/**
 * Drawing part structure check.
 *
 * When a drawing file contains `<xdr:graphicFrame>` nodes but neither a
 * classic `<c:chart>` nor a chartEx `<cx:chart>` reference inside them,
 * the graphic frame is dangling — Excel shows a placeholder or drops the
 * frame on load.
 *
 * We also scan anchor coordinates: every anchor must have `from` and
 * `to` child elements, and EMU values (`x`, `y`, `cx`, `cy`,
 * `colOff`, `rowOff`) when present must parse as finite non-negative
 * numbers. Excel rejects anchors with NaN coordinates outright.
 *
 * Finally we enforce the ChartEx drawing-wrapper invariants that
 * trigger "Removed Part: /xl/drawings/drawingN.xml (Drawing shape)"
 * in production Excel logs:
 *
 *   - Any `<cx:chart>` reference MUST live inside an
 *     `<mc:AlternateContent>` block. The Microsoft ChartEx schema was
 *     never part of the base OOXML spec, so Excel's strict loader
 *     requires MC substitution so legacy readers see a fallback shape.
 *   - The `<mc:Fallback>` MUST be non-empty. An empty Fallback
 *     collapses the anchor to nothing on clients that take that
 *     branch, and Excel's strict loader has been observed to reject
 *     the drawing even on the Choice branch when it sees the
 *     degenerate Fallback.
 *   - `<mc:AlternateContent>` lives INSIDE the `<xdr:twoCellAnchor>`
 *     shape slot (between `<xdr:to>` and `<xdr:clientData>`), NOT
 *     around the whole anchor. Wrapping the entire anchor duplicates
 *     `<xdr:from>`/`<xdr:to>` across Choice and Fallback, which Excel
 *     rejects even though MC substitution permits it in theory.
 */
import type { ValidationContext } from "./context.js";
export declare function checkDrawing(ctx: ValidationContext): void;