I am looking for the best way to make a plugin type system for themes. have allow users to create custom GDI based controls in a dll plugin that is to be able to be switched on runtime by users. My issue is there is no way to have a dynamic inheritance so how can I make it so the controls show in the toolbox and can be changed on runtime?
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Is there a significant enough difference with .NET from regular native code to maketraditional plugin systems not very useful? Either way, there must be some system for making a program extensible after it is compiled. To allow third party development withoureleasing the source code. Anyone have info on this? I said .NET, but of course specifically I mean Visual Basic
View 2 RepliesI am trying to make a plugin system in vb.net and i am using interfaces to do that. I have managed to implement the plugins but now i am having problems with setting the plugins in a dictionary or some sort of array.
The system is simple. I have the main application and i have plugins. The application needs 2 mandatory plugins and that is data and authentication. Other plugins are free to use so i have 3 interfaces. Data, Authentication and CustomPlugins.
I load the plugins with this
CODE:
It works fine like this but i want to make a collection of plugins because i don't know how many plugins the customer make. So initially i thought to make a collection
CODE:
But that doesn't work. The main focus is to load as many plugins as i like but have then in some sort of array. A dictionary would be perfect but is not a must.
i want to implement in a program. I'm not asking for code just some advice and maybe a link or 3 to useful pages on the internet.I want to create a plugin system for an application that i want to make. The idea for the plugin system is based on the following...
1-Some graphics editing programs have what i think is called a filter/effects chain. its where you make a list of filters and settings that the program runs to edit the image.
2-In yahoo pipes you take small parts and use them to complete tasks for you mashup (like pulling all the images returned in a search and displaying them).
The system i want advice on is basically a plugin chain system modeled after these 2 idea's where the user selects plugin's and forms a chain out of them.for instance if i wanted to display a picture then i would form a chain of plugins like this
legend:[(inputs)what it does(outputs)]
[show open dialog plugin(output filepath)] -> [(filepath input)open picture plugin(output bitmap object)]->[(input bitmap object)Display a picture plugin(make a form for display)]
The code for the task's will of course be in the plugin's.The problem is i have never done any plugin system before. the hardest part i need help with is getting the plugin's loaded and sending the output's to each other. Also another problem i think is that the plugin's could be for anything (parsing text, displaying a picture, opening a url, downloading a file, etc, etc)Again I'm not asking for code just advice and some useful links to information.
I've got an MDI form with a menustrip that already detects all .dll files in a folder and adds them to the menu to show the user which plugins are available. The thing is that I don't know what to do from here on out...
I'd like to be able to update my program without having to stifle through all my code (it's a very big program) and be able to create basic new features through external DLLs. It's extremely useful for users to make their own features too
Anyway, what a plugin would look like is most likely just a form with controls on it that the user makes themselves in VB. I'd like the plugin to activate through an init() sub within the plugin by clicking on the menu item shown in my MDI form.
I kind of started with my own code but it didn't really get anywhere:
ListFilesInMenuStrip(PluginsToolStripMenuItem, App_Path() & "Plugins")
For Each c As Control In Me.Controls
If TypeOf c Is MenuStrip Then
[Code]....
...Where ListFilesInMenuStrip() is my function to add all the DLLs to the menu and App_Path is just a shortcut function which serves the same purpose as VB6's App.Path() class.
I've also done research but only came across all their weird complex CodeDom and other weird things...This seems so simple but I just can't wrap my mind around it :I
VB 2008, DataGridView,DataGridView1_CellLeave(sender, New System.EventArgs)
"Unable to cast object of type 'System.EventArgs' to type 'System.Windows.Forms.DataGridViewCellEventArgs'."
What is the Correct String for "New System.EventsArgs"
Anybody there is to help me out.
I am trying to create a plugin system where plugins can be dynamicly loaded (we don't know how many there are, what their classes are called, ...)This is sample code for a plugin:
Code:
Public Interface IPlugin
Sub bla()
Function bla3() As String
End Interface
[code]....
This code SHOULD msgbox("yay") when it finds a type that implements my IPlugin interface. Yet it never finds one. I can't find what I did wrong. It gets to the debug.print("2"), but never gets past the "If GetType(IPlugin).IsAssignableFrom(t) Then".
I am trying to create a plugin system. I have the actual plugins working fine but now I want to implement a system that knows whether the plugin is installed or not. I can get the plugin name when the form is loaded (ex. "Plugin1"). I then want to check this against something to see if that specific plugin is already there (if not add it) and if it is there is it enabled. I was thinking of doing this with an xml file but thought that might be a lot of work reading and writing each value. I then thought of the My.Settings and was wondering if this is possible. I would want to create an "element" for the name and give it a value of either true or false.
View 10 RepliesI'm getting an error after sending a list to a web service.This is the code that is calling the web service:
Dim sProgramInterest As New List(Of Integer)
crmService.InsertProspectGetId(sProgramInterest.ToList)
But I'm getting this error.
[code].....
My project worked a first and now its giving me a problem.The error
Quote:
Unable to cast object of type 'System.Windows.Forms.MouseEventArgs' to type 'System.ComponentModel.RunWorkerCompletedEventArgs'.
[URL]The issue is as soon as I change the value of the text boxes it gives me an error and forces me to close the project.
The error is:Unable to cast object of type 'System.EventArgs' to type 'System.Windows.Forms.KeyPressEventArgs'.
However I'm supposed to clear the number of gallons used and the total charged when a change is made to the contents of the 2 text boxes on the form.
I have an InvalidCastException Error in my program. The program is that i try to insert an employee record into a database table after getting the details from a form. I've used Money data type is SQL Server for salary and SqlTypes.SqlDecimal data type in employee template class. i've used a stored procedure to pass the values and i add the basic value by passing a parameter by the method
Dim prm8 As SqlParameter = com.Parameters.Add("@basic", SqlDbType.Money)
prm8.Direction = ParameterDirection.Input
prm8.Value = emp.Bsc
I've used the money datatype itself even in the stored procedure variable.I get the following error.
failed to convert parameter value from sql decimal to decimal
Even if i use
prm8.Value = Convert.ToDecimal(emp.Bsc)
I get an error Unable to cast object of type 'System.Data.SqlTypes.SqlDecimal' to type 'System.IConvertible'.
Now I want to display picture in picturebox1.To do this I use this codes, but it does not display picture
on this line: Dim arrPicture() As Byte = CType(dt2.Rows(0)("img_path"), Byte())
it shows this message,
Unable to cast object of type 'System.DBNull' to type 'System.Byte[]'.[code]......
I am getting this error when I am tring to load string type to data table)
Using connection As New SqlConnection("connectionstring;")
connection.Open()
Using Command As New SqlCommand("SELECT ClientId,forename,surname from t_clientdetails
[code].....
I get the below error Unable to cast object of type 'System.String' to type 'System.Data.DataTable'.This is the code I'm using
Dim str As String = String.Empty
If (Session("Brief") IsNot Nothing) Then
Dim dt As DataTable = Session("Brief")
If (dt.Rows.Count > 0) Then
[code]....
Unable to cast object of type 'System.String' to type 'System.Windows.Forms.TextBox'.
View 12 RepliesI've got a C#.NET background and due to circumstances I'm trying to make a plugin written in VB.NET. I've created a new class project which gives me a DLL. This class implements a C# interface which all works.My only question is this... In my C# code I've got an implemented DLL (which loads at runtime) with the following declaration before the class...
[Plugin(PluginType.Storage)]
public class XmlPlugin<T> : IStoragePlugin<T>
{
[code]....
How do I write [Plugin(PluginType.Storage)] in VB syntax?
make a way for my webbrowser to be able to add plug in?
View 4 RepliesI'm creating a student evaluation form in a repeater that should submit the evaluation responses and update the SQL database, but I keep getting the error mentioned in the title. I'm coding in ASP.Net using VB.
Here's my code:
Student.aspx
<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="Server">
[Code].....
I am getting a really bizarre error and it makes no sense at all.Basically I have a user entity which has a Password property. This property is of Type Binary, the server data type being Binary(512).I am reading this value in and converting it to a byte array. However whenever I run my code I am getting a completely unrelated error of Unable to cast object of type 'System.Guid' to type 'System.String'.This strikes me as very odd since I am not using a property or variable of type string or GUID anywhere in this procedure where it falls over.
The code is below:
Public Shared Function ValidateUser(ByVal username As String, ByVal password As String) As UserValidationMessage
Using db As New EntityMapDataContext
Dim u = From user In db.Users
Where user.Username = username
[code]....
Code: Dim dom As New DOMDocument30 dom.async = False
dom.Load(serverAddress & "/App/filelist.jsp?type=content")
For i = 0 To dom.childNodes.item(1).childNodes.length - 1 downloadfile(dom.childNodes.item(i), mcount, currentpath) Next
The above code is activated upon clicking of a button. i have the server address declared. and using the domdoc to load the jsp file to generate the xml data. and using for loop, i call the download file function which accepts the following parameters
Code:Public Sub downloadfile(ByVal domdoc As Xml.XmlNode, ByVal totalcount As Integer, ByVal currentpath As String)
The totalcount and currentpath work fine, but when i pass in the dom.childNodes.item(i) , error pops up.
--------------------error message------------------------------------------Unable to cast COM object of type 'System.__ComObject' to class type 'System.Xml.XmlNode'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.-------------------------------------------------------------------------------
[code]....
When testing the followng code from Mastering VB2010, I get an Unable to cast object of type 'System.String' to type 'System.IFormatProvider' exception.In the Button1_Click event code Dim strmOut As New System.IO.StringWriter(SaveFileDialog1.FileName)the 'SaveFileDialog1. FileName' is underlined with a green squiggle and displays the following tool tip:Runtime errors might occur when converting 'String' to'System. Iformat Provider'.This is apparrently the problem but what does it mean and how do I fix it to get the code to work? 'Code being tested that runs the exception:Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click.[code]
View 12 RepliesI have a page that get value from SQL. I'm having a problem when I initialize Label object with field having TEXT data type.[code]...
View 4 RepliesI have a bit of trouble right here, I am trying to get the data from the site and input them in the listview. Well, when my main app start to load through on debug, then it start to display a warning. The warning is: Unable to cast object of type 'System.String' to type 'System.IFormatProvider'.
[Code]...
i am wondering how to make a trackbar with vlc activex plugin i have it part working but i want to make it more accurate meaning how do i make it display the exact seconds then it is right now here is the code
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
With TrackBar1
.Minimum = "0"
[code]....
that is the timer i am using to set the track bar's values and the trackbar1 to take the time and play it at that time?
I'm getting a sporadic 'Unable to cast object of type 'System.Int32' to type 'System.String' Exceptions at .SingleorDefault() in the below code. It works 9/10 times but randomly it throws an exception. I made sure that SettingID that i'm passing has no Null Values and the data in the table always exists for the settingID, and i'm always passing SettingID as Integer.
[Code]...
I am using VB2008 in VS Prof and try to convert at Byte arry stored as a Image format in Sql2000 database.
Code:
Using acnLoc As New SqlConnection(CSLoc)
acnLoc.Open()
Dim G As SqlCommand = New SqlCommand("SELECT [SignatureData] FROM [MyTable] where [OID]=@OID", acnLoc)
G.Parameters.Add("@OID", SqlDbType.Int).Value =Cint(bxShipmentno.Text.Trim())
dim P= G.ExecuteScalar() 'returns a system arry
[Code]...
[Code]...
Unable to cast object of type 'System.Net.FileWebRequest' to type 'System.Net.FtpWebRequest'.
i get the error in following code
Function ReadFile(ByVal sPath As String) As Byte
Dim data As Byte
data = Nothing
[Code].....
iNCEEB = .First.NCEEB '<-- Im getting the error in this line, iNCEEB is integer .First.NCEEB is short.
NCEEB Server Datatype property is smallint
where is that "to type 'System.String'." coming from?
I'm using vs2008 and mssql2008.
[Code]...
