Print to Printer in Awesomium ?

Question

How do I handle window.print() event to actual printing (Not print to PDF) in Awesomium ? I know it'll use WebView.PrintRequest Event but i don't know how to do that

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

oh please, no one here knows ? even if it use psf plugin like adobe reader i would love to know how to use it.. — DennyHiu, Feb 26 '14 at 02:14

score 6 · Accepted Answer · edited May 23 '17 at 11:58

Awesomium does not support printing to a printer device. Instead Awesomium supports printing to a PDF file.

The "right" way

My limited understanding of printing in Windows is that you typically needed to "paint" to the printer using a GDI+ drawing surface passed into your custom event handler for print events. The MSDN documentation for the System.Drawing.Printing.PrintDocument class does a good job of providing an example implementation.

I imagine one could implement this lower level of printing using the Awesomium .Net SDK, however, it will likely be an uphill battle with no support from Awesomium's developers.

Alternatives

A decent "hack" might be to glue together Awesomium's print to PDF feature with printing a PDF file. I can think of at least 3 ways to print a PDF file from C#:

Using Acrobat Reader on the end user's machine to handle printing with a .Net runtime callable wrapper (RCW) around the COM automation object for Acrobat. See an example of using an Acrobat RCW in VB.NET.
Using whatever PDF reader is on the user's machine to handle printing. See an example of using the .Net ProcessStartInfo with the print verb to use the default PDF application on the user's machine.
Using the Windows common dialogs to pick a printer, and then send the PDF to the printer for raw (direct) printing. (This is similar to sending a PostScript [.ps] file directly to a printer). This will only work with printers that accept PDF file directly.

Example Implementation using #3

Below is an example of workaround option #3, using sending the Awesomium PDF file(s) directly to a printer selected by the end user.

This answer combines two existing examples: a Microsoft KB on raw printing with .Net and an Awesomium answer for printing.

Running the demo loads the URL for the Microsoft KB, which includes a "Print" UI button that invokes window.print().

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;
        }
    }
}

I was able to compile and run this example as a single file named demo.cs with the following command line:

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

thx, really appreciated! do you have that source code (the solution files and others) ? i want to follow your implementation of this. — DennyHiu, Mar 05 '14 at 13:53
@denny, this is a working example in a single file; you don't need Visual Studio for this, you could just compile on the command line with csc.exe. I updated the post to show an example — Steve Jansen, Mar 05 '14 at 15:06
@steveJensen: thx for reply. i have some difficulties when tried to compile that code. app.exe just throw System.IO.FileNotFoundException. Nevertheless i managed to run your code in Visual Studio, launch Awesomium, and print the page i want. But it just print a lot of strange code. is it RAW data do you mean? — DennyHiu, Mar 06 '14 at 02:30
just like this: [link to image](https://drive.google.com/file/d/0B_KPBXT3q6YcOFNNWEF5T203aDQ/edit?usp=sharing) — DennyHiu, Mar 06 '14 at 02:45
@denny, your printout contains the actual PDF contents. It looks like you are using a thermal point-of-sale printer, which likely isn't sophisticated enough for printing PDF from a RAW stream. You are likely going to need to send the PDF file to a PDF viewer, which were options #1 and #2 in my answer. Do you want to print receipts? What if you send structured data from Javascript to C#, and have C# properly print the text? — Steve Jansen, Mar 06 '14 at 02:57
yes, i used awesomium to print receipt using thermal miniPOS printer. I want to use your option #1, but it'll invoke print dialog to user. I don't want the user to cancel invoice printing. So, how exactly does i send structured data to C# ? build server to listen to incoming print request maybe ? — DennyHiu, Mar 06 '14 at 03:50

Print to Printer in Awesomium ?

1 Answers1

The "right" way

Alternatives

Example Implementation using #3