之後fileStream.CopyTo（memoryStream），memoryStream爲空

Question

所以，我有這個功能，得到BitmapImage，我需要將它保存到ISO存儲並轉換爲Base64（用於發送到服務器）。但是，從fileStream複製到memoryStream不成功。從已通過SaveJpeg()改變，所以你需要重置的fileStream當前位置

public void SetImage(BitmapImage bitmap) 
{ 
    if (isoFiles.FileExists(Settings.FILE_AVATAR_JPG)) 
     isoFiles.DeleteFile(Settings.FILE_AVATAR_JPG); 

    var fileStream = isoFiles.CreateFile(Settings.FILE_AVATAR_JPG); 
    var wb = new WriteableBitmap(bitmap); 
    wb.SaveJpeg(fileStream, 120, 120, 0, 85); // file is saved 

    var memoryStream = new MemoryStream(); 
    fileStream.CopyTo(memoryStream);   // here, memoryStream is null 
    byte[] result = memoryStream.ToArray(); 
    fileStream.Close(); 

    var base64 = Convert.ToBase64String(result); 
} 

Answer 1

Stream.CopyTo複印件;

var memoryStream = new MemoryStream(); 

fileStream.Position = 0; 
fileStream.CopyTo(memoryStream);