Files
changedetection.io/changedetectionio/static/js/snippet-to-image.js
T
dgtlmoon 3d14df6a11 Development branch merge into release/master
Multi-language / Translations Support (#3696)
  - Complete internationalization system implemented
  - Support for 7 languages: Czech (cs), German (de), French (fr), Italian (it), Korean (ko), Chinese Simplified (zh), Chinese Traditional (zh_TW)
  - Language selector with localized flags and theming
  - Flash message translations
  - Multiple translation fixes and improvements across all languages
  - Language setting preserved across redirects

  Pluggable Content Fetchers (#3653)
  - New architecture for extensible content fetcher system
  - Allows custom fetcher implementations

  Image / Screenshot Comparison Processor (#3680)
  - New processor for visual change detection (disabled for this release)
  - Supporting CSS/JS infrastructure added

  UI Improvements

  Design & Layout
  - Auto-generated tag color schemes
  - Simplified login form styling
  - Removed hard-coded CSS, moved to SCSS variables
  - Tag UI cleanup and improvements
  - Automatic tab wrapper functionality
  - Menu refactoring for better organization
  - Cleanup of offset settings
  - Hide sticky tabs on narrow viewports
  - Improved responsive layout (#3702)

  User Experience
  - Modal alerts/confirmations on delete/clear operations (#3693, #3598, #3382)
  - Auto-add https:// to URLs in quickwatch form if not present
  - Better redirect handling on login (#3699)
  - 'Recheck all' now returns to correct group/tag (#3673)
  - Language set redirect keeps hash fragment
  - More friendly human-readable text throughout UI

  Performance & Reliability

  Scheduler & Processing
  - Soft delays instead of blocking time.sleep() calls (#3710)
  - More resilient handling of same UUID being processed (#3700)
  - Better Puppeteer timeout handling
  - Improved Puppeteer shutdown/cleanup (#3692)
  - Requests cleanup now properly async

  History & Rendering
  - Faster server-side "difference" rendering on History page (#3442)
  - Show ignored/triggered rows in history
  - API: Retry watch data if watch dict changed (more reliable)

  API Improvements

  - Watch get endpoint: retry mechanism for changed watch data
  - WatchHistoryDiff API endpoint includes extra format args (#3703)

  Testing Improvements

  - Replace time.sleep with wait_for_notification_endpoint_output (#3716)
  - Test for mode switching (#3701)
  - Test for #3720 added (#3725)
  - Extract-text difference test fixes
  - Improved dev workflow

  Bug Fixes

  - Notification error text output (#3672, #3669, #3280)
  - HTML validation fixes (#3704)
  - Template discovery path fixes
  - Notification debug log now uses system locale for dates/times
  - Puppeteer spelling mistake in log output
  - Recalculation on anchor change
  - Queue bubble update disabled temporarily

  Dependency Updates

  - beautifulsoup4 updated (#3724)
  - psutil 7.1.0 → 7.2.1 (#3723)
  - python-engineio ~=4.12.3 → ~=4.13.0 (#3707)
  - python-socketio ~=5.14.3 → ~=5.16.0 (#3706)
  - flask-socketio ~=5.5.1 → ~=5.6.0 (#3691)
  - brotli ~=1.1 → ~=1.2 (#3687)
  - lxml updated (#3590)
  - pytest ~=7.2 → ~=9.0 (#3676)
  - jsonschema ~=4.0 → ~=4.25 (#3618)
  - pluggy ~=1.5 → ~=1.6 (#3616)
  - cryptography 44.0.1 → 46.0.3 (security) (#3589)

  Documentation

  - README updated with viewport size setup information

  Development Infrastructure

  - Dev container only built on dev branch
  - Improved dev workflow tooling
2026-01-12 17:50:53 +01:00

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/**
* snippet-to-image.js
* Converts selected diff content to a shareable JPEG image with metadata
*/
// Constants
const IMAGE_PADDING = 5;
const JPEG_QUALITY = 0.95;
const CANVAS_SCALE = 1;
const RENDER_DELAY_MS = 50;
/**
* Utility: Get the target URL from global watch_url or fallback to current URL
*/
function getTargetUrl() {
return (typeof watch_url !== 'undefined' && watch_url) ? watch_url : window.location.href;
}
/**
* Utility: Get formatted current date with timezone
*/
function getFormattedDate() {
return new Date().toLocaleString(undefined, {
year: 'numeric',
month: 'long',
day: 'numeric',
hour: '2-digit',
minute: '2-digit',
second: '2-digit',
timeZoneName: 'short'
});
}
/**
* Utility: Get version comparison info from the diff selectors
*/
function getVersionInfo() {
const fromSelect = document.getElementById('diff-from-version');
const toSelect = document.getElementById('diff-to-version');
if (!fromSelect || !toSelect) {
return '';
}
const fromOption = fromSelect.options[fromSelect.selectedIndex];
const toOption = toSelect.options[toSelect.selectedIndex];
const fromLabel = fromOption ? (fromOption.getAttribute('label') || fromOption.text) : 'Unknown';
const toLabel = toOption ? (toOption.getAttribute('label') || toOption.text) : 'Unknown';
return `Change comparison from <strong>${fromLabel}</strong> to <strong>${toLabel}</strong>`;
}
/**
* Helper: Find text node containing newline in a given direction
*/
function findTextNodeWithNewline(node, searchBackwards = false) {
if (node.nodeType === Node.TEXT_NODE) {
const text = node.textContent;
const idx = searchBackwards ? text.lastIndexOf('\n') : text.indexOf('\n');
if (idx !== -1) {
return { node, offset: searchBackwards ? idx + 1 : idx };
}
} else {
const walker = document.createTreeWalker(node, NodeFilter.SHOW_TEXT);
let textNode;
while (textNode = walker.nextNode()) {
const text = textNode.textContent;
const idx = searchBackwards ? text.lastIndexOf('\n') : text.indexOf('\n');
if (idx !== -1) {
return { node: textNode, offset: searchBackwards ? idx + 1 : idx };
}
}
}
return null;
}
/**
* Helper: Walk through siblings in a given direction to find line boundary
*/
function findLineBoundary(node, container, searchBackwards = false) {
let currentNode = node;
while (currentNode && currentNode !== container) {
const sibling = searchBackwards ? currentNode.previousSibling : currentNode.nextSibling;
let currentSibling = sibling;
while (currentSibling) {
const result = findTextNodeWithNewline(currentSibling, searchBackwards);
if (result) {
return result;
}
currentSibling = searchBackwards ? currentSibling.previousSibling : currentSibling.nextSibling;
}
currentNode = currentNode.parentNode;
}
return null;
}
/**
* Helper: Get the last text node in a container
*/
function getLastTextNode(container) {
const walker = document.createTreeWalker(container, NodeFilter.SHOW_TEXT);
let lastNode = null;
let textNode;
while (textNode = walker.nextNode()) {
lastNode = textNode;
}
return lastNode;
}
/**
* Expands a selection range to include complete lines
* If a user selects partial text, this ensures full lines are captured
*/
function expandRangeToFullLines(range, container) {
const newRange = range.cloneRange();
// Expand start to line beginning
if (newRange.startContainer.nodeType === Node.TEXT_NODE) {
const text = newRange.startContainer.textContent;
const lastNewline = text.lastIndexOf('\n', newRange.startOffset - 1);
if (lastNewline !== -1) {
newRange.setStart(newRange.startContainer, lastNewline + 1);
} else {
const lineStart = findLineBoundary(newRange.startContainer, container, true);
if (lineStart) {
newRange.setStart(lineStart.node, lineStart.offset);
} else {
newRange.setStart(container, 0);
}
}
}
// Expand end to line end
if (newRange.endContainer.nodeType === Node.TEXT_NODE) {
const text = newRange.endContainer.textContent;
const nextNewline = text.indexOf('\n', newRange.endOffset);
if (nextNewline !== -1) {
newRange.setEnd(newRange.endContainer, nextNewline);
} else {
const lineEnd = findLineBoundary(newRange.endContainer, container, false);
if (lineEnd) {
newRange.setEnd(lineEnd.node, lineEnd.offset);
} else {
const lastNode = getLastTextNode(container);
newRange.setEnd(
lastNode || container,
lastNode ? lastNode.textContent.length : container.childNodes.length
);
}
}
}
return newRange;
}
/**
* Create a temporary element with the selected content styled for capture
*/
function createCaptureElement(selectedFragment, originalElement) {
const originalStyles = window.getComputedStyle(originalElement);
// Create container with watermark background
const container = document.createElement("div");
container.innerHTML = `
<div style="
position: absolute;
left: -9999px;
top: 0;
padding: 2px;
background-color: transparent;
">
<div style="
background-color: #ffffff;
width: ${originalElement.offsetWidth}px;
border: 1px solid #ccc;
border-radius: 4px;
overflow: hidden;
">
<!-- Watermark background -->
<div style="
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
overflow: hidden;
pointer-events: none;
z-index: 0;
background-image: url(&quot;data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='400' height='200' viewBox='0 0 400 200'><g font-family='Arial' font-size='18' font-weight='700' fill='%23e8e8e8' transform='rotate(-45 200 100)'><text x='0' y='40'>changedetection.io changedetection.io changedetection.io</text><text x='0' y='100'>changedetection.io changedetection.io changedetection.io</text><text x='0' y='160'>changedetection.io changedetection.io changedetection.io</text></g></svg>&quot;);
background-repeat: repeat;
background-size: 400px 200px;
"></div>
<!-- Content -->
<pre id="temp-capture-element" style="
position: relative;
z-index: 1;
white-space: ${originalStyles.whiteSpace};
font-family: ${originalStyles.fontFamily};
font-size: ${originalStyles.fontSize};
line-height: ${originalStyles.lineHeight};
color: ${originalStyles.color};
word-wrap: ${originalStyles.wordWrap};
overflow-wrap: ${originalStyles.overflowWrap};
background-color: transparent;
padding: ${IMAGE_PADDING}px;
border: ${originalStyles.border};
box-sizing: border-box;
margin: 0;
"></pre>
</div>
</div>
`;
const outerWrapper = container.firstElementChild;
const innerWrapper = outerWrapper.querySelector('div');
const tempElement = innerWrapper.querySelector('#temp-capture-element');
tempElement.appendChild(selectedFragment);
// Store innerWrapper for footer appending
outerWrapper._innerWrapper = innerWrapper;
return outerWrapper;
}
/**
* Count lines in a text string or document fragment
*/
function countLines(content) {
if (!content) return 0;
let text = '';
if (typeof content === 'string') {
text = content;
} else if (content.textContent) {
text = content.textContent;
}
// Count newlines + 1 (for the last line)
const lines = text.split('\n').length;
return lines > 0 ? lines : 1;
}
/**
* Create footer with metadata (URL, version info, line count)
*/
function createFooter(selectedLines, totalLines) {
const url = getTargetUrl();
const versionInfo = getVersionInfo();
const lineInfo = (selectedLines && totalLines) ? ` - ${selectedLines} of ${totalLines} lines selected` : '';
const footer = document.createElement("div");
footer.innerHTML = `
<div style="
position: relative;
z-index: 1;
background-color: #1324fd;
color: #fff;
padding: 10px;
margin-top: 10px;
font-size: 12px;
font-family: Arial, sans-serif;
line-height: 1.5;
border-top: 1px solid #ccc;
">
Watched URL: <strong>${url}</strong><br>
${versionInfo}${lineInfo}<br>
Monitored via automated content change detection on public webpages. Data reflects observed text updates, not editorial verification.
</div>
`;
return footer.firstElementChild;
}
/**
* Add EXIF metadata to JPEG image
*/
function addExifMetadata(jpegDataUrl) {
if (typeof piexif === 'undefined') {
return jpegDataUrl;
}
try {
const url = getTargetUrl();
const timestamp = new Date().toISOString();
const exifObj = {
"0th": {
[piexif.ImageIFD.Software]: "changedetection.io",
[piexif.ImageIFD.ImageDescription]: `Diff snapshot from ${url}`,
[piexif.ImageIFD.Copyright]: "Generated by changedetection.io"
},
"Exif": {
[piexif.ExifIFD.DateTimeOriginal]: timestamp,
[piexif.ExifIFD.UserComment]: `URL: ${url} | Captured: ${timestamp} | Source: changedetection.io`
}
};
const exifBytes = piexif.dump(exifObj);
return piexif.insert(exifBytes, jpegDataUrl);
} catch (error) {
console.warn("Failed to add EXIF metadata:", error);
return jpegDataUrl;
}
}
/**
* Convert data URL to Blob for sharing
*/
function dataURLtoBlob(dataURL) {
const parts = dataURL.split(',');
const byteString = atob(parts[1]);
const mimeString = parts[0].split(':')[1].split(';')[0];
const ab = new ArrayBuffer(byteString.length);
const ia = new Uint8Array(ab);
for (let i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
return new Blob([ab], { type: mimeString });
}
/**
* Download the image
*/
function downloadImage(jpegDataUrl) {
const a = document.createElement("a");
a.href = jpegDataUrl;
a.download = "changedetection-diff-" + Date.now() + ".jpg";
a.click();
}
/**
* Copy image to clipboard
*/
async function copyImageToClipboard(jpegDataUrl) {
try {
const blob = dataURLtoBlob(jpegDataUrl);
await navigator.clipboard.write([
new ClipboardItem({ 'image/jpeg': blob })
]);
alert('Image copied to clipboard!');
} catch (error) {
console.error('Failed to copy image:', error);
alert('Failed to copy image. Your browser may not support this feature.');
}
}
/**
* Share via Web Share API or fallback to platform-specific sharing
*/
async function shareImage(platform, jpegDataUrl) {
const url = getTargetUrl();
const shareText = `Check out this change detected on ${url} via changedetection.io`;
const filename = "changedetection-diff-" + Date.now() + ".jpg";
// Try Web Share API first (works on mobile and some desktop browsers)
if (platform === 'native' && navigator.share) {
try {
const blob = dataURLtoBlob(jpegDataUrl);
const file = new File([blob], filename, { type: 'image/jpeg' });
await navigator.share({
title: 'Change Detection Diff',
text: shareText,
files: [file]
});
return;
} catch (error) {
if (error.name !== 'AbortError') {
console.error('Web Share API failed:', error);
}
return;
}
}
// Platform-specific fallbacks
const encodedText = encodeURIComponent(shareText);
const encodedUrl = encodeURIComponent(url);
let shareUrl;
switch (platform) {
case 'twitter':
shareUrl = `https://twitter.com/intent/tweet?text=${encodedText}`;
break;
case 'facebook':
shareUrl = `https://www.facebook.com/sharer/sharer.php?u=${encodedUrl}&quote=${encodedText}`;
break;
case 'linkedin':
shareUrl = `https://www.linkedin.com/sharing/share-offsite/?url=${encodedUrl}`;
break;
case 'reddit':
shareUrl = `https://reddit.com/submit?url=${encodedUrl}&title=${encodeURIComponent('Change Detection Diff')}`;
break;
case 'email':
shareUrl = `mailto:?subject=${encodeURIComponent('Change Detection Diff')}&body=${encodedText}`;
break;
default:
return;
}
window.open(shareUrl, '_blank', 'width=600,height=400');
}
/**
* Display or download the generated image
*/
function displayImage(jpegDataUrl) {
const win = window.open();
if (win) {
win.document.write(`
<html>
<head>
<title>Diff Screenshot</title>
<style>
body {
margin: 0;
padding: 20px;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
background: #f5f5f5;
}
.container {
max-width: 1200px;
margin: 0 auto;
background: white;
padding: 20px;
border-radius: 8px;
box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
img {
max-width: 100%;
display: block;
margin-bottom: 20px;
border: 1px solid #ddd;
border-radius: 4px;
}
.share-section {
padding: 20px 0;
border-top: 2px solid #e0e0e0;
}
.share-section h3 {
margin: 0 0 15px 0;
color: #333;
font-size: 18px;
}
.share-buttons {
display: flex;
flex-wrap: wrap;
gap: 10px;
}
.share-btn {
padding: 10px 20px;
border: none;
border-radius: 6px;
font-size: 14px;
font-weight: 600;
cursor: pointer;
transition: all 0.2s;
text-decoration: none;
display: inline-flex;
align-items: center;
gap: 8px;
}
.share-btn:hover {
transform: translateY(-2px);
box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}
.btn-download {
background: #4CAF50;
color: white;
}
.btn-native {
background: #2196F3;
color: white;
}
.btn-twitter {
background: #000000;
color: white;
}
.btn-facebook {
background: #1877F2;
color: white;
}
.btn-linkedin {
background: #0A66C2;
color: white;
}
.btn-reddit {
background: #FF4500;
color: white;
}
.btn-email {
background: #757575;
color: white;
}
</style>
</head>
<body>
<div class="container">
<img src="${jpegDataUrl}" alt="Diff Screenshot" id="diffImage"/>
<div class="share-section">
<h3>Share or Download</h3>
<p style="margin: 0 0 15px 0; padding: 12px; background: #f0f7ff; border-left: 4px solid #2196F3; color: #333; font-size: 14px; line-height: 1.5;">
<strong>💡 Tip:</strong> Right-click the image above and select "Copy Image", then click a share button below and paste it into your post (Ctrl+V or right-click → Paste).
</p>
<div class="share-buttons">
<button class="share-btn btn-download" onclick="downloadImage()">
📥 Download Image
</button>
${navigator.share ? '<button class="share-btn btn-native" onclick="shareNative()">📤 Share...</button>' : ''}
<button class="share-btn btn-twitter" onclick="shareToTwitter()">
𝕏 Share to X
</button>
<button class="share-btn btn-facebook" onclick="shareToFacebook()">
Share to Facebook
</button>
<button class="share-btn btn-linkedin" onclick="shareToLinkedIn()">
Share to LinkedIn
</button>
<button class="share-btn btn-reddit" onclick="shareToReddit()">
Share to Reddit
</button>
<button class="share-btn btn-email" onclick="shareViaEmail()">
📧 Share via Email
</button>
</div>
</div>
</div>
<script>
const imageDataUrl = "${jpegDataUrl}";
function dataURLtoBlob(dataURL) {
const parts = dataURL.split(',');
const byteString = atob(parts[1]);
const mimeString = parts[0].split(':')[1].split(';')[0];
const ab = new ArrayBuffer(byteString.length);
const ia = new Uint8Array(ab);
for (let i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
return new Blob([ab], { type: mimeString });
}
function downloadImage() {
const a = document.createElement("a");
a.href = imageDataUrl;
a.download = "changedetection-diff-" + Date.now() + ".jpg";
a.click();
}
async function shareNative() {
try {
const blob = dataURLtoBlob(imageDataUrl);
const file = new File([blob], "changedetection-diff-" + Date.now() + ".jpg", { type: 'image/jpeg' });
await navigator.share({
title: 'Change Detection Diff',
text: 'Check out this change detected via changedetection.io',
files: [file]
});
} catch (error) {
if (error.name !== 'AbortError') {
console.error('Share failed:', error);
}
}
}
function shareToTwitter() {
const text = encodeURIComponent('Check out this change detected via changedetection.io');
window.open('https://twitter.com/intent/tweet?text=' + text, '_blank', 'width=600,height=400');
}
function shareToFacebook() {
const cdUrl = encodeURIComponent('https://changedetection.io');
window.open('https://www.facebook.com/sharer/sharer.php?u=' + cdUrl, '_blank', 'width=600,height=400');
}
function shareToLinkedIn() {
const cdUrl = encodeURIComponent('https://changedetection.io');
window.open('https://www.linkedin.com/sharing/share-offsite/?url=' + cdUrl, '_blank', 'width=600,height=400');
}
function shareToReddit() {
const cdUrl = encodeURIComponent('https://changedetection.io');
const title = encodeURIComponent('Change Detection Tool');
window.open('https://reddit.com/submit?url=' + cdUrl + '&title=' + title, '_blank', 'width=600,height=400');
}
function shareViaEmail() {
const subject = encodeURIComponent('Change Detection Diff');
const body = encodeURIComponent('Check out this change detected via changedetection.io');
window.location.href = 'mailto:?subject=' + subject + '&body=' + body;
}
</script>
</body>
</html>
`);
} else {
// Fallback: trigger download if popup is blocked
const a = document.createElement("a");
a.href = jpegDataUrl;
a.download = "changedetection-diff-" + Date.now() + ".jpg";
a.click();
}
}
/**
* Update button UI state
*/
function setButtonState(button, isLoading, originalHtml = '') {
if (!button) return;
if (isLoading) {
button.innerHTML = 'Generating...';
button.style.opacity = "0.5";
button.style.pointerEvents = "none";
} else {
button.innerHTML = originalHtml;
button.style.opacity = "1";
button.style.pointerEvents = "auto";
}
}
/**
* Main function: Convert selected diff text to a shareable JPEG image
*
* Features:
* - Expands partial selections to full lines
* - Preserves all diff highlighting and formatting
* - Adds metadata footer with URL and version info
* - Embeds EXIF metadata in the JPEG
* - Opens in new window or downloads if popup blocked
*/
async function diffToJpeg() {
// Validate dependencies
if (typeof html2canvas === 'undefined') {
alert("html2canvas library is not loaded yet. Please wait a moment and try again.");
return;
}
// Validate selection
const selection = window.getSelection();
if (!selection || selection.rangeCount === 0 || selection.isCollapsed) {
alert("Please select the text/lines you want to capture first by highlighting with your mouse.");
return;
}
const originalRange = selection.getRangeAt(0);
const differenceElement = document.getElementById("difference");
if (!differenceElement || !differenceElement.contains(originalRange.commonAncestorContainer)) {
alert("Please select text within the diff content.");
return;
}
// Setup UI state
const btn = document.getElementById("share-as-image-btn");
const originalBtnHtml = btn ? btn.innerHTML : '';
setButtonState(btn, true);
let tempElement = null;
try {
// Expand selection to full lines and clone content
const expandedRange = expandRangeToFullLines(originalRange, differenceElement);
const selectedFragment = expandedRange.cloneContents();
// Count lines for footer
const selectedLines = countLines(selectedFragment);
const totalLines = countLines(differenceElement);
// Create temporary element with proper styling
tempElement = createCaptureElement(selectedFragment, differenceElement);
// Append footer to innerWrapper (inside the border), not outerWrapper
tempElement._innerWrapper.appendChild(createFooter(selectedLines, totalLines));
// Add to DOM for rendering
document.body.appendChild(tempElement);
// Wait for rendering
await new Promise(resolve => setTimeout(resolve, RENDER_DELAY_MS));
// Capture to canvas
const canvas = await html2canvas(tempElement, {
scale: CANVAS_SCALE,
useCORS: true,
allowTaint: true,
logging: false,
backgroundColor: '#ffffff',
scrollX: 0,
scrollY: 0
});
// Validate canvas
if (canvas.width === 0 || canvas.height === 0) {
throw new Error("Canvas is empty - no content captured");
}
// Convert to JPEG
let jpeg = canvas.toDataURL("image/jpeg", JPEG_QUALITY);
if (jpeg === "data:," || jpeg.length < 100) {
throw new Error("Failed to generate image data");
}
// Add EXIF metadata
jpeg = addExifMetadata(jpeg);
// Display the image
displayImage(jpeg);
// Clear selection
selection.removeAllRanges();
} catch (error) {
console.error("Error generating image:", error);
alert("Failed to generate image: " + error.message);
} finally {
// Cleanup
if (tempElement && tempElement.parentNode) {
tempElement.parentNode.removeChild(tempElement);
}
setButtonState(btn, false, originalBtnHtml);
}
}