Software Development using C# .Net

Reminder about your invitation from Heidi (Zhaoling) Y.

2012-02-13T01:23:00.001-08:00

This is a reminder that on February 1, Heidi (Zhaoling) Y. sent you an invitation to become part of their professional network at LinkedIn.

Accept Heidi (Zhaoling) Y.'s Invitation

On February 1, Heidi (Zhaoling) Y. wrote:

> To: [houzhip.csdev@blogger.com]

> From: Heidi (Zhaoling) Y. [yaoz2004@gmail.com]

> Subject: Invitation to connect on LinkedIn

> I'd like to add you to my professional network on LinkedIn.
>
> - Heidi (Zhaoling)

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Reminder about your invitation from Heidi (Zhaoling) Y.

2012-02-06T05:15:00.001-08:00

This is a reminder that on February 1, Heidi (Zhaoling) Y. sent you an invitation to become part of their professional network at LinkedIn.

Accept Heidi (Zhaoling) Y.'s Invitation

On February 1, Heidi (Zhaoling) Y. wrote:

> To: [houzhip.csdev@blogger.com]

> From: Heidi (Zhaoling) Y. [yaoz2004@gmail.com]

> Subject: Invitation to connect on LinkedIn

> I'd like to add you to my professional network on LinkedIn.
>
> - Heidi (Zhaoling)

You are receiving Reminder emails for pending invitations. Unsubscribe.

Invitation to connect on LinkedIn

2012-02-01T09:44:00.001-08:00

From Heidi (Zhaoling) Y.

Research Associate at University of Waterloo

Kitchener, Canada Area

I'd like to add you to my professional network on LinkedIn.

- Heidi (Zhaoling)

Confirm that you know Heidi (Zhaoling)

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Different behavior of function atol in VC6, Visual Studio 2005 and Visual Studio 2010

2011-04-06T13:28:00.001-07:00

Recently we have to upgrade a MFC project that can only compiled in VC6 to Visual Studio 2010. The project is pretty complex with 5 static library and dozens of dynamic linking libraries. After removing all the compiling errors caused by c++ language specification changes such as default function parameter is no long supported in function pointer ans so on, the program seems work now.

However, one test case always fails and we do not know why. It seems that it fails only at certain cases. After spending long time to investigate this crash (a memory crash is finally reported) we found out the reason.

In the code we have a function that needs to convert a string to DWORD, which is an unsigned long. The range of DWORD is 0 through 4294967295 Most times the conversion works fine as long as it is smaller than 2,147,483,647. The function we used to perform the conversion is atoi(), which converts a string to a signed integer. However, in VC6 the funciton returns a correct value even if the string contains a integer that is bigger than the maximum signed integer. In Visual Studio 2005, the atoi function returns the maximum value of signed integer, which is 2,147,483,647, if the string contains a bigger value. In Visual Studio 2010 it returns an strange value. Therefore, our code will only work fine in VC6. As soon as it is updated to Visual Studio 2010, a dangerous bug will be introduced.

The solution of this bug is by replacing the atoi() function with _atoi64(), which will work in all of the above situations.

The project file ‘ ‘ has been renamed or is no longer in the VS 2010 solution file

2011-04-06T08:50:00.001-07:00

I had a solution file with about 10 projects (some are libraries, some are dlls) that works very well. However, as soon as I change the name of the folder that contains the solution (including all projects) or move the whole solution from C: to D: drive, I will not be able to compile the solution. Instead, I will receive such an error: The project file ' ' has been renamed or is no longer in the solution.

After checking this problem carefully, I found that the main project (a MFC windows application) that references to other projects are using fixed project path. I think in other project types like C# windows form application all projects are using relative paths.

After removing all the project references, the solution compiles properly without any error message.

Error on Entity Framework: Unable to update the EntitySet ... because it has a DefiningQuery and no element exists in the

2010-12-23T09:27:00.000-08:00

I have this error with following simple code

ObjectKeyakey = new ObjectKey();

var aw = new entities2();

ObjectQuery<ObjectKey> query2 =

aw.LicenseKeys.Where("it.ActivationKey = @ln", new ObjectParameter("ln", strUserActivationKey));

List<LicenseKey> keyList = new List<LicenseKey>();

keyList = query2.ToList();

ObjectKey selectedKey = keyList[0];

selectedKey.ComputerName = "Test Change";

int rowsAffected = aw.SaveChanges(true);

The saveChanges function fails with the error say that I have a DefiningQuery and UpdateFunction mapped.

Following post provides a solution to it

http://social.msdn.microsoft.com/Forums/en/adodotnetentityframework/thread/220262bd-85d4-4f29-96a8-4a7d1d2c8293

Right click on the edmx file, select Open with, XML editor
Locate the entity in the edmx:StorageModels element
Remove the DefiningQuery entirely
Rename the store:Schema="dbo" to Schema="dbo" (otherwise, the code will generate an error saying the name is invalid)

The strange part is that in this database model I actually removed all views, and have confirmed that all table have primary keys set properly. Not sure why the DefiningQuery is still generated.

Anyway, the problem has been solved by following the above 4 steps.

BinaryFormatter deserialization exception

2010-12-08T12:25:00.001-08:00

http://connect.microsoft.com/VisualStudio/feedback/details/119402/binaryformatter-fails-to-deserialize

The BinaryFormatter always includes version information in the serialized stream even if you set FormatterAssemblyStyle.Simple during serialization. If you try to deserialize the stream after rebuilding the assembly, this will fail, even if you set FormatterAssemblyStyle.Simple during deserialization (fails to load the old assembly version used when creating the serialized stream).

This is the post that talks about how to make different version of binding compatible when binary formatter is used by applying the concept of SerializationBinder

http://msdn.microsoft.com/en-us/library/system.runtime.serialization.serializationbinder.aspx

MCV passive design pattern article

2010-11-03T13:42:00.001-07:00

The following is a good article with sample for MVC design pattern

http://www.c-sharpcorner.com/UploadFile/rmcochran/PassiveView01262008091652AM/PassiveView.aspx

http://www.c-sharpcorner.com/UploadFile/rmcochran/PassiveView01262008091652AM/download/MVC_PassiveViewSample.zip

How to create an application without any dialog

2010-09-20T12:18:00.001-07:00

Sometimes we want a simple application to detect the .Net framework installed on a computer before an application installation can continue. A simple console application can do the job. However, we do not want the black console window to be displayed during the installation.

The following solution may solve the problem

1. Create a simple Win32 project.

2. In the function

_int APIENTRY _tWinMain(HINSTANCE hInstance,

HINSTANCE hPrevInstance,

LPTSTR lpCmdLine,

int nCmdShow)

{

...

}

The default value of nCmdShow is 1. Change it to 0. Application will not display any dialog.

Comment out following line of code:

//// Main message loop:

//while (GetMessage(&msg, NULL, 0, 0))

//{

// if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))

// {

// TranslateMessage(&msg);

// DispatchMessage(&msg);

// }

//}

//return (int) msg.wParam;

return 0;

After finish the code. Application will exit.

This article shows how to detect .Net framework installed on a computer with the source code.

http://blogs.msdn.com/b/astebner/archive/2009/06/16/9763379.aspx

The code can be downloaded from

http://public.blu.livefilestore.com/y1p54ENa2JiMI3dWt4PhavbnoIrOcg4XdMypgSNkmuIYmNOHaOD_xI7seKY4VYfVAxluMqBcmzbQDhf3xIVLTYJ_g/detectfx_new.cpp.txt?psid=1

It works great.

Decompress large gzip file

2010-09-19T10:26:00.001-07:00

.Net GZipStream has a limitation of 4GB. It can not be used to compress/decompress files which are greater than 4gb. The following code overcomes the limitation.using dotnetzip library downloaded from http://dotnetzip.codeplex.com/

This code can unzip a Zip format file if the passed in file is right format.

public static string Decompress( string strPath, string dstFile, bool bIsZipFile)

{

if ( bIsZipFile == true)

{

if ( File.Exists( dstFile ) )

{

File.Delete( dstFile );

}

if ( File.Exists( strPath ) == false )

{

return strPath;

}

string strFolder = Path.GetDirectoryName( strPath );

Ionic.Zip.ZipFile zipFile = new Ionic.Zip.ZipFile( strPath );

zipFile.ExtractAll( strFolder );

zipFile.Dispose();

return dstFile;

}

FileStream fsIn = null;

FileStream fsOut = null;

//GZipStream gzip = null;

Ionic.Zlib.GZipStream gzip = null;

const int bufferSize = 4096;

byte[] buffer = new byte[ bufferSize ];

int count = 0;

List<string> lstExtraFilesToBeMerged = new List<string>();

try

{

if ( File.Exists( strPath ) == false )

{

return strPath;

}

if ( File.Exists( dstFile ) )

{

File.Delete(dstFile);

}

fsIn = new FileStream( strPath, FileMode.Open, FileAccess.Read, FileShare.Read );

fsOut = new FileStream( dstFile, FileMode.Create, FileAccess.Write, FileShare.None );

if ( bIsGZip == true )

{

//gzip = new Ionic.Zlib.GZipStream(fsIn, CompressionMode.Decompress, true);

gzip = new Ionic.Zlib.GZipStream(fsIn, Ionic.Zlib.CompressionMode.Decompress, true);

while (true)

{

//if (fsOut.Length > 100000)

//{

// gzip.Close();

// gzip = new GZipStream(fsIn, CompressionMode.Decompress, true);

//}

count = gzip.Read( buffer, 0, bufferSize );

if ( count != 0 )

{

fsOut.Write( buffer, 0, count );

}

if ( count != bufferSize )

{

// have reached the end

break;

}

catch ( Exception ex )

{

// handle or display the error

throw ( new Exception( "Decompress failed.", ex ) );

}

finally

{

if ( gzip != null )

{

gzip.Close();

gzip = null;

}

if ( fsOut != null )

{

fsOut.Close();

fsOut = null;

if (lstExtraFilesToBeMerged.Count > 0)

{

MergeFile(dstFile, lstExtraFilesToBeMerged);

}

if ( fsIn != null )

{

fsIn.Close();

fsIn = null;

}

return dstFile;

}

Customize predefined dialogs in Microsoft Installation Project in Visual Studio 2010

2010-09-17T13:11:00.001-07:00

We can update the dialogs defined in the following folders using ORCA.exe

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\Tools\Deployment\VsdDialogs\

The ORCA can be downloaded from following link

http://msdn.microsoft.com/en-us/library/aa370557(VS.85).aspx

This link gives example to add new controls in the dialog

http://social.msdn.microsoft.com/Forums/en-US/winformssetup/thread/1f8b14f7-2af6-4f54-950c-c5255b1853f1

1. Open %Visual Studio folder%\Common7\Tools\Deployment\VsdDialogs\1033\VsdFolderDlg.wid with Orca.

2. Since we'd like to add a editbox and a button in the folder dialog, we need to add two rows for these two controls in the Control table. I name the new editbox "FolderEdit2" and new browse button "BrowseButton2".

3. In the row for the FolderEdit2, specify a property under the Property column. I name it "DATAFILEDIR".

4. Because the FolderEdit2 is now the next control of the BrowseButton, change the ControlNext property of the BrowseButton to FolderEdit2.

5. In the ControlEvent table, add two rows for the "SpawnDialog" and "[SelectFolderDialog_Property]" events of BrowseButton2.

6. Since "DATAFILEDIR" is used as a directory, we need to add a row for it in the Directory table.

7. Change the display name of the custom dialog. To do this, navigate to the ModuleDialog table and change the value under the DisplayName column. I change the value to "Custom Installation Folder".

8. Save as VsdCustomFolderDlg.wid(this file is saved in the same path as VsdFolderDlg.wid file).

9. Open a setup project in Visual Studio.

10. In the User Interface editor, right click on the Install | Start node and choose "Add Dialog". "Add Dialog" window opens with the "Custom Installation Folder" dialog in it. Add this custom dialog just after the Welcome dialog in the User Interface editor.

11. In the File System editor, add a custom folder in it. Change the "Property" of this custom folder to "DATAFILEDIR". Add a file to this custom folder, e.g. test.txt.

12. Build the setup project and install the resulting MSI package. In the "Select Installation Folder" dialog, two editbox and two browse buttons show. Specify a path in the second editbox, e.g. d:\myfolder, and then the test.txt file is installed in the path "d:\myfolder".

Print preview and html document using IE control in C#

2010-09-09T08:36:00.001-07:00

In order to print/print preview a html file created by a c# windows application, the SHDocVw dll is used.

First, an InternetExplorer instance is created:

SHDocVw.InternetExplorer ie = new SHDocVw.InternetExplorerClass();

Secondly, the document is opened using the InterenetExplorer object:

Object

obj = new Object();

ie.Navigate(strPath, ref obj, ref obj, ref obj, ref obj);

The strPath above can be either a local html file or a real webpage from internet.

After this, the InternetExplorer instance will be used as a com object to carry out print and print preview command.

Just note that in Windows 7, a special object retrieval must be added because after the ie navigate to a local document, it become invalid and all later operation will fail.

The following is a complete function that print and print preview a document using IE in C#. It works for Visual Studion 2005/2010, on Windows XP and Windows 7.

public static void PrintHtmlDocument( bool bPrintPreview, string strPath )

{

SHDocVw.

InternetExplorer ie = new SHDocVw.InternetExplorerClass();

Object obj = new Object();

ie.Navigate(strPath, ref obj, ref obj, ref obj, ref obj);

* The following section is used to deal with the exception caused by the Windows 7.

* In windows 7, the object will become invalid after Navigate function even though the user interface shows the file is loaded

* The following section will first let the application to wait for 250ms, then query all the IE window to find the last IE window that show

* the loaded document.

Thread.Sleep(150);

SHDocVw.

ShellWindows shellWindows = new SHDocVw.ShellWindowsClass();

foreach (SHDocVw.InternetExplorer ie2 in shellWindows)

{

try

{

mshtml.

IHTMLDocument2 doc2 = ie2.Document as mshtml.IHTMLDocument2;

string strTargetFileName = Path.GetFileName(strPath);

string strUrl = ie2.LocationURL.ToString();

if (strUrl.Contains(strTargetFileName))

{

ie = ie2;

}

catch (Exception eee)

{

}

try

{

try

{

//wait until the DHTMLEdit control load the whole document

for (; ie.Busy != false; )

{

System.Windows.Forms.

Application.DoEvents();

}

catch (Exception eee)

{

}

mshtml.

IHTMLDocument2 doc = ie.Document as mshtml.IHTMLDocument2;

SHDocVw.

OLECMDF cmd = ie.QueryStatusWB(SHDocVw.OLECMDID.OLECMDID_PRINTPREVIEW);

if (bPrintPreview == false)

{

cmd = ie.QueryStatusWB(SHDocVw.

OLECMDID.OLECMDID_PRINT);

}

else

{

ie.Visible = true;

object pvaIn;

if (strPath == string.Empty)

{

pvaIn = null;

}

else if (!System.IO.File.Exists(strPath))

{

pvaIn = null;

}

else

{

pvaIn = strPath;

}

bool bPromptUser = true;

Object pvaout = null;

object pv = null;

object pva = null;

ie.ExecWB(SHDocVw.

OLECMDID.OLECMDID_PRINTPREVIEW, SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DODEFAULT, ref

pv,

ref pva);

}

Datagridview Combobox column throws NullReferenceExceptions

2010-08-12T12:44:00.001-07:00

I used several datagridview. Most of them work fine. However, one of them uses datatable binding and then from time to time, following exception is thrown.

System.NullReferenceException was unhandled
Message="Object reference not set to an instance of an object."
Source="System.Windows.Forms"
StackTrace:
at

System.Windows.Forms.DataGridView.InitializeEditingControlValue(DataGridViewCellStyle& dataGridViewCellStyle, DataGridViewCell dataGridViewCell)
at System.Windows.Forms.DataGridView.BeginEditInternal(Boolean
selectAll)
at System.Windows.Forms.DataGridView.BeginEdit(Boolean selectAll)
at
System.Windows.Forms.DataGridViewComboBoxCell.OnMouseClick(DataGridViewCellMouseEventArgs e)
at
System.Windows.Forms.DataGridView.OnCellMouseClick(DataGridViewCellMouseEventArgs e)
at System.Windows.Forms.DataGridView.OnMouseClick(MouseEventArgs e)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons
button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.DataGridView.WndProc(Message& m)
at
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd,
Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at
System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32
dwComponentID, Int32 reason, Int32 pvLoopData)
at
System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32
reason, ApplicationContext context)
at
System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason,
ApplicationContext context)
at System.Windows.Forms.Application.Run(ApplicationContext context)

It looks that sometimes several people have got the same error and however I have not seen any solution to this error yet. Maybe I should just avoid the datatable binding with the combobox for now.

Another difference of BinaryFormatter and XmlSerializer

2010-07-09T13:48:00.001-07:00

In this discussion the list of difference between above two serialization method is provided. However, I recently found another case that I need to use binary formatter instead of XMLSerializer.

In a dialog I have a multiple line text box editor to represent a object attribute. If I use xmlseriealizer to save and load the attribute, the text will become one long line instead of multiple lines. However, with BinaryFormatter, the text will be saved and loaded exactly as it is entered in the multiple line text box editor.

The following code is the method to save and load an object using xml serialization. (Not complete code)

Save:

System.Xml.Serialization.XmlSerializer writer = new System.Xml.Serialization.XmlSerializer( this.GetType() );

System.IO.StreamWriter file;

file = new System.IO.StreamWriter( strFileName );

// serialize the contents of the object

writer.Serialize( file, this );

file.Close();

Load:

System.Xml.Serialization.XmlSerializer reader = new System.Xml.Serialization.XmlSerializer( this.GetType() );

System.IO.StreamReader file;

file = new System.IO.StreamReader( strFileName );

// deserialize the contents of the object

MyObject savedObject = ( MyObject ) reader.Deserialize( file );

file.Close();

The following are the codes to save and load

Save:

//open the file to save the object

FileStream fs = new FileStream( strFileName, FileMode.Create );

BinaryFormatter bf = new BinaryFormatter();

bf.Serialize( fs, this );

// close the file

fs.Close();

Load:

FileStream fs = null;

fs = new FileStream( strFileName, FileMode.Open );

// Create a BinaryFormatter object to perform the deserialization

BinaryFormatter bf = new BinaryFormatter();

MyObject savedObject = ( MyObject ) bf.Deserialize( fs );

// Close the file

fs.Close();

Image List Memory Leakage

2010-05-27T11:29:00.000-07:00

I have followed following article.

http://blog.ramondeklein.nl/index.php/2009/05/18/listview-may-leak-with-imagelists/

However, after a few times of recreation of image list, the system GDI object still gets messed up.

https://connect.microsoft.com/VisualStudio/feedback/details/453810/using-imagelists-with-system-windows-forms-listview-control-may-leak-memory#

Could not load file or assembly

2010-04-20T17:39:00.000-07:00

I am using Asp.Net 2.0 and Visual Web Developer 2005 Express Edition on Windows Vista.

My application works fine until this morning I got following error:

Could not load file or assembly … The parameter is incorrect … HRESULT: 0x80070057 (E_INVALIDARG)

After deleting the following folder everything works fine again.

C:\Users\[User Name]\AppData\Local\Temp\Temporary ASP.NET Files

A Bug Of Black Background For Combo Box Column In DataGridView

2010-04-09T13:13:00.001-07:00

This bug has trapped me for days. Finally I got some clue from here:

http://www.geekpedia.com/Thread12474_A-Bug-Of-Black-Background-For-Combo-Box-Column-In-DataGridView.html

It really helps

I have this problem with both VS 2005 and 2008. Each time we use this event: private void OnEditControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e) in DataGridView, the background color of the combo box column becomes totally black, which makes the items in the combo box difficult to see. If it does not happen in the first look at the combo box, clicking a combo box in another row will definitely show the problem. Very easy to replicate! I would appreciate it if anyone can tell me how to get around this bug/problem. Thanks!
Re: A bug of black background for Combo box Column in DataGridView by outlaw on Tuesday, May 6th 2008 at 07:05 AM
Hi, i have faced the same problem & solved it by resetting the combo's backgroud color at it's GotFocus & Dropdown event. C the following: private void combo_SelectedIndexChanged(object sender, EventArgs e) { _MyController.CalculateTotal(); DataGridViewComboBoxEditingControl combo = (DataGridViewComboBoxEditingControl)sender; combo.SelectedIndexChanged -= new EventHandler(combo_SelectedIndexChanged); combo.DropDown += new EventHandler(combo_DropDown); combo.GotFocus += new EventHandler(combo_DropDown); } void combo_DropDown(object sender, EventArgs e) { ((DataGridViewComboBoxEditingControl)sender).BackColor = Color.White; } Hope this will help u.

Type conversion of C++ and C#

2009-12-01T12:06:00.001-08:00

In C++, type conversion can access member variable. However, in C#, type conversion can not. Every time we cast a type A object to Type B, a new object of Type B will be created.

The following is how type conversion operator is implemented in c++.

=========================================================

#include "stdafx.h"

class TypeA

{

public:

int a;

char b;

TypeA& TypeA::operator=(const double d)

{

this->a = d;

return *this;

}

operator const double ()

{

return this->a;

}

};

int _tmain(int argc, _TCHAR* argv[])

{

TypeA a;

a=3;

a.a = 5;

double d =(double)a;

return 0;

}

=========================================================

The following sample shows how to implement type conversion in c#

========================================================

using System;

using System.Collections.Generic;

using System.Text;

namespace ConsoleApplication1

{

class TypeA

{

public int a;

public int b;

public static implicit operator TypeA( double d )

{

TypeA TypeA = new TypeA();

TypeA.a = (int)d;

return TypeA;

}

public static implicit operator double( TypeA TypeA )

{

return TypeA.a;

}

class Program

{

static void Main( string[] args )

{

TypeA a = 2.5;

double b = a;

}

==========================================================

listview imagelist resource leakage

2009-10-21T13:06:00.001-07:00

ListView may leak with ImageLists

I have worked with the issue for several days. Basically as long as I set the state image list for a list view, I will end up with a big GDI Object leakage and eventually the listview will not be able to work properly.

Following article describes the issue more clearly.

http://blog.ramondeklein.nl/index.php/2009/05/18/listview-may-leak-with-imagelists/

Use Web Browser control to print and preview a html document

2009-10-13T07:02:00.001-07:00

The following article provides the idea to print preview using web browser.

http://www.developmentnow.com/g/36_2003_7_0_0_192939/Preview-control.htm

Make sure the web browser control is visible and in a windows form.

=======================

You can use COM object Microsoft Web Browser (customize your toolbox)
After that put the web browser control to form.

In your code it looks like:
private AxSHDocVw.AxWebBrowser axWebBrowser1;

You can get HTML content and show it so:
object flags=null;
object postData=null;
object header=null;
object targetFrame=null;
axWebBrowser1.Navigate("www.namip.ru", ref flags, ref targetFrame, ref
postData, ref header);

When the fetching will be finished you can do so:
object pv = null;
object pva = null;
axWebBrowser1.ExecWB(SHDocVw.OLECMDID.OLECMDID_PRINTPREVIEW,SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DODEFAULT,ref
pv, ref pva);

===========================

We can also use the IE browser to directly perform the task.

================================

SHDocVw.InternetExplorer browser = new SHDocVw.InternetExplorerClass();

browser .Visible=true;

Object obj = new Object();

browser.Navigate(strPath, ref obj, ref obj, ref obj, ref obj);

//wait until the DHTMLEdit control load the whole document

for (; browser.Busy != false; )

{

System.Windows.Forms.Application.DoEvents();

}

mshtml.IHTMLDocument2 doc = browser.Document as mshtml.IHTMLDocument2;

SHDocVw.OLECMDF cmd = browser.QueryStatusWB( SHDocVw.OLECMDID.OLECMDID_PRINTPREVIEW );

//IOleCommandTarget ct = ( IOleCommandTarget ) doc;

if ( bPrintPreview == true )

{

object pvaIn;

if ( strPath == string.Empty )

{

pvaIn = null;

}

else if ( ! System.IO.File.Exists( strPath ) )

{

pvaIn = null;

}

else

{

pvaIn = strPath;

}

Object pvaout = null;

object pv = null;

object pva = null;

ie.ExecWB( SHDocVw.OLECMDID.OLECMDID_PRINTPREVIEW, SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DODEFAULT, ref

pv, ref pva );

}

else

{

doc.execCommand( "Print", true, 0 );

}

================================

How to create a trigger to insert a record in a backup table when a record is modified or inserted in one table

2009-09-25T18:36:00.001-07:00

The following is a quick example that works on SQL Server 7.0

set ANSI_NULLS ON

set QUOTED_IDENTIFIER ON

Create TRIGGER [dbo].[trgInsertUpdatePrice]

ON [dbo].[Prices]

After INSERT, Update

INSERT INTO Prices_log

select * from Inserted

Open Source Bug track software in ASP.Net

2009-09-24T20:50:00.001-07:00

I am trying to find some good open source asp.net bug track software. I found the following article to be a good start point.

http://devpinoy.org/blogs/keithrull/archive/2007/11/02/a-comparisson-of-open-source-bug-tracking-softwares-in-asp-net.aspx

The following page is the bug track.net page. It is a very nice bug track system.

http://www.ifdefined.com/README.html#connection

How to trace down memory leakage in C++ code

2009-09-22T09:44:00.001-07:00

Following link provide a good method.

http://msdn.microsoft.com/en-us/library/4wth1ha5(VS.80).aspx

For example, if following memory leaks were detected: (Check the output window of VS after you close application in debug mode)

Detected memory leaks!

Dumping objects ->

f:\dd\vctools\vc7libs\ship\atlmfc\src\mfc\strcore.cpp(141) : {214137} normal block at 0x06C6B2B8, 42 bytes long.

Data: <, ?x > 2C 08 3F 78 19 00 00 00 19 00 00 00 01 00 00 00

f:\dd\vctools\vc7libs\ship\atlmfc\src\mfc\strcore.cpp(141) : {214136} normal block at 0x06C6B3A8, 91 bytes long.

Data: <, ?xJ J > 2C 08 3F 78 4A 00 00 00 4A 00 00 00 01 00 00 00

f:\dd\vctools\vc7libs\ship\atlmfc\src\mfc\strcore.cpp(141) : {214116} normal block at 0x06C6B258, 30 bytes long.

Data: <, ?x > 2C 08 3F 78 0D 00 00 00 0D 00 00 00 01 00 00 00

{214115} normal block at 0x06C6B208, 20 bytes long.

Data: < > B0 AA C6 06 00 AD C6 06 B0 A9 C6 06 00 AE C6 06

You can put following code at the start of the application. Make sure it is called before the allocation happened.

int allocateNo = 214137;

_CrtSetBreakAlloc(allocateNo);

_crtBreakAlloc = allocateNo;

allocateNo = 214136;

_CrtSetBreakAlloc(allocateNo);

_crtBreakAlloc = allocateNo;

allocateNo = 214116;

_CrtSetBreakAlloc(allocateNo);

_crtBreakAlloc = allocateNo;

allocateNo = 214115;

_CrtSetBreakAlloc(allocateNo);

_crtBreakAlloc = allocateNo;

Now when you start application in debug mode, VS will break when the memory that is not properly freed is allocated and you will be able to trace down the object that need to be properly handled.

webbrowser control DocumentCompleted triggered multiple times

2009-07-23T09:45:00.001-07:00

I am struggling with the documentCompleted event of web browser control for quite a little while.

There are many posts about how to decide whether the whole page has been loaded. Unfortunately none of them worked.

The following is one sample.

http://codinghut.com/2008/08/how-to-tell-when-a-webbrowser-has-fully-loaded-the-final-answer/

With following page, the event has never been triggered with the parameter url equals to the browser url.

http://www.canadiantire.ca/browse/product_detail.jsp?PRODUCT<>prd_id=845524441893435&FOLDER<>folder_id=1408474396672077&bmUID=1230691825032

Some people suggest to use a indes in the control navigating event because everytime a new document downloading will trigger the navigating event. However,

The indicator never reaches 0 if you add one to the index in navigating event and minus 1 in the document completed event.

I have also tried the browser ready state and check whether the browser has a ready state equal to Complete.

private void timer1_Tick(object sender, EventArgs e)

{

if (webBrowser1.ReadyState == WebBrowserReadyState.Complete)

{

...

timer1.Stop();

}

for the above web page, the ready state changed from Uninitialized to downloading and the interactive and stays as interactive forever.

So far I have not found a valid way to detect whether a page has been fully loaded.

Cross-thread Operation Not Valid

2009-07-16T12:34:00.001-07:00

I am working on a problem that UI response is very slow because the application has to initialize a collection of very complex grid view and the process will take as long as 8 seconds. I am trying to create another thread to initialize the grid views in a parallel thread. Then I came across the problem of cross thread operation not valid error because .Net does not allow the form controls to be updated in a thread other than the thread to create it.

The following is a solution that I can found from web.

http://www.astahost.com/info.php/Needed-Cross-thread-Operation-Valid_t15008.html

However, I noticed that even I can remove the exception, I can not solve the problem of performance because the time consuming operation is still executed in the main thread with invoke.

The following is the code.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Timers;

namespace UIThread
{

class SampleThread
{
public delegate void TestEventHandler(string sParameter);
public event TestEventHandler TestEvent;

protected System.Timers.Timer TestTimer = new System.Timers.Timer();
protected ISynchronizeInvoke SyncObject;

public SampleThread(ISynchronizeInvoke SyncObject)
{
this.SyncObject = SyncObject;
TestTimer.Elapsed += new ElapsedEventHandler(Tick);
TestTimer.Interval = 300;
}

protected delegate void TickDelegate(object source, ElapsedEventArgs e);
private void Tick(object source, ElapsedEventArgs e)
{
if (SyncObject.InvokeRequired)
{
SyncObject.BeginInvoke(new TickDelegate(Tick), new object[] { source, e });

//the following funciton are executed in the parellel thread
string sParameter = "";
for (int i = 0; i < 2000000; i++)
{
sParameter = sParameter + (i * i * i).ToString();
}
}
else
{
TestEvent(DateTime.Now.ToString());
}
}

public void Go()
{
TestTimer.Enabled = true;
}
}

public partial class Form1 : Form
{
SampleThread sampleThread;

public Form1()
{
InitializeComponent();
sampleThread = new SampleThread(this);
sampleThread.TestEvent += new SampleThread.TestEventHandler(FunctionInMainThread);
}

void FunctionInMainThread(string sParameter)
{
//basically this funciton is called from other thread by executed in main thread.
this.Text = sParameter;

//If following lines are turned on, the UI will become very slow in response.
//for (int i = 0; i < 2000000; i++)
//{
// sParameter = sParameter + (i * i * i).ToString();
//}
}

private void Form1_Load(object sender, EventArgs e)
{
sampleThread.Go();
}
}
}

Communication between managed c++ dll and C# form application

2009-07-03T08:22:00.001-07:00

Step 1:

Create a new C++ dynamic library project by default and name it as MCDLL. The default class will be as following.

First file:

// MCDll.h

#pragma once

using namespace System;

namespace MCDll {

public ref class Class1

{

// TODO: Add your methods for this class here.

};

}

Second file:

// This is the main DLL file.

#include "stdafx.h"

#include "MCDll.h"

Step 2:

Now we can add a class in the empty dll as following

// MCDll.h

#pragma once

using namespace System;

namespace MCDll {

public ref class Class1

{

// TODO: Add your methods for this class here.

public:

array<double>^ m_adTestArray; // array that can be passed to C#

//function to return double array

array<double>^ GetTestArray(int iLength);

};

}

Second file:

// This is the main DLL file.

#include "stdafx.h"

#include "MCDll.h"

array<double>^

MCDll::

Class1::

GetTestArray(int iLength)

{

m_adTestArray = gcnew array<double>(iLength);

for(int i=0;i<iLength;i++)

{

m_adTestArray[i] = i*i*i;

}

return m_adTestArray;

}

Compile the MCDLL project and you will see how it works.

Step 3:

Now we can create a simple window Form application with C#, and the project MCDll as a project reference to our C# form application in order to access the function defined in C++.

The following is a simple code to demo the use of the c++ class.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

namespace CSApp

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void button1_Click( object sender, EventArgs e )

{

MCDll.Class1 class1 = new MCDll.Class1();

double[] adFromC = null;

adFromC = class1.GetTestArray( 5 );

for ( int i = 0; i < adFromC.Length; i++ )

{

Console.WriteLine( adFromC[ i ].ToString() );

}

Compile above application and execute it, we will see that the double array is initialized in C++ dll but is accessible from C# application.

A few more cases are demoed here to show how to pass parameters by reference, how to return a dimensional array back and how to return a string array. Full code can be found at following

// MCDll.h

#pragma once

using namespace System;

namespace MCDll {

public ref class Class1

{

// TODO: Add your methods for this class here.

private:

array<double>^ m_adTestArray; // array that can be passed to C#

array<double,3>^ m_adDimensionalArray;

public:

//function to return double array

array<double>^ GetTestArray(int iLength);

//funciton to return a string array

array<System::String^>^ GetTestStringArray( int iLength );

//function to return double array with dimension

array<double,3>^ GetMultiDimensionArray(int iLength);

//pass parameter by reference

double PassParameterByReference( double dInput, double% dOutput1, double% dOutput2);

//pass parameter by reference

double PassParameterByReference2( double dInput, double% dOutput1, double% dOutput2);

};

}

// This is the main DLL file.

#include "stdafx.h"

#include "MCDll.h"

array<double>^

MCDll::

Class1::

GetTestArray(int iLength)

{

m_adTestArray = gcnew array<double>(iLength);

for(int i=0;i<iLength;i++)

{

m_adTestArray[i] = i*i*i;

}

return m_adTestArray;

}

array<System::String^>^

MCDll::

Class1::

GetTestStringArray(int iLength )

{

array<System::String^>^ astrArray = gcnew array<System::String^>(iLength);

for ( int i = 0; i < iLength; i++ )

{

System::String^ str;

str = gcnew System::String( i.ToString() );

astrArray[i] = str;

}

return astrArray;

}

array<double, 3>^

MCDll::

Class1::

GetMultiDimensionArray(int iLength )

{

m_adDimensionalArray = gcnew array<double,3>(iLength, iLength, iLength);

for(int i=0;i<iLength;i++)

{

for(int j=0;j<iLength;j++)

{

for(int k=0;k<iLength;k++)

{

m_adDimensionalArray[i,j,k]=i*100+j*10+k;

}

return m_adDimensionalArray;

}

// pass parameters by reference

double

MCDll::

Class1::

PassParameterByReference( double dInput, double% dOutput1, double% dOutput2)

{

dOutput1 =dInput * dInput;

dOutput2 =dInput * dInput *2;

return PassParameterByReference2(dInput,dOutput1,dOutput2);

}

// pass parameters by reference and called

double

MCDll::

Class1::

PassParameterByReference2( double dInput, double% dOutput1, double% dOutput2)

{

dOutput1 =dInput * dInput * dInput;

dOutput2 =dInput * dInput * dInput*2 ;

return dOutput2 *2;

}

The following code shows how to call the dll functions.

private static void TestFunctions()

{

MCDll.Class1 class1 = new MCDll.Class1();

double[] adFromC = null;

adFromC = class1.GetTestArray( 5 );

for ( int i = 0; i < adFromC.Length; i++ )

{

Console.WriteLine( adFromC[ i ].ToString() );

}

string[] astrArray = class1.GetTestStringArray( 10 );

for ( int i = 0; i < astrArray.Length; i++ )

{

Console.WriteLine( astrArray[ i ] );

}

int iLength = 5;

double[ , , ] adDimensionArray = class1.GetMultiDimensionArray( iLength );

for ( int i = 0; i < iLength; i++ )

{

for ( int j = 0; j < iLength; j++ )

{

for ( int k = 0; k < iLength; k++ )

{

Console.Write( adDimensionArray[ i, j, k ] );

Console.Write( "\t" );

}

Console.Write( "\n" );

}

Console.Write( "\n" );

}

double dInput = 3.0;

double dOutput1 = 0;

double dOutput2 = 0;

double dReturn = class1.PassParameterByReference( dInput, ref dOutput1, ref dOutput2 );

Console.WriteLine( "Input: " + dInput.ToString() );

Console.WriteLine( "dOutput1: " + dOutput1.ToString() );

Console.WriteLine( "dOutput2: " + dOutput2.ToString() );

Console.WriteLine( "dReturn: " + dReturn.ToString() );

}

Use the free REST web service to extact geo information from IP address

2009-07-02T12:43:00.001-07:00

The following sample provides a class to extract geo information from any IP address using a completely free web service provided by www.IPInfoDB.com.

This is the code for a simple windows form application in C#. The class IPInfor will construct itself from an IP address and return available attributes as properties.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.IO;

using System.Net;

using System.Xml;

namespace test

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

/// <summary>

/// A class respresent the data structure from IPInfoDB REST web service

/// </summary>

public class IPInfor

{

private string m_sIP;

private string m_sCountryCode;

private string m_sCountryName;

private string m_sRegionCode;

private string m_sRegionName;

private string m_sCityName;

private string m_sZipPostCode;

private double m_dLatitude;

private double m_dLongigitude;

private double m_dGmtoffset;

private double m_dDstoffset;

public string IP

{

get

{

return m_sIP;

}

public string CountryCode

{

get

{

return m_sCountryCode;

}

public string CountryName

{

get

{

return m_sCountryName;

}

public string RegionCode

{

get

{

return m_sRegionCode;

}

public string RegionName

{

get

{

return m_sRegionName;

}

public string CityName

{

get

{

return m_sCityName;

}

public string ZipPostCode

{

get

{

return m_sZipPostCode;

}

public double Latitude

{

get

{

return m_dLatitude;

}

public double Longigitude

{

get

{

return m_dLongigitude;

}

public double Gmtoffset

{

get

{

return m_dGmtoffset;

}

public double Dstoffset

{

get

{

return m_dDstoffset;

}

///

/// return the orignal REST response returned by "http://ipinfodb.com/ip_query.php?ip=" + sIP;

///

/// the original response string from web service based on the

private static string ShowOriginalResponse( StreamReader streamReader, bool bNoTranslation )

{

//directly return it;

if ( bNoTranslation == true )

{

return streamReader.ReadToEnd();

}

using ( XmlTextReader reader = new XmlTextReader( streamReader ) )

{

StringBuilder sb = new StringBuilder();

sb.Append( "\n ================ Start ===========\n" );

while ( reader.Read() )

{

switch ( reader.NodeType )

{

case XmlNodeType.Element: // The node is an Element.

sb.Append( "<" + reader.Name );

while ( reader.MoveToNextAttribute() ) // Read attributes.

sb.Append( " " + reader.Name + "='" + reader.Value + "'" );

sb.Append( ">" );

sb.Append( ">\n" );

break;

case XmlNodeType.Text: //Display the text in each element.

sb.Append( reader.Value );

sb.Append( "\n" );

break;

case XmlNodeType.EndElement: //Display end of element.

sb.Append( "<"+"/" + reader.Name );

sb.Append( ">\n" );

break;

}

sb.Append( "\n ================ End ===========\n" );

return sb.ToString();

}

//extract REST response to the IPInfor data structure

private void GetDataFromStreamReader( StreamReader streamReader )

{

XmlTextReader reader = new XmlTextReader( streamReader );

string sCurrentName = "";

while ( reader.Read() )

{

switch ( reader.NodeType )

{

case XmlNodeType.Element: // The node is an Element.

while ( reader.MoveToNextAttribute() )

{

}// Read attributes.

sCurrentName = reader.Name;

break;

case XmlNodeType.Text: //Display the text in each element.

switch ( sCurrentName )

{

case "Ip":

m_sIP = reader.Value;

break;

case "CountryCode":

m_sCountryCode = reader.Value;

break;

case "CountryName":

m_sCountryName = reader.Value;

break;

case "RegionCode":

m_sRegionCode = reader.Value;

break;

case "RegionName":

m_sRegionName = reader.Value;

break;

case "City":

m_sCityName = reader.Value;

break;

case "ZipPostalCode":

m_sZipPostCode = reader.Value;

break;

case "Latitude":

try

{

m_dLatitude = Convert.ToDouble( reader.Value );

}

catch ( Exception eee )

{

m_dLatitude = 0;

}

break;

case "Longitude":

try

{

m_dLongigitude = Convert.ToDouble( reader.Value );

}

catch ( Exception eee )

{

m_dLongigitude = 0;

}

break;

case "Gmtoffset":

try

{

m_dGmtoffset = Convert.ToDouble( reader.Value );

}

catch ( Exception eee )

{

m_dGmtoffset = 0;

}

break;

case "Dstoffset":

try

{

m_dDstoffset = Convert.ToDouble( reader.Value );

}

catch ( Exception eee )

{

m_dDstoffset = 0;

}

break;

default:

break;

}

break;

case XmlNodeType.EndElement: //Display end of element.

break;

}

//default constructor

public IPInfor()

{

}

//get original REST response from

public static string ShowOriginalResponse( string sIP, bool bNoTranslation )

{

try

{

string sQueryMain = "http://ipinfodb.com/ip_query.php?ip=" + sIP;

HttpWebRequest request = WebRequest.Create( sQueryMain ) as HttpWebRequest;

// Get response

using ( HttpWebResponse response = request.GetResponse() as HttpWebResponse )

{

// Get the response stream

StreamReader reader = new StreamReader( response.GetResponseStream() );

return ShowOriginalResponse( reader, bNoTranslation );

}

catch ( Exception eee )

{

//using backup service

string sQueryBackup = "http://backup.ipinfodb.com/ip_query.php?ip=" + sIP;

HttpWebRequest request = WebRequest.Create( sQueryBackup ) as HttpWebRequest;

// Get response

using ( HttpWebResponse response = request.GetResponse() as HttpWebResponse )

{

// Get the response stream

StreamReader reader = new StreamReader( response.GetResponseStream() );

return ShowOriginalResponse( reader, bNoTranslation );

}

//contruct an IPInfor class from IP address using REST web service from IPInforDB

public IPInfor( string sIP )

{

try

{

string sQueryMain = "http://ipinfodb.com/ip_query.php?ip=" + sIP;

HttpWebRequest request = WebRequest.Create( sQueryMain ) as HttpWebRequest;

// Get response

using ( HttpWebResponse response = request.GetResponse() as HttpWebResponse )

{

// Get the response stream

StreamReader reader = new StreamReader( response.GetResponseStream() );

GetDataFromStreamReader( reader );

}

catch ( Exception eee )

{

//using backup service

string sQueryBackup = "http://backup.ipinfodb.com/ip_query.php?ip=" + sIP;

HttpWebRequest request = WebRequest.Create( sQueryBackup ) as HttpWebRequest;

// Get response

using ( HttpWebResponse response = request.GetResponse() as HttpWebResponse )

{

// Get the response stream

StreamReader reader = new StreamReader( response.GetResponseStream() );

GetDataFromStreamReader( reader );

return;

}

private void button1_Click( object sender, EventArgs e )

{

//us ip

//string sIP = "74.125.45.100";

string sIP = "202.90.224.90"; //china ip http://www.adsensepublish.com/china-ip-address.html

sIP = "217.8.101.90"; //china ip http://www.adsensepublish.com/china-ip-address.html

sIP = "219.242.247.90"; //china ip http://www.adsensepublish.com/china-ip-address.html

sIP = "59.107.0.127"; //china ip http://www.adsensepublish.com/china-ip-address.html

//local ip

//string sIP = "";

string sQueryMain = "http://ipinfodb.com/ip_query.php?ip=" + sIP;

string sQueryBackup = "http://backup.ipinfodb.com/ip_query.php?ip=" + sIP;

Console.Write( IPInfor.ShowOriginalResponse( sIP, true ) );

//Console.Write( IPInfor.ShowOriginalResponse( sIP, false ) );

IPInfor ipInfo = new IPInfor( sIP );

Console.WriteLine( ipInfo.IP );

Console.WriteLine( ipInfo.CountryName );

Console.WriteLine( ipInfo.CountryCode );

Console.WriteLine( ipInfo.RegionName );

Console.WriteLine( ipInfo.RegionCode );

Console.WriteLine( ipInfo.CityName);

Console.WriteLine( ipInfo.Latitude );

Console.WriteLine( ipInfo.Longigitude);

Console.WriteLine( ipInfo.ZipPostCode );

Console.WriteLine( ipInfo.Gmtoffset );

Console.WriteLine( ipInfo.Dstoffset);

}

set a column of a table equal to the lower case of another column in SQL Server

2009-06-06T20:08:00.001-07:00

You can use following sql script to perform the above task.

In Query editor of SQL Server Management Studio, type in following command,

update users set lowerCase = lower(Username)

click execute.

The column of lowerCase will be set to lower case of the Username
column for each row in in table users.

Layered 2D drawing using GDI+ and C#

2009-06-05T12:26:00.001-07:00

Sometimes we want store each layer of object in memory and does not refresh them always. Instead, we will only redraw the layers that we need to redraw, and compose the final drawing with existing bitmaps in memory. Following sample shows how to draw multi layers on one control.

Steps:

1. Create a windows form application using C# in visual studio 2005

2. Draw a panel control to Form1. Rename the panel name to panelDrawing.

3. Replace the Form1 class with following code.

4. Link the OnPaint event of the panel to event panelDrawing_Paint

5. Compile and run.

You will see that the final image we have actually comes from three different layers. If we add a button to update only second layer, we will end up with much faster drawing effect. The disadvantage of this method is that it requires a lot of memory to store each layer, especially when the view area is big.

public partial class Form1 : Form

{

int iBitMapWidth = 1024;

int iBitMapHeight = 1024;

Bitmap btmap;

Bitmap btmapLayer2;

Bitmap btmapLayer3;

public Form1()

{

InitializeComponent();

btmap = new Bitmap( iBitMapWidth, iBitMapHeight );

btmapLayer2 = new Bitmap( iBitMapWidth, iBitMapHeight );

btmapLayer3 = new Bitmap( iBitMapWidth, iBitMapHeight );

for ( int i = 0; i < iBitMapWidth; i++ )

{

for ( int j = 0; j < iBitMapHeight; j++ )

{

int iRemain = 0;

int iColor = Math.DivRem( i, 255, out iRemain );

int jRemain = 0;

int jColor = Math.DivRem( j, 255, out jRemain );

btmap.SetPixel( i, j, Color.FromArgb( iRemain, jRemain, jRemain ) );

}

private void panelDrawing_Paint( object sender, PaintEventArgs e )

{

Font stringFont = new Font( "Arial", 10, FontStyle.Bold );

panelDrawing.AutoScrollMinSize = new Size( iBitMapWidth, iBitMapHeight );

Graphics gr = Graphics.FromImage( btmap );

gr.DrawEllipse( Pens.Blue, 10, 10, 20, 20 );

gr.DrawString( "From layer 1", stringFont, Brushes.Red, 30, 10 );

Graphics grLayer2 = Graphics.FromImage( btmapLayer2 );

//very important to clear the layer with transparent color

grLayer2.Clear( Color.Transparent);

grLayer2.FillEllipse( Brushes.Red, 40, 50, 20, 20 );

grLayer2.DrawString( "From layer 2", stringFont, Brushes.Red, 60, 50 );

Graphics grLayer3 = Graphics.FromImage( btmapLayer3 );

grLayer3.Clear( Color.Transparent );

grLayer3.FillRectangle( Brushes.Yellow, 80, 80, 20, 20 );

grLayer3.DrawString( "From layer 3", stringFont, Brushes.Yellow, 100, 80 );

gr.DrawImage( btmapLayer2, 0, 0 );

gr.DrawImage( btmapLayer3, 0, 0 );

// Determine the drawing origin from the scroll bar positions

int x = panelDrawing.AutoScrollPosition.X;

int y = panelDrawing.AutoScrollPosition.Y;

Rectangle clientRectangle = panelDrawing.ClientRectangle;

clientRectangle.Offset( -x, -y );

Region visible = new Region( clientRectangle );

e.Graphics.DrawImage( btmap, x, y );

}

Programmatically disable and enable tab page in C# winform application

2009-06-05T11:34:00.001-07:00

Tab control of .Net does not come with a handy enable and disable property for each tab page. The enabled property is available, but actually it is not working as it should be, like a text box control or other list view, etc. Therefore, you need to implement a few event handlers in order to make a tab page really support disable and enable.

The following sample gives detailed method to implement a function to disable and enable a tab control in a win form.

Steps to use following code:

1. Create a window form application using C#

2. Drag a tab control to the form1

3. Copy following code into form1.cs.

4. Draw one button to each of the default tab page and link the click event of the button to a proper click event.

5. Compile and run.

Now you will see that if you click the button on one tab page, the other tab page will be disabled and enabled like a text box control, grayed out and no selecting is allowable.

You can use this method to control more than one tab control in one windows form. If you want to have tab control in more than one windows form to have similar behavior, you will need to implement a tab control first that include a tab control and implement this feature in the user control to avoid duplication.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

namespace TabEnable

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

//programatically set the tab control property to allow disable and enable

this.tabControl1.DrawMode = TabDrawMode.OwnerDrawFixed;

this.tabControl1.DrawItem += new DrawItemEventHandler( DisableTab_DrawItem );

this.tabControl1.Selecting += new TabControlCancelEventHandler( DisableTab_Selecting );

}

private void buttonEnablePage2_Click( object sender, EventArgs e )

{

if ( tabControl1.TabPages[ 1 ].Enabled == false )

{

this.EnalbleTabPageByIndex( tabControl1, 1 );

}

else

this.DisableTabPageByIndex( tabControl1, 1 );

this.tabControl1.Invalidate();

}

private void buttonEnablePage1_Click( object sender, EventArgs e )

{

if ( tabControl1.TabPages[ 0 ].Enabled == false )

{

this.EnalbleTabPageByIndex( tabControl1, 0 );

}

else

this.DisableTabPageByIndex( tabControl1, 0 );

this.tabControl1.Invalidate();

}

//if a tab page is selected, the selecting event will be canceled if it is disabled.

private void DisableTab_Selecting( object sender, TabControlCancelEventArgs e )

{

if ( !e.TabPage.Enabled )

{

e.Cancel = true;

}

//draw a tab page based on whether it is disabled or enabled.

private void DisableTab_DrawItem( object sender, DrawItemEventArgs e )

{

TabControl tabControl = sender as TabControl;

TabPage page = tabControl.TabPages[ e.Index ];

if ( !page.Enabled )

{

using ( SolidBrush brush = new SolidBrush( SystemColors.GrayText ) )

{

e.Graphics.DrawString( page.Text, page.Font, brush, e.Bounds.X + 3, e.Bounds.Y + 3 );

}

else

{

using ( SolidBrush brush = new SolidBrush( page.ForeColor ) )

{

e.Graphics.DrawString( page.Text, page.Font, brush, e.Bounds.X + 3, e.Bounds.Y + 3);

}

//disable a page of a tab control by index

public void DisableTabPageByIndex( TabControl tabControl, int iPageIndex )

{

if ( iPageIndex >= tabControl.TabCount || iPageIndex < 0 )

{

return;

}

TabPage tabPage = tabControl.TabPages[ iPageIndex ];

tabPage.Enabled = false;

}

//enable a tab page by index

public void EnalbleTabPageByIndex( TabControl tabControl, int iPageIndex )

{

if ( iPageIndex >= tabControl.TabCount || iPageIndex < 0 )

{

return;

}

TabPage tabPage = tabControl.TabPages[ iPageIndex ];

tabPage.Enabled = true;

}

Performance issue with WPF

2009-06-01T07:19:00.001-07:00

I found a few posts about the performance issue with WPF when large number of geometry objects will be rendered. Unfotunately this is the situation we are at. I will try it later and if this is the case, then I may stick with GDI+.

What to use for fast 2D graphics?

http://www.fernicola.org/loquitor/index.php?/archives/48-What-to-use-for-fast-2D-graphics.html

A few people mentioned that WPF was not so good at big number of geometry handling. Performance is quite slow.

In another blog, it is mentioned that

" However, if you were in the position to have to be constantly recreating the geometry of the objects that you are trying to render, then you might need the immediate mode API that GDI+ offers."

http://stackoverflow.com/questions/275222/relative-merits-of-gdi-and-wpf

WPF Development

2009-06-01T07:03:00.001-07:00

I am considering about converting my code from using GDI+ to WPF and try to find out a valid reason that I need do this now.

The following are a few sources about WPF.

Official WPF site

http://msdn.microsoft.com/en-us/netframework/aa663321.aspx

A detailed comparison of GDI and WPF.

http://www.leadtools.com/help/LEADTOOLS/v15/DH/Wpf/TO/Leadtools.Wpf.Topics~Leadtools.Wpf.Topics.DifferencesBetweenGDIANDWPF.html

This is a more formal discussion of WPF

http://olafurandri.com/nyti/papers2006/Windows%20Presentation%20Foundation%20(WPF).pdf

WPF is compatible with OpenGL. See this article.

http://69.10.233.10/KB/WPF/WPFOpenGL.aspx

Code of the linear brush

2009-05-29T09:01:00.001-07:00

This is the project code.

How to create a linear brush using GDI+ and C#

2009-05-29T08:56:00.001-07:00

This sample shows how to custom draw a customized button.

Just create a simple window form application and add a button to the form, then in the paint event of the button add a function like following.

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Drawing.Drawing2D;

namespace LinearBrush

{

public partial class MainForm : Form

{

public MainForm()

{

InitializeComponent();

}

private void button1_Paint( object sender, PaintEventArgs e )

{

using ( LinearGradientBrush brush =

new LinearGradientBrush( e.ClipRectangle, Color.Orange,

Color.Maroon, LinearGradientMode.Horizontal ) )

{

e.Graphics.FillEllipse( brush, e.ClipRectangle.X,e.ClipRectangle.Y,e.ClipRectangle.Width,e.ClipRectangle.Height/3 );

System.Drawing.Font fnt = new Font( "Microsoft Sans Serif", 10 );

e.Graphics.DrawString( "Test" +DateTime.Now.ToString(), fnt, Brushes.Green, e.ClipRectangle );

}

private void button1_Click( object sender, EventArgs e )

{

this.Text = "Hello, " + DateTime.Now.ToString();

button1.Text = "Clicked at " + DateTime.Now.ToString();

}

How to create a chm file using HTLM Help Workshop

2009-05-14T18:31:00.000-07:00

Start from here

http://frogleg.mvps.org/helptechnologies/htmlhelp/hhtutorials.html

Double click a hhp file, the HTML help workshop will open automatically. With this tool you can create new project, create new html file and insert it into the project, add index, heading and so on.

Software component market

2009-05-04T06:00:00.000-07:00

A good start is here. It lists lots of available components to buy.
Component Source

Software Development using C# .Net

Reminder about your invitation from Heidi (Zhaoling) Y.

Reminder about your invitation from Heidi (Zhaoling) Y.

Invitation to connect on LinkedIn

Different behavior of function atol in VC6, Visual Studio 2005 and Visual Studio 2010

The project file ‘ ‘ has been renamed or is no longer in the VS 2010 solution file

Error on Entity Framework: Unable to update the EntitySet ... because it has a DefiningQuery and no element exists in the

BinaryFormatter deserialization exception

MCV passive design pattern article

How to create an application without any dialog

Decompress large gzip file

Customize predefined dialogs in Microsoft Installation Project in Visual Studio 2010

Print preview and html document using IE control in C#

Datagridview Combobox column throws NullReferenceExceptions

Another difference of BinaryFormatter and XmlSerializer

Image List Memory Leakage

Could not load file or assembly

Could not load file or assembly … The parameter is incorrect … HRESULT: 0x80070057 (E_INVALIDARG)

A Bug Of Black Background For Combo Box Column In DataGridView

http://www.geekpedia.com/Thread12474_A-Bug-Of-Black-Background-For-Combo-Box-Column-In-DataGridView.html

Re: A bug of black background for Combo box Column in DataGridView

Type conversion of C++ and C#

listview imagelist resource leakage

ListView may leak with ImageLists

Use Web Browser control to print and preview a html document

How to create a trigger to insert a record in a backup table when a record is modified or inserted in one table

Open Source Bug track software in ASP.Net

How to trace down memory leakage in C++ code

webbrowser control DocumentCompleted triggered multiple times

Cross-thread Operation Not Valid

Communication between managed c++ dll and C# form application

Use the free REST web service to extact geo information from IP address

set a column of a table equal to the lower case of another column in SQL Server

Layered 2D drawing using GDI+ and C#

Programmatically disable and enable tab page in C# winform application

Performance issue with WPF

WPF Development

Code of the linear brush

How to create a linear brush using GDI+ and C#

How to create a chm file using HTLM Help Workshop

Software component market