從PictureBox將圖像上傳到服務器

Question

我在form1上有一個pictureBox和一個按鈕。當按鈕被點擊時，它應該將文件上傳到服務器。現在我正在使用下面的方法。首先在本地保存圖像，然後上傳到服務器：

Bitmap bmp = new Bitmap(this.form1.pictureBox1.Width, this.form1.pictureBox1.Height); 
Graphics g = Graphics.FromImage(bmp); 
Rectangle rect = this.form1.pictureBox1.RectangleToScreen(this.form1.pictureBox1.ClientRectangle); 
g.CopyFromScreen(rect.Location, Point.Empty, this.form1.pictureBox1.Size); 
g.Dispose(); 
bmp.Save("filename", ImageFormat.Jpeg); 

然後上傳該文件：

using (var f = System.IO.File.OpenRead(@"F:\filename.jpg")) 
{ 
    HttpClient client = new HttpClient(); 
    var content = new StreamContent(f); 
    var mpcontent = new MultipartFormDataContent(); 
    content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg"); 
    mpcontent.Add(content); 
    client.PostAsync("http://domain.com/upload.php", mpcontent); 
} 

在StreamContent我不能使用位圖型。如何直接從pictureBox流式傳輸圖像，而不是直接將其保存爲文件？

我想出使用MemoryStream的下面的代碼，但上傳的文件大小是0使用這種方法。爲什麼？

byte[] data; 

using (MemoryStream m = new MemoryStream()) 
{ 
    bmp.Save(m, ImageFormat.Png); 
    m.ToArray(); 
    data = new byte[m.Length]; 
    m.Write(data, 0, data.Length); 

    HttpClient client = new HttpClient(); 
    var content = new StreamContent(m); 
    var mpcontent = new MultipartFormDataContent(); 
    content.Headers.ContentType = new MediaTypeHeaderValue("image/png"); 
    mpcontent.Add(content, "file", filename + ".png"); 
    HttpResponseMessage response = await client.PostAsync("http://domain.com/upload.php", mpcontent); 
    //response.EnsureSuccessStatusCode(); 
    string body = await response.Content.ReadAsStringAsync(); 
    MessageBox.Show(body); 
} 

Answer 1

我不知道這是否是做了正確的方式，但我已經通過創建一個新的數據流，然後複製前輩一到它解決了這個問題：

using (MemoryStream m = new MemoryStream()) 
{ 
    m.Position = 0; 
    bmp.Save(m, ImageFormat.Png); 
    bmp.Dispose(); 
    data = m.ToArray(); 
    MemoryStream ms = new MemoryStream(data); 
    // Upload ms 
} 

Answer 2

Image returnImage = Image.FromStream(....);