Function buildScrollMarker

Lib/profiling/sampling/_heatmap_assets/heatmap.js:146–185

()

// ============================================================================

function buildScrollMarker() {
    const existing = document.getElementById('scroll_marker');
    if (existing) existing.remove();

    if (document.body.scrollHeight <= window.innerHeight) return;

    const allLines = document.querySelectorAll('.code-line');
    const lines = Array.from(allLines).filter(line => line.style.display !== 'none');
    const markerScale = window.innerHeight / document.body.scrollHeight;
    const lineHeight = Math.min(Math.max(3, window.innerHeight / lines.length), 10);
    const maxSamples = Math.max(...Array.from(lines, getSampleCount));

    const scrollMarker = createElement('div', '');
    scrollMarker.id = 'scroll_marker';

    let prevLine = -99, lastMark, lastTop;

    lines.forEach((line, index) => {
        const samples = getSampleCount(line);
        if (samples === 0) return;

        const lineTop = Math.floor(line.offsetTop * markerScale);
        const lineNumber = index + 1;
        const intensityClass = maxSamples > 0 ? (intensityToClass(samples / maxSamples) || 'cold') : 'cold';

        if (lineNumber === prevLine + 1 && lastMark?.classList.contains(intensityClass)) {
            lastMark.style.height = `${lineTop + lineHeight - lastTop}px`;
        } else {
            lastMark = createElement('div', `marker ${intensityClass}`);
            lastMark.style.height = `${lineHeight}px`;
            lastMark.style.top = `${lineTop}px`;
            scrollMarker.appendChild(lastMark);
            lastTop = lineTop;
        }

        prevLine = lineNumber;
    });

    document.body.appendChild(scrollMarker);
}

function applyLineColors() {
    const lines = document.querySelectorAll('.code-line');