fix a ton of issues + improvement

apps/web/src/lib/preview/element-bounds.ts

@@ -2,9 +2,11 @@ import type { TimelineTrack, TimelineElement } from "@/types/timeline";
 import type { MediaAsset } from "@/types/assets";
 import { isMainTrack } from "@/lib/timeline";
 import {
+	DEFAULT_TEXT_ELEMENT,
 	DEFAULT_LINE_HEIGHT,
 	FONT_SIZE_SCALE_REFERENCE,
 } from "@/constants/text-constants";
+import { getTextVisualRect, measureTextBlock } from "@/lib/text/layout";
 
 export interface ElementBounds {
 	cx: number;
@@ -121,27 +123,36 @@ export function getElementBounds({
 
 			const lines = element.content.split("\n");
 			const lineMetrics = lines.map((line) => ctx.measureText(line));
-
-			let top = Number.POSITIVE_INFINITY;
-			let bottom = Number.NEGATIVE_INFINITY;
-			let maxWidth = 0;
-
-			for (let i = 0; i < lineMetrics.length; i++) {
-				const metrics = lineMetrics[i];
-				const y = i * lineHeightPx;
-				top = Math.min(
-					top,
-					y - (metrics.actualBoundingBoxAscent ?? scaledFontSize * 0.8),
-				);
-				bottom = Math.max(
-					bottom,
-					y + (metrics.actualBoundingBoxDescent ?? scaledFontSize * 0.2),
-				);
-				maxWidth = Math.max(maxWidth, metrics.width);
-			}
-
-			measuredWidth = maxWidth;
-			measuredHeight = bottom - top;
+			const block = measureTextBlock({
+				lineMetrics,
+				lineHeightPx,
+				fallbackFontSize: scaledFontSize,
+			});
+			const fontSizeRatio = element.fontSize / DEFAULT_TEXT_ELEMENT.fontSize;
+			const visualRect = getTextVisualRect({
+				textAlign: element.textAlign,
+				block,
+				background: element.background,
+				fontSizeRatio,
+			});
+			measuredWidth = visualRect.width;
+			measuredHeight = visualRect.height;
+			const localCenterX = visualRect.left + visualRect.width / 2;
+			const localCenterY = visualRect.top + visualRect.height / 2;
+			const scaledCenterX = localCenterX * element.transform.scale;
+			const scaledCenterY = localCenterY * element.transform.scale;
+			const rotationRad = (element.transform.rotate * Math.PI) / 180;
+			const cos = Math.cos(rotationRad);
+			const sin = Math.sin(rotationRad);
+			const rotatedCenterX = scaledCenterX * cos - scaledCenterY * sin;
+			const rotatedCenterY = scaledCenterX * sin + scaledCenterY * cos;
+			return {
+				cx: canvasWidth / 2 + element.transform.position.x + rotatedCenterX,
+				cy: canvasHeight / 2 + element.transform.position.y + rotatedCenterY,
+				width: measuredWidth * element.transform.scale,
+				height: measuredHeight * element.transform.scale,
+				rotation: element.transform.rotate,
+			};
 		}
 
 		const width = measuredWidth * element.transform.scale;

apps/web/src/lib/text/layout.ts

@@ -0,0 +1,167 @@
+import { DEFAULT_TEXT_BACKGROUND } from "@/constants/text-constants";
+import type { TextElement } from "@/types/timeline";
+
+type TextRect = {
+	left: number;
+	top: number;
+	width: number;
+	height: number;
+};
+
+export interface TextBlockMeasurement {
+	visualCenterOffset: number;
+	height: number;
+	maxWidth: number;
+}
+
+export function getMetricAscent({
+	metrics,
+	fallbackFontSize,
+}: {
+	metrics: TextMetrics;
+	fallbackFontSize: number;
+}): number {
+	return metrics.actualBoundingBoxAscent ?? fallbackFontSize * 0.8;
+}
+
+export function getMetricDescent({
+	metrics,
+	fallbackFontSize,
+}: {
+	metrics: TextMetrics;
+	fallbackFontSize: number;
+}): number {
+	return metrics.actualBoundingBoxDescent ?? fallbackFontSize * 0.2;
+}
+
+export function measureTextBlock({
+	lineMetrics,
+	lineHeightPx,
+	fallbackFontSize,
+}: {
+	lineMetrics: TextMetrics[];
+	lineHeightPx: number;
+	fallbackFontSize: number;
+}): TextBlockMeasurement {
+	let top = Number.POSITIVE_INFINITY;
+	let bottom = Number.NEGATIVE_INFINITY;
+	let maxWidth = 0;
+
+	for (let index = 0; index < lineMetrics.length; index++) {
+		const metrics = lineMetrics[index];
+		const lineY = index * lineHeightPx;
+		top = Math.min(
+			top,
+			lineY - getMetricAscent({ metrics, fallbackFontSize }),
+		);
+		bottom = Math.max(
+			bottom,
+			lineY + getMetricDescent({ metrics, fallbackFontSize }),
+		);
+		maxWidth = Math.max(maxWidth, metrics.width);
+	}
+
+	const height = bottom - top;
+	const visualCenterOffset = (top + bottom) / 2;
+
+	return { visualCenterOffset, height, maxWidth };
+}
+
+function getTextRect({
+	textAlign,
+	block,
+}: {
+	textAlign: TextElement["textAlign"];
+	block: TextBlockMeasurement;
+}): TextRect {
+	const left =
+		textAlign === "left" ? 0 : textAlign === "right" ? -block.maxWidth : -block.maxWidth / 2;
+
+	return {
+		left,
+		top: -block.height / 2,
+		width: block.maxWidth,
+		height: block.height,
+	};
+}
+
+function isTextBackgroundVisible({
+	background,
+}: {
+	background: TextElement["background"];
+}): boolean {
+	return Boolean(background.color) && background.color !== "transparent";
+}
+
+export function getTextBackgroundRect({
+	textAlign,
+	block,
+	background,
+	fontSizeRatio = 1,
+}: {
+	textAlign: TextElement["textAlign"];
+	block: TextBlockMeasurement;
+	background: TextElement["background"];
+	fontSizeRatio?: number;
+}): TextRect | null {
+	if (!isTextBackgroundVisible({ background })) {
+		return null;
+	}
+
+	const textRect = getTextRect({ textAlign, block });
+	const paddingX =
+		(background.paddingX ?? DEFAULT_TEXT_BACKGROUND.paddingX) * fontSizeRatio;
+	const paddingY =
+		(background.paddingY ?? DEFAULT_TEXT_BACKGROUND.paddingY) * fontSizeRatio;
+	const offsetX = background.offsetX ?? DEFAULT_TEXT_BACKGROUND.offsetX;
+	const offsetY = background.offsetY ?? DEFAULT_TEXT_BACKGROUND.offsetY;
+
+	return {
+		left: textRect.left - paddingX + offsetX,
+		top: textRect.top - paddingY + offsetY,
+		width: textRect.width + paddingX * 2,
+		height: textRect.height + paddingY * 2,
+	};
+}
+
+export function getTextVisualRect({
+	textAlign,
+	block,
+	background,
+	fontSizeRatio = 1,
+}: {
+	textAlign: TextElement["textAlign"];
+	block: TextBlockMeasurement;
+	background: TextElement["background"];
+	fontSizeRatio?: number;
+}): TextRect {
+	const textRect = getTextRect({ textAlign, block });
+	const backgroundRect = getTextBackgroundRect({
+		textAlign,
+		block,
+		background,
+		fontSizeRatio,
+	});
+
+	if (!backgroundRect) {
+		return textRect;
+	}
+
+	const left = Math.min(textRect.left, backgroundRect.left);
+	const top = Math.min(textRect.top, backgroundRect.top);
+	const right = Math.max(
+		textRect.left + textRect.width,
+		backgroundRect.left + backgroundRect.width,
+	);
+	const bottom = Math.max(
+		textRect.top + textRect.height,
+		backgroundRect.top + backgroundRect.height,
+	);
+
+	return {
+		left,
+		top,
+		width: right - left,
+		height: bottom - top,
+	};
+}

apps/web/src/lib/timeline/element-utils.ts

@@ -154,7 +154,14 @@ export function buildTextElement({
 				: DEFAULT_TEXT_ELEMENT.fontSize,
 		fontFamily: t.fontFamily ?? DEFAULT_TEXT_ELEMENT.fontFamily,
 		color: t.color ?? DEFAULT_TEXT_ELEMENT.color,
-		backgroundColor: t.backgroundColor ?? DEFAULT_TEXT_ELEMENT.backgroundColor,
+		background: {
+		color: t.background?.color ?? DEFAULT_TEXT_ELEMENT.background.color,
+		cornerRadius: t.background?.cornerRadius,
+		paddingX: t.background?.paddingX,
+		paddingY: t.background?.paddingY,
+		offsetX: t.background?.offsetX,
+		offsetY: t.background?.offsetY,
+	},
 		textAlign: t.textAlign ?? DEFAULT_TEXT_ELEMENT.textAlign,
 		fontWeight: t.fontWeight ?? DEFAULT_TEXT_ELEMENT.fontWeight,
 		fontStyle: t.fontStyle ?? DEFAULT_TEXT_ELEMENT.fontStyle,