What should be the VB signature for the unmanaged function void PopulateBSTR(BSTR outstring)?The function PopulateBSTR does a SysAllocString and populates the string. Note the unmanagaed signature has the argument BSTR and not BSTR*. I can marshal the BSTR string using IntPtr signature when the C++ signature has BSTR* as the argument.
(The unmanaged code is an external dll which I cannot modify but I need to use.)
Currently in our VB.Net windows application, C libraries are present under the 'bin' directory but we want to store it under application root directory where other forms and classes are present...How can we do this in Vb.Net 2008?
View 1 RepliesI have an application which has been succesfully installed on a number of different client machines.
The problem I now have is that I have been asked to allow third party applications, possibly written in a non .net language set to plug into my application and execute some of the code. Just a handfull of properties and half a dozen methods.
Now I can wrap up these properties/methods, make them public and have them in their own project which will be part of my solution but I have no idea where to go from here.
How do I make this portion of my application accessible to a third party application written in unmanaged code ?
I am trying to develop a dll in VisualStudio2005 in vb.net that will communicate with a spectrometer attached to the USB port of the computer.Now the dll exists in C++ and it works like a charm. It is unmanaged code.Now if I try to translate this code in VB.net (because our app is in VB and my boss wants it in VB for maintainability) I have problems.
First of all, I am trying to create a file to open that port. The code in C++ looks like below and it works. Needles to say I tried to call the C++ dll from our app and it works. If I call the vb dll it doesn't. It gives me "access denied" no matter what I tried. I am not sure if my CreateFile is wrong or it's .net. I read somewhere that I need a manifest file included in the dll? Has anyone experience something like this? Why would i get "ACCESS DENIED" all the time?
// close and clear current stuff
ClosePort();
swprintf( sDevice, L"\\?\usb#vid_0765&pid_%s#******#{%s}", Device, PRIVATE_IID_STR );
[code].....
I need to write a DLL in C that is used a plugin for an existing application.The DLL has to be compiled by the Visual Studio 2008 compiler with the following options.[code]It's then linked to applications library's.What it actually needs to do and what's causing me the issues is that within one of the methods it needs to pull data from a sql server 2008 r2. From what I've seen today you wouldn't be able to do this directly in C as SQL Server past 2005 is designed to communicate with CLR languages( C#, C++, VB.Net).It was suggested that I handle all the database communication with a VB.Net dll and then call said function from within the C dll. Most of what I've found on the topic of calling managed dll's from unmanaged code has talked about pinvoke or com wrappers and mainly from the perspective of c++.
View 2 RepliesI am having a problem marshaling data between managed and unmanaged code. So I need to inspect the data at the byte level. What I need to do is store a number, say 8 into a 4-byte integer then copy it to an array bytArray(4) and compare those bytes with other data. I also need to set up the same array and copy it to an integer variable.
View 2 RepliesFirst of all; I'm completely new to VB.
Pass a string array from Visual Basic Express 2008 to unmanaged code in a Dll.The array is Dimmed as in DIM myArray(11) as String
I'm developing the dll myself using Powerbasic.
The dll expect a 4 bytes pointer to a safearray's handle. As far as I have understood it; the array's string elements must be passed in ANSI format. The code in the dll will then use OLE Api to get the LBound and Ubound of the array and the address of the first element in array.
We have a VB.NET program that needs to periodically call a function in an external, unmanaged DLL to communicate with our legacy application. We are having a problem with the application (seemingly) randomly not being able to find the DLL with the unmanaged code. Currently we use DECLARE FUNCTION blah LIB for the unmanaged code. Would it be better/more reliable to use DllImportAttribute instead? Or am I missing something else?
View 1 RepliesI'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.
In my managed VB.NET code, I am able to write a file out to my desktop. Although, the statically referenced unmanaged code is unable to. I have hunted all over MSDN to find out how I can elevate the security permissions for this library method, but am unableto find anything.I declare the method as...Declare Sub WriteFile Lib "DataLog.dll" (ByVal fileName As String)Although, it throws an exception due to being forbidden from writing to the desktop. Is there an attribute
View 7 RepliesI am refactoring a large and complicated code base in .NET that makes heavy use of P/Invoke to Win32 APIs. The structure of the project is not the greatest and I am finding DllImport statements all over the place, very often duplicated for the same function, and also declared in a variety of ways:The import directives and methods are sometimes declared as public, sometimes private, sometimes as static and sometimes as instance methods. My worry is that refactoring may have unintended consequences but this might be unavoidable.
My instict is to organize a static/shared Win32 P/Invoke API class that lists all of these methods and associated constants in one file... EDIT There are over 70 imports to the user32 DLL.(The code base is made up of over 20 projects with a lot of windows message passing and cross-thread calls. It's also a VB.NET project upgraded from VB6 if that makes a difference.)
I've written the code to post the information to a page, however I don't know how to make the post target the iframe I've placed on the page. (I haven't tested this code so I'm not sure if the post even works)
Dim param1, param2, result, url As String
Dim request As HttpWebRequest
Dim paramStream() As Byte[code].....
That is what I have written to post to the website, however I would like the post to affect an iframe which I have placed on the page. I know when you're writing html you can have a target specified in the form tag
<form target="my_iframe" method="post" action="dosomething.php" />
But I wasn't sure if there is one similar to target that I can specify from VB code.Just a note: I am trying to do a post from a ASP.NET page to a PHP page that is contained in an iframe.
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?
View 9 RepliesWhat is Platform Invoke Service (P/Invoke)?
View 1 RepliesWe 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]...
i need to pass commands through a C++ dll to vb.net and the other way around. is there some code that needs to be in the C++ dll to make it work? im not good at C++ at all,
View 5 Repliesim trying to make a simple wrapper for lua. The only problem so far is that lua only accepts a method in a specific format.Delegate Function LuaC Function(ByVal lua_state As IntPtr) As Integer..That is how lua wants the method to look like. So it only accepts a function that looks like this: [code]
View 2 RepliesI created a vb.net dll called "WSdll.dll".I compiled it, created a type library (tlb), and registered it globally(gacutil)..It includes a file called wsutils.vb, which includes a namespace called "wsutils".In the namespace, there's an interface (with attribute) called "IWSconnection", and a class called "WSconnection".The interface and class are public, as are all methods and properties.[code]...
View 2 RepliesI have an application written in .NET 4.0 that needs to load in memory a native DLL (written C). At the moment I am using a P/Invoke call to LoadLibrary passing the path where the DLL is located. This works, but due to the fact that this DLL comes from a DB, I would like to know if it is possible loading it through a stream, avoiding then the necessity to store the DLL somewhere in the filesystem.
View 2 RepliesQuestion: I use an embedded Firebird database in ASP.NET.
Now, Firebird has a .NET wrapper around native dlls.
The problem is, with the ASP.NET compilation and execution process, the dlls get shadow copied to a temporary folder. Unfortunately, only the .NET dlls, and not the native dll.
See [URL] for details.
Now, this makes it necessary to put the unmanaged dll somewhere into the system32 directory (or any other directory in the path environment variable).
Now, I want to change the wrapper/native dll (opensource), so it loads the dlls also if they are only in the bin folder.
Now, my problem is, how can I, in .NET, load an unmanaged dll from an absolute path ? The absolute path is determined at runtime, not at compile-time...
I have an unmanaged DLL and need to call one of its functions. Here's the [code]...
View 5 RepliesMaybe this is not true ... But how to connect an unmanaged DirectX to VB.NET? For anyone dll I use <DllImport()>, but Unmaged DirectX have interface.... Than I tried use "<ComImport(), Guid(...)...>", but I do not know how to use COM interfaces Maybe I did not really understand COM technolgy... I tried find documentation "how to use com interfaces", but found nothing.
View 1 RepliesI'm having some trouble finding the syntax for making function calls to unmanaged DLLs in VB.NET. Let's just assume there's a function "Connected" in unmanaged DLL "Connector.DLL". I want to call this function by creating an abstract function call to it.
I've seen some code out there that looks something like
[DllImport("Connector.DLL")]
Public Shared Function Connect(ByVal intPort)
But that syntax doesn't work for me.
I need to call a function in an unmanaged .dll written in C lang from vb.net. The function declaration looks like this [code]Now the behavior of this function is that it copies some data in argument "reply" and returns a numeric value which signals its pass/fail status. How do i pass it a string object so that it can copy data. Following is how i access this function.[code]When the call completes, returned status is absolutely fine but there is nothing in string "str". What is it that i am missing. I'm not sure about the string object that i am passing as argument.
View 3 RepliesI need to call a function in an unmanaged .dll written in C lang from vb.net. The function declaration looks like thisLONG _stdcall ReadInfo(char *reply);Now the behavior of this function is that it copies some data in argument "reply" and returns a numeric value which signals its pass/fail status. How do i pass it a string object so that it can copy data.Following is how i access this function.
View 2 RepliesI'm migrating some VB6 code to VB.net,the code contains a structure that contains 1d arrays, 2d arrays, and few other variables.The general outline of the Vb.net structure is as under
[code]...
The call to the dll is declared as under Public Declare Sub getState Lib "val.dll" (ByRef state As Test)Elsewhere on this site I realized that we have to "marshal" the structure to allow it to be compatible with the unmanaged code that is about to accept it.However I still receiving runtime errors when running the code, I don't have any clue of how to use the System.Runtime.InteropServices.Marshal class.What would be the correct way to pass this structure to the dll?EDIT: The original VB6 data type is
[code]...
I've read about this issue on MSDN and on CLR via c#.Imagine we have a 2Mb unmanaged HBITMAP allocated and a 8 bytes managed bitmap pointing to it. What's the point of telling the GC about it with AddMemoryPressure if it is never going to be able to make anything about the object, as it is allocated as unmanaged resource, thus, not susceptible to garbage collections?
View 3 RepliesI am using a function from a dll in unmanaged code that requires a callback to my managed code in Visual Basic 2010. The callback is asynchronous and is called continuously over the life of the application. What's the best way to protect the callback function from the garbage collector? Right now it is being collected after several dozen calls from the dll.
View 11 RepliesI am trying to get some data from a C Dll via a structure and I am getting incorrect values back. I tried a couple of examples I found but they do not work. Since I do not know the proper way. I do not know how to fix it. Can anyone give me any advice, hints, redirection or any assistance what-so-ever. I've been struggling with this for weeks.
View 3 RepliesI've been using a simple mouse hook and some accessiblity api stuff to retreive caption under mouse (ObjectFromPoint) and accessibility api for events (ObjectFromEvent).It seems like there is memory leaks with unmanaged callbacks.With the global mouse hook it seems there is 4 - 8k of ram added every time the mouse is just moved even though I only monitor mousedown and mouseup with:
Private Const WM_LBUTTONDOWN As UInteger = &H201
Private Const WM_LBUTTONUP As UInteger = &H202
Private Const WM_MBUTTONDOWN As UInteger = &H207
[code]....
And with accessibility it seems there is also memory issues with my code. Is this to do with delegates?I only managed to find one mention on the mouse hook issues which led me in to a dead end.A long shot and maybe not even needed but I was wondering, if these mem leaks can't be stopped, would it free up the memory if I used threads which could be exited and new ones started eg.mem usage 3000k of which 1000k is leaked mem (for round figures) I exit global mouse hook thread and start a new m-hook thread.would this free up the memory? If so, how would i do this, not use threading before.