Question

我有一个应用程序，用于在图片框中保存图像。按ctrl + C时，它会将图像复制到剪贴板。我使用一个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），将产生一个新线程。如何更改代码以便重新使用剪贴板线程，并让它告诉我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

现在可行了

我已将其更改为使用后台工作程序

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();
}

但是现在

发生了异常

Clipboard.Clear();

说

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.

Answer 1

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。网上有很多例子。

Answer 2

我建议在点击期间进行保存 - 无论如何你应该在UI线程上进行保存。你可以使用InvokeRequired / Invoke;但是你无法控制Save何时接管UI线程。点击后可能会花费相当多的时间并让用户感到不安。或者，在用户更改图像后，它可能是。它很糟糕，它将需要任何时间远离UI线程;但从可用性的角度来看，越接近点击越好。在这种情况下，可能会像：

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(); } }

Answer 3

尝试类似的东西：

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!";
                        }
                    } 
            }
        }

Answer 4

您不能只将该主题存储为成员吗？除非我误解了这个问题，否则Thread.IsAlive会做你想要的。但是，如果你正在修改UI控件作为上面的海报说你应该使用Invoke来确保在UI线程上发生这种情况。



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!";
    }
}
}

使用线程将图像复制到剪贴板并管理线程

4 个答案: