从 c#.net 桌面应用程序中的 picturebox.image 下载图像

Question

我正在开发一个桌面应用程序，我想在其中执行特定任务，即将图像保存在数据库中、从数据库中获取图像并在 PictureBox 中显示和从 Picturebox Tool 下载图像并保存在文件夹中

这是任务代码，

1. 将图像保存在数据库中，因为我使用 ImageToBase64 函数以字符串格式保存在数据库中。喜欢：ImageToBase64(pictureBox1.Image, System.Drawing.Imaging.ImageFormat.Jpeg)

ImageToBase64 函数代码：

public string ImageToBase64(Image image, System.Drawing.Imaging.ImageFormat format)
{
    using (MemoryStream ms = new MemoryStream())
    {
        if (image != null)
        {
            // Convert Image to byte[]
            image.Save(ms, format);
            byte[] imageBytes = ms.ToArray();

            // Convert byte[] to Base64 String
            string base64String = Convert.ToBase64String(imageBytes);
            return base64String;
        }
        else
        {
            return null;
        }
    }
}

现在从数据库中获取图像并在图片框中显示图像

picturebox1.image = Base64ToImage(dtSelStock.Rows[0]["DesignImage"].ToString())

Base64ToImage 函数代码：

public Image Base64ToImage(string base64String)
{
    if (base64String != "")
    {
        // Convert Base64 String to byte[]
        byte[] imageBytes = Convert.FromBase64String(base64String);
        MemoryStream ms = new MemoryStream(imageBytes, 0,
          imageBytes.Length);

        // Convert byte[] to Image
        ms.Write(imageBytes, 0, imageBytes.Length);
        Image image = Image.FromStream(ms, true);
        return image;
    }
    else
    {
        return null;
    }
}

所以，这两个任务完美地工作。但是第三个也是最后一个任务是从图片框中将图像保存在文件夹中。我尝试了一些代码但没有正常工作，实际上显示错误，即

pictureBox1.Image.Save("D\\Image\\'" + pictureBox1.Image + "'", ImageFormat.JPEGImage);

Answer 1

以下代码 sn-p 重现了您的问题。

   var dataString = ImageToBase64(pictureBox1.Image, System.Drawing.Imaging.ImageFormat.Jpeg);
   pictureBox2.Image = Base64ToImage(dataString);
   pictureBox2.Image.Save("D\\Images\\'" + pictureBox2.Image + "'", System.Drawing.Imaging.ImageFormat.Jpeg);

与"D\\Image\\'" + pictureBox1.Image + "'"有关

我在运行这些 sn-ps 时收到以下异常堆栈跟踪

System.Runtime.InteropServices.ExternalException
  HResult=0x80004005
  Message=A generic error occurred in GDI+.
  Source=System.Drawing
  StackTrace:
   at System.Drawing.Image.Save(String filename, ImageCodecInfo encoder, EncoderParameters encoderParams)
   at System.Drawing.Image.Save(String filename, ImageFormat format)
   at WindowsFormsApp1.Form1.button1_Click(Object sender, EventArgs e) in C:\Users\brcaswell\Source\Repos\WindowsFormsApp1\WindowsFormsApp1\Form1.cs:line 25
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at WindowsFormsApp1.Program.Main() in C:\Users\brcaswell\Source\Repos\WindowsFormsApp1\WindowsFormsApp1\Program.cs:line 19

它不是有效的文件路径并且\或目录不存在。

这将纠正它

   var filePath = @"D:\Images\";
   Directory.CreateDirectory(filePath);
   pictureBox2.Image.Save(Path.Combine(filePath, $"'{pictureBox2.Image}'"), System.Drawing.Imaging.ImageFormat.Jpeg);

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但是，您应该注意'{pictureBox2.Image}' 将导致类型的toString 并将'System.Drawing.Bitmap' 作为文件名。您应该更正它并包含文件扩展名

Path.Combine(filePath, "myImage.jpeg")

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另外，正如@'Peter Duniho' 在他对这个问题的评论中提到的，您应该考虑以与图片框控件的图形上下文无关的方式保存此图像文件。

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此外，您应该考虑将图像保存为数据库中的二进制 byte[]，而不是 base64 字符串表示形式。