Malin/ZPLify
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feat: add image preview and Labelary ZPL render preview

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This commit is contained in:
Malin
2026-03-26 10:00:41 +01:00
parent 22edd37352
commit 6bec06c470
1 changed files with 142 additions and 0 deletions
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142
cmd/web/main.go
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@@ -8,11 +8,13 @@ import (
_ "image/gif"
_ "image/jpeg"
_ "image/png"
"io"
"log"
"math"
"net/http"
"strconv"
"strings"
"time"
"github.com/anthonynsimon/bild/blur"
"github.com/anthonynsimon/bild/effect"
@@ -163,10 +165,61 @@ func previewHandler(w http.ResponseWriter, r *http.Request) {
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))
@@ -302,6 +355,34 @@ const indexHTML = `<!DOCTYPE html>
.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;
@@ -324,6 +405,13 @@ const indexHTML = `<!DOCTYPE html>
<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>
@@ -382,6 +470,15 @@ const indexHTML = `<!DOCTYPE html>
</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>
@@ -398,6 +495,7 @@ 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); }
@@ -473,6 +571,12 @@ function setFile(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 })
@@ -496,6 +600,9 @@ function setFile(file) {
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;
})
@@ -515,12 +622,46 @@ function getPixelDimensions() {
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);
@@ -540,6 +681,7 @@ convertBtn.addEventListener('click', async () => {
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';