Malin/ZPLify
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

feat: add PDF support with page navigation (poppler/pdftoppm)

Browse Source
This commit is contained in:
Malin
2026-03-26 10:28:22 +01:00
parent 6bec06c470
commit 8ccee3e9ac
2 changed files with 215 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
Dockerfile
View File

@@ -15,7 +15,7 @@ RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /zplgfa-web ./cmd/web
# ─── Final stage ────────────────────────────────────────────────────────────
FROM alpine:3.20
RUN apk add --no-cache ca-certificates
RUN apk add --no-cache ca-certificates poppler-utils
COPY --from=builder /zplgfa-web /usr/local/bin/zplgfa-web

227
cmd/web/main.go
View File

@@ -7,11 +7,14 @@ import (
"image/color"
_ "image/gif"
_ "image/jpeg"
_ "image/png"
"image/png"
"io"
"log"
"math"
"net/http"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"time"
@@ -26,6 +29,71 @@ import (
const maxUploadSize = 20 << 20 // 20 MB
func isPDF(data []byte) bool {
return len(data) >= 4 && string(data[:4]) == "%PDF"
}
// pdfPageToImage renders one page of a PDF to an image using pdftoppm.
// dpi controls the render resolution (use 150 for thumbnails, 300 for conversion).
// Returns the image, total page count, and any error.
func pdfPageToImage(data []byte, page, dpi int) (image.Image, int, error) {
tmpDir, err := os.MkdirTemp("", "zplgfa-*")
if err != nil {
return nil, 0, err
}
defer os.RemoveAll(tmpDir)
pdfPath := filepath.Join(tmpDir, "input.pdf")
if err := os.WriteFile(pdfPath, data, 0600); err != nil {
return nil, 0, err
}
// Get total page count via pdfinfo
pageCount := 1
if out, err := exec.Command("pdfinfo", pdfPath).Output(); err == nil {
for _, line := range strings.Split(string(out), "\n") {
if strings.HasPrefix(line, "Pages:") {
if n, err := strconv.Atoi(strings.TrimSpace(strings.TrimPrefix(line, "Pages:"))); err == nil {
pageCount = n
}
}
}
}
if page < 1 {
page = 1
}
if page > pageCount {
page = pageCount
}
// Convert the requested page to PNG
outBase := filepath.Join(tmpDir, "out")
cmd := exec.Command("pdftoppm",
"-png",
"-r", strconv.Itoa(dpi),
"-f", strconv.Itoa(page),
"-l", strconv.Itoa(page),
pdfPath, outBase)
if out, err := cmd.CombinedOutput(); err != nil {
return nil, pageCount, fmt.Errorf("pdftoppm: %s", string(out))
}
matches, err := filepath.Glob(filepath.Join(tmpDir, "out-*.png"))
if err != nil || len(matches) == 0 {
return nil, pageCount, fmt.Errorf("pdftoppm produced no output")
}
f, err := os.Open(matches[0])
if err != nil {
return nil, pageCount, err
}
defer f.Close()
img, _, err := image.Decode(f)
return img, pageCount, err
}
func getGraphicType(t string) zplgfa.GraphicType {
switch strings.ToUpper(t) {
case "ASCII":
@@ -111,12 +179,31 @@ func convertHandler(w http.ResponseWriter, r *http.Request) {
}
defer file.Close()
img, _, err := image.Decode(file)
data, err := io.ReadAll(file)
if err != nil {
http.Error(w, fmt.Sprintf("cannot decode image: %s", err), http.StatusBadRequest)
http.Error(w, "failed to read file", http.StatusBadRequest)
return
}
var img image.Image
if isPDF(data) {
page := 1
if p, e2 := strconv.Atoi(r.FormValue("page")); e2 == nil && p > 0 {
page = p
}
img, _, err = pdfPageToImage(data, page, 300)
if err != nil {
http.Error(w, "PDF conversion failed: "+err.Error(), http.StatusBadRequest)
return
}
} else {
img, _, err = image.Decode(bytes.NewReader(data))
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)
@@ -156,13 +243,72 @@ func previewHandler(w http.ResponseWriter, r *http.Request) {
var buf bytes.Buffer
buf.ReadFrom(file)
cfg, _, err := image.DecodeConfig(bytes.NewReader(buf.Bytes()))
data := buf.Bytes()
if isPDF(data) {
page := 1
if p, e2 := strconv.Atoi(r.FormValue("page")); e2 == nil && p > 0 {
page = p
}
img, pageCount, err := pdfPageToImage(data, page, 150)
if err != nil {
http.Error(w, "PDF conversion failed: "+err.Error(), http.StatusBadRequest)
return
}
b := img.Bounds()
w.Header().Set("Content-Type", "application/json")
fmt.Fprintf(w, `{"width":%d,"height":%d,"pages":%d,"isPDF":true}`, b.Dx(), b.Dy(), pageCount)
return
}
cfg, _, err := image.DecodeConfig(bytes.NewReader(data))
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)
fmt.Fprintf(w, `{"width":%d,"height":%d,"pages":1,"isPDF":false}`, cfg.Width, cfg.Height)
}
func pageThumbHandler(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()
data, err := io.ReadAll(file)
if err != nil {
http.Error(w, "failed to read file", http.StatusBadRequest)
return
}
if !isPDF(data) {
http.Error(w, "not a PDF", http.StatusBadRequest)
return
}
page := 1
if p, e2 := strconv.Atoi(r.FormValue("page")); e2 == nil && p > 0 {
page = p
}
img, _, err := pdfPageToImage(data, page, 150)
if err != nil {
http.Error(w, "PDF conversion failed: "+err.Error(), http.StatusBadRequest)
return
}
w.Header().Set("Content-Type", "image/png")
png.Encode(w, img)
}
var labelaryClient = &http.Client{Timeout: 15 * time.Second}
@@ -219,6 +365,7 @@ func main() {
mux := http.NewServeMux()
mux.HandleFunc("/convert", convertHandler)
mux.HandleFunc("/preview", previewHandler)
mux.HandleFunc("/page-thumb", pageThumbHandler)
mux.HandleFunc("/render", renderHandler)
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
@@ -398,13 +545,22 @@ const indexHTML = `<!DOCTYPE html>
<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">
<input type="file" id="fileInput" accept="image/png,image/jpeg,image/gif,application/pdf,.pdf">
<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="hint">PNG, JPEG, GIF, PDF — max 20 MB</div>
<div class="preview-info" id="previewInfo"></div>
</div>
<!-- PDF page selector (shown only for PDFs) -->
<div id="pdfPageRow" style="display:none; margin-bottom:1rem;">
<label for="pdfPage">PDF Page <span id="pdfPageMax" style="font-weight:400;color:#718096"></span></label>
<div style="display:flex; gap:0.5rem; align-items:center;">
<input type="number" id="pdfPage" min="1" value="1" style="width:100px">
<button id="pdfPageBtn" style="width:auto;padding:0.45rem 1rem;font-size:0.85rem;">Load Page</button>
</div>
</div>
<!-- Image preview (original) -->
<div class="preview-panel" id="imgPreviewPanel">
<div class="panel-header">Image Preview</div>
@@ -496,6 +652,8 @@ let selectedFile = null;
let currentUnit = 'px'; // 'px' or 'cm'
let origPxW = 0, origPxH = 0; // image native pixel dimensions
let imgObjectURL = null;
let fileIsPDF = false;
let pdfPageCount = 1;
function getDPI() { return parseInt(document.getElementById('dpi').value, 10); }
@@ -570,12 +728,16 @@ function setFile(file) {
selectedFile = file;
previewInfo.textContent = 'Loading…';
convertBtn.disabled = true;
fileIsPDF = file.type === 'application/pdf' || file.name.toLowerCase().endsWith('.pdf');
// Show image preview immediately
if (imgObjectURL) URL.revokeObjectURL(imgObjectURL);
imgObjectURL = URL.createObjectURL(file);
document.getElementById('imgPreviewEl').src = imgObjectURL;
document.getElementById('imgPreviewPanel').style.display = 'block';
// For non-PDFs show the image immediately; for PDFs we wait for the server thumb
if (!fileIsPDF) {
if (imgObjectURL) URL.revokeObjectURL(imgObjectURL);
imgObjectURL = URL.createObjectURL(file);
document.getElementById('imgPreviewEl').src = imgObjectURL;
document.getElementById('imgPreviewPanel').style.display = 'block';
}
document.getElementById('pdfPageRow').style.display = fileIsPDF ? 'block' : 'none';
const fd = new FormData();
fd.append('file', file);
@@ -585,6 +747,14 @@ function setFile(file) {
origPxW = info.width;
origPxH = info.height;
if (info.isPDF) {
pdfPageCount = info.pages;
document.getElementById('pdfPageMax').textContent = '(1 – ' + info.pages + ')';
document.getElementById('pdfPage').max = info.pages;
document.getElementById('pdfPage').value = 1;
loadPDFPageThumb(1);
}
const wEl = document.getElementById('width');
const hEl = document.getElementById('height');
if (currentUnit === 'px') {
@@ -596,8 +766,9 @@ function setFile(file) {
}
const cmW = pxToCm(origPxW), cmH = pxToCm(origPxH);
const pageInfo = info.isPDF ? ' — ' + info.pages + ' page' + (info.pages !== 1 ? 's' : '') : '';
previewInfo.textContent =
file.name + ' — ' + origPxW + ' × ' + origPxH + ' px' +
file.name + pageInfo + ' — ' + origPxW + ' × ' + origPxH + ' px' +
' (' + cmW + ' × ' + cmH + ' cm at ' + getDPI() + ' dpi)';
document.getElementById('imgPreviewMeta').textContent =
@@ -612,6 +783,33 @@ function setFile(file) {
});
}
async function loadPDFPageThumb(page) {
if (!selectedFile) return;
const fd = new FormData();
fd.append('file', selectedFile);
fd.append('page', page);
document.getElementById('imgPreviewPanel').style.display = 'block';
document.getElementById('imgPreviewMeta').textContent = 'Loading page ' + page + '…';
try {
const res = await fetch('/page-thumb', { method: 'POST', body: fd });
if (!res.ok) throw new Error(await res.text());
const blob = await res.blob();
if (imgObjectURL) URL.revokeObjectURL(imgObjectURL);
imgObjectURL = URL.createObjectURL(blob);
document.getElementById('imgPreviewEl').src = imgObjectURL;
const cmW = pxToCm(origPxW), cmH = pxToCm(origPxH);
document.getElementById('imgPreviewMeta').textContent =
'Page ' + page + ' — ' + origPxW + ' × ' + origPxH + ' px | ' + cmW + ' × ' + cmH + ' cm at ' + getDPI() + ' dpi';
} catch(e) {
document.getElementById('imgPreviewMeta').textContent = 'Preview failed: ' + e.message;
}
}
document.getElementById('pdfPageBtn').addEventListener('click', () => {
const page = parseInt(document.getElementById('pdfPage').value, 10) || 1;
loadPDFPageThumb(page);
});
// Returns pixel values regardless of current unit
function getPixelDimensions() {
const w = parseFloat(document.getElementById('width').value) || 0;
@@ -671,6 +869,9 @@ convertBtn.addEventListener('click', async () => {
fd.append('height', h);
fd.append('type', document.getElementById('enctype').value);
fd.append('edit', edits.join(','));
if (fileIsPDF) {
fd.append('page', document.getElementById('pdfPage').value || '1');
}
try {
const res = await fetch('/convert', { method: 'POST', body: fd });