如何将Bitmap转换为Base64字符串？

Question

我正在尝试捕获屏幕,然后将其转换为Base64字符串.这是我的代码:

Rectangle bounds = Screen.GetBounds(Point.Empty);
Bitmap bitmap = new Bitmap(bounds.Width, bounds.Height);

using (Graphics g = Graphics.FromImage(bitmap))
{
   g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);
}

// Convert the image to byte[]
System.IO.MemoryStream stream = new System.IO.MemoryStream();
bitmap.Save(stream, System.Drawing.Imaging.ImageFormat.Bmp);
byte[] imageBytes = stream.ToArray();

// Write the bytes (as a string) to the textbox
richTextBox1.Text = System.Text.Encoding.UTF8.GetString(imageBytes);

// Convert byte[] to Base64 String
string base64String = Convert.ToBase64String(imageBytes);

使用richTextBox进行调试,它显示:

BM6〜

因此,由于某种原因,字节不正确会导致base64String变为null.知道我做错了什么吗？谢谢.

Answer 1

我找到了解决问题的方法:

Bitmap bImage = newImage;  // Your Bitmap Image
System.IO.MemoryStream ms = new MemoryStream();
bImage.Save(ms, ImageFormat.Jpeg);
byte[] byteImage = ms.ToArray();
var SigBase64= Convert.ToBase64String(byteImage); // Get Base64

Answer 2

你通过做的字符System.Text.Encoding.UTF8.GetString(imageBytes)(几乎可以肯定)包含不可打印的字符.这可能会导致您只看到这几个字符.如果您首先将其转换为base64字符串,那么它将只包含可打印字符,并可以显示在文本框中:

// Convert byte[] to Base64 String
string base64String = Convert.ToBase64String(imageBytes);

// Write the bytes (as a Base64 string) to the textbox
richTextBox1.Text = base64String;

Answer 3

不需要byte[]......只需直接转换流(使用构造)

using (var ms = new MemoryStream())
{    
  using (var bitmap = new Bitmap(newImage))
  {
    bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
    var SigBase64= Convert.ToBase64String(ms.GetBuffer()); //Get Base64
  }
}