Using The Invoke Method Of IDispatch?
Aug 31, 2010
I am implementing a custom iDispatchLLInvoke handler for VB.NET - some of this is working.So Far - I have been able to intercept and provide custom handling of simple functions and property calls - but I am stuck when I try to set a property and get an error "Invalid Pointer (Exception from HRESULT: 0x80004003 (E_Pointer))".
I am using the new .NET 4.0 ICustomQueryInterface to do this. In Summary - I intercept and provide my own implementation of iDispatch - I load the dispIDs on the first call - and return a the dispID for each call within GetIDsOfNames - this ID is than passed to Invoke where reflection is used to get the value and return the result.
When I attempt to set a property - a call is made to GetIDsofNames and I return a valid dispID - the application than crashes with the error above and no call is made to Invoke.As a result - I am assuming that the issue relates to my interface definition been wrong becase the code never get's back to .NET code - see below for this code:
<ComImport(), Guid("00020400-0000-0000-C000-000000000046"), InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)> _
Public Interface IDispatch
Sub GetTypeInfoCount(ByRef pctInfo
As UInt32)
[code]....
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Nov 11, 2009
Public Class StateObject
Public workSocket As Socket = Nothing
Public Const BufferSize As Integer = 1024
Public buffer(BufferSize) As Byte
[CODE]....
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Oct 7, 2010
I have been using a pretty slick generic invoke method for UI updating from background threads. I forget where I copied it from (converted it to VB.NET from C#), but here it is: Public Sub InvokeControl(Of T As Control)(ByVal Control As t, ByVal Action As Action(Of t))
[Code]....
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Aug 20, 2009
1. On the main form a scanner class is instantiated that (in the scanner's constructor) sets the scanner settings (baud rate, parity, etc) and opens the scanner for use
2. A barcode is scanned (via a scanner connected to the device in a seral port) while on the main form
3. In the scanner class, the DataRecieved event gets the needed info from the scanned code.
4. Then that info is passed back to the main form to a method RunCommandCode (which takes the scanned info as an argument)
5. On the main form the RunCommandCode calls another method CommandCodeHandler, passing the scanned info again
6. In the CommandCodeHandler sub a method is called in a Utils class (SetSelectedTab), which interacts with the form itself (determines how many tabs exist on a tab control), which is the reason for the invoke in the first place
So, before I figured out I needed to use the Invoke method (and, more specifically, that the scanner was working in a different thread), I was getting an error in step 6 on the line that got the TabControl.TabPages.Count.
[code]...
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Nov 16, 2011
I've created a MyFunc extension (in Module Extensions) for all the base types as well as generic arrays, ICollection(Of T) and Dictionary(Of String,T):
Function MyFunc(Of T)(a() As T) As String
Function MyFunc(Of T)(collection As ICollection(Of T)) As String
Function MyFunc(Of T)(dict As Dictionary(Of String,T)) As String
[code].....
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Apr 3, 2009
Using VB.NET, is there a way to pass a reference argument when invoking a function in a dll.
Suppose I want to pass arg2 as a reference argument, how would I do that?
method.Invoke(obj, New [Object]() {arg1, arg2, arg3})
In other words I want to point arg2 to something else within the invoked function.
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May 29, 2012
I want to invoke a method on a class that i have a reference to. The method that I want to call has a custom attributes. Currently I can find this attributes and call the property of my class Attribute.
is there a way to invoke that method ?
PS/ The project is written in vbnet, but I think the solution is the same in c#.
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May 5, 2011
I'm trying to make this code with reflection since I want it to manage Technician and other types too.
[Code]....
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Aug 16, 2010
I have some code in c#
BeginInvoke(new MethodInvoker( delegate() {myAppMethod_Tick(sender, e); }));
Now, When I tried to convert that code to vb.net I have below..
BeginInvoke(New MethodInvoker(Function() Do myAppMethod_Tick(sender, e) End Function))
But it does not compile.. What's problem for it?
Because my c# application works ok without any problem..
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May 25, 2011
Is it possible to somehow invoke foo("SomeAwesomeString") from VBScript directly (i.e., without it having to launch an additional process)?
The use case is this: I am trying to write an 'extension' application for hMailServer (hMS), but hMS can only invoke VBscript scripts when an event happened. I can have the VBscript launch an .exe every time the event happened, but the processing involve opening and closing a connection to a back-end database. So, every invocation is very expensive. I had been thinking that I can reduce the expense by having a Service to maintain the connection (i.e., opening it once and re-open it if the connection closed). Plus by implementing the processing as background worker threads will result in a non-blocking processing + less process-starting overhead.
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Aug 19, 2010
This is the code i have so far (no i didn't write it all by my self took help from net) but i am unable to understand why i am getting this error
Imports CookComputing.XmlRpc
Public Structure blogInfo
Public title As String
[code]....
error i get is "Invoke on Non-Existent or Non-public proxy method"
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May 22, 2009
I have a COM component that I want to call using late-binding from VB.NET (using Primary Interop Assembly - PIA method). My IDL signature for the COM method looks like:
HRESULT Send([in]BSTR bstrRequestData,
[out]VARIANT *pvbstrResponseData,
[out]VARIANT *pvnExtCompCode,
[out,retval]int *pnCompletionCode);
So 2 'ByRef' parameters in VB.NET lingo, and a return value. I attempt to invoke this method like so:
Dim parameters(2) As Object
parameters(0) = "data"
parameters(1) = New Object()
parameters(2) = New Object()
Dim p As New ParameterModifier(3)
[Code] .....
This fails spectactularly with an exception: {"Invalid callee. (Exception from HRESULT: 0x80020010 (DISP_E_BADCALLEE))"}
I assume this means I'm doing something wrong in my parameterMods array. Because if I comment out setting any value of the ParameterMods array to 'True' - it works. It of course doesnt update the parameters that are [out] parameters and so it's not working as intended. Is there something else to consider since the method also has a return value? The MSDN example pretty much does exactly what I am doing, with the exception that example did not have a return value.
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Mar 3, 2009
Attempting to invoke a method of an interface, of which the return type is _variant_t
Code:
_variant_t resultsDataString;
_bstr_t simObjectNames;
simObjectNames = SysAllocString (L"TEST example 3");
resultsDataString = pis8->GetSimObject (simObjectNames);
[code].....
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Jan 2, 2010
I Have a Function on my frmMain Class wich will update my control to something else after an invoke. When i type "?Label1.Text" on the Immediate Window, the text property IS updated, but when i go check the Form, nothing happened. The code is just like this
[Code]...
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Jul 27, 2010
I have a ASP.NET (C#) web page which utilizes a VB class library. The VB library performs a SOAP POST to a remote web service and returns a message. However the VB library keeps running into a "No connection could be made because the target machine actively refused it xxx.xxx.xxx.xxx" However, I've also created a C# test client which consumes the same VB class library and can perform the post just fine! [code]
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Mar 16, 2010
I've got the following code:
[code]...
The problem is that, when I call the "SetStatusBarText" sub from another thread, InvokeRequired is True (as it should be), but then my threads stall on the Me.Invoke statement - pausing execution shows them all just sitting there, not actually invoking anything.
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Jul 14, 2009
I've run into a bit of a problem.. I am unsure as to how many people know how "IRC" Servers work here but basically, i'll explain. We are re-creating an IRC Client we made for our Chat site in VB.NET originally vb6. We have serveral different forms but the main problme we are having at the moment is FrmMain is where you login to the servers, it grabs your data from our MySQL database such as "Nick, Gender, Font" etc. Then proceeds with connection to IRC server on Raw 001 we know the connection to the IRC server has been established... so therefore we open up FrmAuth which in this case they can see roomlist etc. We are unable to get FrmAuth to load probably.
We originally had this working opening up FrmAuth before the connection to IRC server has been established.. This really is no good for us causes alot of errors etc. So when we use just simply "me.show()" the form loads but freezes we tried doing Me.Invoke(New Del(AddressOf me.show))
however, this didnt work in which I assume that is because the "FrmAuth" hasn't yet loaded the GUI thread therefore there is no Thread to invoke so we tried FrmMain.Invoke(New Del(AddressOf me.show))
This didn't work either i assume you cannot access another forms Invoke method?
we are receiving the error A first chance exception of type.'System.InvalidOperationException' occurred in System.Windows.Forms.dll which i assume has something to do with it but not quite sure..
So my question comes down to the fact of, how do we open up FrmAuth without it freezing? Is there a way to access the invoke method on another form?
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Nov 17, 2010
I have a C++ method with this signature:
[Code]...
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Jul 14, 2009
We are re-creating an IRC Client we made for our Chat site in VB.NET originally vb6
We have serveral different forms but the main problme we are having at the moment is
FrmMain is where you login to the servers, it grabs your data from our MySQL database such as "Nick, Gender, Font" etc. Then proceeds with connection to IRC server on Raw 001 we know the connection to the IRC server has been established... so therefore we open up FrmAuth which in this case they can see roomlist etc. We are unable to get FrmAuth to load probably.
We originally had this working opening up FrmAuth before the connection to IRC server has been established.. This really is no good for us causes alot of errors etc.
So when we use just simply "me.show()" the form loads but freezes we tried doing
Me.Invoke(New Del(AddressOf me.show))
however, this didnt work in which I assume that is because the "FrmAuth" hasn't yet loaded the GUI thread therefore there is no Thread to invoke so we tried
FrmMain.Invoke(New Del(AddressOf me.show)) This didn't work either i assume you cannot access another forms Invoke method..?? we are receiving the error A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll which i assume has something to do with it but not quite sure..
So my question comes down to the fact of, how do we open up FrmAuth without it freezing? Is there a way to access the invoke method on another form?
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Jul 4, 2010
I am trying to use the SolutionEvents interface in Visual Studio and the sample it have is in C#. When I try to port it I get compile or run-time errors ("COM target does not implement IDispatch"). The problem is with the bold line on the bottom with the "+=" which does not work in VB. Removing the + causes a run-time error.
The C# code is:
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Aug 27, 2010
I have a filesystewatcher object. On it`s event it runs a procedure which fills a treeview with a data. I had problems with treeview methods, but when I run them using invoke method everything is ok. But I still have one problem. When I load the form for the first time, everything works fine. But, when I then close the form (me.dispose, me.close), and load it once again, when Filesystemwathcer start the procedure i have an exception "invoke or begininvoke cannot be called on a control until the window handle has been created" trying to run a treeview.invoke method?
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Apr 10, 2009
What is Platform Invoke Service (P/Invoke)?
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Oct 13, 2010
We have a UI with a progressbar. I know how to invoke, safely, the control from which it was not created from a thread. there are threads being processed in a threadpool, all of which calls an "agent" (which is a notifier to raise an event back to the UI to then increase the progressbar). an "agent" is set as a property in a State object, which is then passed into a method which will be executed on the ThreadPool. so, I invoke on the UI the method to update the progressbar, but the bar does not seem to update at all (screen frozen) and it takes a very very long time for it to execute. without threading, no problem.
[Code]...
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Oct 19, 2010
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
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Nov 12, 2009
Does calling the Dispose method on a Windows.Forms.Timer call it's Stop method? Or should I stop the timer before I dispose it?
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Oct 12, 2009
how do i create dll application in vb.net? how do i call a dll application from an exe application?
using VB.NET, is there sample code where an exe application invokes a dll appliction?
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Mar 5, 2009
Is it possible to execute some sort of code to determine whether or not it's a good idea to call Invoke? I dunno what you would do once you'd found out you can't but it could be useful for detecting some dead locks (like the one I have a the moment).
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Nov 25, 2011
I have a large problem with inheritance in vb.net. The problem is the following:
I have 2 forms => frmBase and frmChild
In frmBase i want to create a method Called StartWorking() and i want frmChild to inherit this method.
But here is the tricky thing: when frmChild.StartWorking is called i would like the following => without calling MyBase.StartWorking()
I want frmBase.StartWorking() to be executed first and after a test in frmBase.StartWorking if blnValue is true then frmChild.StartWorking has to be activated. if blnValue is false that frmChild.StartWorking cannot be activated.
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Dec 18, 2010
I have nine pictures that I need to animate -I need to use the ToString method and a counter to concatenate a file name into a string variable from the Image.FromFile method. Once the counter reaches its maximum value, and the last picture is displayed, the counter should be reset to zero or one depending on how the first image file has been name. Also a static counter variable should be incremented in the time routine. what I have so far -- I know what I have to do; however, I just do not know how to code this properly.. Right now I have this going thru a button procedure but it needs to go through a timer.
[code]....
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Sep 16, 2010
Write an overload for every numeric type or if possible constrain a generic extension method to just numeric types.
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