使用线程将图像复制到剪贴板并管理线程

我有一个在图片框中保存图像的应用程序。当您按下ctrl+C时，它会将图像复制到剪贴板。我使用线程来执行实际的剪贴板操作。

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (keyData == (Keys.Control | Keys.C))
    {
        clipboardThread = new Thread(copy_to_clipboard);
        clipboardThread.SetApartmentState(ApartmentState.STA);
        clipboardThread.Start();
        return true;
    }
    return base.ProcessCmdKey(ref msg, keyData);
}
private void copy_to_clipboard()
{
    if (pic_display.Image != null)
    {
        using (MemoryStream stream = new MemoryStream())
        {
            clipboardStatus.Text = "Copying image to clipboard...";
            pic_display.Image.Save(stream, ImageFormat.Png);
            var data = new DataObject("PNG", stream);
            Clipboard.Clear();
            Clipboard.SetDataObject(data, true);
            clipboardStatus.Text = "Copied successfully!";
        }
    }
}

现在，如果我重复发送ctrl+C（例如：按住键），就会产生一个新的线程。我如何更改代码以重复使用剪贴板线程，并让它告诉我它当前是否正在复制数据，这样我就不会在它仍在工作时尝试执行另一个复制命令。

更新

现在它工作

我已将其更改为使用后台工作者

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (keyData == (Keys.Control | Keys.C))
    {
        if (!backgroundWorker1.IsBusy)
            backgroundWorker1.RunWorkerAsync();
        return true;
    }
    return base.ProcessCmdKey(ref msg, keyData);
}
private void copy_to_clipboard()
{
    using (var stream = new MemoryStream())
    {
        clipboardStatus.Text = "Copying image to clipboard...";
        pic_display.Invoke((Action)(() => {
            if (pic_display.Image != null)
              pic_display.Image.Save(stream, ImageFormat.Png); 
        }));
        if (stream.Position == 0) return; // No image was saved
        var data = new DataObject("PNG", stream);
        BeginInvoke ( (Action) ( ()=> {
            Clipboard.Clear();
            Clipboard.SetDataObject(data, true);
        }
        clipboardStatus.Text = "Copied successfully!";
    }
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    copy_to_clipboard();
}

但现在出现异常

Clipboard.Clear();

表示

Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it.

首先，您应该在从后台线程访问UI控件时调用：

private void copy_to_clipboard()
{
    using (var stream = new MemoryStream())
    {
        clipboardStatus.Text = "Copying image to clipboard...";
        pic_display.Invoke((Action)()=> { 
            if (pic_display.Image != null)
              pic_display.Image.Save(stream, ImageFormat.Png); 
        });
        if (stream.Position == 0) return; // No image was saved
        var data = new DataObject("PNG", stream);
        Clipboard.Clear();
        Clipboard.SetDataObject(data, true);
        clipboardStatus.Text = "Copied successfully!";
    }
}

然后从BackgroundWorker调用它。网上有很多这样的例子。

我建议在单击时执行Save操作——无论如何都应该在UI线程上执行。您可以使用InvokeRequired/Invoke；但是您无法控制Save何时接管UI线程。点击后可能会有相当长的时间，这会让用户感到不安。或者，它可能是之后用户更改图像。它会占用用户界面线程的任何时间，这太糟糕了；但从可用性的角度来看，离Click越近越好。在这种情况下，可能类似于：

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (keyData == (Keys.Control | Keys.C))
    {
        if (pic_display.Image != null)
        {
            MemoryStream stream = new MemoryStream())
            clipboardStatus.Text = "Copying image to clipboard...";
            pic_display.Image.Save(stream, ImageFormat.Png);
            clipboardThread = new Thread(copy_to_clipboard);
            clipboardThread.SetApartmentState(ApartmentState.STA);
            clipboardThread.Start(stream);
        }
        return true;
    }
    return base.ProcessCmdKey(ref msg, keyData);
}
private void copy_to_clipboard(object state)
{
    var stream = (Stream) state;
    try
    {
        var data = new DataObject("PNG", stream);
        Clipboard.Clear();
        Clipboard.SetDataObject(data, true);
        BeginInvoke((MethodInvoker) (() => clipboardStatus.Text = "Copied successfully!"));
    }
    finally
    {
        stream.Dispose();
    }
}

试试这样的东西：

object lockObj = new object();
        private void copy_to_clipboard()
        {
            lock (lockObj)
            {
                if (pictureBox1.Image != null)
                    {
                        using (MemoryStream stream = new MemoryStream())
                        {
                            clipboardStatus.Text = "Copying image to clipboard...";                            
                            pictureBox1.Image.Save(stream, ImageFormat.Png);
                            var data = new DataObject("PNG", stream);
                            Clipboard.Clear();
                            Clipboard.SetDataObject(data, true);                            
                            clipboardStatus.Text = "Copied successfully!";
                        }
                    } 
            }
        }

难道不能将线程存储为成员吗？除非我误解了这个问题，否则Thread.IsAlive会做你想做的事。但是，如果您正在修改UI控件，就像上面的海报所说的那样，您应该真正使用Invoke来确保这在UI线程上发生。


protected Thread clipboardThread;
protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
if (keyData == (Keys.Control | Keys.C))
{
    if (clipBoardThread == null)
    {
       clipboardThread = new Thread(copy_to_clipboard);
       clipboardThread.SetApartmentState(ApartmentState.STA);
       clipboardThread.IsBackGround = false;
    }
    if (!clipboardThread.IsAlive)
    {
       clipboardThread.Start();
    }
    return true;
}
return base.ProcessCmdKey(ref msg, keyData);
}
private void copy_to_clipboard()
{
if (pic_display.Image != null)
{
    using (MemoryStream stream = new MemoryStream())
    {
        clipboardStatus.Text = "Copying image to clipboard...";
        pic_display.Image.Save(stream, ImageFormat.Png);
        var data = new DataObject("PNG", stream);
        Clipboard.Clear();
        Clipboard.SetDataObject(data, true);
        clipboardStatus.Text = "Copied successfully!";
    }
}
}

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