import { ReplaceCommand } from "ssg-api";
import { HtmlRR0Context } from "./RR0Context.js";
import { Canvas, CanvasRenderingContext2D } from "canvas";
import { TimeService, TimeTextBuilder } from "./time/index.js";
/**
 * Create a preview image for each page sharing.
 */
export declare class OpenGraphCommand implements ReplaceCommand<HtmlRR0Context> {
    protected outDir: string;
    protected timeFiles: string[];
    protected baseUrl: string;
    protected timeService: TimeService;
    readonly timeTextBuilder: TimeTextBuilder;
    protected width: number;
    protected height: number;
    protected num: number;
    constructor(outDir: string, timeFiles: string[], baseUrl: string, timeService: TimeService, timeTextBuilder: TimeTextBuilder, width?: number, height?: number);
    execute(context: HtmlRR0Context): Promise<void>;
    getInfoStr(context: HtmlRR0Context): string;
    contentStepEnd(): Promise<void>;
    /**
     * Draw text on the canvas, with line returns when required.
     *
     * @param canvasCtx
     * @param text The text to write.
     * @param margin
     * @param lineHeight
     * @param font
     * @protected
     */
    protected drawText(canvasCtx: CanvasRenderingContext2D, text: string, margin: number, lineHeight: number, font: string): void;
    /**
     * Draw a left-to-right gradient from white to transparent.
     *
     * @param canvasCtx
     * @param widthRatio
     * @param startColor
     * @param endColor
     * @private
     */
    protected drawGradient(canvasCtx: CanvasRenderingContext2D, widthRatio: number, startColor?: string, endColor?: string): void;
    readonly supportedFiles = "img[src$='.png'],img[src$='.jpg'],img[src$='.gif']";
    /**
     * Draw a height-scaled image on the right of the canvas.
     *
     * @param context
     * @param canvasCtx
     * @param dy
     * @protected
     */
    protected drawImage(context: HtmlRR0Context, canvasCtx: CanvasRenderingContext2D, dy?: number): Promise<number>;
    protected writeImageFile(context: HtmlRR0Context, canvas: Canvas): string;
}