Web control questions - C# Discussion Boards

How to read records of a file of dbf in c# ?

17-Mar-04 4:58

As I mentioned, you can use the ServiceController to execute commands if your ServiceBase-derived services overrides the OnCustomCommand. You still need an instance of the ServiceController for your service (using the service's registered name, not the display name) in order to call ServiceController.ExecuteCommand. Your commands are limited to passing an int, so you'll need to establish an identification protocol, like 0 = Kill threads or something like that. If you use bitwise operations, you could even use this int to have threads sleep for a time, such that the mask 0x80000000 indicates that threads should sleep while the mask 0x0000ffff gets the amount of seconds (or milliseconds, or whatever) to sleep.

If you need more control beyond that, you'll need to use remoting. You can use ASP.NET as a remoting client, but I wouldn't recommend it unless you're using a singleton pattern for a server-activated type (which would be the most likely choice anyway).

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Solaer15-Mar-04 23:06

Solaer

15-Mar-04 23:06

I wonder how to get the information of a file of dbf in c#.
For example,record numbers,the header information of file ,record data ,etc.

main []args parameter to run another instance

hazzem elrefai15-Mar-04 22:57

hazzem elrefai

15-Mar-04 22:57

i have application that open word document when the user open the applicatoin and try to open another document from the application, the application starts new instance by shell command and passes the file name as parameter.
the problem is i always get the message "can not find the file specified"
but when i deguged the application and copyed the command string and tryed to ru it from the prompet it worked well.

here is my code:::
/////////////////////////////////////////////////////////////////////////////////////
string action="";
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.EnableRaisingEvents=false;
string path = Environment.CurrentDirectory;
int pos=ienum.Current.ToString().IndexOf("bin");//get the first parameter
action=path+"\\Almogahed.exe "+ienum.Current.ToString().Substring pos+12);
ienum.MoveNext();
action+=" "+ienum.Current.ToString().Substring(pos+12);//get second parameter
proc.StartInfo.FileName=action;
proc.Start(); // file can not found why!!!!!!!!!!!!!
/////////////////////////////////////////////////////////////////////////////////////

Re: main []args parameter to run another instance

hazzem elrefai16-Mar-04 1:41

hazzem elrefai

16-Mar-04 1:41

thank u
i did it by using
/////////////////////////////////
proc.StartInfo.Arguments=param;
/////////////////////////////////

Drag and Drop feature in TreeView

viru15-Mar-04 21:04

viru

15-Mar-04 21:04

How to set the focus on the treeview nodes for placing the Text in Drag Drop functionality.
I used Drag_Enter event in which , the
treeview.SelectedNode = treeview.GetNodeAt(e.X, e.Y) but
the treeview.SelectedNode always returns Undefined Vaule.
Also, wherever the treeview control was placed , instead of e.X , i used
e.X - treeView.Left and e.Y - treeView.Top
Still, i am not able to get the solution.
Can anyone look into this.

Thanks and Regards,
Viru

Re: Drag and Drop feature in TreeView

Heath Stewart16-Mar-04 3:23

Re: Web control questions

16-Mar-04 3:23

Never set the TreeNode under the cursor while dragging to the SelectedNode. It is NOT the selected node. Instead, you'll have to override the painting and - while dragging (which you can set a flag for instance) - paint the node under the cursor using the highlight colors and any appropriate colors from SystemColors.

The TreeView in the .NET FCL is very limited, and you often have to go to a lot of work for something like this. I recommend you look into tree controls like those from http://www.devexpress.com[^] and http://www.infragistics.com[^].

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Web control questions

Den2Fly15-Mar-04 19:55

Den2Fly

15-Mar-04 19:55

Hello buddies,
I am developing a web control, whose class is derrived from System.Web.UI.Control class. as you know Control Class doesn't include "Style:CssStyleCollection" Property which exists in System.Web.UI.Webcontrols.Webcontrol class. In the latter class this property is magically filled with 'styl'e attribute available in the HTML-side control's tag and I would really be thankful if someone tell me how this happens so I implement it in my System.Web.UI.Control based webcontrol.

Also Webcontrol contains Width and Height properties and all derrived webcontrols can be resized on the design surface of VS using resize handles arround their rectangle, I have added custom Width and Height properties to my System.Web.UI.Control based webcontrol and it works in rendered HTML and also in direct property assignment in properties panel and code, BUT on the design surface of VS it can not be resized with the mouse.

I appreciate any help,
- Den to Fly

---
"Art happens when you least expect it."

Heath Stewart16-Mar-04 3:19

Re: Web control questions

16-Mar-04 3:19

Why don't you just extend WebControl instead of Control? This is the correct way to make your own WebControl so that you inherit all the functionality from WebControl, which you obviously seem to want.

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Den2Fly16-Mar-04 3:44

Den2Fly

16-Mar-04 3:44

I initially desired to do so but you know Heath, Webcontrol has 'forecolor', 'bordercolor', ... and other properties that I don't need in my Wencontrol at all. I guess Microsoft should have not include all these properties that are not really generic in all webcontrols or I can say better they could include other light weight class that only had properties available to all UI webcontrols.

anyway can you help me to implement 'Style', 'Width' & 'Height' myself?

Thanks

---
"Art happens when you least expect it."

Re: Web control questions

Heath Stewart16-Mar-04 3:53

16-Mar-04 3:53

If you don't need them, don't use them. Nothing says you have to. And if you don't want them to show up in the designer, override the properties and attribute them with BrowsableAttribute(false) and EditorBrowsableAttribute(EditorBrowsableState.Never), which is very common in many classes throughout the entire .NET FCL.

If you want to do it the hard way, the Width and Height are simple properties that store the width and height either in private fields your class can use or - more commonly - in the ViewState. The Style property is a little extra work but there are classes in the respectible ASP.NET namespaces that can help you parse and resolve these. Just read the documentation for the namespaces and browse the classes.

Seriously, though, just hide the members you don't want to support from the WebControl base class. You'll save yourself a lot of work. For example:

public class MyWebControl : WebControl
{
  // ...
  // Just don't use the Width in your code anywhere when you render.
  [Browsable(false)]
  [EditorBrowsable(EditorBrowsableState.Never)]
  public override Unit Width
  {
    get { return base.Width; }
    set { base.Width = value; }
  }
}

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Thank you so much -nt

Den2Fly16-Mar-04 4:53

Den2Fly

16-Mar-04 4:53

nt

---
"Art happens when you least expect it."

DoubleBuffer Exception

Amberite0015-Mar-04 16:40

Amberite00

15-Mar-04 16:40

Hi,

I have a control I am making (inherits from Control), called ExtendedListView, in which I use two sub controls to perform drawing operations in. Problem is, in these sub controls (which are classes inheriting from Control, inside of ExtendedListView), when I call this.SetStyle(ControlStyles.DoubleBuffer, true), an exception is thrown (not on that line, but sometime after) in System.drawing.dll.

If I call DoubleBuffer in the main class (ExtendedListView), everything is ok. If I delete the DoubleBuffer code from the sub-controls then everything is ok. However, I need these sub-controls to have DoubleBuffer as I am using them to draw into.

I can't see where the exception is because it happens somewhere not in my code. Does anyone know of this error? Why is it happening?

Thanks!

Yaron

John Fisher15-Mar-04 17:08

15-Mar-04 17:08

One easy way to get missed exceptions is to wrap the code inside of your

static void Main()

function with this:

try
{
    // Your code here.
}
catch (Exception err)
{
    System.Diagnostics.Trace.WriteLine(err.ToString());
}

With that, you should get a detailed report of the error information, which is always a help.

John

"You said a whole sentence with no words in it, and I understood you!" -- my wife as she cries about slowly becoming a geek.

Amberite0015-Mar-04 17:32

Amberite00

15-Mar-04 17:32

Thanks John,

Here is what comes up:

System.ArgumentException: Invalid parameter used.
at System.Drawing.Graphics.EndContainer(GraphicsContainer container)
at System.Windows.Forms.DibGraphicsBufferManager.ReleaseBuffer(GraphicsBuffer buffer)
at System.Windows.Forms.GraphicsBuffer.Dispose()
at System.Windows.Forms.Control.WmPaint(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.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.ComponentManager.System.Windows.Forms.UnsafeNativeMethods+IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at Test.Form1.Main() in c:\documents and settings\yaron\my documents\visual studio projects\visual c#\extendedlistview\test\form1.cs:line 146

John Fisher16-Mar-04 12:49

16-Mar-04 12:49

I personally don't have an answer to this one. Sorry.

John

"You said a whole sentence with no words in it, and I understood you!" -- my wife as she cries about slowly becoming a geek.

Heath Stewart16-Mar-04 3:15

16-Mar-04 3:15

Typically, a better way is to handle the AppDomain.UnhandledException or Application.ThreadException events. Putting a try-catch around your Application.Run statement only catches exception that would cause the message pump to terminate.

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John Fisher16-Mar-04 12:48

16-Mar-04 12:48

Right. I just thought that this was easier to explain and understand, and it would get him the error message he needed to see.

John

"You said a whole sentence with no words in it, and I understood you!" -- my wife as she cries about slowly becoming a geek.

Heath Stewart16-Mar-04 3:18

16-Mar-04 3:18

If you look at the dcoumentation for the ControlStyles.DoubleBuffer member, you'll see that the ControlStyles.AllPaintingInWmPaint and ControlStyles.UserPaint are also required to be set to true in SetStyle. This means that you'll have to make sure to call base.OnPaint in your OnPaint override and handle the WM_ERASEBKGND message (if not already handled by the ListView,w hich you can find out using ildasm.exe) to call OnPaint as well.

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Insert new Array ?

azusakt15-Mar-04 16:24

azusakt

15-Mar-04 16:24

Dear All,

I want to know, is there any inconvenients / mistakes will occur if I use an ArrayList to store up some classes dynamically? The class contains quite a lot of infos.

In my application, I need to create a class array e.g: ImageInfo[] imgInf, however, I the size maybe change at anytime.

For example, inside Init function, I will create an array as :
ImageInfo[] imgInf = new ImageInfo[1];

The size of array should be at least one, and its size will increase / decrease when I add/delete infos.
I don't know, how can I dynamically insert/remove a new array to imgInf, so I decided to use ArrayList to store the class,; e.g. use ArrayList.Add();
but I'm worried about it will cause some mistakes..

Could anyone give me some idea?? Thank you

Re: Insert new Array ?

John Fisher15-Mar-04 17:03

15-Mar-04 17:03

ArrayList is a good choice when the array will be changing size. If you used an actual array (whatever[]), you would need to write your own code to re-allocate the new block and copy the old stuff to the new array, making sure to insert and delete appropriately. Writing your own code when other code already exists to do the job is generally a mistake, since you'll create new bugs and spend time that didn't need to be spent.

In short, the only mistake you would need to worry about with ArrayList is if you put something in it that is not of the type that you want to be storing there. (Casting is required in order to use the object when you pull it out.)

John

"You said a whole sentence with no words in it, and I understood you!" -- my wife as she cries about slowly becoming a geek.

Re: Insert new Array ?

Heath Stewart16-Mar-04 3:13

Convert from true type font to vector image

16-Mar-04 3:13

You could also always extend CollectionBase (or make your own, which would implement IList which implements ICollection and IEnumerable) and make strongly-typed params for the type you want. The CollectionBase (and many other collections, for that matter) use a backing ArrayList to store objects, but by having typed parameters you avoid putting objects of different Types in the list because the compiler would fail if you tried adding something else. Extending CollectionBase isn't hard (see the documentation in the .NET Framework SDK for information on which methods have to be overridden and an example) and ensures that you won't add an instance of a different Type to the list.

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Zhang Songling15-Mar-04 15:32

Zhang Songling

15-Mar-04 15:32

Currently I am doing a vector drawing program which user need to input text using true type font.

Previously in C++ I am doing the conversion by myself.

But I heard that .Net can do the conversion automatically for me, is that true?

Thanks a lot Big Grin | :-D

songling

Re: Convert from true type font to vector image

Heath Stewart16-Mar-04 3:09