We've been unable to get events working going from C# to VJ++. We
think that the C# component is being exposed properly as a
ConnectionPoint, and the Advise() from the VJ++ side seems to be
working, because the delegate on the C# side has 1 item in its
invocation list after the Advise(). However when we try to make the
callback, we get:
System.NullReferenceException: Object reference not set to an instance
of an object
at System.RuntimeType.InvokeDispMethod(String name, BindingFlags
invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers,
Int32 culture, String[] namedParameters)
at System.RuntimeType.InvokeMember(String name, BindingFlags
invokeAttr, Binder binder, Object target, Object[] args,
ParameterModifier[] modifiers, CultureInfo culture, String[]
namedParameters)
at System.RuntimeType.ForwardCallToInvokeMember(Strin g memberName,
BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData&
msgData)
at IWeatherEvents.OnWeatherChanged(Int32 nTemperature)
at TemperatureComponent.StateChange(Object sender, EventArgs args)
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.DebuggableCallback(IntP tr hWnd, Int32
msg, IntPtr idEvent, IntPtr dwTime)
We'd appreciate help. We have a significant code base of VJ++ and
we've determined that the JCLA has too many issues, so we're going to
have to be hybrid for a little while. I think this is supposed to
work.
ITemp.idl
---------
/////
import "oaidl.idl";
interface ITemp; // defined below
interface IWeatherEvents; // defined below
[
uuid(ABA21482-DDE2-4cf8-9BF9-D95464AC77C2),
helpstring("ITemp type library"),
version(1.0)
]
library LTempLib
{
importlib ("stdole2.tlb");
// out going interface ///////////////////////
[
object,
uuid(36EAE5EA-633E-474f-B6F1-5CDE5552487E),
helpstring("IWeatherEvents"),
oleautomation
]
interface IWeatherEvents : IUnknown
{
[helpstring("IWeatherEvents callback")]
HRESULT OnWeatherChanged( [in] long nTemperature );
}
[
object,
uuid(9F0C939C-99E2-4a07-94AC-9D84E25AF8EF),
helpstring("ITemp"),
oleautomation,
pointer_default(unique)
]
interface ITemp : IUnknown
{
[propput,helpstring("Set the temp")]
HRESULT Temperature([in] float t);
[propget,helpstring("Get the temp")]
HRESULT Temperature([out,retval] float *t);
[helpstring("Display temp")]
HRESULT DisplayCurrentTemperature();
};
//////////////////////////////////////////////
interface ITemp;
[
uuid(33FE55E3-C85B-4475-B7B4-0B5196FAB0E7)
]
coclass InsideCOM
{
interface ITemp;
[source] interface IWeatherEvents;
}
}
Class1.cs
---------
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
// Outgoing interface which the sink implements
[InterfaceType(ComInterfaceType.InterfaceIsIDispatc h)]
[GuidAttribute("36EAE5EA-633E-474f-B6F1-5CDE5552487E")]
public interface IWeatherEvents
{
void OnWeatherChanged( int nTemperature );
}
// delegate representing the OnWeatherChanged method
// of the outgoing exposed to COM aware clients.
public delegate void WeatherChangedDelegate( int nTemperature );
// [InterfaceType(ComInterfaceType.InterfaceIsDual)]
//public interface ITemperature
//{
// float Temperature { get; set; }
// void DisplayCurrentTemperature();
//
//}
// this is required to tell typelibrary generation tool REGASM.EXE
// to export the public members of TemperatureComponent into a default
// Class Interface in the generated typelibrary
[
//ComSourceInterfacesAttribute(typeof(IWeatherEvents )),
ComSourceInterfaces("IWeatherEvents"),
GuidAttribute("33FE55E3-C85B-4475-B7B4-0B5196FAB0E7"),
ProgId("TemperatureComponent.TemperatureComponentI nterface")
]
// this tells the type lib generation tools to add this class
// along with all of its methods and properties to the typelib file.
//[ClassInterface(ClassInterfaceType.AutoDual)]
public class TemperatureComponent : LTempLib.ITemp
{
private float m_fTemperature = 0;
private Timer _t;
// define an event associated with the WeatherChangedDelegate
private event WeatherChangedDelegate OnWeatherChanged;
// Public Constructor
public TemperatureComponent()
{
m_fTemperature = 30.0f;
_t = new Timer();
_t.Interval = 1000; // 1 seconds
_t.Tick += new EventHandler(StateChange);
_t.Enabled = true;
}
private void StateChange(object sender, EventArgs args)
{
m_fTemperature++;
if( null != OnWeatherChanged )
{
System.Delegate[] foo = OnWeatherChanged.GetInvocationList(); //
just used to check in debugger that there is one thing to invoke
Object bar = OnWeatherChanged.Target; // didn't tell me anything
helpful just _ComObject
OnWeatherChanged( (int)m_fTemperature ); // This call causes the
exception
}
}
//WeatherIndications GetWeatherIndications();
//Public Property Accessors (Defines get/set methods)
public float Temperature
{
get { return m_fTemperature; }
set { m_fTemperature = value;}
}/* end Temperature get/set property */
// Public Method that displays the Current Temperature
public void DisplayCurrentTemperature()
{
String strTemp = String.Format("The current temperature at
Marlinspike is : " +
"{0:####} degrees fahrenheit", m_fTemperature);
MessageBox.Show(strTemp,"Today's Temperature");
}/* end DisplayCurrentTemperature */
// Another public method that returns an enumerated type
//public WeatherIndications GetWeatherIndications()
//{
// if(m_fTemperature > 70)
// {
// return WeatherIndications.Sunny;
// }
// else
// {
// // Let's keep this simple and just return Cloudy
// return WeatherIndications.Cloudy;
// }
//}/* end GetWeatherIndications */
}/* end class Temperature */
Form1.java (VJ++)
----------
import com.ms.wfc.app.*;
import com.ms.wfc.core.*;
import com.ms.wfc.ui.*;
import com.ms.wfc.html.*;
import com.ms.com.*;
import itemp.ITemp;
import itemp.IWeatherEvents;
import itemp.InsideCOM;
/**
* This class can take a variable number of parameters on the command
* line. Program execution begins with the main() method. The class
* constructor is not invoked unless an object of type 'Form1' is
* created in the main() method.
*/
public class Form1 extends Form implements itemp.IWeatherEvents
{
Object o;
ITemp it;
private int cookie = -1;
private IWeatherEvents m_iEventListener = null;
public Form1()
{
System.setOut( com.ms.debug.Debugger.out );
System.setErr( com.ms.debug.Debugger.out );
// Required for Visual J++ Form Designer support
initForm();
try
{
//TemperatureComponent t = new TemperatureComponent();
com.ms.com._Guid g = new com.ms.com._Guid(
"{33FE55E3-C85B-4475-B7B4-0B5196FAB0E7}" );
o = com.ms.win32.Ole32.CoCreateInstance(
g,
null,
com.ms.win32.win.CLSCTX_INPROC_SERVER,
InsideCOM.iid );
it = (ITemp)o;
IConnectionPoint cp = null;
IConnectionPointContainer container = (IConnectionPointContainer)o;
cp = container.FindConnectionPoint( IWeatherEvents.iid );
//cookie = cp.Advise( (IUnknown)
com.ms.com.ComLib.makeProxyRef(this) );
cookie = cp.Advise( this ); // didn't seem to matter whether
proxyref or not
} catch( Exception e )
{
e.printStackTrace();
String s = e.getMessage();
com.ms.wfc.util.Debug.println( s );
}
// TODO: Add any constructor code after initForm call
}
public void OnWeatherChanged( int nTemperature )
{
// nTemperature;
MessageBox.show("got change event"); // Never reaches this point
label1.setText( String.valueOf(nTemperature) );
}
/**
* Form1 overrides dispose so it can clean up the
* component list.
*/
public void dispose()
{
super.dispose();
components.dispose();
// CUnknown iun = (CUnknown)o;
// iun.Release();
IConnectionPoint cp = null;
IConnectionPointContainer container = (IConnectionPointContainer)o;
cp = container.FindConnectionPoint( IWeatherEvents.iid );
cp.Unadvise(cookie);
}
private void button1_click(Object source, Event e)
{
it.setTemperature( (float) 12.3 );
float x = it.getTemperature();
it.DisplayCurrentTemperature();
}
/**
* NOTE: The following code is required by the Visual J++ form
* designer. It can be modified using the form editor. Do not
* modify it using the code editor.
*/
Container components = new Container();
Button button1 = new Button();
Label label1 = new Label();
private void initForm()
{
this.setText("Form1");
this.setAutoScaleBaseSize(new Point(5, 13));
this.setClientSize(new Point(292, 273));
button1.setLocation(new Point(24, 24));
button1.setSize(new Point(136, 23));
button1.setTabIndex(0);
button1.setText("Help me...");
button1.addOnClick(new EventHandler(this.button1_click));
label1.setLocation(new Point(24, 80));
label1.setSize(new Point(168, 32));
label1.setTabIndex(1);
label1.setTabStop(false);
label1.setText("help m. . . . . ");
this.setNewControls(new Control[] {
label1,
button1});
}
/**
* The main entry point for the application.
*
* @param args Array of parameters passed to the application
* via the command line.
*/
public static void main(String args[])
{
Application.run(new Form1());
}
}
