ProgressBar

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

复制代码

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

    
    
    
    
    设置 ProgressBar 控件的 Minimum 和 Maximum 值。

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。

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 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


    
    设置 ProgressBar 控件的 Minimum 和 Maximum 值。
    
    
    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 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();
}
}