[Mixed] Snippet Requests

To help get this thread started I invite requests for code snippets and I will do my best to provide answers, hopefully others can help too. Only requests for snippets not full applications please, for example

How do I detect that the application is running in a Terminal Services session.
How do I convert RGB (0-255) Colour values to HLS (Hue, Luminosity, Saturation).
Answers at bottom of page.

My professional areas of expertise are Windows NT4 to current (all versions), c++, C#, Windows Applications, COM, ASP.Net, MS SQL Server 2000, 2005, 2008. MS CRM Dynamics 4.0 and networking.

If we get a good collection it could for the basis of a Knowledge Base section.

Snippet code.

[C++]

How do I detect that the application is running in a Terminal Services session.

Code:

bool IsTerminalServicesSession()
{
HANDLE hToken;
BOOL bOK = OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY,  &hToken);

  DWORD TokenSessionID = NULL;
DWORD dwBufferSize = sizeof(TokenSessionID);
  
  GetTokenInformation(hToken,
                          TokenSessionId,
                          &TokenSessionID,
                          dwBufferSize,
                          &dwBufferSize
                          );

CloseHandle(hToken);

return (TokenSessionID != 0);
}

How do I convert RGB (0-255) Colour values to HLS (Hue, Luminosity, Saturation).

Code:

VOID CHLS::RGBtoHSL(COLORREF rgb, double *H, double *S, double *L)
{
double delta;
double r = (double)GetRValue(rgb)/255;
double g = (double)GetGValue(rgb)/255;
double b = (double)GetBValue(rgb)/255;   
double cmax = max(r,max(g,b));
double cmin = min(r,min(g,b));   
*L=(cmax+cmin)/2.0;   

if(cmax==cmin) 
{
*S = 0;      
*H = 0; // it's really undefined   
}
else 
{
if(*L < 0.5) 
*S = (cmax-cmin)/(cmax+cmin);      
else
*S = (cmax-cmin)/(2.0-cmax-cmin);      

delta = cmax - cmin;
if(r==cmax) 
*H = (g-b)/delta;      
else
if(g==cmax)
*H = 2.0 +(b-r)/delta;
else          
*H=4.0+(r-g)/delta;
*H /= 6.0; 
if(*H < 0.0)
*H += 1;  
}
}

 

Hi.

I'll get the info you need today hopefully and I'll add the info to this post. ASP .Net question will be answered later today.


a) GC.Collect();

b) At the top of your class

[DllImport("User32.dll")]
static extern Boolean MessageBeep(UInt32 beepType);

in your code

MessageBeep(0);

 

For your ASP.Net question I do not have a code snippet (yet). I think it will be much more than a code snippet too.

Normally you would bind the GridView to a Datasource, creating INSERT, DELETE AND UPDATE commands for the DataSource, Enable Edit and Delete buttons for the GridView. Now all you need to do is implement the Insert command in the GridView and this is where it will get more complicated than a "snippet".

So to implement this you'd create a DataTable and bind this to the GridView. Now all your automatic editing and delete are no longer available so you would have to implement that your self.
You would then add command buttons to the GridView for Edit, Del, Ins and implement the code in their repective events to update the DataTable.
When you're ready to commit the changes you would have to start an SQL transaction, iterate the DataTable detecting changes, update/insert/delete and finally commit the changes.

To detect the Insert Command you would use event RowCommand of the GridView. I have created a very basic app which while not your complete solution should help you on your way with the other information I have given.

http://www.datafilehost.com/download-6d3b06bf.html