导出图片

let spread = new GC.Spread.Sheets.Workbook(document.getElementById('ss'),{sheetCount:3})

let sheet = spread.getSheet(0)
let printInfo = sheet.printInfo() || new GC.Spread.Sheets.Print.PrintInfo()
//只有打印质量大于等于4时才会生成图片
printInfo.qualityFactor(5)
//需要将margin清除，否则导出图片会有空白图
printInfo.margin({top:0, bottom:0, left:0, right:0, header:0, footer:0});
//打印时隐藏列头          
printInfo.showColumnHeader(GC.Spread.Sheets.Print.PrintVisibilityType.hide)
// 打印时隐藏行头         
printInfo.showRowHeader(GC.Spread.Sheets.Print.PrintVisibilityType.hide)
//设置打印纸张，大一点导出的图片会在一张
printInfo.paperSize(new GC.Spread.Sheets.Print.PaperSize(GC.Spread.Sheets.Print.PaperKind.a3))

spread.bind(GC.Spread.Sheets.Events.BeforePrint,(s,e) => {
    let iframe = e.iframe
    let imgs = iframe.contentWindow.document.getElementsByTagName("img")
    for(let i=0; i<imgs.length; i++){
        let img = imgs[i]
        let canvas = document.createElement("canvas")
        canvas.height = img.naturalHeight
        canvas.width = img.naturalWidth
        let ctx = canvas.getContext('2d')
        ctx.fillStyle = '#fff'
        ctx.fillRect(0,0,canvas.width,canvas.height)
        ctx.drawImage(img,0,0)
        canvas.toBlob((blob) => {
            saveAs(blob,'print'+i+'.jpeg')
        })
        e.cancel = true
    }
})