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HOW TO：設定 Windows Form ProgressBar 控制項顯示的值

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重要事項重要事項

ToolStripProgressBar 控制項會取代 ProgressBar 控制項並加入其他功能，不過您也可以選擇保留 ProgressBar 控制項，以提供回溯相容性及未來使用。

.NET Framework 對於在 ProgressBar 控制項內部顯示特定值方面，提供數種不同的方式。 您所選擇的方法，端視手邊的工作或正在解決的問題而定。 下表顯示了您可選擇的形式：

處理方式

說明

直接設定 ProgressBar 控制項的值。

對於已知道所含測量項目總數的工作，例如從資料來源讀取記錄而言，這個方法就很實用。 此外，如果只需要設定值一次或兩次，這個方法也很容易。 最後，如果需要降低進度列所顯示的值，也請使用這個處理序。

以固定值增加 ProgressBar 顯示。

在最小和最大之間顯示簡單計數時，例如已耗用時間或已知總數中已處理的檔案數，這個方法就很實用。

以變化值增加 ProgressBar 顯示。

需要數次以不同數量變更顯示值時，這個方法就很有用。 稍後會提供範例，說明將一系列檔案寫入磁碟時所耗用的硬碟空間量。

由進度列顯示該值最直接的方法就是設定 Value 屬性。 您可以在設計階段或執行階段執行此作業。

若要直接設定 ProgressBar 值

  1. 設定 ProgressBar 控制項的 Minimum 和 Maximum 的值。

  2. 在程式碼中，將控制項的 Value 屬性設定為介於已建立的最小和最大值之間的整數值。

    注意事項注意事項

    如果您在由 Minimum 和 Maximum 屬性建立的界限之外，設定 Value 屬性，此控制項會擲回 ArgumentException 例外狀況。

    下列程式碼範例說明如何直接設定 ProgressBar 值。 程式碼會從資料來源讀取記錄，然後在每次讀取資料記錄時更新進度列和標籤。 這個範例需要您的表單具有 Label 控制項、ProgressBar 控制項，以及具有稱為 CustomerRow 的資料列 (其中包含 FirstName 和 Last Name 欄位) 的資料表。

    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();
}

    如果顯示的進度是以固定間隔進行，則可設定該值，然後呼叫方法，以該間隔增加 ProgressBar 控制項的值。 對於計時器和未以整體百分比測量進度的其他案例而言，這個方法很有用。

若要以固定值增加進度列

  1. 設定 ProgressBar 控制項的 Minimum 和 Maximum 的值。

  2. 將控制項的 Step 屬性設定為整數，表示增加進度列顯示值的數量。

  3. 呼叫 PerformStep 方法，依在 Step 屬性中設定的數量變更顯示值。

    下列程式碼範例說明進度列如何在複製作業中維持檔案計數。

    在下列範例中，當每個檔案讀取至記憶體時，系統會更新進度列和標籤，以反映讀取的檔案總數。 在這個範例中，您的表單必須有 Label 控制項和 ProgressBar 控制項。

    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();
   }
}

    最後，您可以增加進度列的顯示值，如此一來每次增加的數量都是唯一的。 在追蹤一系列唯一作業時，例如將不同大小的檔案寫入磁碟，或是以整體百分比測量進度時，這個方法就很有用。

若要以動態值增加進度列

  1. 設定 ProgressBar 控制項的 Minimum 和 Maximum 的值。

  2. 呼叫 Increment 方法，依您指定的整數變更顯示值。

    下列程式碼範例說明進度列如何計算複製作業期間，已經使用的磁碟空間有多少。

    在下列範例中，當每個檔案寫入硬碟時，進度列和標籤會進行更新，以反映可用的硬碟空間量。 在這個範例中，您的表單必須有 Label 控制項和 ProgressBar 控制項。

    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();
   }
}

請參閱

參考

ProgressBar 控制項概觀 (Windows Form)

ProgressBar

ToolStripProgressBar

其他資源

ProgressBar 控制項 (Windows Form)