如何:设置 Windows 窗体 ProgressBar 控件显示的值

更新:2007 年 11 月

重要说明:

ToolStripProgressBar 控件替换了 ProgressBar 控件并添加了功能;但是也可选择保留 ProgressBar 控件以备向后兼容和将来使用。

.NET Framework 使您可以通过几种不同的方法显示 ProgressBar 控件中的给定值。选择的方法将取决于您所要执行的任务或要解决的问题。下表说明了可以选择的方法。

方法

说明

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。

设置进度栏的显示值的最直接方式是设置 Value 属性。该操作可以在设计时或运行时进行。

直接设置 ProgressBar 值

  1. 设置 ProgressBar 控件的 MinimumMaximum 值。

  2. 在代码中,将该控件的 Value 属性设置为已设定的最小值与最大值之间的一个整数值。

    说明:

    如果将 Value 属性设置为 MinimumMaximum 属性设定的边界之外的值,该控件将引发 ArgumentException 异常。

    下面的代码示例说明如何直接设置 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。该示例要求窗体有一个 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。

    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
    
    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();
    }
    

    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 MinimumMaximum 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递增的数量。

  3. 调用 PerformStep 方法,使显示值按 Step 属性中设置的数量进行更改。

    下面的代码示例说明进度栏如何维护复制操作中的文件计数。

    在下面的示例中,当每个文件读入内存时,进度栏和标签都会相应地更新,以反映读取的文件总数。该示例要求窗体有一个 Label 控件和一个 ProgressBar 控件。

    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
    
    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();
       }
    }
    

    最后,可以使进度栏的显示值每次递增的数量都是唯一的。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 MinimumMaximum 值。

  2. 调用 Increment 方法,使显示值按指定的整数进行更改。

    下面的代码示例说明在复制操作期间,进度栏如何计算已使用的磁盘空间量。

    在下面的示例中,当每个文件写入硬盘时,进度栏和标签都会相应地更新,以反映可用的硬盘空间量。该示例要求窗体有一个 Label 控件和一个 ProgressBar 控件。

    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
    
    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

参考

ProgressBar 控件概述(Windows 窗体)

ProgressBar

ToolStripProgressBar

其他资源

ProgressBar 控件(Windows 窗体)