如何使用.ContinueWith調用異步任務

Question

我正在幾個位圖中構建一個位圖。 我正在做的是調用多個返回Task的方法。

我遇到的問題是死鎖，因為我正試圖通過.Result從.ContinueWith（）中的異步方法中檢索值，但此方法不起作用，因為它將把異步方法轉換為int同步方法，這導致我陷入僵局。

我的問題是如何在.ContinueWith中調用異步方法，或者實現這種方法的正確方法是什么？

我需要刪除.Result並正確調用異步方法Task。 正確的方法是什么？

這是我的代碼。

 public async static Task<Bitmap> RollUpDrawingsImage(IElevation elevation)
{
    int height = 0, width = 800;
    Bitmap completeDrawings = null;

    using (Bitmap elevationDoor = await ShopDrawing.Merger.MergeElevationAndDoor(elevation, RotateFlipType.Rotate90FlipNone))
    {
        using (Bitmap partsList = await MaterialsList.Manager.GetMaterialList(elevation).ContinueWith(async (ml) => await ml.Result.GetDrawing()).Result)
        {
            using (Bitmap optimized = await Optimization.Manager.GetOptimizedParts(elevation).ContinueWith(async (op) => await op.Result.GetDrawing()).Result)
            {
                using (Bitmap cutSheet = await CutSheet.Manager.GetCutSheet(elevation).ContinueWith(async (cs) => await cs.Result.GetDrawing()).Result)
                {
                    height = (elevationDoor.Height + optimized.Height + cutSheet.Height + partsList.Height);
                    completeDrawings = new Bitmap(width, height + 40);

                    using (var dc = Graphics.FromImage(completeDrawings))
                    {
                        dc.DrawImageUnscaled(elevationDoor, 0, 0);

                        dc.DrawImageUnscaled(partsList, 0, elevationDoor.Height + 10);

                        dc.DrawImageUnscaled(optimized, 0, (elevationDoor.Height + partsList.Height) + 20);

                        dc.DrawImageUnscaled(cutSheet, 0, (elevationDoor.Height + partsList.Height + optimized.Height) + 30);
                    };

                    return completeDrawings;
                }
            }
        }
    };
}

Answer 1

是什么讓您認為您需要ContinueWith ？

正在await Result的適當替換。 附帶說明一下，您應該以“異步”結束async方法：

public async static Task<Bitmap> RollUpDrawingsImage(IElevation elevation)
{
  int height = 0, width = 800;
  Bitmap completeDrawings = null;

  using (Bitmap elevationDoor = await ShopDrawing.Merger.MergeElevationAndDoorAsync(elevation, RotateFlipType.Rotate90FlipNone))
  using (Bitmap partsList = await (await MaterialsList.Manager.GetMaterialListAsync(elevation)).GetDrawingAsync())
  using (Bitmap optimized = await (await Optimization.Manager.GetOptimizedPartsAsync(elevation)).GetDrawingAsync())
  using (Bitmap cutSheet = await (await CutSheet.Manager.GetCutSheetAsync(elevation)).GetDrawingAsync())
  {
    height = (elevationDoor.Height + optimized.Height + cutSheet.Height + partsList.Height);
    completeDrawings = new Bitmap(width, height + 40);

    using (var dc = Graphics.FromImage(completeDrawings))
    {
      dc.DrawImageUnscaled(elevationDoor, 0, 0);
      dc.DrawImageUnscaled(partsList, 0, elevationDoor.Height + 10);
      dc.DrawImageUnscaled(optimized, 0, (elevationDoor.Height + partsList.Height) + 20);
      dc.DrawImageUnscaled(cutSheet, 0, (elevationDoor.Height + partsList.Height + optimized.Height) + 30);
    }

    return completeDrawings;
  }
}