@mlightcad/shx-parser/dist/glyphLayout.d.ts

A TypeScript library for parsing AutoCAD SHX font files

import { ShxAdvanceWidthStrategy } from './advanceWidthStrategy';
import { ShxFontContentData, ShxFontData } from './fontData';
import { ShxShape } from './shape';
/**
 * Scaled font metrics derived from shape #0 (`baseUp`, `baseDown`, `height`, `width`).
 *
 * These values describe the font cell at a target render size. Text renderers use them
 * to align mixed-font lines on a shared baseline without modifying individual glyphs.
 */
export interface ShxFontMetrics {
    /** Target render size (font cell height in drawing units) */
    size: number;
    /** Distance from the baseline to the top of the cap band */
    capHeight: number;
    /** Distance from the baseline downward into the descender band */
    descenderHeight: number;
    /** Scaled cell width */
    cellWidth: number;
    /** Sum of cap and descender bands (`capHeight + descenderHeight`) */
    totalHeight: number;
}
/**
 * Computes scaled font metrics for a target render size.
 *
 * @param content - Parsed font content from shape #0
 * @param size - Target font size in drawing units
 */
export declare function computeFontMetrics(content: ShxFontContentData, size: number): ShxFontMetrics;
/**
 * True when a SHAPES text font (shape #0 present) stores glyphs in UNIFONT-style
 * top-origin coordinates: ink extends well below the descender band unless shifted
 * by {@link ShxFontMetrics.capHeight}. gdt.shx is a common example.
 */
export declare function shapeEncodedWithTopOrigin(fontData: ShxFontData, shape: ShxShape, metrics: ShxFontMetrics): boolean;
/**
 * True when a UNIFONT glyph already encodes with the baseline at y = 0 and ink
 * above it (for example isocp.shx, tssdeng.shx with dualOrientation).
 *
 * These fonts must not receive the capHeight shift applied to top-origin UNIFONTs.
 */
export declare function unifontUsesBaselineOrigin(shape: ShxShape, metrics: ShxFontMetrics): boolean;
/**
 * Detects the median baseline ink padding for a BIGFONT with no descender band.
 *
 * Extended-style BIGFONT files such as hztxt.shx encode full-width Han glyphs with
 * their lowest ink above y = 0. When paired with baseline-origin UNIFONT primaries
 * (tssdeng.shx), ASCII digits sit on y = 0 while CJK appears visually higher.
 * Layout shifts these BIGFONT glyphs down by the detected padding so mixed lines
 * share a common visual baseline without cross-font reference metrics.
 *
 * @param fontData - Parsed font header and content
 * @param getRawShape - Returns scaled raw geometry for a character code
 * @param size - Font size used when sampling glyph geometry (typically shape #0 height)
 * @returns Median minimum y of sampled body glyphs in font units at `size`
 */
export declare function detectBigfontBaselineInkPadding(fontData: ShxFontData, getRawShape: (code: number) => ShxShape | undefined, size: number): number;
/**
 * Detects whether a UNIFONT file encodes horizontal glyphs with baseline at y = 0.
 *
 * Samples common ASCII letter/digit codes from the font. When any sample matches
 * {@link unifontUsesBaselineOrigin}, the whole font skips capHeight shifting so
 * punctuation such as hyphen and tilde keep their in-cell vertical positions.
 */
export declare function detectUnifontBaselineOriginFont(fontData: ShxFontData, getRawShape: (code: number) => ShxShape | undefined, size: number): boolean;
/**
 * Applies font metrics to scaled SHX geometry for text layout.
 *
 * Raw {@link ShxFont.getCharShape} output keeps encoded coordinates from the SHX file;
 * this function repositions glyphs so mixed-font lines share a common baseline at y = 0.
 */
export declare function alignShxGlyphForLayout(shape: ShxShape, fontData: ShxFontData, size: number, advanceStrategy?: ShxAdvanceWidthStrategy, unifontBaselineOriginFont?: boolean, bigfontBaselineInkPaddingNative?: number): ShxShape;