatusBadRequest)
return
}
file, _, err := r.FormFile("file")
if err != nil {
http.Error(w, "missing file", http.StatusBadRequest)
return
}
defer file.Close()
var buf bytes.Buffer
buf.ReadFrom(file)
cfg, _, err := image.DecodeConfig(bytes.NewReader(buf.Bytes()))
if err != nil {
http.Error(w, "cannot decode image", http.StatusBadRequest)
return
}
w.Header().Set("Content-Type", "application/json")
fmt.Fprintf(w, `{"width":%d,"height":%d}`, cfg.Width, cfg.Height)
}
var labelaryClient = &http.Client{Timeout: 15 * time.Second}
func renderHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
dpmm := r.URL.Query().Get("dpmm")
width := r.URL.Query().Get("width")
height := r.URL.Query().Get("height")
if dpmm == "" {
dpmm = "8"
}
if width == "" {
width = "4"
}
if height == "" {
height = "6"
}
body, err := io.ReadAll(r.Body)
if err != nil {
http.Error(w, "failed to read body", http.StatusBadRequest)
return
}
url := fmt.Sprintf("http://api.labelary.com/v1/printers/%s/labels/%sx%s/0/", dpmm, width, height)
req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
if err != nil {
http.Error(w, "failed to build request", http.StatusInternalServerError)
return
}
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
req.Header.Set("Accept", "image/png")
resp, err := labelaryClient.Do(req)
if err != nil {
http.Error(w, "labelary unreachable: "+err.Error(), http.StatusBadGateway)
return
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
http.Error(w, "labelary returned "+resp.Status, http.StatusBadGateway)
return
}
w.Header().Set("Content-Type", "image/png")
io.Copy(w, resp.Body)
}
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/convert", convertHandler)
mux.HandleFunc("/preview", previewHandler)
mux.HandleFunc("/render", renderHandler)
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.Write([]byte(indexHTML))
})
addr := ":4543"
log.Printf("zplgfa web UI listening on %s", addr)
log.Fatal(http.ListenAndServe(addr, mux))
}
const indexHTML = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>zplgfa Image to ZPL Converter</title>
<style>
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
font-family: system-ui, sans-serif;
background: #0f1117;
color: #e2e8f0;
min-height: 100vh;
display: flex;
align-items: center;
justify-content: center;
padding: 2rem;
}
.card {
background: #1e2130;
border: 1px solid #2d3348;
border-radius: 12px;
padding: 2rem;
width: 100%;
max-width: 640px;
box-shadow: 0 8px 32px rgba(0,0,0,0.4);
}
h1 { font-size: 1.5rem; font-weight: 700; margin-bottom: 0.25rem; }
.subtitle { color: #718096; font-size: 0.875rem; margin-bottom: 1.75rem; }
.drop-zone {
border: 2px dashed #3a4060;
border-radius: 8px;
padding: 2.5rem 1rem;
text-align: center;
cursor: pointer;
transition: border-color .2s, background .2s;
margin-bottom: 1.5rem;
}
.drop-zone:hover, .drop-zone.over { border-color: #6366f1; background: #1a1e2e; }
.drop-zone input { display: none; }
.drop-zone .icon { font-size: 2.5rem; margin-bottom: 0.5rem; }
.drop-zone .hint { color: #718096; font-size: 0.85rem; }
.preview-info { margin-top: 0.75rem; font-size: 0.8rem; color: #a0aec0; min-height: 1.2em; }
.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-bottom: 1rem; }
.grid3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 1rem; margin-bottom: 1rem; }
label { display: block; font-size: 0.8rem; font-weight: 600; color: #a0aec0; margin-bottom: 0.35rem; }
input[type=number], select {
width: 100%;
background: #252a3d;
border: 1px solid #3a4060;
border-radius: 6px;
color: #e2e8f0;
padding: 0.5rem 0.75rem;
font-size: 0.9rem;
outline: none;
transition: border-color .2s;
}
input[type=number]:focus, select:focus { border-color: #6366f1; }
/* unit toggle */
.unit-row {
display: flex; align-items: center; gap: 0.5rem;
margin-bottom: 0.75rem;
}
.unit-row span { font-size: 0.8rem; color: #a0aec0; font-weight: 600; }
.toggle-group { display: flex; border: 1px solid #3a4060; border-radius: 6px; overflow: hidden; }
.toggle-group button {
flex: 1; background: #252a3d; color: #a0aec0;
border: none; border-radius: 0; padding: 0.3rem 0.8rem;
font-size: 0.8rem; font-weight: 600; cursor: pointer; width: auto;
transition: background .15s, color .15s;
}
.toggle-group button.active { background: #6366f1; color: #fff; }
.sub-label { font-size: 0.7rem; color: #718096; font-weight: 400; margin-top: 0.15rem; }
.checks { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.5rem; }
.checks label {
display: flex; align-items: center; gap: 0.4rem;
background: #252a3d; border: 1px solid #3a4060;
border-radius: 6px; padding: 0.35rem 0.7rem;
cursor: pointer; font-size: 0.8rem; font-weight: 500; color: #cbd5e0;
margin-bottom: 0;
transition: border-color .2s, background .2s;
}
.checks label:hover { border-color: #6366f1; }
.checks input[type=checkbox] { accent-color: #6366f1; width: 14px; height: 14px; }
button {
width: 100%;
background: #6366f1;
color: #fff;
border: none;
border-radius: 8px;
padding: 0.75rem;
font-size: 1rem;
font-weight: 600;
cursor: pointer;
transition: background .2s, opacity .2s;
}
button:hover { background: #4f52d0; }
button:disabled { opacity: 0.5; cursor: not-allowed; }
.output { margin-top: 1.5rem; display: none; }
.output-header {
display: flex; justify-content: space-between; align-items: center;
margin-bottom: 0.5rem;
}
.output-header span { font-size: 0.8rem; font-weight: 600; color: #a0aec0; }
.copy-btn {
background: #252a3d; border: 1px solid #3a4060; border-radius: 6px;
color: #a0aec0; font-size: 0.75rem; padding: 0.25rem 0.6rem;
width: auto; font-weight: 500;
}
.copy-btn:hover { background: #2d3348; }
textarea {
width: 100%; height: 220px;
background: #0f1117; border: 1px solid #2d3348; border-radius: 6px;
color: #7dd3fc; font-family: monospace; font-size: 0.75rem;
padding: 0.75rem; resize: vertical; outline: none;
}
.dl-btn { margin-top: 0.75rem; background: #2d6a4f; }
.dl-btn:hover { background: #215040; }
.error { color: #fc8181; font-size: 0.85rem; margin-top: 0.75rem; display: none; }
/* previews */
.preview-panel {
margin-bottom: 1.5rem; display: none;
}
.preview-panel .panel-header {
font-size: 0.8rem; font-weight: 600; color: #a0aec0; margin-bottom: 0.5rem;
}
.preview-panel img {
max-width: 100%; max-height: 260px; object-fit: contain;
border-radius: 6px; border: 1px solid #2d3348; background: #fff;
display: block;
}
.preview-panel .panel-meta {
font-size: 0.75rem; color: #718096; margin-top: 0.35rem;
}
.label-preview-wrap {
margin-top: 1.25rem; display: none;
}
.label-preview-wrap .panel-header {
display: flex; justify-content: space-between; align-items: center;
font-size: 0.8rem; font-weight: 600; color: #a0aec0; margin-bottom: 0.5rem;
}
.label-preview-wrap img {
max-width: 100%; border-radius: 6px; border: 1px solid #2d3348;
background: #fff; display: block;
}
.render-status { font-size: 0.75rem; color: #718096; font-weight: 400; }
.spinner {
display: none; width: 18px; height: 18px;
border: 2px solid #ffffff40; border-top-color: #fff;
border-radius: 50%; animation: spin .6s linear infinite;
margin: 0 auto;
}
@keyframes spin { to { transform: rotate(360deg); } }
</style>
</head>
<body>
<div class="card">
<h1>zplgfa</h1>
<p class="subtitle">Convert images to ZPL Graphic Fields for Zebra label printers</p>
<div class="drop-zone" id="dropZone">
<input type="file" id="fileInput" accept="image/png,image/jpeg,image/gif">
<div class="icon">🖼️</div>
<div>Drop an image here or <strong>click to browse</strong></div>
<div class="hint">PNG, JPEG, GIF — max 20 MB</div>
<div class="preview-info" id="previewInfo"></div>
</div>
<!-- Image preview (original) -->
<div class="preview-panel" id="imgPreviewPanel">
<div class="panel-header">Image Preview</div>
<img id="imgPreviewEl" alt="preview">
<div class="panel-meta" id="imgPreviewMeta"></div>
</div>
<!-- Unit toggle + DPI -->
<div class="unit-row">
<span>Dimensions in</span>
<div class="toggle-group">
<button id="btnPx" class="active" onclick="setUnit('px')">px</button>
<button id="btnCm" onclick="setUnit('cm')">cm</button>
</div>
<span style="margin-left:auto">Printer DPI</span>
<select id="dpi" style="width:110px">
<option value="203" selected>203 dpi</option>
<option value="300">300 dpi</option>
<option value="600">600 dpi</option>
</select>
</div>
<div class="grid">
<div>
<label id="labelW">Width (px)</label>
<input type="number" id="width" min="0" step="1" value="0" placeholder="0">
<div class="sub-label" id="subW"></div>
</div>
<div>
<label id="labelH">Height (px)</label>
<input type="number" id="height" min="0" step="1" value="0" placeholder="0">
<div class="sub-label" id="subH"></div>
</div>
</div>
<div class="grid" style="margin-bottom:1rem">
<div>
<label for="enctype">Encoding</label>
<select id="enctype">
<option value="CompressedASCII" selected>CompressedASCII (default)</option>
<option value="ASCII">ASCII</option>
<option value="Binary">Binary</option>
</select>
</div>
</div>
<div class="checks">
<label><input type="checkbox" name="edit" value="monochrome"> Monochrome</label>
<label><input type="checkbox" name="edit" value="invert"> Invert</label>
<label><input type="checkbox" name="edit" value="blur"> Blur</label>
<label><input type="checkbox" name="edit" value="edge"> Edge detect</label>
<label><input type="checkbox" name="edit" value="segment"> Segment</label>
</div>
<button id="convertBtn" disabled>Convert to ZPL</button>
<div class="spinner" id="spinner"></div>
<div class="error" id="error"></div>
<div class="output" id="output">
<div class="output-header">
<span>ZPL Output</span>
<button class="copy-btn" id="copyBtn">Copy</button>
</div>
<textarea id="zplOutput" readonly></textarea>
<button class="dl-btn" id="dlBtn">⬇ Download .zpl</button>
<!-- Labelary rendered preview -->
<div class="label-preview-wrap" id="labelPreviewWrap">
<div class="panel-header">
<span>Label Preview <span style="font-weight:400;color:#718096">(rendered by Labelary)</span></span>
<span class="render-status" id="renderStatus"></span>
</div>
<img id="labelPreviewImg" alt="label preview">
</div>
</div>
</div>
<script>
const dropZone = document.getElementById('dropZone');
const fileInput = document.getElementById('fileInput');
const previewInfo = document.getElementById('previewInfo');
const convertBtn = document.getElementById('convertBtn');
const spinner = document.getElementById('spinner');
const output = document.getElementById('output');
const zplOutput = document.getElementById('zplOutput');
const errorEl = document.getElementById('error');
let selectedFile = null;
let currentUnit = 'px'; // 'px' or 'cm'
let origPxW = 0, origPxH = 0; // image native pixel dimensions
let imgObjectURL = null;
function getDPI() { return parseInt(document.getElementById('dpi').value, 10); }
// cm ↔ px helpers
function pxToCm(px) { return +(px * 2.54 / getDPI()).toFixed(3); }
function cmToPx(cm) { return Math.round(cm * getDPI() / 2.54); }
function setUnit(unit) {
const wEl = document.getElementById('width');
const hEl = document.getElementById('height');
const curW = parseFloat(wEl.value) || 0;
const curH = parseFloat(hEl.value) || 0;
if (unit === 'cm' && currentUnit === 'px') {
wEl.step = '0.01';
hEl.step = '0.01';
wEl.value = curW > 0 ? pxToCm(curW) : 0;
hEl.value = curH > 0 ? pxToCm(curH) : 0;
} else if (unit === 'px' && currentUnit === 'cm') {
wEl.step = '1';
hEl.step = '1';
wEl.value = curW > 0 ? cmToPx(curW) : 0;
hEl.value = curH > 0 ? cmToPx(curH) : 0;
}
currentUnit = unit;
document.getElementById('btnPx').classList.toggle('active', unit === 'px');
document.getElementById('btnCm').classList.toggle('active', unit === 'cm');
updateLabels();
}
function updateLabels() {
const unit = currentUnit;
document.getElementById('labelW').textContent = 'Width (' + unit + ')' + (unit === 'px' ? ' — 0 = auto' : '');
document.getElementById('labelH').textContent = 'Height (' + unit + ')' + (unit === 'px' ? ' — 0 = auto' : '');
updateSubLabels();
}
function updateSubLabels() {
if (!origPxW) return;
if (currentUnit === 'px') {
document.getElementById('subW').textContent = pxToCm(origPxW) + ' cm at ' + getDPI() + ' dpi';
document.getElementById('subH').textContent = pxToCm(origPxH) + ' cm at ' + getDPI() + ' dpi';
} else {
document.getElementById('subW').textContent = origPxW + ' px native';
document.getElementById('subH').textContent = origPxH + ' px native';
}
}
// Recalc sub-labels when DPI changes
document.getElementById('dpi').addEventListener('change', () => {
if (currentUnit === 'cm') {
// re-fill cm fields based on original px
if (origPxW) {
document.getElementById('width').value = pxToCm(origPxW);
document.getElementById('height').value = pxToCm(origPxH);
}
}
updateSubLabels();
});
dropZone.addEventListener('click', () => fileInput.click());
dropZone.addEventListener('dragover', e => { e.preventDefault(); dropZone.classList.add('over'); });
dropZone.addEventListener('dragleave', () => dropZone.classList.remove('over'));
dropZone.addEventListener('drop', e => {
e.preventDefault();
dropZone.classList.remove('over');
if (e.dataTransfer.files[0]) setFile(e.dataTransfer.files[0]);
});
fileInput.addEventListener('change', () => { if (fileInput.files[0]) setFile(fileInput.files[0]); });
function setFile(file) {
selectedFile = file;
previewInfo.textContent = 'Loading…';
convertBtn.disabled = true;
// Show image preview immediately
if (imgObjectURL) URL.revokeObjectURL(imgObjectURL);
imgObjectURL = URL.createObjectURL(file);
document.getElementById('imgPreviewEl').src = imgObjectURL;
document.getElementById('imgPreviewPanel').style.display = 'block';
const fd = new FormData();
fd.append('file', file);
fetch('/preview', { method: 'POST', body: fd })
.then(r => r.ok ? r.json() : Promise.reject())
.then(info => {
origPxW = info.width;
origPxH = info.height;
const wEl = document.getElementById('width');
const hEl = document.getElementById('height');
if (currentUnit === 'px') {
wEl.value = origPxW;
hEl.value = origPxH;
} else {
wEl.value = pxToCm(origPxW);
hEl.value = pxToCm(origPxH);
}
const cmW = pxToCm(origPxW), cmH = pxToCm(origPxH);
previewInfo.textContent =
file.name + ' — ' + origPxW + ' × ' + origPxH + ' px' +
' (' + cmW + ' × ' + cmH + ' cm at ' + getDPI() + ' dpi)';
document.getElementById('imgPreviewMeta').textContent =
origPxW + ' × ' + origPxH + ' px | ' + cmW + ' × ' + cmH + ' cm at ' + getDPI() + ' dpi';
updateSubLabels();
convertBtn.disabled = false;
})
.catch(() => {
previewInfo.textContent = file.name;
convertBtn.disabled = false;
});
}
// Returns pixel values regardless of current unit
function getPixelDimensions() {
const w = parseFloat(document.getElementById('width').value) || 0;
const h = parseFloat(document.getElementById('height').value) || 0;
if (currentUnit === 'cm') {
return { w: cmToPx(w), h: cmToPx(h) };
}
return { w: Math.round(w), h: Math.round(h) };
}
function dpmmFromDPI(dpi) {
const map = { 203: 8, 300: 12, 600: 24 };
return map[dpi] || 8;
}
async function fetchLabelPreview(zpl, pxW, pxH) {
const dpi = getDPI();
const dpmm = dpmmFromDPI(dpi);
// Labelary needs label size in inches; clamp minimum to avoid API errors
const wIn = Math.max(pxW / dpi, 0.1).toFixed(4);
const hIn = Math.max(pxH / dpi, 0.1).toFixed(4);
const wrap = document.getElementById('labelPreviewWrap');
const status = document.getElementById('renderStatus');
wrap.style.display = 'block';
status.textContent = 'Rendering…';
document.getElementById('labelPreviewImg').src = '';
try {
const res = await fetch(
'/render?dpmm=' + dpmm + '&width=' + wIn + '&height=' + hIn,
{ method: 'POST', headers: { 'Content-Type': 'text/plain' }, body: zpl }
);
if (!res.ok) throw new Error(await res.text());
const blob = await res.blob();
const url = URL.createObjectURL(blob);
document.getElementById('labelPreviewImg').src = url;
status.textContent = wIn + '" × ' + hIn + '" at ' + dpi + ' dpi';
} catch (e) {
status.textContent = 'Preview unavailable: ' + e.message;
}
}
convertBtn.addEventListener('click', async () => {
if (!selectedFile) return;
errorEl.style.display = 'none';
convertBtn.style.display = 'none';
spinner.style.display = 'block';
output.style.display = 'none';
document.getElementById('labelPreviewWrap').style.display = 'none';
const { w, h } = getPixelDimensions();
const edits = [...document.querySelectorAll('input[name=edit]:checked')].map(c => c.value);
const fd = new FormData();
fd.append('file', selectedFile);
fd.append('width', w);
fd.append('height', h);
fd.append('type', document.getElementById('enctype').value);
fd.append('edit', edits.join(','));
try {
const res = await fetch('/convert', { method: 'POST', body: fd });
if (!res.ok) {
const msg = await res.text();
throw new Error(msg);
}
const text = await res.text();
zplOutput.value = text;
output.style.display = 'block';
fetchLabelPreview(text, w || origPxW, h || origPxH);
} catch (e) {
errorEl.textContent = 'Error: ' + e.message;
errorEl.style.display = 'block';
} finally {
spinner.style.display = 'none';
convertBtn.style.display = 'block';
}
});
document.getElementById('copyBtn').addEventListener('click', () => {
navigator.clipboard.writeText(zplOutput.value);
document.getElementById('copyBtn').textContent = 'Copied!';
setTimeout(() => document.getElementById('copyBtn').textContent = 'Copy', 1500);
});
document.getElementById('dlBtn').addEventListener('click', () => {
const blob = new Blob([zplOutput.value], { type: 'text/plain' });
const a = document.createElement('a');
a.href = URL.createObjectURL(blob);
a.download = (selectedFile ? selectedFile.name.replace(/\.[^.]+$/, '') : 'label') + '.zpl';
a.click();
});
// init labels
updateLabels();
</script>
</body>
</html>
`