Inheriting Forms - Expose Control Events?
Nov 2, 2009
I am using an inherited form extensively for the first time, and I'd like to know if what I'm doing is correct.I have a base form with a grid and four buttons (Add, Edit, Remove and Close). There is no functionality in any of the button click events, as the specific implementation of each derived form will be different. The only exception perhaps is that the Close button closes the form. The only reason I am using a base form really is because I've many forms that look the same.How do I now expose the button click events to any derived forms? The only straightforward way I could think of was to have the button click events call an Overridable method, which I then override in the derived form:
Public Class frmTableBase
Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
Me.AddButtonClicked()[code]...
Is that the correct way? It seems a little bit overkill to have to do this, although I can't think of another way really... Perhaps I could add the Overridable keyword to the event handlers themselves (and make them public)..?I'm doing it the way I showed now however. It works, but I'd just like to know if this is the generally accepted way of doing this.
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May 15, 2012
When inheriting class or control e.g. ListView, TreeView, etc..., what is the best way to distinguish between built-in methods/property/events and mine?
Currently, i start my methods/property/events with "aa" in order to make them at the top of auto complete list.
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Mar 23, 2009
I declared a browser in my VB.NET project (Dim browse as new WebBrowser). How am I supposed to get to the events (browse_NewWindow) of the declared thing?Oh yeah, my code for my browser is CType(TabControl1.SelectedTab.WebBrowser(1))
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Jul 17, 2011
Can a custom control NEW Sub be the only one that executes when Inheriting from an existing control please?I am Inheriting from TabControl and I do not want the base New Sub called, is this possible?In other words, I do not want TabPage1 and TabPage2 to be added.A Form has an Activated Sub which runs once a Form is activated.It is a pity that Microsoft have not got such a method in the baseControl Class otherwise I could have used it within a custom TabControl.
Public Class Form1
Private Sub Form1_Activated(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Activated
End Sub
[code]....
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Jul 3, 2010
I've created a class called connector. By clicking on project and adding a class.And I want to inherit from that class in the forms But I get this error.
Base class '<baseclassname1>' specified for class '<partialclassname>' cannot be different from the base class '<baseclassname2>' of one of its other partial types`
what do I do?Here's the class named connect.vb:Imports MySql.Data.MySqlClient
[Code]...
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Apr 1, 2010
I have an .exe project with a form in it that I want to use as a base class for other forms in the project. So I try to add a new inherited form to the project, but it says "Warning: No build assemblies contain components to inherit from. Build the current application, or click Browse and select a previously built assembly from another application". My base class is declared public and my exe has been built. I don't understand. Can you only do form inheritance in a dll?
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Feb 13, 2012
I have created a Windows Form inherited from an existing form using the Inheritance Picker: Project menu ==> Add Inherited Form.So now I have the Form-base (FrmP1) and the inherited form (FrmP2)The form works perfectly. If I open the "code" window of FrmP2 I can see only the main class:
Public Class FrmP2
End Class
I have added now a FormClosed event in P2:
[code].....
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Dec 31, 2010
I created a control that has picture box control docked within it. This control allows me to "animate" the image by swapping them out by setting the interval to swap them at. I want to use this control kind of like an animated icon within a application, but because the picture box is docked, the control I created won't respond to the events, MouseHover specifically. [Code]
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Oct 28, 2011
I have a component class that inherits a user control class and i'm trying to inherit from that same class in a new class.public class B inherits class Unfortunately, I get an error pointing to the .g.vb file saying:Base class 'System.Windows.Controls.UserControl' specified for class '...' cannot be different from the base class '...' of one of its other partial types When I swap the "Inherits System.Windows.Controls.UserControl" with inherits from the base class in .vb files the program compiles but when I try to access any of the components I get an error saying "Object reference not set to an instance of an object."Why is it doing this? it's as if the my sub class isn't inheritingUserControl method at all.
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Apr 19, 2011
I've got a WPF control hosted inside a Windows Forms form via ElementHost. My WPF control (let's just call it WpfControl for the sake of an example) contains a variable that I'd like to expose to my Form.
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Aug 8, 2011
I'm creating a composite user control and trying to exposing the controls as properties so that I can databind them from the form that I drop the user control onto. One of the controls I'm trying to expose is a combobox and I can't seem to figure out how to expose this combobox to the designer. I'm trying the following code that I've cobbled together from what bits of documentation I can find but so far no joy.
<Category("Data"), Bindable(True), _
Browsable(True), EditorBrowsable(EditorBrowsableState.Always), _
DesignerSerializationVisibility(DesignerSerializationVisibility.Visible), _
AttributeProvider(GetType(IListSource))> _
Public Property RollbackCombo As ComboBox
[Code] .....
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May 18, 2009
Hi, I am inheriting the telerik radcombo control however I am unable to view any items that i add to the combo list.
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Aug 25, 2010
I need a multiline TextBox which is always disabled, but it shouldn't paint itself in gray, but I want to keep its designer choosen color. I previously had the same requirement with an always-black Label (no multiline) and so I inherited from Label like:
Imports System.ComponentModel
Public Class LabelDisabled
Inherits Label
Sub New()
InitializeComponent()
Enabled = False
End Sub
[Code] .....
But this way, neither I can set the "real" Enabled property, I mean the backing field.
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Oct 27, 2010
I have a simple user control which wraps some logic around an AutoCompleteBox. This question could apply to any ItemsControl control like a dropdown or listbox though.
<UserControl>
<Grid Background="White">
<sdk:AutoCompleteBox Name="myACB" ItemsSource="{Binding myData}" />
[code].....
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Oct 15, 2011
I seem to be having a problem with controls that I am creating as new classes (not UserControls) inheriting from an existing system control. Everything seems ok while I create the control code, through to the compile (which is successful and adds the control to the toolbox) and dragging the control from the toolbox to the GUI surface. However, when I then debug or compile the project, I get a message such
[Code]...
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May 25, 2010
I have googled high and low to find an answer to this but I must be searching wrong.I have an application which has a listview displaying some items that are stored in a SQL Compact database. I am using a second form to add new items to this list directly into the database.When the second form closes I want to call the sub in my first form to refresh the list from the database.
How can I get it to fire the form1 sub routine on the close event of form2
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Jul 23, 2011
I am looking how to set events to a webrowser which is being created by the following:
[Code]...
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Dec 4, 2009
I am bringing back here the subject of the communication between forms. The reason for this is that in a recent discussion in this forum it was conclude that using the events for communication between forms was a good practice. In a first time, I want to say, and everybody should agree with this that no form should never access directly any value or control values that belong to another form. There are many reasons for this but the principal one can be seen in this example
IN FORM1:
TextBox1.Text="CrazyPennie"
Dim MyNane as string = Textbox1.text
With this code, Form1 will expect "MyName" to have the value "CrazyPennie".
But, if Form2 does access the directly the controls of Form1, it is possible for the value of MyName to be set to something else since Form2 can have changed the value of TextBox1.Text before the assignment by Form1 to MyName. Now, what is wrong about using the events for the communication? The problem is that an event is broadcasted throughout the entire application, so the conversations in between two forms are not private.
Look at this scenario:
You have 3 forms in an application that communicate with each other with events. It is then possible for Form3 to listen to a communication between Form1 and Form2. It is also possible for Form3 to make the error to believe that the message send by Form1 to Form2 was address to itself. In this case, Form3, following this message may take some action that should not have been done and that result in some undesirable repercussion throughout the application.
This code keep the communication in between 2 forms private so no other forms or class in the application can listen at it and accidentally take an undesirable action due to a mistake.
Option Strict On
Public Class Form1
Delegate Sub MessageDelegate(ByVal sender As Object, ByVal Message As String)
Dim Form2 As New Frm2
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
[Code] .....
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Feb 6, 2009
I have a form set up that allows the user to do many things to manipulate items. One of the things they can do is replace an item with another. To do so, what I have them do is click the Replace button on the main form. This calls the show of a choose replacement form where there is a grid view containing the replacement options and a Replace and Cancel button. When the user selects a product from the grid, and clicks the replace button, I want the item's ID to be sent back to the main form to be used in the replacement sub.This is what I have:
Main form:
Form Load:
AddHandler replaceComponentForm.Replace, AddressOf Me.Replace
ReplaceButton.Click[code].....
The problem is the events don't seem to be reaching the main form. The replacement form closes, but Replace does not get called in the main form.
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Aug 16, 2011
I have a tabbed webbrowser I want to add an event to it to make it so IE doesn't pop up when I click a link, with a normal webrowser that is easy but I guess I have to do a handler with the tabs being part of the browser and all. I have little experience with handlers. [Code]
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May 6, 2010
How can i code my application so that it can handle two sets of key events at the same time? For example, if I was making a game where one player used the WASD, and the other the arrow keys for moving, how can i make it so that both can move at the same time? The code I used only allows one to move at a time.. (key press event, If e.KeyData = Windows.Forms.Keys.down then.... etc)
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Mar 27, 2010
i'm making a astoroids clone and i use pointF to store units position, but they lost y value on events like form.losefocus(i think)Is there any ways to prevent this?
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Jun 4, 2012
I have 3 classes in 3 separate dll.
1) Class "BaseForm" that inherits from System.Windows.Forms.Form with "MyEvent" declared as Public Event ()
2) Class "MyForm" which inherits from "BaseForm"
3) class "MyClass" which has a public property "ExternalObject" of "BaseForm" type (the private variable is declared WithEvents)
I make the following steps:
1) intercept the Form LOAD event in "BaseForm"
- Instance the class "MyClass", Assign public property "ExternalObject" = Me
- I do a RaiseEvent "MyEvent" in "BaseForm"
2) "MyEvent" is triggered BEFORE in "MyForm"
3) AFTER "MyEvent" is triggered in "MyClass".How Can I Raise event Befor in "MyClass" and then in "MyForm"?
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Jun 16, 2009
I have a form with 2 contols that I with to connect by drawing a "wire" on the screen. It goes like this: you mouse down on the first control then move the mouse while holding the mouse button down. When the mouse is over the 2nd control the mouse button is released and the controls are wired.
So I am playing with mouseup, down, move, etc. When the mouse is over the first control I get mouse moves from that control, but when it moves off the events stop, and I get no events from the form even though the mouse is there.
Is there a way to do this? I have seen it done in a Java app. I could brute force it and just draw a box on the form instead of a control, but that sounds like a step back.
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Oct 27, 2009
I have form 1 which will raise an event for form2 after doing some calculations. I know how to raise an event in form2 and then write the sub in form1 but i cannot do the reverse... how can I do this in reverse??? I cannot raise the event sub in form2 is not responding.
Example:
Form1:
Code:
Public Class Form1
Event test()
RaiseEvent test()
[Code] .....
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Jun 11, 2011
Is it possible to have multiple click events for a button based on the button text? In other words, if I change the button text can i create a new click event based on that text but use the same button?
for example:
button1.text starts as "steel"
button2.text starts as "brass"
If I click button1 then the text would change to:
button1.text="Stainless"
button2.text="Cold rolled"
If I click button1 again a string would then be added to a textbox and the process would start over again. can I have a different click event or would I need to put an If/Then or Select/Case in the sub to handle this? I have 10 buttons I would need to do this with and each needing at least 3 different choices for each depending on the previous button press.
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Jan 7, 2010
I have two questions for anyone who can throw some idea's my way question 1:I am currently working on a control with three combo box's. This control will be nested on a form, and I want the on-board timer to track how long each control is active. I am trying to use the focus events of the combobox's to determine if the control is active so the program will know when the timer should be started and stopped. My problem is, for example, when the user causes the text property of the combo boxes to change, the folowing code runs:
[Code]...
As you can see, there are points in this sub-routine that can cause the focus to shift, as well as fire the text changed event. While this all happens faster than is really noticable, I would like to eliminate the extra cycles if at all possible. As I mentioned in question one, I am adding this control to a form, to be more clear I am adding multiple instances of this control to a single form, and I am trying to use the focus events to determine which of the controls within the form are active; however, when the form itself is no longer the active application, whether it is minimized, behind another application or otherwise, all of the timers stop. I want whichever control was active at the time that the form was deactivated, to continue as if nothing changed.
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Sep 28, 2010
I am creating a project with a maximized per-pixel alpha form. However, the normal input events (MouseDown, MouseWheel, KeyPress, etc) are never raised. I've been able to create some bare-bones functionality by overriding the WndProc method, but some things elude me. For example, I want to detect mouse wheel scrolling. When I check for the mouse wheel message, it works fine. Then I try to use the GetLParam function to get a MSLLMOUSESTRUCT with the scroll data. However, when I try to use it, I always get an error:"Attempted to read or write protected memory. This is often an indication that other memory is corrupt." What can I do?-Must Program! Error: Not enough time to program
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Mar 21, 2011
We have a vb.net 2010 application with a base form and an inherited form When we change the position of a control coded on the inherited form we lose handles on the events in the inherited form for that control. We also lose the handles on the Load event in the inherited form.
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Feb 8, 2012
My application has 1 main form and three other forms which raise events to my main form. I noticed that the memory starts at 77,000 K and increases substationally over a few hours maby be to 250,000k and ever increases.The main form has a dataset and a bound datagridview which gets refreshed with data. Basically it's a taxi booking application. The booking form raises an event to the main form and the main form refreshes the jobs and displays them on the dgv.
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