[原译]C#制作进度窗体

ProgressForm form = new ProgressForm();form.DoWork += new ProgressForm.DoWorkEventHandler(form_DoWork); // 如果想为后台任务提供参数的话form.Argument = something;

DialogResult result = form.ShowDialog(); if (result == DialogResult.Cancel){ // 用户点击了取消 } else if (result == DialogResult.Abort){/ 未处理的异常抛出 // 你可以得到异常信息 MessageBox.Show(form.Result.Error.Message);} else if (result == DialogResult.OK){ // 正常完成 // 结果存储在 form.Result里}

void form_DoWork(ProgressForm sender, DoWorkEventArgs e){ // 得到参数 object myArgument = e.Argument; // 做一些耗时的任务... for ( int i = 0; i < 100; i++ ){ // 通知进度sender.SetProgress(i, " Step " + i.ToString() + " / 100... " ); // ... // 检查是否点击了取消 if (sender.CancellationPending){e.Cancel = true ; return ;}}}

public void SetProgress( string status); public void SetProgress( int percent); public void SetProgress( int percent, string status);

public partial class ProgressForm : Form{ public ProgressForm(){InitializeComponent();worker = new BackgroundWorker();worker.WorkerReportsProgress = true ;worker.WorkerSupportsCancellation = true ;worker.DoWork += new System.ComponentModel.DoWorkEventHandler(worker_DoWork);worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);} void worker_DoWork( object sender, DoWorkEventArgs e){} void worker_ProgressChanged( object sender, ProgressChangedEventArgs e){} void worker_RunWorkerCompleted( object sender, RunWorkerCompletedEventArgs e){}BackgroundWorker worker;}

public delegate void DoWorkEventHandler(ProgressForm sender, DoWorkEventArgs e); public event DoWorkEventHandler DoWork; void worker_DoWork( object sender, DoWorkEventArgs e){ // 后台任务开始 // 调用用户的事件处理程序 if (DoWork != null )DoWork( this , e);}

void ProgressForm_Load( object sender, EventArgs e){worker.RunWorkerAsync();}现在写一个方法通知进度。添加代码到ProgressChanged 事件处理程序中 public void SetProgress( int percent, string status){worker.ReportProgress(percent, status);} void worker_ProgressChanged( object sender, ProgressChangedEventArgs e){ if (e.ProgressPercentage >= progressBar.Minimum && e.ProgressPercentage <= progressBar.Maximum){progressBar.Value = e.ProgressPercentage;} if (e.UserState != null )labelStatus.Text = e.UserState.ToString();}

void buttonCancel_Click( object sender, EventArgs e){ // 通过worker我们要取消 worker.CancelAsync(); // 使取消按钮不可用，改变状态文本buttonCancel.Enabled = false ;labelStatus.Text = " Cancelling... " }最后一件事是我们想要当worker完成的时候自动关闭窗体，因为我们的worker通过ShowDialog 方法启动。如果直接接收返回结果会很好 void worker_RunWorkerCompleted( object sender, RunWorkerCompletedEventArgs e){ // ShowDialog返回值会指示worker是不是正确完成了 if (e.Error != null )DialogResult = DialogResult.Abort; else if (e.Cancelled)DialogResult = DialogResult.Cancel; else DialogResult = DialogResult.OK; // 关闭窗体 Close();}

/// <summary> /// 简单的进度窗体 /// </summary> public partial class ProgressForm : Form{ /// <summary> /// 获得进度条以对他自定义 /// 在显示窗体之前. /// 不要在后台任务中直接使用 ! /// </summary> public ProgressBar ProgressBar { get { return progressBar; } } /// <summary> /// 传递给后台任务的参数. /// </summary> public object Argument { get; set ; } /// <summary> /// 后台任务的结果. /// 也可以检查ShowDialog返回值 /// 来看看是不是正确完成了. /// </summary> public RunWorkerCompletedEventArgs Result { get; private set ; } /// <summary> /// 如果点击了取消按钮则为true /// 后台任务还在执行 /// </summary> public bool CancellationPending{ get { return worker.CancellationPending; }} /// <summary> /// 取消按钮被点击之后的显示文本 /// </summary> public string CancellingText { get; set ; } /// <summary> /// 缺省状态文本. /// </summary> public string DefaultStatusText { get; set ; } /// <summary> /// DoWork事件的委托. /// </summary> /// <param name="sender"> T事件源. </param> /// <param name="e"> 包含事件数据. </param> public delegate void DoWorkEventHandler(ProgressForm sender, DoWorkEventArgs e); /// <summary> /// 当后台任务开始的时候发生. /// </summary> public event DoWorkEventHandler DoWork; /// <summary> /// 构造函数. /// </summary> public ProgressForm(){InitializeComponent();DefaultStatusText = " Please wait... " ;CancellingText = " Cancelling operation... " ;worker = new BackgroundWorker();worker.WorkerReportsProgress = true ;worker.WorkerSupportsCancellation = true ;worker.DoWork += new System.ComponentModel.DoWorkEventHandler(worker_DoWork);worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);} /// <summary> /// 改变状态文本. /// </summary> /// <param name="status"> 新状态文本. </param> public void SetProgress( string status){ // 如果没有改变 // 或者取消请求还在处理就不改变状态文本 if (status != lastStatus && ! worker.CancellationPending){lastStatus = status;worker.ReportProgress(progressBar.Minimum - 1 , status);}} /// <summary> /// 改变进度条的值 /// </summary> /// <param name="percent"> 新值. </param> public void SetProgress( int percent){ // 如果值没有改变就不要更新进度条 if (percent != lastPercent){lastPercent = percent;worker.ReportProgress(percent);}} /// <summary> /// 改变进度条值和文本. /// </summary> /// <param name="percent"> N新值. </param> /// <param name="status"> 新文本. </param> public void SetProgress( int percent, string status){ // 如果至少一个改变就调用 if (percent != lastPercent || (status != lastStatus && ! worker.CancellationPending)){lastPercent = percent;lastStatus = status;worker.ReportProgress(percent, status);}} private void ProgressForm_Load( object sender, EventArgs e){ // 重用窗体，恢复缺省值Result = null ;buttonCancel.Enabled = true ;progressBar.Value = progressBar.Minimum;labelStatus.Text = DefaultStatusText;lastStatus = DefaultStatusText;lastPercent = progressBar.Minimum; // 窗体已载入就开始后台任务 worker.RunWorkerAsync(Argument);} private void buttonCancel_Click( object sender, EventArgs e){ // 通知后台任务，我们要取消 worker.CancelAsync(); // 取消按钮不可用，改变文本buttonCancel.Enabled = false ;labelStatus.Text = CancellingText;} void worker_DoWork( object sender, DoWorkEventArgs e){ // 后台任务开始 // 调用用户的处理程序 if (DoWork != null )DoWork( this , e);} void worker_ProgressChanged( object sender, ProgressChangedEventArgs e){ // 确保新值可用并更新 if (e.ProgressPercentage >= progressBar.Minimum && e.ProgressPercentage <= progressBar.Maximum){progressBar.Value = e.ProgressPercentage;} // 如果取消请求正在处理就不要更新 if (e.UserState != null && ! worker.CancellationPending)labelStatus.Text = e.UserState.ToString();} void worker_RunWorkerCompleted( object sender, RunWorkerCompletedEventArgs e){ // 后台任务完成 // 保持结果，关闭窗体Result = e; if (e.Error != null )DialogResult = DialogResult.Abort; else if (e.Cancelled)DialogResult = DialogResult.Cancel; else DialogResult = DialogResult.OK;Close();}BackgroundWorker worker; int lastPercent; string lastStatus;}