/**
 * Windowing helpers for the paper editor's highlight overlay and gutter.
 * Rendering every token span and gutter row of a multi-thousand-line
 * `main.tex` on each keystroke is the editor's dominant cost, so the overlay
 * mounts only the lines around the textarea's viewport and pads the rest
 * with fixed-height spacers (the editor forbids soft wrap, so every logical
 * line is exactly {@link EDITOR_LINE_HEIGHT_PX} tall). All functions here are
 * pure; the component owns the scroll state.
 * @module dsh-client-ui-mimir/client/highlight-window
 */
import type { LatexToken } from './latex-highlight.ts';
/** Editor line height in px; keep in sync with `.editor` in the module CSS. */
export declare const EDITOR_LINE_HEIGHT_PX = 19;
/** Extra lines mounted above/below the viewport so small scrolls reuse the DOM. */
export declare const HIGHLIGHT_OVERSCAN_LINES = 20;
/** A half-open line window: `start` inclusive, `end` exclusive, both 0-based. */
export interface LineRange {
    readonly start: number;
    readonly end: number;
}
/**
 * Convert a scroll position into the line window to mount, clamped to
 * `[0, lineCount]` and widened by the overscan on both sides.
 * @param scrollTop - the textarea's vertical scroll offset in px.
 * @param viewportHeight - the textarea's visible height in px (0 when hidden).
 * @param lineCount - total logical lines of the source.
 * @param lineHeight - the fixed editor line height in px.
 * @param overscan - extra lines mounted on each side of the viewport.
 * @returns the clamped half-open line window.
 */
export declare function visibleLineRange(scrollTop: number, viewportHeight: number, lineCount: number, lineHeight?: number, overscan?: number): LineRange;
/**
 * Split a flat token list into one token list per logical line. Newlines are
 * consumed by the split, so the concatenation of `lines[i]` equals
 * `content.split('\n')[i]`; a token spanning lines (only `$$...$$` math and
 * `plain` runs can) is divided at the line boundary with its type preserved.
 * @param tokens - the full-document tokens from `tokenizeLatex`.
 * @returns per-line token lists; `lines.length` is the source's line count.
 */
export declare function splitTokensByLine(tokens: readonly LatexToken[]): LatexToken[][];
/**
 * Display width of one line in monospace columns: a tab advances to the next
 * multiple of `tabSize`, East-Asian wide code points count double, everything
 * else counts one. Heuristic by design — it only picks the sizer line that
 * keeps the overlay's scrollable width in step with the textarea's.
 * @param line - one logical source line (no trailing newline).
 * @param tabSize - the editor's tab stop (CSS `tab-size`).
 * @returns the line's width in `ch` columns.
 */
export declare function displayColumns(line: string, tabSize?: number): number;
/**
 * Pick the widest line by {@link displayColumns}. The overlay renders it in a
 * zero-height hidden sizer so its scrollable width matches the textarea's
 * even though only a window of lines is mounted (the browser measures the
 * glyphs itself, so tabs and wide chars expand exactly as in the textarea).
 * @param lines - the source split into logical lines.
 * @param tabSize - the editor's tab stop (CSS `tab-size`).
 * @returns the widest line's text, or `''` for an empty source.
 */
export declare function widestLine(lines: readonly string[], tabSize?: number): string;
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