Progress on canvasses

src/lib/painter/canvas.ts

@@ -1,6 +1,47 @@
+import { tryCatch } from '@maxmorozoff/try-catch-tuple';
+import type { CursorPosition } from '../util/terminal';
+
+const setInitialEnd = (pos: {
+  origin: CursorPosition;
+  end?: CursorPosition;
+  lines?: number;
+}) => {
+  if (!pos.end || !pos.lines)
+    throw TypeError("One of 'end' or 'lines' must be set");
+  if (Object.keys(pos).includes('end') || Object.keys(pos).includes('end'))
+    throw TypeError("Cannot set both 'end' and 'lines'");
+  if (pos.end) return pos.end;
+  return {
+    row: pos.origin.row + pos.lines,
+    col: pos.origin.col,
+  };
+};
+
 export const createCanvas = (
-  paint: () => Promise<number, Error>,
-  cleanup?: () => Promise<number, Error>
+  pos: { origin: CursorPosition; end?: CursorPosition; lines?: number },
+  paint: () => Promise<number>,
+  cleanup?: () => Promise<number>
 ) => {
+  let currentOrigin = pos.origin;
+
+  let currentEnd;
+  const [endVal, endError] = tryCatch(() => setInitialEnd(pos));
+  if (endError) throw endError;
+  currentEnd = endVal;
+
+  paint();
+  //
+  // Paint function
+  //
+  // Restore origin position
+  // Clear to cursor end position
+  //
+  // API
+  // ---
+  // get origin
+  // get end
+  // move end
+  // get line count
+  // clear canvas
   return [1];
 };