Hi guys,

I am writing some interop code to print graphics to an eps file
and I use adobe printer driver. The piece of code I have written is
working fine. but if I loop for more than 200 times, it is throwing an
error. Can anybody tell me why it throws an error or am I having memory
problems? I debuged through it and I see that createDC is returning 0
on 203rd loop and throws an exception. Why is createDC returning a 0?


This is the piece of code that does the interop.

using System;
using System.Drawing;
using System.IO;
using System.Drawing.Printing;
using System.Runtime.InteropServices;
using System.Drawing.Text;

namespace Printer
{
public class CPrinter
{
private Graphics pDC;
private IntPtr dc1;
private IntPtr hdevmode;

[StructLayout( LayoutKind.Sequential)]
public struct DOCINFO
{
[MarshalAs(UnmanagedType.LPWStr)]public string pDocName;
[MarshalAs(UnmanagedType.LPWStr)]public string pOutputFile;
[MarshalAs(UnmanagedType.LPWStr)]public string pDataType;
}

[DllImport(
"winspool.drv",CharSet=CharSet.Unicode,ExactSpelling=false,
CallingConvention=CallingConvention.StdCall )]
public static extern long StartDocPrinter(IntPtr hPrinter, int Level,
ref DOCINFO pDocInfo);

[DllImport("gdi32.dll", EntryPoint="CreateDCA")]
public static extern IntPtr CreateDC(string lpDriverName, string
lpDeviceName,
string lpOutput, IntPtr pDevMode);

[DllImport("gdi32.dll")]
static extern bool DeleteDC(IntPtr hdc);

[DllImport("gdi32", EntryPoint="StartDocA")]
public static extern int StartDoc(IntPtr dc1, ref DOCINFO di);

[DllImport("gdi32")] public static extern int StartPage(IntPtr hDC);


[DllImport("gdi32")] public static extern int EndDoc(IntPtr hDC);

[DllImport("gdi32")] public static extern int EndPage(IntPtr hDC);

public CPrinter()
{
}
public void StartPrinter(string outputFile)
{
try
{
DOCINFO di = new DOCINFO();
di.pOutputFile = outputFile;
PrintDocument pd = new PrintDocument();
hdevmode = pd.PrinterSettings.GetHdevmode();
dc1 = CreateDC("","Acrobat Distiller 3x2",outputFile,hdevmode);
int result = StartDoc(dc1, ref di);
result = StartPage(dc1);
pDC = Graphics.FromHdc(dc1);
pDC.PageUnit = GraphicsUnit.Pixel;
}
catch(Exception ex)
{
throw(ex);
}
}

public void EndPrinter()
{
int result = EndPage(dc1);
result = EndDoc(dc1);
DeleteDC(dc1);
}
}
}

This is the piece of code where I loop :

using System;
using Printer;

namespace ConsoleApplication1
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
int i = 0;
try
{
while (true)
{
CPrinter AdobePrinter = new CPrinter();
AdobePrinter.StartPrinter("temp.wrk");
AdobePrinter.EndPrinter();
i++;
Console.WriteLine(i);
}
}
catch (Exception ex)
{
Console.WriteLine( i + " : " + ex);
}
}
}
}

Thanks,
Lalasa.

"L" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi guys,
>
> I am writing some interop code to print graphics to an eps file
> and I use adobe printer driver. The piece of code I have written is
> working fine. but if I loop for more than 200 times, it is throwing an
> error. Can anybody tell me why it throws an error or am I having memory
> problems? I debuged through it and I see that createDC is returning 0
> on 203rd loop and throws an exception. Why is createDC returning a 0?
>

You are using a Disposable object (Graphics) without disposing it.


>
> This is the piece of code that does the interop.
>
> using System;
> using System.Drawing;
> using System.IO;
> using System.Drawing.Printing;
> using System.Runtime.InteropServices;
> using System.Drawing.Text;
>
> namespace Printer
> {
> public class CPrinter
> {
> private Graphics pDC;
> private IntPtr dc1;
> private IntPtr hdevmode;
>
> [StructLayout( LayoutKind.Sequential)]
> public struct DOCINFO
> {
> [MarshalAs(UnmanagedType.LPWStr)]public string pDocName;
> [MarshalAs(UnmanagedType.LPWStr)]public string pOutputFile;
> [MarshalAs(UnmanagedType.LPWStr)]public string pDataType;
> }
>
> [DllImport(
> "winspool.drv",CharSet=CharSet.Unicode,ExactSpelling=false,
> CallingConvention=CallingConvention.StdCall )]
> public static extern long StartDocPrinter(IntPtr hPrinter, int Level,
> ref DOCINFO pDocInfo);
>
> [DllImport("gdi32.dll", EntryPoint="CreateDCA")]
> public static extern IntPtr CreateDC(string lpDriverName, string
> lpDeviceName,
> string lpOutput, IntPtr pDevMode);
>
> [DllImport("gdi32.dll")]
> static extern bool DeleteDC(IntPtr hdc);
>
> [DllImport("gdi32", EntryPoint="StartDocA")]
> public static extern int StartDoc(IntPtr dc1, ref DOCINFO di);
>
> [DllImport("gdi32")] public static extern int StartPage(IntPtr hDC);
>
>
> [DllImport("gdi32")] public static extern int EndDoc(IntPtr hDC);
>
> [DllImport("gdi32")] public static extern int EndPage(IntPtr hDC);
>
> public CPrinter()
> {
> }
> public void StartPrinter(string outputFile)
> {
> try
> {
> DOCINFO di = new DOCINFO();
> di.pOutputFile = outputFile;
> PrintDocument pd = new PrintDocument();
> hdevmode = pd.PrinterSettings.GetHdevmode();
> dc1 = CreateDC("","Acrobat Distiller 3x2",outputFile,hdevmode);
> int result = StartDoc(dc1, ref di);
> result = StartPage(dc1);
> pDC = Graphics.FromHdc(dc1);
> pDC.PageUnit = GraphicsUnit.Pixel;
> }
> catch(Exception ex)
> {
> throw(ex);
> }
> }
>
> public void EndPrinter()
> {
> int result = EndPage(dc1);
> result = EndDoc(dc1);
> DeleteDC(dc1);
> }
> }
> }
>
> This is the piece of code where I loop :
>
> using System;
> using Printer;
>
> namespace ConsoleApplication1
> {
> class Class1
> {
> [STAThread]
> static void Main(string[] args)
> {
> int i = 0;
> try
> {
> while (true)
> {
> CPrinter AdobePrinter = new CPrinter();
> AdobePrinter.StartPrinter("temp.wrk");
> AdobePrinter.EndPrinter();
> i++;
> Console.WriteLine(i);
> }
> }
> catch (Exception ex)
> {
> Console.WriteLine( i + " : " + ex);
> }
> }
> }
> }
>
> Thanks,
> Lalasa.
>

I added the pDC.Dispose() to my EndPrinter() function and still I am
having the problem.

public void EndPrinter()
{
int result = EndPage(dc1);
result = EndDoc(dc1);
pDC.Dispose();
DeleteDC(dc1);
}

Thanks,
L.

>Can anybody tell me why it throws an error or am I having memory
>problems?

You're net freeing the handle returned by GetHDevmode.


> public static extern long StartDocPrinter(IntPtr hPrinter, int Level,
^^^^

The return type should be (u)int.



Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

Can you tell me the method I should use to release the handle returned
by GetHDevmode? I am not able to find one.

Thanks,
Lalasa.

>Can you tell me the method I should use to release the handle returned
>by GetHDevmode?

The GlobalFree Win32 API, just like thie documentation says.

http://msdn.microsoft.com/library/en...modeTopic1.asp

Marshal.FreeHGlobal probably works as well.



Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

Thankyou very much for helping out.

Hi,

Is there anything else I got to correct. Because I am having the
same error now after 1122 loops.
Here is my EndPrinter() function

public void EndPrinter()
{
int result = EndPage(dc1);
result = EndDoc(dc1);
pDC.Dispose();
Marshal.FreeHGlobal(hdevmode); // Frees the memory. You could also
free the memory by calling the native win32 globalfree method.
DeleteDC(dc1);
}

Thanks in advance
Lalasa.

Mattias Sjögren wrote:
> >Can you tell me the method I should use to release the handle
returned
> >by GetHDevmode?
>
> The GlobalFree Win32 API, just like thie documentation says.
>
>
http://msdn.microsoft.com/library/en...modeTopic1.asp
>
> Marshal.FreeHGlobal probably works as well.
>
>
>
> Mattias
>
> --
> Mattias Sjögren [MVP] mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.

> Is there anything else I got to correct. Because I am having the
>same error now after 1122 loops.

Well your DOCINFO struct doesn't look correct compared to the one in
the MSDN documentation.

Then I recommend that you use Task Manager to monitor the number of
GDI handles used in your application to ensure that you're not leaking
any.



Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

Well, I figured it out. The memory leak was happening in my main code
where I was using interop calls for creating fonts. I fixed my dispose
function to delete all the fonts and it is working in an end less loop
now. Thanks for the help.

Lalasa.