1 files changed, 76 insertions, 0 deletions
diff --git a/apps/web/src/lib/preview/preview-coords.ts b/apps/web/src/lib/preview/preview-coords.ts
new file mode 100644
index 00000000..08c16735
--- /dev/null
+++ b/apps/web/src/lib/preview/preview-coords.ts
@@ -0,0 +1,76 @@
+export function screenToCanvas({
+	clientX,
+	clientY,
+	canvas,
+}: {
+	clientX: number;
+	clientY: number;
+	canvas: HTMLCanvasElement;
+}): { x: number; y: number } {
+	const rect = canvas.getBoundingClientRect();
+	const scaleX = canvas.width / rect.width;
+	const scaleY = canvas.height / rect.height;
+	return {
+		x: (clientX - rect.left) * scaleX,
+		y: (clientY - rect.top) * scaleY,
+	};
+}
+
+export function canvasToOverlay({
+	canvasX,
+	canvasY,
+	canvasRect,
+	containerRect,
+	canvasSize,
+}: {
+	canvasX: number;
+	canvasY: number;
+	canvasRect: DOMRect;
+	containerRect: DOMRect;
+	canvasSize: { width: number; height: number };
+}): { x: number; y: number } {
+	const scaleX = canvasRect.width / canvasSize.width;
+	const scaleY = canvasRect.height / canvasSize.height;
+	return {
+		x: canvasRect.left - containerRect.left + canvasX * scaleX,
+		y: canvasRect.top - containerRect.top + canvasY * scaleY,
+	};
+}
+
+export function positionToOverlay({
+	positionX,
+	positionY,
+	canvasRect,
+	containerRect,
+	canvasSize,
+}: {
+	positionX: number;
+	positionY: number;
+	canvasRect: DOMRect;
+	containerRect: DOMRect;
+	canvasSize: { width: number; height: number };
+}): { x: number; y: number } {
+	const scaleX = canvasRect.width / canvasSize.width;
+	const scaleY = canvasRect.height / canvasSize.height;
+	const centerScreenX =
+		canvasRect.left - containerRect.left + (canvasSize.width / 2) * scaleX;
+	const centerScreenY =
+		canvasRect.top - containerRect.top + (canvasSize.height / 2) * scaleY;
+	return {
+		x: centerScreenX + positionX * scaleX,
+		y: centerScreenY + positionY * scaleY,
+	};
+}
+
+export function getDisplayScale({
+	canvasRect,
+	canvasSize,
+}: {
+	canvasRect: DOMRect;
+	canvasSize: { width: number; height: number };
+}): { x: number; y: number } {
+	return {
+		x: canvasRect.width / canvasSize.width,
+		y: canvasRect.height / canvasSize.height,
+	};
+}