export interface IToImageDataOptions {
    width?: number
    height?: number
    sx?: number
    sy?: number
    sw?: number
    sh?: number
}

/** 转换到 ImageData  */
export function toImageData(drawable: ImageBitmap | HTMLImageElement, opts: IToImageDataOptions = {}): ImageData {
    let canvas!: HTMLCanvasElement
    let ctx!: CanvasRenderingContext2D

    const {
        width = getWidth(drawable),
        height = getHeight(drawable),
        sx = 0,
        sy = 0,
        sw = getWidth(drawable),
        sh = getHeight(drawable),
    } = opts

    if (!canvas) {
        canvas = document.createElement("canvas")
        ctx = <any>canvas.getContext("2d")
        if (!ctx) throw new Error("Could not create canvas context")
    }

    canvas.width = width
    canvas.height = height
    ctx.clearRect(0, 0, canvas.width, canvas.height)

    ctx.drawImage(drawable, sx, sy, sw, sh, 0, 0, width, height)
    return ctx.getImageData(0, 0, width, height)
}

function getWidth(drawable: ImageBitmap | HTMLImageElement): number {
    if ("displayWidth" in drawable) {
        return (<any>drawable).displayWidth
    }
    return drawable.width
}

function getHeight(drawable: ImageBitmap | HTMLImageElement): number {
    if ("displayHeight" in drawable) {
        return (<any>drawable).displayHeight
    }
    return drawable.height
}