HOW TO：使用 Visual C# .NET 打印 RichTextBox 控件的内容

创建 RichTextBoxPrintCtrl 控件

1. 在 Visual C# .NET 中，新建一个名为 RichTextBoxPrintCtrl 的类库项目。默认情况下创建 Class1.cs。
2. 将 Class1.cs 的名称改为 RichTextBoxPrintCtrl.cs。
3. 在解决方案资源管理器中，右键单击“引用”，然后单击“添加引用”。
4. 在“添加引用”对话框中，双击“System.Drawing.dll”和“System.Windows.Forms.dll”，然后单击“确定”。
5. 将 RichTextBoxPrintCtl.cs 中的现有代码替换为以下代码：

   using System;
   using System.Windows.Forms;
   using System.Drawing;
   using System.Runtime.InteropServices;
   using System.Drawing.Printing;
   
   namespace RichTextBoxPrintCtrl
   {
   	public class RichTextBoxPrintCtrl:RichTextBox
   	{
   		//Convert the unit used by the .NET framework (1/100 inch) 
   		//and the unit used by Win32 API calls (twips 1/1440 inch)
   		private const double anInch = 14.4;
   
   		[StructLayout(LayoutKind.Sequential)] 
   			private struct RECT
   		{
   			public int Left;
   			public int Top;
   			public int Right;
   			public int Bottom;
   		}
   
   		[StructLayout(LayoutKind.Sequential)]
   			private struct CHARRANGE
   		{
   			public int cpMin;         //First character of range (0 for start of doc)
   			public int cpMax;           //Last character of range (-1 for end of doc)
   		}
   
   		[StructLayout(LayoutKind.Sequential)]
   			private struct FORMATRANGE
   		{
   			public IntPtr hdc;             //Actual DC to draw on
   			public IntPtr hdcTarget;       //Target DC for determining text formatting
   			public RECT rc;                //Region of the DC to draw to (in twips)
   			public RECT rcPage;            //Region of the whole DC (page size) (in twips)
   			public CHARRANGE chrg;         //Range of text to draw (see earlier declaration)
   		}
   
   		private const int WM_USER  = 0x0400;
   		private const int EM_FORMATRANGE  = WM_USER + 57;
   		
   		[DllImport("USER32.dll")]
   		private static extern IntPtr SendMessage (IntPtr hWnd , int msg , IntPtr wp, IntPtr lp); 
   
   		// Render the contents of the RichTextBox for printing
   		//	Return the last character printed + 1 (printing start from this point for next page)
   		public int Print( int charFrom, int charTo,PrintPageEventArgs e)
   		{
   			//Calculate the area to render and print
   			RECT rectToPrint; 
   			rectToPrint.Top = (int)(e.MarginBounds.Top * anInch);
   			rectToPrint.Bottom = (int)(e.MarginBounds.Bottom * anInch);
   			rectToPrint.Left = (int)(e.MarginBounds.Left * anInch);
   			rectToPrint.Right = (int)(e.MarginBounds.Right * anInch);
   
   			//Calculate the size of the page
   			RECT rectPage; 
   			rectPage.Top = (int)(e.PageBounds.Top * anInch);
   			rectPage.Bottom = (int)(e.PageBounds.Bottom * anInch);
   			rectPage.Left = (int)(e.PageBounds.Left * anInch);
   			rectPage.Right = (int)(e.PageBounds.Right * anInch);
   
   			IntPtr hdc = e.Graphics.GetHdc();
   
   			FORMATRANGE fmtRange;
   			fmtRange.chrg.cpMax = charTo;				//Indicate character from to character to 
   			fmtRange.chrg.cpMin = charFrom;
   			fmtRange.hdc = hdc;                    //Use the same DC for measuring and rendering
   			fmtRange.hdcTarget = hdc;              //Point at printer hDC
   			fmtRange.rc = rectToPrint;             //Indicate the area on page to print
   			fmtRange.rcPage = rectPage;            //Indicate size of page
   
   			IntPtr res = IntPtr.Zero;
   
   			IntPtr wparam = IntPtr.Zero;
   			wparam = new IntPtr(1);
   
   			//Get the pointer to the FORMATRANGE structure in memory
   			IntPtr lparam= IntPtr.Zero;
   			lparam = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange));
   			Marshal.StructureToPtr(fmtRange, lparam, false);
   
   			//Send the rendered data for printing 
   			res = SendMessage(Handle, EM_FORMATRANGE, wparam, lparam);
   
   			//Free the block of memory allocated
   			Marshal.FreeCoTaskMem(lparam);
   
   			//Release the device context handle obtained by a previous call
   			e.Graphics.ReleaseHdc(hdc);
   
   			//Return last + 1 character printer
   			return res.ToInt32();
   		}
   
   	}
   }

6. 在“生成”菜单中，单击“生成解决方案”以创建 RichTextBoxPrintCtrl.dll。

测试控件

1. 在 Visual C# .NET 中创建一个新的 Windows 应用程序项目。默认情况下将创建出 Form1.cs。
2. 将一个按钮控件从工具箱拖入 Form1。将 Name 属性更改为 btnPageSetup，并将 Text 属性更改为页面设置。
3. 将另一个按钮控件从工具箱拖入 Form1。将 Name 属性更改为 btnPrintPreview，并将 Text 属性更改为打印预览。
4. 将另一个按钮控件从工具箱拖入 Form1。将 Name 属性更改为 btnPrint，并将 Text 属性更改为打印。
5. 在工具箱中，双击“PrintDialog”、“PrintPreviewDialog”、“PrintDocument”和“PageSetupDialog”以将这些控件添加到 Form1 中。
6. 将 PrintDialog1、PrintPreviewDialog1 和 PageSetupDialog1 控件的 Document 属性修改为 PrintDocument1。
7. 在“工具”菜单上，单击“自定义工具箱”。
8. 在“.NET Framework 组件”选项卡上，单击“浏览”，单击以选中“RichTextBoxPrintCtrl.dll”，然后单击“确定”。
9. 将 RichTextBoxPrintCtrl 从工具箱拖入 Form1。
10. 在解决方案资源管理器中，右键单击 Form1.cs，然后单击查看代码。
11. 将以下代码添加到 InitializeComponent 方法中：

    		this.printDocument1.BeginPrint += new System.Drawing.Printing.PrintEventHandler(this.printDocument1_BeginPrint);
    		this.printDocument1.PrintPage += new System.Drawing.Printing.PrintPageEventHandler(this.printDocument1_PrintPage);
    		this.btnPrint.Click += new System.EventHandler(this.btnPrint_Click);
    		this.btnPrintPreview.Click += new System.EventHandler(this.btnPrintPreview_Click);
    		this.btnPageSetup.Click += new System.EventHandler(this.btnPageSetup_Click);

12. 将下面的代码添加到 Form1 类：

    		private int checkPrint;
    		private void btnPageSetup_Click(object sender, System.EventArgs e)
    		{
    			pageSetupDialog1.ShowDialog();
    		}
    
    		private void btnPrintPreview_Click(object sender, System.EventArgs e)
    		{
    			printPreviewDialog1.ShowDialog();
    		}
    
    		private void btnPrint_Click(object sender, System.EventArgs e)
    		{
    			if (printDialog1.ShowDialog() == DialogResult.OK)
    				printDocument1.Print();
    		}
    
    		private void printDocument1_BeginPrint(object sender, System.Drawing.Printing.PrintEventArgs e)
    		{
    			checkPrint = 0;
    		}
    
    		private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
    		{
    			// Print the content of RichTextBox. Store the last character printed.
    			checkPrint = richTextBoxPrintCtrl1.Print(checkPrint, richTextBoxPrintCtrl1.TextLength, e);
    
    			// Check for more pages
    			if (checkPrint < richTextBoxPrintCtrl1.TextLength)
    				e.HasMorePages = true;
    			else
    				e.HasMorePages = false;
    		}

13. 在“调试”菜单上，单击“启动”以运行该应用程序。Form1 将显示出来。
14. 在 RichTextBoxPrintCtrl 中键入一些文本。
15. 单击“页面设置”以设置页面设置。
16. 单击“打印预览”以查看页面的打印预览。
17. 单击“打印”以打印“RichTextBoxPrintCtrl”的内容。