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Web / Guides / Extract layer
Make sure you have Full API enabled in WebViewer.
To extract PDF layers or OCG (optional content group) from a document.
<html>
<script src="../lib/core/webviewer-core.min.js"></script>
<script src="../lib/core/pdf/PDFNet.js"></script>
<script>
(async function() {
Core.setWorkerPath('../lib/core');
const doc = await PDFNet.PDFDoc.createFromURL(filename);
const page = await doc.getPage(1);
const initCfg = await doc.getOCGConfig();
const ctx = await PDFNet.OCGContext.createFromConfig(initCfg);
const pdfdraw = await PDFNet.PDFDraw.create();
pdfdraw.setImageSize(1000, 1000);
pdfdraw.setOCGContext(ctx);
// Disable drawing of content that is not optional (i.e. is not part of any layer).
ctx.setNonOCDrawing(false);
// Now render each layer in the input document to a separate image.
const ocgs = await doc.getOCGs(); // Get the array of all OCGs in the document.
let i;
const sz = await ocgs.size();
for (i = 0; i < sz; ++i) {
const ocg = await PDFNet.OCG.createFromObj(await ocgs.getAt(i));
ctx.resetStates(false);
ctx.setState(ocg, true);
let fname = 'pdf_layers_';
fname += await ocg.getName();
fname += '.png';
const pageBuffer = await pdfdraw.exportStream(page);
//optionally save the blob to a file or upload to a server
const layerBlob = new Blob([pageBuffer], { type: 'image/png' });
}
// Now draw content that is not part of any layer...
ctx.setNonOCDrawing(true);
ctx.setOCDrawMode(PDFNet.OCGContext.OCDrawMode.e_NoOC);
const nonLayerBuffer = await pdfdraw.exportStream(page);
// optionally save the blob to a file or upload to a server
const nonLayerBlob = new Blob([nonLayerBuffer], { type: 'image/png' });
})()
</script>
</html>PDF layers (OCG)
Full sample code which demonstrates how to create, extract, render PDF layers.
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