Question Bug In Inherited Controls?
Aug 22, 2009
on the custom inherited control i created, i noticed that when i bind my custom property to a data column, if that data column returns a value other than Null it always return a datarowstate of modified even if there were no changes.to produce this issue, i have below a sample code for a test inherited control
Imports System.Windows.Forms
Imports System.ComponentModel
Public Class TestControl
[code]....
create a form, add the usual objects necessary for data bindings, (datasource, datatable). make sure the data column bound to this TestControl will return non null values.also create a procedure for position changed to catch the datarowstate like below...
Private Sub PositionChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim rowstate As DataRowState = DataRowState.Unchanged
[code]....
Note that i used Position - 1 so that when you go to the next record, it will show you the rowstate of the previous record.
on your Form_Load add the ff:
AddHandler YourBindingSource.PositionChanged, AddressOf PositionChanged
don't make any changes to the current record before you go to the next record. you will see that the rowstate will still return Modified.
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Aug 22, 2009
on the custom inherited control i created, i noticed that when i bind my custom property to a data column, if that data column returns a value other than Null it always return a datarowstate of modified even if there were no changes. to produce this issue, i have below a sample code for a test inherited control
Imports System.Windows.Forms
Imports System.ComponentModel
Public Class TestControl
[code].....
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Oct 28, 2009
I have setup some base forms with some bottons on it The buttons are situated in a panel.Both the panel and the buttons modifer properties have been set up as "Friend".The problem I have is when I inherit these base forms, the buttons seem to jump around by themselves allot
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Jun 26, 2010
am trying to make use of inheritance to keep consistency in my user control appearance. I created a usercontrol to use as my base design, as a platform to link to a tab as acontainer. To this I added a few framing visual items like a header panel andsome labels.I then created another usercontrol that inherits from my base control, with the intention of adding the necessary items to this derived control to build it into a complete functional usercontrol that I can associate with a tab on my main form. I want to keep the visual appearance consistent across all similar derived controls. Then later if I change the design of the base form, this flows through to the derived controls.
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Jul 2, 2010
Unable to add Controls to Inherited Form I should be able to add an inherited form by simply[code]...
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Mar 23, 2009
I am using visual inheritance and was wondering if there is a way to change the properties of inherited controls at design time, preferably in the form designer. If not, then in the designer code. I have my control declared as Public in the base class. I can access it in the child form code, but not in the form designer. Is this just not possible?
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Dec 14, 2009
what is the diff between custom control ,inherited controls adn usercontrol in vb.netadil
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Aug 22, 2009
on the custom inherited control i created, i noticed that when i bind my custom property to a data column, if that data column returns a value other than Null it always return a datarowstate of modified even if there were no changes. don't make any changes to the current record before you go to the next record. you will see that the rowstate will still return Modified.
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Jul 19, 2009
Pretending I have a class that inherits off Control, how would I handle the parent form's Resize and Move events within the control? I have a painting glitch that happens when the form is resized or moved. Right now in the form I just have:
vb.net Private Sub frmMain_ResizeMove(ByVal sender As Object, ByVal e As System.EventArgs) _ Handles Me.Resize, Me.Move Me.Refresh()End Sub
But this can't be the proper way to do it, considering Refresh() invalidates all children (will be slow and flashing if the form has lots of controls). I want to basically do the above code inside the control.
Edit:This is the glitch after a resize of the parent form:
And this is what the button is supposed to look like:
Also, I experience this issue if something like a message box is dragged over top of it. How can I remedy these issues by forcing a repaint?
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Jun 24, 2010
I have a base form and I inherit other forms from it. However, if i go back and change say the size of the base form, I don't see those changes take effect in my inherited forms. Does anyone know why that is? Is there a solution to this issue?So as far as design is goes, what exactly gets inherited by other forms?
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Oct 14, 2011
I have two classes[code]...
How can I modify class1 in a sub in class2?
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Oct 27, 2009
I am having a problem with closing a form which I have inherited I have a form called frmAddForm_Simple, which contains 4 main controls (A Data Grid, A Save Button, A Close Button and a Text Box). The idea around the form is to create a form which could be used for inputting of many different types of data which are all entered in the same way (i.e. to add a new row to a database for [Status] table or [Location] table, all of which contain 2 columns in the database (an [Id] and a [value]). On the form I have a property called _FormChanged, which when the textbox text changes, sets the property to True. I then have the following code on the Close Button:-
Public Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
If _FormChanged Then
If MessageBox.Show("Are you sure you want to close and discard any changes?", "Discard Changes",
[CODE]...
Is opened as a dialog (ShowDialog) and when I go to close the inherited form (by click on btnClose) and answer No to the above MessageBox the form closes anyway. Using the Debugged I have worked out that the following events occur in sequence (all of which runs in the Master Form mentioned above):-
1) btnClose_Click sub Routine runs
2) I answer No to the question do I want to close the form
3) The debugger steps over the Me.Close() line (as expected)
4) The debugger jumps up to the Sub Initialise (where ShowDialog was called from) and closes the form.
So at no point has the debugger even ran a line of code which reads Me.Close(), but the form closes anyway so Im fairly confused as to why the form should close.
My Master Form (frmAddForm_Simple) Code:-
Public Class frmAddForm_Simple
Private _FormChanged As Boolean = False
Private _FormLoading As Boolean = False
[CODE].............................
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Jun 24, 2010
I'm confused regarding the MS examples for inheriting a treenode. I have created the following class to allow an addtion description field on the treenode:-
[Code]...
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Mar 9, 2009
[code].....
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Sep 12, 2009
I am trying to create an inherited form- when I go to add it, I get the following message- "CustomerInformation --- The base class 'Object' could not be loaded. Ensure the assembly has been referenced and that all projects have been built"
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Sep 3, 2010
I am writing a COM Add-in for Microsoft Access 2010 using Visual Basic 2010.
I do not understand why the members of an inherited interface are not available to VBA. They do not appear in the VBA Object Browser and a run-time error occurs if an attempt is made to use them.
Here is a full code sample which demonstrates the problem:
First I have a base class with a defined interface:
Public Interface IClassBase
Property id As String
Property Name As String
End Interface
[Code]....
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Apr 21, 2010
When I pass an an object 'MyObject' which implements 'IMyInterface' to a method parameter declared as IMyInterface, I understand that this method parameter 'sees MyObject through the eyes of its interface'.
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May 1, 2010
I know this is random but is there a way to specify that a property explicitly does not need to be inherited? So you can have two sub classes and one object will have that property and the other doesn't?
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Sep 2, 2011
I have a class, Vehicle. I created two child classes, Car and Plane. I want to monitor the speed, which is a Vehicle Property, and bind it to a control (label, or image, for example) in WPF. When i create a static Class which only purpose is watching the Speed Property, it works, as far as the INotifyPropertyChanged is declared with the Speed Property name.
But the problem is, I have to create dynamicly multiple Cars and Planes by looking in an XML file and deserializing my objects, and creating multiple Car or Plane UserControl (Let's not discuss this way of working, please). So I have to get the Speed property inside the Vehicle Class (which is normal), and I have to get a INotifyPropertyChanged on each Speed of each Vehicle Created. So, my Cars and Planes are loaded, and I have to get all speeds, but I can't create a static Speed property by Vehicle. By the way, by creating a non-static Speed property (as int, for example) in Vehicle Class with INotifyPropertyChanged raised in the setter, it does not work. The event seems to be raised, but my converter is not fired, and my controls does not update.
In my Vehicle Class
Private SpeedValue As Integer
<XmlIgnore()>
Public Property Speed() As Short
Get
[Code]....
The PlaneView Class is almost the same for this part.
I confirm that the converter is fired just once, the first time, when the tabs are created, because I put a breakpoint on the Convert function definition. After that, the converter is never fired again. So the picture img_fonctionnement is displayed, but it is never updated. But the Speed property is updated, I swear. And the INotifyPropertyChanged (in Speed's setter) is raised, as far as i know with the help of the debugger.
And the "an item with the same key has already been added" (which appears in a messageBox, and not as an exception) seems to appear only when I am to long with the debugger. In normal execution mode, it never shows.
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Jun 25, 2010
This is more of a conceptual question than anything.
I have a base class called "RawReader".
It sets up the framework for classes to inherit it and read in specific data systems.
For example, I want an app read in a known format of FoxPro database, a CSV file, or a SQL database (there is about 8 more formats currently), then transfer it over a webservice and create a SQL database from it.
I have everything working with CSV, FoxPro, Access, Excel, etc... Easy enough.
The classes that inherit RawReader, like RawCSV, RawFoxPro, RawAccess all return a struct that contains a dataset as one of the members. The dataset contains the data from the raw system. The webservice receives this struct and creates sql tables and loads the data into it. This has already been coded and works great.
My issue now comes to reading in SQL. Obviously, I could follow the same path, read the remote SQL DB into a dataset, transfer the dataset as above, etc... My "issue" comes in where I feel like it doesnt make much sense to transfer a SQL db to a dataset, transfer it through the webservice, and then try to programmatically recreate the SQL database. I feel like I lose a lot of the granular details from the SQL database (field sizes, extended info, etc..) It seems easier in practice to just create a backup of the database, convert it to a stream object and transfer the backup over to the webservice. But this is where the problem lies...
Since all of the classes inherit from the base class, they are set up to return a DataSet. The hack-ish way would be to just add a stream object to the return struct and in my webservice add other code to make a special case for SQL sources, but I was trying to avoid that.
Any thoughts on the "proper" way to go about something like this?
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Dec 29, 2010
I have a base form class that is providing a new property that looks Like this
Public Class BaseForm
Private _HappyTime As Boolean
Public Property HappyTime() As Boolean
[Code]....
Now when I inherit the BaseForm on a new form, the HappyTime property displays in the properties window as false, and is uneditable.
I've recreated this BaseForm and Inheriting Form in an entirely new soloution and, the HappyTime property is editable and works as expected. For some reason in the existing project (where these changes need to be made) it's not behaving properly.
Environment Information: .Net Framework 3.5, Visual Studio 2010, Win7 x64
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Dec 15, 2010
I'm currently working on binding an objects properties to fields on a Form. Whilst I have managed to get it so that I can get standard objects to bind, I am having a problem figuring out how I would go about binding an inherited object.
For example, if I had a Client class (the parent class) and then two sub-classes called CompanyClient and IndividualClient. The CompanyClient would have an extra field company name for example.The problem I'm having is that I'm not certain how to set up the binding, as if I set up the binding against the Client class then I would be missing the Company Name property for the CompanyClient, if I set up against the CompanyClient, then it wouldn't work with the IndividualClient as it doesn't have all the fields.
I know I could get around this by having different forms for each of the different Client types, but as almost all of the properties are the same I would like to avoid this if I can.I was wondering whether anyone knows how I might be able to go about doing this
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Mar 30, 2012
It's been a while since I've had the time to browse through here, answer questions and ask some of my own. Just got a job at a custom business software developing company! But I do have a question I'd like some clearing up on.
What I have here is 2 classes, one inherits the other. Both function similar so a lot of the methods are the same for each. The one in particular is Reset_Class()
Here is a sample code of what I'm trying to do.. My question is, is it correct?
vbnet
Public Class Form1
Private Sub Button1_Click( ByVal sender As System.Object, ByVal e As
[Code].....
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Dec 15, 2011
I have a an inherited form that has a panel control on it. I want to paste other controls onto this panel but the paste option is grayed out and won't let me do it. I made sure that the template form did not lock the panel. I'm stymied from making progress until I can get this resolved.
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May 19, 2010
The program below trhows an error in the line "mTable2 = mTable.Copy". The error is: "Unable to cast object of type 'System.Data.DataTable' to type InherintanceQuestion.InheritedTable". This is because mTables is an instance of the InheritedTable class which inherits a DataTable and mTable is a DataTable. So, is there any way I can create the mTable2 to the mTable.copy to the mTable.
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code].....
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Oct 31, 2010
On form1 I put a picturebox from the toolbox.[code]Is it possible to set picturebox.visible=true of the inherited picturebox?
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Aug 17, 2011
When I try to create an Inherited User Control everything goes fine until I specify the base control and press "Add" in the Inheritance dialog. The code in the newly created Control should have a "Inherited From" statement, but it doesn't and nothing works after that. I even tried following the ctlClocklib project and the same thing happened. ctlAlarmClock.vb was created but the "Inherited From" statement was missing.
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Jan 11, 2010
I'm having trouble with the definition of an inherited generic class. I have two base classes that are defined like this:[code]
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Feb 13, 2010
Is there a way to hide a method of a base class that has been inherited?Lets say the base class has the properties:
x
y
Height
Width
and the method
sub SpecialInstructions()
Now this class is inherited by some classes that either use the SpecialInstructions method or override it. But one class inherits it but cant make use of the method and therefore wants to hide it. I tried shadowing but it still seems that the method is visible ex
Private Shadows Sub SpecialInstructions()
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Sep 1, 2011
I've got a form that needs to inherit a base form. The problem is that the base form has a menu strip. How can I hide the inherited menu strip? Alternatively, how can I exchange the inherited menu for something I construct myself in the new form?
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