Question

如何在Awesomium中处理window.print（）事件到实际打印（不打印到PDF）？我知道它会使用WebView.PrintRequest事件，但我不知道该怎么做

http://docs.awesomium.net/1_7_0/html/E_Awesomium_Core_WebView_PrintRequest.htm

Answer 1

Awesomium不支持打印到打印机设备。相反，Awesomium支持打印到PDF文件。

“正确”的方式

我对Windows打印的有限理解是，您通常需要使用打印机“打印”到打印机 GDI +绘图表面传递到打印事件的自定义事件处理程序中。 The MSDN documentation for the System.Drawing.Printing.PrintDocument class在提供示例实现方面做得很好。

我想可以使用Awesomium .Net SDK实现这种较低级别的打印，但是，它可能是一场艰苦的战斗，没有任何支持来自Awesomium的开发人员。

替代

一个体面的“黑客”可能是将Awesomium的打印与PDF功能粘合在一起并打印PDF文件。我可以想到至少3种方法从C＃打印PDF文件：

在最终用户的计算机上使用Acrobat Reader，以便在Acrobat的COM自动化对象周围使用.Net运行时可调用包装器（RCW）进行打印。请参阅an example of using an Acrobat RCW in VB.NET。
使用用户机器上的任何PDF阅读器来处理打印。请参阅an example of using the .Net ProcessStartInfo with the print verb to use the default PDF application on the user's machine。
使用Windows常用对话框选择打印机，然后将PDF发送到打印机进行原始（直接）打印。（这类似于将PostScript [.ps]文件直接发送到打印机）。这仅适用于直接接受PDF文件的打印机。

使用＃3

以下是变通方案选项＃3的示例，使用将Awesomium PDF文件直接发送到最终用户选择的打印机。

此答案结合了两个现有示例：Microsoft KB on raw printing with .Net和Awesomium answer for printing。

运行演示程序会加载Microsoft KB的URL，其中包含一个调用window.print()的“打印”UI按钮。

using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Printing;
using System.IO;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Awesomium.Core;

namespace Demo
{
    static class Program
    {
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new PrinterDemo());
        }
    }

    public class PrinterDemo : Form
    {
        private Awesomium.Windows.Forms.WebControl webControl;
        private PrinterSettings printerSettings;
        private string printerName;

        public PrinterDemo()
        {
            InitializeComponent();
            WindowState = FormWindowState.Maximized;
        }

        private void InitializeComponent()
        {
            this.webControl = new Awesomium.Windows.Forms.WebControl();
            this.SuspendLayout();
            // 
            // webControl1
            // 
            this.webControl.Dock = System.Windows.Forms.DockStyle.Fill;
            this.webControl.Location = new System.Drawing.Point(0, 0);
            this.webControl.Size = new System.Drawing.Size(784, 562);
            this.webControl.Source = new System.Uri("http://support.microsoft.com/kb/322091", System.UriKind.Absolute);
            this.webControl.TabIndex = 0;

            this.webControl.PrintRequest += WebControl_PrintRequest;
            this.webControl.PrintComplete += WebControl_PrintComplete;
            this.webControl.PrintFailed += WebControl_PrintFailed;

            // 
            // PrinterDemo
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(784, 562);
            this.Controls.Add(this.webControl);
            this.Name = "PrinterDemo";
            this.Text = "PrinterDemo";
            this.ResumeLayout(false);
        }

        /// <summary>Handle `window.print()` events</summary>
        private void WebControl_PrintRequest(object sender, PrintRequestEventArgs e)
        {
            this.Print();
            e.Handled = true;
        }


        /// <summary>Event handler for successful printing</summary>
        private void WebControl_PrintComplete(object sender, PrintCompleteEventArgs e)
        {
            // Print the file to the printer.
            if (String.IsNullOrWhiteSpace(printerName))
            {
                return;
            }

            foreach (string file in e.Files)
            {
                System.Diagnostics.Debug.Print("Printing file {0}", file);
                RawPrinterHelper.SendFileToPrinter(printerName, file);
            }
        }

        /// <summary>Event handler for unsuccessful printing</summary>
        private void WebControl_PrintFailed(object sender, PrintOperationEventArgs e)
        {
            MessageBox.Show("MyApp", "Printing failed", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        }

        /// <summary>Sends a PDF file to the printer</summary>
        private void Print()
        {
            PrintDialog printerDialog;
            int requestId;
            string path = System.IO.Path.GetTempPath();

            if (!webControl.IsLive)
                return;

            printerDialog = new PrintDialog();
            printerSettings = new PrinterSettings();
            printerDialog.PrinterSettings = printerSettings;

            if (DialogResult.OK == printerDialog.ShowDialog(this))
            {
                printerName = printerDialog.PrinterSettings.PrinterName;
                requestId = webControl.PrintToFile(path, PrintConfig.Default);
            }
        }
    }

    public class RawPrinterHelper
    {
        // Structure and API declarions:
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public class DOCINFOA
        {
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDocName;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pOutputFile;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDataType;
        }
        [DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);

        [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool ClosePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

        [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndDocPrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);

        // SendBytesToPrinter()
        // When the function is given a printer name and an unmanaged array
        // of bytes, the function sends those bytes to the print queue.
        // Returns true on success, false on failure.
        public static bool SendBytesToPrinter(string szPrinterName, IntPtr pBytes, Int32 dwCount)
        {
            Int32 dwError = 0, dwWritten = 0;
            IntPtr hPrinter = new IntPtr(0);
            DOCINFOA di = new DOCINFOA();
            bool bSuccess = false; // Assume failure unless you specifically succeed.

            di.pDocName = "My C#.NET RAW Document";
            di.pDataType = "RAW";

            // Open the printer.
            if (OpenPrinter(szPrinterName.Normalize(), out hPrinter, IntPtr.Zero))
            {
                // Start a document.
                if (StartDocPrinter(hPrinter, 1, di))
                {
                    // Start a page.
                    if (StartPagePrinter(hPrinter))
                    {
                        // Write your bytes.
                        bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                        EndPagePrinter(hPrinter);
                    }
                    EndDocPrinter(hPrinter);
                }
                ClosePrinter(hPrinter);
            }
            // If you did not succeed, GetLastError may give more information
            // about why not.
            if (bSuccess == false)
            {
                dwError = Marshal.GetLastWin32Error();
            }
            return bSuccess;
        }

        public static bool SendFileToPrinter(string szPrinterName, string szFileName)
        {
            // Open the file.
            FileStream fs = new FileStream(szFileName, FileMode.Open);
            // Create a BinaryReader on the file.
            BinaryReader br = new BinaryReader(fs);
            // Dim an array of bytes big enough to hold the file's contents.
            Byte[] bytes = new Byte[fs.Length];
            bool bSuccess = false;
            // Your unmanaged pointer.
            IntPtr pUnmanagedBytes = new IntPtr(0);
            int nLength;

            nLength = Convert.ToInt32(fs.Length);
            // Read the contents of the file into the array.
            bytes = br.ReadBytes(nLength);
            // Allocate some unmanaged memory for those bytes.
            pUnmanagedBytes = Marshal.AllocCoTaskMem(nLength);
            // Copy the managed byte array into the unmanaged array.
            Marshal.Copy(bytes, 0, pUnmanagedBytes, nLength);
            // Send the unmanaged bytes to the printer.
            bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, nLength);
            // Free the unmanaged memory that you allocated earlier.
            Marshal.FreeCoTaskMem(pUnmanagedBytes);
            return bSuccess;
        }
        public static bool SendStringToPrinter(string szPrinterName, string szString)
        {
            IntPtr pBytes;
            Int32 dwCount;
            // How many characters are in the string?
            dwCount = szString.Length;
            // Assume that the printer is expecting ANSI text, and then convert
            // the string to ANSI text.
            pBytes = Marshal.StringToCoTaskMemAnsi(szString);
            // Send the converted ANSI string to the printer.
            SendBytesToPrinter(szPrinterName, pBytes, dwCount);
            Marshal.FreeCoTaskMem(pBytes);
            return true;
        }
    }
}

我能够使用以下命令行将此示例编译并运行为名为demo.cs的单个文件：

SETLOCAL
PATH C:\Windows\Microsoft.NET\Framework\v4.0.30319\;%PATH%
IF EXIST demo.exe DEL demo.exe
csc.exe /target:winexe /lib:"%ProgramFiles%\Awesomium Technologies LLC\Awesomium SDK\1.7.3.0\wrappers\Awesomium.NET\Assemblies" /reference:Awesomium.Core.dll,Awesomium.Windows.Forms.dll demo.cs 
demo.exe
ENDLOCAL

在Awesomium打印到打印机？

1 个答案:

“正确”的方式

替代

使用＃3