求打印预览和打印的C#代码和命名空间

/// <summary>
/// 定义打印文档
/// </summary>
private PrintDocument printDocument = new PrintDocument();
/// <summary>
/// 定义打印文本变量
/// </summary>
private string text = string.Empty;

/// <summary>
/// 打印事件处理代码
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void 打印ToolStripMenuItem_Click(object sender, EventArgs e)
{
//关联打印预处理代码
printDocument.BeginPrint += new PrintEventHandler(printDocument_BeginPrint);
//关联打印代码
printDocument.PrintPage += new PrintPageEventHandler(printDocument_PrintPage);

//定义打印对话框
PrintDialog printDialog = new PrintDialog();

//获得用户输入
DialogResult dr = printDialog.ShowDialog();

//如果确认则打印
if (dr == DialogResult.OK)
{
printDocument.Print();
}
else
{
return