设置 Windows 窗体 ProgressBar 控件显示的值

.NET Framework 使您可以使用多种不同的方法在 ProgressBar 控件中显示给定的值。选择的方法将取决于您所要执行的任务或要解决的问题：

• 直接设置 ProgressBar 控件的值。如果您知道任务中涉及的测量项总数，此方法非常有用，例如从数据源中读取记录。此外，如果您只需要设置该值一次或两次，这将是实现该目的的简便方法。最后，如果您需要减小进度栏显示的值，请使用此方法。
• 使 ProgressBar 的显示值按固定值递增。如果需要显示最小值和最大值之间的简单计数，此方法非常有用，例如运行时间或已知文件总数中已处理的文件数。
• 使 ProgressBar 的显示值按可变值递增。如果需要多次以不同数量更改显示值，此方法非常有用。例如，显示将一系列文件写入磁盘时所占用的硬盘空间量。

直接设置 ProgressBar 值

设置进度栏显示的值的最直接的方法是设置 Value 属性。这可以在设计时或运行时完成。

直接设置 ProgressBar 值

1. 设置 ProgressBar 控件的 Minimum 和 Maximum 值。
2. 在代码中，将该控件的 Value 属性设置为已设定的最小值和最大值之间的整数值。

   注意如果为 Value 属性设置的值超出了由 Minimum 和 Maximum 属性确定的边界，则该控件将引发 ArgumentException 异常。

   以下示例阐释如何直接设置 ProgressBar 值。该代码从数据源中读取记录，并在每次读取数据记录时更新进度栏和标签。本示例假设您的窗体具有一个 Label 控件、一个 ProgressBar 控件以及一个数据表，该数据表中名为 CustomerRow 的行具有 FirstName 和 Last Name 字段。

   ' Visual Basic
   Public Sub CreateNewRecords()
     ' Sets the progress bar's Maximum property to
     ' the total number of records to be created.
     ProgressBar1.Maximum = 20
   
     ' Creates a new record in the dataset.
     ' NOTE: The code below will not compile, it merely
     ' illustrates how the progress bar would be used.
     Dim anyRow As CustomerRow = DatasetName.ExistingTable.NewRow
     anyRow.FirstName = "Stephen"
     anyRow.LastName = "James"
     ExistingTable.Rows.Add(anyRow)
   
     ' Increases the value displayed by the progress bar.
     ProgressBar1.Value += 1
     ' Updates the label to show that a record was read.
     Label1.Text = "Records Read = " & ProgressBar1.Value.ToString()
   End Sub
   
   // C#
   public void createNewRecords()
   {
     // Sets the progress bar's Maximum property to
     // the total number of records to be created.
     progressBar1.Maximum = 20;
   
     // Creates a new record in the dataset.
     // NOTE: The code below will not compile, it merely
     // illustrates how the progress bar would be used.
     CustomerRow anyRow = DatasetName.ExistingTable.NewRow();
     anyRow.FirstName = "Stephen";
     anyRow.LastName = "James";
     ExistingTable.Rows.Add(anyRow);
   
     // Increases the value displayed by the progress bar.
     progressBar1.Value += 1;
     // Updates the label to show that a record was read.
     label1.Text = "Records Read = " + progressBar1.Value.ToString();
   }

使 ProgressBar 值按固定时间间隔递增

如果要显示按固定时间间隔增长的进度，则可以设置该值，然后调用方法，使 ProgressBar 控件的值按该时间间隔递增。对于计时器以及其他一些您无法以整体的百分比测量进度的方案，这是非常有用的。

使进度栏按固定值递增

1. 设置 ProgressBar 控件的 Minimum 和 Maximum 值。
2. 将控件的 Step 属性设置为一个整数，该整数代表进度栏的显示值增加的数量。
3. 调用 PerformStep 方法，使显示值按 Step 属性中设置的数量更改。

   以下示例阐释进度栏如何维护复制操作中的文件计数。

   在以下示例中，将每个文件读入内存时，进度栏和标签都会进行更新，以反映读取的文件总数。此示例假定您的窗体具有 Label 控件和 ProgressBar 控件。

   ' Visual Basic
   Public Sub LoadFiles()
     ' Sets the progress bar's minimum value to a number representing
     ' no operations complete -- in this case, no files read.
     ProgressBar1.Minimum = 0
     ' Sets the progress bar's maximum value to a number representing
     ' all operations complete -- in this case, all five files read.
     ProgressBar1.Maximum = 5
     ' Sets the Step property to amount to increase with each iteration.
     ' In this case, it will increase by one with every file read.
     ProgressBar1.Step = 1
   
     ' Dimensions a counter variable.
     Dim i As Integer
     ' Uses a For...Next loop to iterate through the operations to be
     ' completed. In this case, five files are to be copied into memory,
     ' so the loop will execute 5 times.
     For i = 0 To 4
      ' Insert code to copy a file
      ProgressBar1.PerformStep()
      ' Update the label to show that a file was read.
      Label1.Text = "# of Files Read = " & ProgressBar1.Value.ToString
     Next i
   End Sub
   
   // C#
   public void loadFiles()
   {
     // Sets the progress bar's minimum value to a number representing
     // no operations complete -- in this case, no files read.
     progressBar1.Minimum = 0;
     // Sets the progress bar's maximum value to a number representing
     // all operations complete -- in this case, all five files read.
     progressBar1.Maximum = 5;
     // Sets the Step property to amount to increase with each iteration.
     // In this case, it will increase by one with every file read.
     progressBar1.Step = 1;
   
     // Uses a for loop to iterate through the operations to be
     // completed. In this case, five files are to be copied into memory,
     // so the loop will execute 5 times.
     for (int i = 0; i <= 4; i++)
     {
      // Inserts code to copy a file
      progressBar1.PerformStep();
      // Updates the label to show that a file was read.
      label1.Text = "# of Files Read = " + progressBar1.Value.ToString();
     }
   }

使 ProgressBar 值按可变数量递增

最后，您可以使进度栏的显示值每次增加的数量都是唯一的。这在您记录一系列唯一的操作时非常有用，例如将不同大小的文件写入硬盘，或者按整体的百分比测量进度。

使进度栏按动态值递增

1. 设置 ProgressBar 控件的 Minimum 和 Maximum 值。
2. 调用 Increment 方法，使显示值按指定的整数更改。

   以下示例阐释在复制操作期间，进度栏如何计算已使用的磁盘空间量。有关确定当前可用的磁盘空间的更多信息，请参见代码：查找可用的磁盘空间量 (Visual Basic)。

   在以下示例中，将每个文件写入硬盘时，进度栏和标签都会进行更新，以反映可用的硬盘空间量。此示例假定您的窗体具有 Label 控件和 ProgressBar 控件。

   ' Visual Basic
   Public Sub ReadFiles()
     ' Sets the progress bar's minimum value to a number 
     ' representing the hard disk space before the files are read in.
     ' You will most likely have to set this using a system call.
     ' NOTE: The code below is meant to be an example and
     ' will not compile.
     ProgressBar1.Minimum = AvailableDiskSpace()
     ' Sets the progress bar's maximum value to a number 
     ' representing the total hard disk space.
     ' You will most likely have to set this using a system call.
     ' NOTE: The code below is meant to be an example 
     ' and will not compile.
     ProgressBar1.Maximum = TotalDiskSpace()
   
     ' Dimension a counter variable.
     Dim i As Integer
     ' Uses a For...Next loop to iterate through the operations to be
     ' completed. In this case, five files are to be written to the disk,
     ' so it will execute the loop 5 times.
     For i = 1 To 5
      ' Insert code to read a file into memory and update file size.
      ' Increases the progress bar's value based on the size of 
      ' the file currently being written.
      ProgressBar1.Increment(FileSize)
      ' Updates the label to show available drive space.
      Label1.Text = "Current Disk Space Used = " &_ 
      ProgressBar1.Value.ToString()
     Next i
   End Sub
   
   // C#
   public void readFiles()
   {
     // Sets the progress bar's minimum value to a number 
     // representing the hard disk space before the files are read in.
     // You will most likely have to set this using a system call.
     // NOTE: The code below is meant to be an example and 
     // will not compile.
     progressBar1.Minimum = AvailableDiskSpace();
     // Sets the progress bar's maximum value to a number 
     // representing the total hard disk space.
     // You will most likely have to set this using a system call.
     // NOTE: The code below is meant to be an example 
     // and will not compile.
     progressBar1.Maximum = TotalDiskSpace();
   
     // Uses a for loop to iterate through the operations to be
     // completed. In this case, five files are to be written
     // to the disk, so it will execute the loop 5 times.
     for (int i = 1; i<= 5; i++)
     {
      // Insert code to read a file into memory and update file size.
      // Increases the progress bar's value based on the size of 
      // the file currently being written.
      progressBar1.Increment(FileSize);
      // Updates the label to show available drive space.
      label1.Text = "Current Disk Space Used = " + progressBar1.Value.ToString();
     }
   }

请参见

Windows 窗体 ProgressBar 控件介绍 | ProgressBar 控件（Windows 窗体） | ProgressBar 类




[C#]
private void CopyWithProgress(string[] filenames)
{
// Display the ProgressBar control.
pBar1.Visible = true;
// Set Minimum to 1 to represent the first file being copied.
pBar1.Minimum = 1;
// Set Maximum to the total number of files to copy.
pBar1.Maximum = filenames.Length;
// Set the initial value of the ProgressBar.
pBar1.Value = 1;
// Set the Step property to a value of 1 to represent each file being copied.
pBar1.Step = 1;
// Loop through all files to copy.
for (int x = 1; x <= filenames.Length; x++)
{
// Copy the file and increment the ProgressBar if successful.
if(CopyFile(filenames[x-1]) == true)
{
// Perform the increment on the ProgressBar.
pBar1.PerformStep();
}
}
}