feat: Add PDF viewer and preview components with styling and functionality
- Implemented DeesPdfViewer for full-featured PDF viewing with toolbar and sidebar navigation. - Created DeesPdfPreview for lightweight PDF previews. - Introduced PdfManager for managing PDF document loading and caching. - Added CanvasPool for efficient canvas management. - Developed utility functions for performance monitoring and file size formatting. - Established styles for viewer and preview components to enhance UI/UX. - Included demo examples for showcasing PDF viewer capabilities.
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ts_web/elements/dees-pdf-preview/component.ts
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290
ts_web/elements/dees-pdf-preview/component.ts
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import { DeesElement, property, html, customElement, domtools, type TemplateResult, css, cssManager } from '@design.estate/dees-element';
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import { PdfManager } from '../dees-pdf-shared/PdfManager.js';
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import { CanvasPool, type PooledCanvas } from '../dees-pdf-shared/CanvasPool.js';
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import { PerformanceMonitor, throttle } from '../dees-pdf-shared/utils.js';
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import { previewStyles } from './styles.js';
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import { demo as demoFunc } from './demo.js';
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declare global {
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interface HTMLElementTagNameMap {
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'dees-pdf-preview': DeesPdfPreview;
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}
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}
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@customElement('dees-pdf-preview')
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export class DeesPdfPreview extends DeesElement {
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public static demo = demoFunc;
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public static styles = previewStyles;
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@property({ type: String })
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public pdfUrl: string = '';
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@property({ type: Number })
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public maxPages: number = 3;
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@property({ type: Number })
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public stackOffset: number = 8;
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@property({ type: Boolean })
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public clickable: boolean = true;
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@property({ type: Number })
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private pageCount: number = 0;
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@property({ type: Boolean })
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private loading: boolean = false;
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@property({ type: Boolean })
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private rendered: boolean = false;
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@property({ type: Boolean })
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private error: boolean = false;
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private observer: IntersectionObserver;
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private pdfDocument: any;
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private canvases: PooledCanvas[] = [];
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private renderRequestId: number;
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constructor() {
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super();
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}
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public render(): TemplateResult {
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return html`
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<div
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class="preview-container ${this.loading ? 'loading' : ''} ${this.error ? 'error' : ''} ${this.clickable ? 'clickable' : ''}"
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@click=${this.handleClick}
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>
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${this.loading ? html`
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<div class="preview-loading">
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<div class="preview-spinner"></div>
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<div class="preview-text">Loading preview...</div>
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</div>
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` : ''}
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${this.error ? html`
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<div class="preview-error">
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<dees-icon icon="lucide:FileX"></dees-icon>
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<div class="preview-text">Failed to load PDF</div>
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</div>
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` : ''}
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${!this.loading && !this.error ? html`
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<div class="preview-stack">
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${this.getStackedCanvases()}
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</div>
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${this.pageCount > 0 ? html`
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<div class="preview-info">
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<dees-icon icon="lucide:FileText"></dees-icon>
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<span class="preview-pages">${this.pageCount} page${this.pageCount > 1 ? 's' : ''}</span>
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</div>
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` : ''}
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${this.clickable ? html`
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<div class="preview-overlay">
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<dees-icon icon="lucide:Eye"></dees-icon>
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<span>View PDF</span>
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</div>
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` : ''}
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` : ''}
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</div>
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`;
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}
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private getStackedCanvases(): TemplateResult[] {
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const pagesToShow = Math.min(this.pageCount, this.maxPages);
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const canvases: TemplateResult[] = [];
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for (let i = pagesToShow - 1; i >= 0; i--) {
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const offset = i * this.stackOffset;
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canvases.push(html`
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<canvas
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class="preview-canvas"
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data-page="${i + 1}"
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style="
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top: ${offset}px;
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left: ${offset}px;
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z-index: ${pagesToShow - i};
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${i > 0 ? `box-shadow: 0 2px 8px rgba(0, 0, 0, ${0.1 + (i * 0.05)});` : ''}
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"
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></canvas>
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`);
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}
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return canvases;
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}
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public async connectedCallback() {
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super.connectedCallback();
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this.setupIntersectionObserver();
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}
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public async disconnectedCallback() {
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super.disconnectedCallback();
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this.cleanup();
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}
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private setupIntersectionObserver() {
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const options = {
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root: null,
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rootMargin: '200px',
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threshold: 0.01,
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};
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this.observer = new IntersectionObserver(
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throttle((entries) => {
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for (const entry of entries) {
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if (entry.isIntersecting && !this.rendered && this.pdfUrl) {
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this.loadAndRenderPreview();
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} else if (!entry.isIntersecting && this.rendered) {
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// Optional: Clear canvases when out of view for memory optimization
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// this.clearCanvases();
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}
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}
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}, 100),
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options
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);
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this.observer.observe(this);
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}
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private async loadAndRenderPreview() {
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if (this.rendered || this.loading) return;
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this.loading = true;
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this.error = false;
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PerformanceMonitor.mark(`preview-load-${this.pdfUrl}`);
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try {
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this.pdfDocument = await PdfManager.loadDocument(this.pdfUrl);
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this.pageCount = this.pdfDocument.numPages;
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await this.updateComplete;
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await this.renderPages();
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this.rendered = true;
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const duration = PerformanceMonitor.measure(`preview-render-${this.pdfUrl}`, `preview-load-${this.pdfUrl}`);
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console.log(`PDF preview rendered in ${duration}ms`);
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} catch (error) {
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console.error('Failed to load PDF preview:', error);
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this.error = true;
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} finally {
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this.loading = false;
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}
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}
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private async renderPages() {
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const canvasElements = this.shadowRoot?.querySelectorAll('.preview-canvas') as NodeListOf<HTMLCanvasElement>;
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const pagesToRender = Math.min(this.pageCount, this.maxPages);
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// Release old canvases
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this.clearCanvases();
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// Calculate available width for preview (container width minus padding and stacking offset)
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const containerWidth = 160; // 200px container - 40px padding
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const maxStackOffset = (pagesToRender - 1) * this.stackOffset;
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const availableWidth = containerWidth - maxStackOffset;
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// Render pages in reverse order (back to front for stacking)
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for (let i = 0; i < pagesToRender; i++) {
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const canvas = canvasElements[i];
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if (!canvas) continue;
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const pageNum = parseInt(canvas.dataset.page || '1');
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const page = await this.pdfDocument.getPage(pageNum);
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// Calculate scale to fit within available width
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const initialViewport = page.getViewport({ scale: 1 });
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const scale = Math.min(availableWidth / initialViewport.width, 0.5); // Cap at 0.5 for quality
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const viewport = page.getViewport({ scale });
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// Acquire canvas from pool
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const pooledCanvas = CanvasPool.acquire(viewport.width, viewport.height);
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this.canvases.push(pooledCanvas);
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// Render to pooled canvas first
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const renderContext = {
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canvasContext: pooledCanvas.ctx,
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viewport: viewport,
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};
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await page.render(renderContext).promise;
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// Transfer to display canvas
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canvas.width = viewport.width;
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canvas.height = viewport.height;
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canvas.style.width = `${viewport.width}px`;
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canvas.style.height = `${viewport.height}px`;
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const ctx = canvas.getContext('2d');
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if (ctx) {
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ctx.drawImage(pooledCanvas.canvas, 0, 0);
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}
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// Release page to free memory
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page.cleanup();
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}
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}
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private clearCanvases() {
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// Cancel any pending render
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if (this.renderRequestId) {
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cancelAnimationFrame(this.renderRequestId);
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this.renderRequestId = 0;
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}
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// Release pooled canvases
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for (const pooledCanvas of this.canvases) {
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CanvasPool.release(pooledCanvas);
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}
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this.canvases = [];
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}
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private cleanup() {
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if (this.observer) {
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this.observer.disconnect();
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}
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this.clearCanvases();
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if (this.pdfUrl && this.pdfDocument) {
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PdfManager.releaseDocument(this.pdfUrl);
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this.pdfDocument = null;
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}
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this.rendered = false;
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}
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private handleClick() {
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if (!this.clickable) return;
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// Dispatch custom event for parent to handle
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this.dispatchEvent(new CustomEvent('pdf-preview-click', {
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detail: {
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pdfUrl: this.pdfUrl,
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pageCount: this.pageCount,
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},
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bubbles: true,
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composed: true,
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}));
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}
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public async updated(changedProperties: Map<PropertyKey, unknown>) {
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super.updated(changedProperties);
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if (changedProperties.has('pdfUrl') && this.pdfUrl) {
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this.cleanup();
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this.rendered = false;
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// Check if in viewport and render if so
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if (this.observer) {
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const rect = this.getBoundingClientRect();
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if (rect.top < window.innerHeight && rect.bottom > 0) {
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this.loadAndRenderPreview();
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}
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}
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}
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}
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}
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