import { NonConstructiable } from '../foundation';
import { CrossPlatformCanvasElement, CrossPlatformOffscreenCanvas } from '../platform';
export interface FontMetrics {
    ascent: number;
    descent: number;
    fontSize: number;
    cssFontProp: string;
}
type MeasureOptions = {
    context: CanvasFillStrokeStyles & CanvasRect & CanvasTextDrawingStyles & CanvasText & CanvasImageData;
    canvas: CrossPlatformCanvasElement | CrossPlatformOffscreenCanvas;
    metricsString: string;
    baselineSymbol: string;
    baselineMultiplier: number;
    heightMultiplier: number;
};
export declare class FontMetrics extends NonConstructiable {
    static readonly HEIGHT_MULTIPLIER = 2;
    private static _defaultMeasureOptions?;
    static get defaultMeasureOptions(): MeasureOptions;
    /**
     * 获得字体的 ascent 和 descent 等信息
     *
     * 由于字体的选择是逐字进行的，也就是说即使某个字符周围都在某个字体中可以显示，但该字符在当前的字体文件中没有适合的图形，那么会继续尝试列表中靠后的字体
     *
     * 所以含有多个 font-family 时，测量结果可能不准确
     *
     * @param cssFontProp CSS 的 font 属性
     */
    static measure(cssFontProp: string, options?: Partial<MeasureOptions>): FontMetrics;
    static measureWidth(text: string, cssFontProp: string, cache: Record<string, number>): number;
}
export {};