From 49426f19cd8eaed7cf6c47999b66fee7ee637a56 Mon Sep 17 00:00:00 2001
From: Maze Winther <mazewinther@gmail.com>
Date: Fri, 27 Feb 2026 16:33:57 +0100
Subject: feat: implement keyframe animation system

Add keyframe support for transform, opacity, and volume properties.
Includes animation engine (interpolation, mutations, resolvers), timeline
markers with selection/snapping, properties panel toggles, keyframe-aware
renderer, and full undo/redo command support.

Also refactor element command constructors to object params, extract
timeline pixel math to pixel-utils.ts, and update cursor rules.
---
 apps/web/src/lib/timeline/pixel-utils.ts | 79 ++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 apps/web/src/lib/timeline/pixel-utils.ts

(limited to 'apps/web/src/lib/timeline/pixel-utils.ts')

diff --git a/apps/web/src/lib/timeline/pixel-utils.ts b/apps/web/src/lib/timeline/pixel-utils.ts
new file mode 100644
index 00000000..4c0c243c
--- /dev/null
+++ b/apps/web/src/lib/timeline/pixel-utils.ts
@@ -0,0 +1,79 @@
+import { TIMELINE_CONSTANTS } from "@/constants/timeline-constants";
+
+export const TIMELINE_INDICATOR_LINE_WIDTH_PX = 2;
+
+function getDevicePixelRatio({
+	devicePixelRatio,
+}: {
+	devicePixelRatio?: number;
+}): number {
+	if (
+		typeof devicePixelRatio === "number" &&
+		Number.isFinite(devicePixelRatio) &&
+		devicePixelRatio > 0
+	) {
+		return devicePixelRatio;
+	}
+
+	if (typeof window === "undefined") {
+		return 1;
+	}
+
+	if (Number.isFinite(window.devicePixelRatio) && window.devicePixelRatio > 0) {
+		return window.devicePixelRatio;
+	}
+
+	return 1;
+}
+
+export function getTimelinePixelsPerSecond({
+	zoomLevel,
+}: {
+	zoomLevel: number;
+}): number {
+	return TIMELINE_CONSTANTS.PIXELS_PER_SECOND * zoomLevel;
+}
+
+export function timelineTimeToPixels({
+	time,
+	zoomLevel,
+}: {
+	time: number;
+	zoomLevel: number;
+}): number {
+	return time * getTimelinePixelsPerSecond({ zoomLevel });
+}
+
+export function snapPixelToDeviceGrid({
+	pixel,
+	devicePixelRatio,
+}: {
+	pixel: number;
+	devicePixelRatio?: number;
+}): number {
+	const safeDevicePixelRatio = getDevicePixelRatio({ devicePixelRatio });
+	return Math.round(pixel * safeDevicePixelRatio) / safeDevicePixelRatio;
+}
+
+export function timelineTimeToSnappedPixels({
+	time,
+	zoomLevel,
+	devicePixelRatio,
+}: {
+	time: number;
+	zoomLevel: number;
+	devicePixelRatio?: number;
+}): number {
+	const rawPixel = timelineTimeToPixels({ time, zoomLevel });
+	return snapPixelToDeviceGrid({ pixel: rawPixel, devicePixelRatio });
+}
+
+export function getCenteredLineLeft({
+	centerPixel,
+	lineWidthPx = TIMELINE_INDICATOR_LINE_WIDTH_PX,
+}: {
+	centerPixel: number;
+	lineWidthPx?: number;
+}): number {
+	return centerPixel - lineWidthPx / 2;
+}
-- 
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