Section:

Create Thumbnail Showcase Demo Code Sample

Requirements
View Demo
Web SDK
Package: Page Manipulation

Easily create high resolution thumbnail images from selected document pages.

This demo allows you to:

  • Choose your own document file.
  • Create high-resolution thumbnails.
  • Define PNG or JPEG image format.
  • Specify scale factor [0.1, 10], where low values yield smaller thumbnail sizes .

Implementation steps

To add Thumbnail Creation capability with WebViewer:
Step 1: Get started with WebViewer in your preferred web stack.
Step 2: Add the ES6 JavaScript sample code provided in this guide.

Once you generate your license key, it will automatically be included in your sample code below.

License Key

1// ES6 Compliant Syntax
2// GitHub Copilot v1.0, GPT-4.1, October 15, 2025
3// File: index.js
4
5import WebViewer from '@pdftron/webviewer';
6
7// Create Thumbnail Demo
8// This code demonstrates how to create a high resolution JPG or PNG thumbnail for a PDF document using the loadCanvas API.
9
10function initializeWebViewer() {
11
12    // This code initializes the WebViewer with the basic settings.
13    WebViewer({
14        path: '/lib',
15        licenseKey: 'YOUR_LICENSE_KEY',
16        enableFilePicker: true,
17        loadAsPDF: true, // Ensure files are loaded as PDF documents for best thumbnail quality.
18    }, document.getElementById('viewer')).then((instance) => {
19        // Enable the measurement toolbar so it appears with all the other tools, and disable Cloudy rectangular tool.
20        const cloudyTools = [
21            instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT,
22            instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT2,
23            instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT3,
24            instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT4,
25        ];
26        instance.UI.enableFeatures([instance.UI.Feature.Measurement, instance.UI.Feature.Initials]);
27        instance.UI.disableTools(cloudyTools);
28        // Set default toolbar group to Annotate.
29        instance.UI.setToolbarGroup('toolbarGroup-Annotate');
30        // Set default tool on mobile devices to Pan.
31        if (UIElements.isMobileDevice()) {
32            instance.UI.setToolMode(instance.Core.Tools.ToolNames.PAN);
33        }
34
35        instance.Core.documentViewer.addEventListener('documentUnloaded', () => {
36            if (searchParams.has('file')) {
37                searchParams.delete('file');
38                history.replaceState(null, '', '?' + searchParams.toString());
39            }
40        });
41
42        instance.Core.annotationManager.enableAnnotationNumbering();
43        instance.UI.NotesPanel.enableAttachmentPreview();
44        // Add the demo-specific functionality.
45        customizeUI(instance).then(() => {
46            // Create UI controls after demo is initialized.
47            UIElements.createUIControls(instance);
48        });
49    });
50}
51
52const searchParams = new URLSearchParams(window.location.search);
53const history = window.history || window.parent.history || window.top.history;
54
55window.pageNum = 1;
56window.scaleNum = 1.0;
57window.thumbnailName = 'thumbnail';
58window.thumbnailType = 'png';
59
60window.thumbnailOptions = ['PNG', 'JPEG'];
61
62
63const customizeUI = async (instance) => {
64    // Load the default document.
65    await instance.UI.loadDocument('https://apryse.s3.us-west-1.amazonaws.com/public/files/samples/WebviewerDemoDoc.pdf');
66};
67
68// Function to handle the Create Thumbnail button click.
69window.onThumbnailButtonClick = (instance) => {
70    // Get the document.
71    const doc = instance.Core.documentViewer.getDocument();
72
73    // Get the page number from user input.
74    let pageNumber = parseInt(window.pageNum, 10);
75
76    // Validate the page number.
77    if (isNaN(pageNumber) || pageNumber < 1 || pageNumber > doc.getPageCount()) {
78        alert('Please enter a valid page number between 1 and ' + doc.getPageCount());
79        return; // Exit if page number is invalid.
80    }
81
82    // Clamp the page number to valid range.
83    pageNumber = isNaN(pageNumber) ? 1 : Math.min(Math.max(pageNumber, 1), doc.getPageCount());
84
85    // Get the scale (zoom level) from user input.
86    const zoom = parseFloat(window.scaleNum);
87    if (isNaN(zoom) || zoom <= 0 || zoom > 10) {
88        alert('Please enter a valid zoom level between 0.1 and 10');
89        return; // Exit if zoom is invalid.
90    }
91    
92    // Compensate for device pixel ratio to ensure consistent output across devices.
93    // Normalize to standard DPR of 1.0 by dividing by actual DPR.
94    const devicePixelRatio = window.devicePixelRatio || 1;
95    const adjustedZoom = zoom / devicePixelRatio;
96    
97    console.log(`Device Pixel Ratio: ${devicePixelRatio}`);
98    console.log(`Original zoom: ${zoom}, Adjusted zoom: ${adjustedZoom}`);
99    console.log(`This should produce thumbnails equivalent to DPR=1.0 environment`);
100
101    // Get the file name and type from user input.
102    const name = window.thumbnailName;
103    const type = window.thumbnailType;
104
105    // Save to blob using the loadCanvas API.
106    doc.loadCanvas({
107        pageNumber,
108        zoom: adjustedZoom, // Use DPI-adjusted zoom for consistent output.
109        drawComplete: async (thumbnail) => {
110            // Optionally, comment out "drawAnnotations" to exclude annotations.
111            await instance.Core.documentViewer
112                .getAnnotationManager()
113                .drawAnnotations(pageNumber, thumbnail);
114            // Thumbnail is an HTMLCanvasElement or HTMLImageElement.
115            thumbnail.toBlob(
116                (blob) => {
117                    saveAs(blob, name + '.' + type);
118                },
119                'image/' + type,
120                1
121            );
122        },
123    });
124};
125
126// Cleanup function for when the demo is closed or page is unloaded.
127const cleanup = (instance) => {
128    if (typeof instance !== 'undefined' && instance.UI) {
129        if (instance.Core.documentViewer.getDocument()) {
130            // Insert any other cleanup code here.
131        }
132        console.log('Cleaning up demo');
133    }
134};
135
136// Register cleanup for page unload.
137window.addEventListener('beforeunload', () => cleanup(instance));
138window.addEventListener('unload', () => cleanup(instance));
139
140// UI Elements Script Loader
141// Loads the ui-elements.js script.
142function loadUIElementsScript() {
143    return new Promise((resolve, reject) => {
144        if (window.UIElements) {
145            console.log('UIElements already loaded');
146            resolve();
147            return;
148        }
149        const script = document.createElement('script');
150        script.src = '/showcase-demos/create-thumbnail/ui-elements.js';
151        script.onload = function () {
152            console.log('✅ UIElements script loaded successfully');
153            resolve();
154        };
155        script.onerror = function () {
156            console.error('Failed to load UIElements script');
157            reject(new Error('Failed to load ui-elements.js'));
158        };
159        document.head.appendChild(script);
160    });
161}
162
163// Load UIElements script first, then initialize WebViewer.
164loadUIElementsScript().then(() => {
165    initializeWebViewer();
166}).catch((error) => {
167    console.error('Failed to load UIElements:', error);
168});
169

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