.net miner

In one of my previously published article (very old 🙂 one), I mentioned briefly about reflection, and discuss how reflection is an important concept in .Net Framework. While it is a very important concept there is a performance issue related with the Reflection. If you over use reflection codes in your projects you have to face with performance issues compared with the code that is implemented in this sample project.

In that context, I have explained two methods to have a better performance when manipulating objects dynamically and I have shared code examples about them. As a summary, I created a ObjectCreateMethod class which uses DynamicMethods and creates an IL which calls type constructors. By calling that generated DynamicMethod we can create instance of types faster than traditional reflection. If you are interested in and need more information, you can access article from here.

After reviewing previous article, now you are ready to get more information about the usage of the DynamicMethods that improve the performance of traditional reflection which is the subject of this article.

In the previous article, maybe you have discerned an imperfection. The ObjectCreateMetod class – which uses DynamicMethods for creating instance of a type – is only suitable for creating instance of types which has parameter-less constructors.

While I was surfing the web, I found a feedback about my article. Someone asks if it is possible to use ObjectCreateMethod class with types which has parameterized constructors. Because of this, I decided to updated my code, and now it also supports the constructors with parameter(s).

To resolve this issue I created a dynamic method which takes object[] argument as the constructor arguments. Than I take these parameters on to the stack and call new opcode. Here is the code;

/// <summary>
///  Creates the dynamic proxy method which calls given <see cref="ConstructorInfo"/>
/// </summary>
/// <param name="methodInfo"></param>
private static DynamicMethodDelegate CreateProxyMethod(ConstructorInfo constructor)
{
    var method = new DynamicMethod(constructor.DeclaringType.Name + "_ctor_Proxy",
        typeof(object),
        new Type[] { typeof(object[]) },
        constructor.DeclaringType);

    var wrapper = new ILGeneratorWrapper(method.GetILGenerator());

    var parameters = constructor.GetParameters();
    var parameterTypes = new Type[parameters.Length + 1];
    parameterTypes[0] = constructor.DeclaringType;
    for (int i = 0; i < parameters.Length; i++)
    {
        parameterTypes[i + 1] = parameters[i].ParameterType;
    }

    wrapper.DeclareLocals(parameterTypes);

    for (int i = 1; i < parameterTypes.Length; i++)
    {
        wrapper.EmitLoadArg(0);
        wrapper.EmitLoadCons(i - 1);
        wrapper.Emit(OpCodes.Ldelem_Ref);
        wrapper.EmitCast(parameterTypes[i]);
        wrapper.EmitStoreLocal(i);
    }

    for (int i = 1; i < parameterTypes.Length; i++)
    {
        wrapper.EmitLoadLoc(i);
    }

    wrapper.Emit_NewObj(constructor);

    wrapper.EmitStoreLocal(0);
    wrapper.EmitLoadLoc(0);
    wrapper.Emit(OpCodes.Ret);

    return method.CreateDelegate(typeof(DynamicMethodDelegate)) as DynamicMethodDelegate;
}

I also added some other helper proxy classes which provides invoking other type members (fields, properties and methods) by using DynamicMethods too.

Download Source Code From GitHub | Watch Sample Movie(v1.0.5.0)

 What is Process Viewer?

I can say that Process Viewer is a program like Microsoft Spy++. Unlikely to Spy++ it allows you to edit some properties of the Controls and also allows you to manage its window messages. You can change Text, Visibility, Enabled, Window Styles and Window Ex Styles properties of a control by using PV during run time. There withal you can ignore window messages, change incoming message to a different message or edit parameters of any window messages by putting breakpoints to the control’s window procedure with PV.

An example screenshot of the Process Viewer

An example screenshot of the Flags Editor

PropertyGrid will use default editor for the properties which’s type is enum. This default editor does not allow multiple selections even the Enum has Flags attribute.

I have been prepared a new Editor for this kind of properties.

Our editor’s code is as follows;

internal class FlagsEditor : UITypeEditor
{
   FlagsEditorControl editor = null;
   public FlagsEditor()
   { }
    
   // our editor is a Drop-down editor
   public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
   {
      return UITypeEditorEditStyle.DropDown;
   } 
  
   public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
   {
       // if value is not an enum than we can not edit it
      if  (!(value is Enum))
         throw new Exception("Value doesn't support");
     
      // try to figure out that is this a Flags enum or not ?
      Type enumType = value.GetType();
      object[] attributes =  enumType.GetCustomAttributes(typeof(FlagsAttribute), true);
      if (attributes.Length == 0)
         throw new Exception("Editing enum hasn't got Flags attribute");
      // check the underlying type
      Type type = Enum.GetUnderlyingType(value.GetType());
      if (type != typeof(byte) && type != typeof(sbyte)  && 
            type != typeof(short) && type != typeof(ushort) && 
           type != typeof(int)&& type != typeof(uint))
        return value;
      if (provider != null)
      {
         // use windows forms editor service to show drop down
         IWindowsFormsEditorService edSvc = provider.GetService( 
              typeof(IWindowsFormsEditorService)) as IWindowsFormsEditorService;
         if (edSvc == null)
             return value;
         if (editor == null)
             editor = new FlagsEditorControl(this);
         // prepare list
         editor.Begin(edSvc, value);
         // show drop down now
         edSvc.DropDownControl(editor);
         // now we take the result
         value = editor.Value;
         // reset editor
         editor.End();
      }
      return Convert.ChangeType(value, type);
   }
}

In this code FlagsEditorControl is a UserControl which PropertyGrid hosts it in a drop down during the edit operation.
You can change your design by changing this Control.

To use this editor for a property, we have to write Editor Attribute to that property as the below;

// set editor of this property to our FlagsEditor
[Editor(typeof(FlagsEditor), typeof(UITypeEditor))]
public FileAttributes FlagsAttribute
{
       get { return _FlagsAttribute; }
       set { _FlagsAttribute = value; }
}

Today I wrote a simple application, which shows what the difference is between initializing a static field in the explicit static constructor and doing the same during the declaration time (inline). I know that even when we initialize our static fields inline, the compiler will add an implicit static constructor to that class and initialize static values in that method. But this example showed me that there is really a long time difference between initializing static fields inline and in explicit static constructor. Here are a screenshot from the example – in this example BeforeFieldInit means that the static fields are initialized inline and NotBeforeFieldInit means that static fields are initialized in the explicit static constructor:

An example screenshot of the Screen Capturing

For a very long time ago, in one of my projects, I needed to capture the screenshot which must have to support both full screen capturing and specific regional capturing.

Also I need to paste that captured image back to the screen programmatically. At that moment I solved my problem by using some WinApi methods in the user32.dll and gdi32.dll. Here I want to share that code with you.

Download Source Code From GitHub

Tonight i uploaded an example about Server-Client applications to the server. The name of the example is B-MSN which is an instant messaging program like MSN, AOL or Yahoo IM.

Some of the specifications of the B-MSN are;

Supports Smileys
Supports personal image
NetServer and NetClient components which you can also use them as standalone
Flashes window when a new message received
Supports RTF text sending
Informs you while the person whom you chat with is writing a message to you
Supports Saving Message Histories