我刚刚偶然发现了Backgroundworker对象，它似乎是我正在寻找的工具，可以在执行计算时使我的GUI响应。我正在为ArcGIS编写IO插件。
我正在ArcGIS外部进行一些数据处理，使用backgroundworker可以正常工作。但是当我将数据插入ArcGIS时，后台工作人员似乎将持续时间增加了9倍左右。将处理代码放在DoWork方法之外，可以将性能提高9倍。
我已经在网上读过这几个地方，但我没有多线程编程的经验，像STA和MTA这样的术语对我来说毫无意义。 link text 我也试图使用一个简单的线程实现，但结果相似。
有谁知道我能做些什么才能使用ArcGIS处理和维护响应式GUI？
编辑：我已经包含了我与后台工作者的交互示例。如果我将位于StartImporting方法中的代码放在cmdStart_Click方法中，它的执行速度会快得多。
private void StartImporting(object sender, DoWorkEventArgs e)
{
DateTime BeginTime = DateTime.Now;
// Create a new report object.
SKLoggingObject loggingObject = new SKLoggingObject("log.txt");
loggingObject.Start("Testing.");
SKImport skImporter = new SKImport(loggingObject);
try
{
// Read from a text box - no writing.
skImporter.Open(txtInputFile.Text);
}
catch
{
}
SKGeometryCollection convertedCollection = null;
// Create a converter object.
GEN_SK2ArcGIS converter = new GEN_SK2ArcGIS(loggingObject);
// Convert the data.
convertedCollection = converter.Convert(skImporter.GetGeometry());
// Create a new exporter.
ArcGISExport arcgisExporter = new ArcGISExport(loggingObject);
// Open the file.
// Read from a text box - no writing.
arcgisExporter.Open(txtOutputFile.Text);
// Insert the geometry collection.
try
{
arcgisExporter.Insert(convertedCollection);
}
catch
{
}
TimeSpan totalTime = DateTime.Now - BeginTime;
lblStatus.Text = "Done...";
}
private void ChangeProgress(object sender, ProgressChangedEventArgs e)
{
// If any message was passed, display it.
if (e.UserState != null && !((string)e.UserState).Equals(""))
{
lblStatus.Text = (string)e.UserState;
}
// Update the progress bar.
pgStatus.Value = e.ProgressPercentage;
}
private void ImportDone(object sender, RunWorkerCompletedEventArgs e)
{
// If the process was cancelled, note this.
if (e.Cancelled)
{
pgStatus.Value = 0;
lblStatus.Text = "Operation was aborted by user...";
}
else
{
}
}
private void cmdStart_Click(object sender, EventArgs e)
{
// Begin importing the sk file to the geometry collection.
// Initialise worker.
bgWorker = new BackgroundWorker();
bgWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(ImportDone);
bgWorker.ProgressChanged += new ProgressChangedEventHandler(ChangeProgress);
bgWorker.DoWork += new DoWorkEventHandler(StartImporting);
bgWorker.WorkerReportsProgress = true;
bgWorker.WorkerSupportsCancellation = true;
// Start worker.
bgWorker.RunWorkerAsync();
}
private void cmdCancel_Click(object sender, EventArgs e)
{
bgWorker.CancelAsync();
}
亲切的问候，卡斯帕
答案 0 :(得分：3)
在ArcGIS中使用COM对象时，应该使用STA线程是正确的。尽管如此，您仍然可以获得BackgroundWorker的便利，后者始终是系统线程池中的MTA线程。
private static void OnBackgroundWorkerDoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = (BackgroundWorker)sender;
ToolToStart tool = e.Argument as ToolToStart;
if (tool != null)
{
tool.BackgroundWorker = worker;
// The background worker thread is an MTA thread,
// and should not operate on ArcObjects/COM types.
// Instead we create an STA thread to run the tool in.
// When the the tool finishes the infomation from the STA thread
// is transferred to the background worker's event arguments.
Thread toolThread = new Thread(STAThreadStart);
toolThread.SetApartmentState(ApartmentState.STA);
toolThread.Start(tool);
toolThread.Join();
e.Cancel = m_ToolCanceled;
e.Result = m_ToolResult;
}
}
STA线程现在可以使用BackgroundWorker的方法，例如报告进度，检查取消和报告结果。
protected virtual void StatusUpdateNotify(ProgressState progressState)
{
if (BackgroundWorker.CancellationPending)
{
throw new OperationCanceledException();
}
BackgroundWorker.ReportProgress(progressState.Progress, progressState);
}
除了在ArcGIS对象上操作时仅使用STA线程，您不应在两个thred之间共享对象。从您的代码中，您似乎可以从后台工作人员lblStatus.Text = "Done...";访问GUI，这可以在例如RunWorkerComplete的委托。
答案 1 :(得分：1)
通常，为了维护响应式GUI，您需要执行在不同线程中执行工作的代码。使用BeginInvoke方法使用.net非常容易：http://msdn.microsoft.com/en-us/library/aa334867(VS.71).aspx
简而言之，将所有非GUI代码包含在单独的类（或类）中，而不是直接调用每个方法，您创建一个委托并在其上调用BeginInvoke方法。然后该方法将关闭，并且不与GUI进一步交互。如果您希望更新GUI（例如进度条），那么您可以从类中引发事件并从GUI中捕获它们，但是您需要确保以线程安全的方式更新控件。如果希望GUI在方法完成时更新，则可以使用EndInvoke方法来处理
答案 2 :(得分：1)
我一直在努力寻找解决方案，以下是我最终要做的事情。代码是从各种文件中剪切和粘贴的，并提供给我一个想法。它演示了如何使用线程调用与ArcGIS通信的方法。该代码允许我更新主线程中的GUI，中止操作，并执行后期操作。我最终使用了我最初发布的链接中的第一个线程部分。
最初性能下降的原因可能是ArcGIS需要的单线程单元（STA）。 Backgroundworker似乎是MTA，因此不适合使用ArcGIS
好吧，我希望我没有忘记任何事情，并且可以自由地编辑我的解决方案。它既可以帮助我，也可能帮助其他人为ArcGIS开发东西。
public class Program
{
private volatile bool AbortOperation;
Func<bool> AbortOperationDelegate;
FinishProcessDelegate finishDelegate;
UpdateGUIDelegate updateGUIDelegate;
private delegate void UpdateGUIDelegate(int progress, object message);
private delegate void FinishProcessDelegate();
private void cmdBegin_Click(...)
{
// Create finish delegate, for determining when the thread is done.
finishDelegate = new FinishProcessDelegate(ProcessFinished);
// A delegate for updating the GUI.
updateGUIDelegate = new UpdateGUIDelegate(UpdateGUI);
// Create a delegate function for abortion.
AbortOperationDelegate = () => AbortOperation;
Thread BackgroundThread = new Thread(new ThreadStart(StartProcess));
// Force single apartment state. Required by ArcGIS.
BackgroundThread.SetApartmentState(ApartmentState.STA);
BackgroundThread.Start();
}
private void StartProcess()
{
// Update GUI.
updateGUIDelegate(0, "Beginning process...");
// Create object.
Converter converter = new Converter(AbortOperationDelegate);
// Parse the GUI update method to the converter, so it can update the GUI from within the converter.
converter.Progress += new ProcessEventHandler(UpdateGUI);
// Begin converting.
converter.Execute();
// Tell the main thread, that the process has finished.
FinishProcessDelegate finishDelegate = new FinishProcessDelegate(ProcessFinished);
Invoke(finishDelegate);
// Update GUI.
updateGUIDelegate(100, "Process has finished.");
}
private void cmdAbort_Click(...)
{
AbortOperation = true;
}
private void ProcessFinished()
{
// Post processing.
}
private void UpdateGUI(int progress, object message)
{
// If the call has been placed at the local thread, call it on the main thread.
if (this.pgStatus.InvokeRequired)
{
UpdateGUIDelegate guidelegate = new UpdateGUIDelegate(UpdateGUI);
this.Invoke(guidelegate, new object[] { progress, message });
}
else
{
// The call was made on the main thread, update the GUI.
pgStatus.Value = progress;
lblStatus.Text = (string)message;
}
}
}
public class Converter
{
private Func<bool> AbortOperation { get; set;}
public Converter(Func<bool> abortOperation)
{
AbortOperation = abortOperation;
}
public void Execute()
{
// Calculations using ArcGIS are done here.
while(...) // Insert your own criteria here.
{
// Update GUI, and replace the '...' with the progress.
OnProgressChange(new ProgressEventArgs(..., "Still working..."));
// Check for abortion at anytime here...
if(AbortOperation)
{
return;
}
}
}
public event ProgressEventHandler Progress;
private virtual void OnProgressChange(ProgressEventArgs e)
{
var p = Progress;
if (p != null)
{
// Invoke the delegate.
p(e.Progress, e.Message);
}
}
}
public class ProgressEventArgs : EventArgs
{
public int Progress { get; set; }
public string Message { get; set; }
public ProgressEventArgs(int _progress, string _message)
{
Progress = _progress;
Message = _message;
}
}
public delegate void ProgressEventHandler(int percentProgress, object userState);