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// timeline-viewport.js - Viewport zoom/scroll control
export class ViewportController {
constructor(state, dom, renderCallback) {
this.state = state;
this.dom = dom;
this.renderCallback = renderCallback;
// Constants
this.TIMELINE_LEFT_PADDING = 20;
this.SCROLL_VIEWPORT_FRACTION = 0.4;
this.SMOOTH_SCROLL_SPEED = 0.1;
this.VERTICAL_SCROLL_SPEED = 0.3;
this.init();
}
init() {
// Zoom controls
this.dom.zoomSlider.addEventListener('input', e => this.handleZoomSlider(e));
// Scroll sync
this.dom.timelineContent.addEventListener('scroll', () => this.handleScroll());
// Wheel handling
const wheelHandler = e => this.handleWheel(e);
this.dom.timelineContent.addEventListener('wheel', wheelHandler, { passive: false });
this.dom.waveformContainer.addEventListener('wheel', wheelHandler, { passive: false });
// Prevent wheel bubbling from UI containers
document.querySelector('header').addEventListener('wheel', e => e.stopPropagation());
this.dom.propertiesPanel.addEventListener('wheel', e => e.stopPropagation());
document.querySelector('.zoom-controls').addEventListener('wheel', e => e.stopPropagation());
document.querySelector('.stats').addEventListener('wheel', e => e.stopPropagation());
}
handleZoomSlider(e) {
this.state.pixelsPerSecond = parseInt(e.target.value);
this.dom.zoomLevel.textContent = `${this.state.pixelsPerSecond}%`;
this.renderCallback('zoom');
}
handleScroll() {
const scrollLeft = this.dom.timelineContent.scrollLeft;
this.dom.cpuLoadCanvas.style.left = `-${scrollLeft}px`;
this.dom.waveformCanvas.style.left = `-${scrollLeft}px`;
document.getElementById('timeMarkers').style.transform = `translateX(-${scrollLeft}px)`;
this.updateIndicatorPosition(this.timeToBeats(this.state.playbackOffset), false);
}
handleWheel(e) {
e.preventDefault();
// Zoom with ctrl/cmd
if (e.ctrlKey || e.metaKey) {
this.handleZoomWheel(e);
return;
}
// Horizontal scroll
this.dom.timelineContent.scrollLeft += e.deltaY;
// Auto-scroll to active sequence
this.autoScrollToSequence();
}
handleZoomWheel(e) {
const rect = this.dom.timelineContent.getBoundingClientRect();
const mouseX = e.clientX - rect.left;
const scrollLeft = this.dom.timelineContent.scrollLeft;
const timeUnderCursor = (scrollLeft + mouseX) / this.state.pixelsPerSecond;
const zoomDelta = e.deltaY > 0 ? -10 : 10;
const newPixelsPerSecond = Math.max(10, Math.min(500, this.state.pixelsPerSecond + zoomDelta));
if (newPixelsPerSecond !== this.state.pixelsPerSecond) {
this.state.pixelsPerSecond = newPixelsPerSecond;
this.dom.zoomSlider.value = this.state.pixelsPerSecond;
this.dom.zoomLevel.textContent = `${this.state.pixelsPerSecond}%`;
this.renderCallback('zoomWheel');
this.dom.timelineContent.scrollLeft = timeUnderCursor * newPixelsPerSecond - mouseX;
this.updateIndicatorPosition(this.timeToBeats(this.state.playbackOffset), false);
}
}
autoScrollToSequence() {
const currentScrollLeft = this.dom.timelineContent.scrollLeft;
const viewportWidth = this.dom.timelineContent.clientWidth;
const slack = (viewportWidth / this.state.pixelsPerSecond) * 0.1;
const currentTime = (currentScrollLeft / this.state.pixelsPerSecond) + slack;
let targetSeqIndex = 0;
for (let i = 0; i < this.state.sequences.length; i++) {
if (this.state.sequences[i].startTime <= currentTime) targetSeqIndex = i;
else break;
}
if (targetSeqIndex !== this.state.lastActiveSeqIndex && this.state.sequences.length > 0) {
this.state.lastActiveSeqIndex = targetSeqIndex;
const seqDivs = this.dom.timeline.querySelectorAll('.sequence');
if (seqDivs[targetSeqIndex]) {
seqDivs[targetSeqIndex].classList.add('active-flash');
setTimeout(() => seqDivs[targetSeqIndex]?.classList.remove('active-flash'), 600);
}
}
const targetScrollTop = this.state.sequences[targetSeqIndex]?._yPosition || 0;
const currentScrollTop = this.dom.timelineContent.scrollTop;
const scrollDiff = targetScrollTop - currentScrollTop;
if (Math.abs(scrollDiff) > 5) {
this.dom.timelineContent.scrollTop += scrollDiff * this.VERTICAL_SCROLL_SPEED;
}
}
updateIndicatorPosition(beats, smoothScroll = false) {
const timelineX = beats * this.state.pixelsPerSecond;
const scrollLeft = this.dom.timelineContent.scrollLeft;
this.dom.playbackIndicator.style.left = `${timelineX - scrollLeft + this.TIMELINE_LEFT_PADDING}px`;
if (smoothScroll) {
const targetScroll = timelineX - this.dom.timelineContent.clientWidth * this.SCROLL_VIEWPORT_FRACTION;
const scrollDiff = targetScroll - scrollLeft;
if (Math.abs(scrollDiff) > 5) {
this.dom.timelineContent.scrollLeft += scrollDiff * this.SMOOTH_SCROLL_SPEED;
}
}
}
// Helper
timeToBeats(seconds) {
return seconds * this.state.bpm / 60.0;
}
}
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