HtmlCbz/index.html at main · MaxAdams0/HtmlCbz · GitHub

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<!DOCTYPE html>
<html>
	<head>
		<base target="_top">
		<title>Html-only Cbz Reader</title>
		<style>
			html, body {
			overflow-x: hidden;
			margin: 0;
			padding: 0;
			height: 100vh;
			color: white;
			background-color: rgb(0,0,0);
			font-family: Verdana, sans-serif;
			display: flex;
			flex-direction: column;
		}

		#bar {
			display: flex;
			align-items: center;
			gap: 10px;
			position: sticky;
			background: rgb(11,11,11);
			height: 35px;
			padding: 5px 10px;
		}

		#bar input {
			background: rgb(22,22,22);
			padding: 5px;
			border: none;
			width: 500px;
		}

		#bar input[type="range"] {
			accent-color: rgb(22,22,22);
			width: 200px;
		}

		#bar input[type="number"] {
			color: white;
			width: 50px;
			margin-left: 10px;
		}

		#imageContainer {
			flex-grow: 1;
			text-align: center;
			overflow: auto;
		}

		img {
			max-width: 100%;
			max-height: 100vh;
			display: block;
			margin: auto;
			padding-bottom: 5px;
		}

		#pageCounter {
			margin-left: auto;
			white-space: nowrap;
		}

		#messageContainer {
			width: 100%;
			position: absolute;
			top: 50%;
			left: 50%;
			transform: translate(-50%, -50%);
			text-align: center;
			pointer-events: none;
		}

		.message {
			font-size: 32px;
			text-shadow: 0 0 4px #000;
			pointer-events: none;
		}

		#loadingMessage {
			opacity: 0%;
			transition: opacity 0.5s ease-in-out;
		}
		</style>
	</head>

	<body>
		<div id="messageContainer">
			<p class="message" id="loadingMessage">Loading... (0 / 0)</p>
		</div>
		<div id="imageContainer"></div>
		<div id="bar">
			<input type="file" id="fileInput" accept=".cbz">
			<text>Zoom:</text>
			<input type="range" id="zoomSlider" min="60" max="160" value="100">
			<input type="number" id="zoomInput" min="60" max="160" value="100" step="1">
			<text id="pageCounter">Page 0 / 0</text>
		</div>
	</body>

	<script>
		const imageContainer = document.getElementById('imageContainer');
		const loadingMessage = document.getElementById("loadingMessage");
		const pageCounter = document.getElementById('pageCounter');
		const zoomSlider = document.getElementById("zoomSlider");
		const zoomInput = document.getElementById("zoomInput");
		let imageOffsets = [];

		document.getElementById('fileInput').addEventListener('change', async function(event) {
			loadingMessage.textContent = `Loading... (0 / 0)`;

			const file = event.target.files[0];
			if (!file) return; // verify that at least one file exists
			loadingMessage.style.opacity = "1";

			const totalPages = await loadBook(file);
			if (totalPages == 0) {
				console.log(`'${file.name}' failed to load. Please check encoding...`);

				setTimeout(() => {
					loadingMessage.style.opacity = "0";
				}, 500);
			}
			else {
				console.log(`'${file.name}' loaded with ${totalPages} pages. Happy reading! =)`);

				setTimeout(() => {
					loadingMessage.style.opacity = "0";
				}, 500);

				// Set up zooming after images are loaded
				setupZoom(totalPages);

				// Page counter logic
				imageContainer.addEventListener('scroll', function() {
					setPageCounter(totalPages);
				});
			}
		});


		async function loadBook(file) {
			const d = new Uint8Array(await file.arrayBuffer()), len = d.length;
			let e = len - 22;
			while (e >= 0 && !(d[e]===0x50 && d[e+1]===0x4b && d[e+2]===0x05 && d[e+3]===0x06)) e--;
			if (e < 0) { alert("Could not load cbz file. It may be 7z encoded. Please use zip encoded cbz files only!"); return 0; }
			const num = d[e+10] | (d[e+11]<<8);
			let off = d[e+16] | (d[e+17]<<8) | (d[e+18]<<16) | (d[e+19]<<24), entries = [];
			for (let i = 0; i < num; i++) {
				const comp = d[off+10] | (d[off+11]<<8), csize = d[off+20] | (d[off+21]<<8) | (d[off+22]<<16) | (d[off+23]<<24), usize = d[off+24] | (d[off+25]<<8) | (d[off+26]<<16) | (d[off+27]<<24), nlen = d[off+28] | (d[off+29]<<8), elen = d[off+30] | (d[off+31]<<8), clen = d[off+32] | (d[off+33]<<8), loff = d[off+42] | (d[off+43]<<8) | (d[off+44]<<16) | (d[off+45]<<24);
				let name = '';
				for (let j = 0; j < nlen; j++) name += String.fromCharCode(d[off+46+j]);
				off += 46 + nlen + elen + clen;
				entries.push({ name, comp, csize, usize, loff });
			}
			const imageFiles = entries.filter(e => e.name.match(/\.(jpg|jpeg|png|gif)$/i)).sort((a, b) => a.name < b.name ? -1 : 1);
			imageContainer.innerHTML = '';
			const totalPages = imageFiles.length;
			let pagesLoaded = 1;
			const loadPromises = [];
			for (const entry of imageFiles) {
				const fnlen = d[entry.loff+26] | (d[entry.loff+27]<<8), exlen = d[entry.loff+28] | (d[entry.loff+29]<<8), dataOff = entry.loff + 30 + fnlen + exlen;
				const compressed = d.subarray(dataOff, dataOff + entry.csize);
				let imgData;
				if (entry.comp === 0) {
					imgData = new Blob([compressed]);
				} else if (entry.comp === 8) {
					const ds = new DecompressionStream('deflate-raw'), writer = ds.writable.getWriter();
					await writer.write(compressed); await writer.close();
					const reader = ds.readable.getReader(), chunks = [];
					while (true) { const {value, done} = await reader.read(); if (done) break; chunks.push(value); }
					const result = new Uint8Array(entry.usize); let pos = 0;
					for (const chunk of chunks) { result.set(chunk, pos); pos += chunk.length; }
					imgData = new Blob([result]);
				} else continue;
				const imgUrl = URL.createObjectURL(imgData);
				const img = document.createElement('img');
				img.src = imgUrl;
				imageContainer.appendChild(img);
				loadPromises.push(new Promise(resolve => { img.onload = resolve; img.onerror = resolve; }));
				loadingMessage.textContent = `Loading... (${pagesLoaded} / ${totalPages})`;
				pagesLoaded += 1;
			}
			await Promise.all(loadPromises);
			computeImageOffsets();
			return totalPages;
		}


		function computeImageOffsets() {
			const images = document.querySelectorAll("#imageContainer img");
			imageOffsets = [];
			let cumulative = 0;
			images.forEach(img => {
				cumulative += (img.offsetHeight || 0) + 5;
				imageOffsets.push(cumulative);
			});
		}

		function setPageCounter(pageCount) {
			const scrollPosition = imageContainer.scrollTop;
			let currentPage = 1;
			for (let i = 0; i < imageOffsets.length; i++) {
				if (scrollPosition < imageOffsets[i]) {
					currentPage = i + 1;
					break;
				}
			}
			if (imageOffsets.length > 0 && scrollPosition >= imageOffsets[imageOffsets.length - 1]) {
				currentPage = pageCount;
			}
			pageCounter.textContent = `Page ${currentPage} / ${pageCount}`;
		}


		// Function to update zoom
		function updateZoom(value, pageCount) {
			// Find which page is currently at the top of the viewport
			const scrollTop = imageContainer.scrollTop;
			let targetPage = 0;
			for (let i = 0; i < imageOffsets.length; i++) {
				if (scrollTop < imageOffsets[i]) {
					targetPage = i;
					break;
				}
			}
			if (imageOffsets.length > 0 && scrollTop >= imageOffsets[imageOffsets.length - 1]) {
				targetPage = imageOffsets.length - 1;
			}

			// How far into that page we've scrolled
			const pageStart = targetPage > 0 ? imageOffsets[targetPage - 1] - 5 : 0;
			const offsetInPage = scrollTop - pageStart;

			const images = document.querySelectorAll("#imageContainer img");
			images.forEach(img => {
				img.style.maxHeight = `${value}vh`;
			});
			computeImageOffsets();

			// Restore scroll to keep the same page in view
			const newPageStart = targetPage > 0 ? imageOffsets[targetPage - 1] - 5 : 0;
			const imageHeight = imageOffsets[targetPage] - (targetPage > 0 ? imageOffsets[targetPage - 1] - 5 : 0) - 5;
			const fraction = imageHeight > 0 ? Math.min(offsetInPage, imageHeight) : 0;
			imageContainer.scrollTop = Math.min(newPageStart + fraction, imageContainer.scrollHeight - imageContainer.clientHeight);

			setPageCounter(pageCount);
		}


		function setupZoom(pageCount) {
			const images = document.querySelectorAll("#imageContainer img");
			let zoomLevel = zoomSlider.value || 100; // Default zoom level at 100%

			// Initialize with the default zoom level
			updateZoom(zoomLevel, pageCount);

			// Slider event listener
			zoomSlider.addEventListener("input", function () {
				const value = parseInt(zoomSlider.value);
				zoomInput.value = value; // Sync the input box with the slider
				updateZoom(value, pageCount);
			});

			// Input event listener
			zoomInput.addEventListener("input", function () {
				const value = parseInt(zoomInput.value);
				if (value >= 60 && value <= 160) {
					zoomSlider.value = value; // Sync the slider with the input box
					updateZoom(value, pageCount);
				} else {
					// Reset to last valid zoom level if input is out of bounds
					zoomInput.value = zoomLevel;
				}
			});
		}
	</script>
</html>