封装代码，如下：

import scala.scalajs.js
import scala.scalajs.js.annotation._
package object pdfJS {

import org.scalajs.dom.CanvasRenderingContext2D

@JSGlobal("PDFJS")
@js.native
object PDFJS extends js.Object {
var workerSrc: String = js.native

def getDocument(url: String): PDFDocumentLoadingTask = js.native
}

@js.native
class PageViewport extends js.Object {
  val height: Double= js.native

  val width: Double = js.native
}


@js.native
class PDFPageProxy extends js.Object {
  def getViewport(scale: Double): PageViewport = js.native

  def render(params: js.Object): js.Promise[RenderTask] = js.native
}

@ScalaJSDefined
trait RenderContext extends js.Object {
  val canvasContext: CanvasRenderingContext2D
  val viewport: PageViewport
}


 @js.native
class RenderTask extends js.Object {

}

@js.native
class PDFDocumentProxy extends js.Object {
  def getPage(pageNumber: Int ): js.Promise[PDFPageProxy] = js.native

  val numPages: Int = js.native
}

@js.native
class PDFDocumentLoadingTask extends js.Object {
  def promise: js.Promise[PDFDocumentProxy] = js.native
  def onProgress:js.Object=js.native
}
}

这只是封装了一部分代码，还有好多东西由于没有用到就没有封装进去。目前PDFDocumentLoadingTask 中的onProgress的值一直为null 还没有理解，别的都可以正常使用。
下面是使用的代码：

object DrawPDF {

def draw(area: HTMLElement, url: String) = {

//1.8.618
PDFJS.workerSrc = "/zhishiku/static/js/pdf.worker.min.js"
val loadingTask = PDFJS.getDocument(url)

println(JSON.stringify(loadingTask))

println(loadingTask.onProgress)

loadingTask.promise.toFuture.map {
  rsp =>

    area.textContent = ""
    println(url + "PDF loaded")

    for (i <- 1 to rsp.numPages) {

      rsp.getPage(i).toFuture.onComplete {
        case Success(rsp1) =>
          println("Page loaded")


          val viewportDiv = rsp1.getViewport(1.5)

          val pdfArea = canvas("Your browser does not support the canvas element.").render

          area.appendChild(pdfArea)
          val context = pdfArea.getContext("2d").asInstanceOf[CanvasRenderingContext2D]


          pdfArea.height = viewportDiv.height.toInt+1
          pdfArea.width = viewportDiv.width.toInt+1

          val renderContext = new RenderContext {
            override val canvasContext = context
            override val viewport = viewportDiv
          }

          println(renderContext)
          println("2")

          val renderTask =
            try {
              rsp1.render(renderContext)
            }
            catch {
              case error: Exception =>
                error.printStackTrace()
                throw error
            }
          renderTask.toFuture.onComplete {
            case Success(rsp2) =>
              println("Page rendered")
            case Failure(error) =>
              println("rsp.render" + error)
          }
        case Failure(error) =>
          println("rsp.getPage()" + error)
        }
      }
    }
  }
}