refactor(renderer): extract artboard checkerboard drawing

renderer/artboard.ts

@@ -0,0 +1,21 @@
+import type { Artboard } from "@core/artboard";
+import type { ViewportState } from "@editor/state";
+import { renderCheckerboard } from "./checkerboard";
+import type { ScreenRect, WebGlRendererContext } from "./types";
+
+export function renderArtboard(context: WebGlRendererContext, artboard: Artboard, viewport: ViewportState) {
+  const rect = artboardScreenRect(context.canvas, artboard, viewport);
+
+  if (artboard.backgroundColor === "transparent") {
+    renderCheckerboard(context, rect, Math.max(4, Math.round(12 * viewport.zoom)));
+  }
+}
+
+function artboardScreenRect(canvas: HTMLCanvasElement, artboard: Artboard, viewport: ViewportState): ScreenRect {
+  return {
+    x: Math.round(canvas.width / 2 + (artboard.bounds.x - viewport.center.x) * viewport.zoom),
+    y: Math.round(canvas.height / 2 + (artboard.bounds.y - viewport.center.y) * viewport.zoom),
+    w: Math.max(0, Math.round(artboard.bounds.w * viewport.zoom)),
+    h: Math.max(0, Math.round(artboard.bounds.h * viewport.zoom)),
+  };
+}