Clipboard.SetImage不起作用

Question

I'm trying to download image from a URL and set it to the Clipboard (WPF). I can paste image to Paint but not to a local directory.

Here is my codes downloading and setting to clipboard:

var request = WebRequest.Create(urlImg); // urlImg  - url of image
var response = request.GetResponse();
var responseStream = response.GetResponseStream();
var bitmap2 = new Bitmap(responseStream);

var orgimg = LoadBitmap2(bitmap2); // converting to BitmapSource
Clipboard.SetImage(orgimg);

Answer 1

When you cut/copy and paste an image to the file system only the path(s) are in the clipboard data.

If you want to 'paste' a downloaded image to a directory you'll need to emulate that behaviour:

1. Write the downloaded image to a temp directory
2. Set up the clipboard with the appropriate paste data (see DataFormats.FileDrop )
3. Make sure the mode is set to 'cut' so that the image isn't left in the temp location

string url = "http://example.com/images/someimage.jpeg";
var img = GetImageFromUrl(url);

//write the image to a temporary location (todo: purge it later)
var tmpFilePath = Path.Combine(Path.GetTempPath(), Path.GetFileName(url));
img.Save(tmpFilePath);

//group image(s)
var imgCollection = new System.Collections.Specialized.StringCollection();
imgCollection.Add(tmpFilePath);

//changing the drop affect to 'move' from the temp location
byte[] moveEffect = new byte[] { 2, 0, 0, 0 };
MemoryStream dropEffect = new MemoryStream();
dropEffect.Write(moveEffect, 0, moveEffect.Length);

//set up our clipboard data
DataObject data = new DataObject();
data.SetFileDropList(imgCollection);
data.SetData("Preferred DropEffect", dropEffect);

//push it all to the clipboard
Clipboard.Clear();
Clipboard.SetDataObject(data, true);

Where GetImageFromUrl() is:

private System.Drawing.Image GetImageFromUrl(string url)
{
    HttpWebRequest httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);

    using (HttpWebResponse httpWebReponse = (HttpWebResponse)httpWebRequest.GetResponse())
    {
        using (Stream stream = httpWebReponse.GetResponseStream())
        {
            return System.Drawing.Image.FromStream(stream);
        }
    }
}

Note: You'll need to add a reference to System.Drawing for the Image class. I'm sure there's an alternative in the WPF spaces.

• MSDN System.Windows.Forms.Clipboard
• How the clipboard works, pt 1
• How the clipboard works, pt 2