Changing A Control's Properties In A Threaded VB Application?
May 11, 2011
I am running into an issue with changing properties of controls on a VB.net project that I am working on. The portion of code that I am having trouble with is re-enabling a couple of buttons and a ComboBox after a Threaded operation completes. The point of it is to disable the buttons after clicking the main "run process" type of button (called cmdCrawlSearch) so that the process can run on a new thread while the form is updated with the status. I was able to learn about Thread Safe calls using delegates in order to update the Text property of the TextBox (txtOutput) on the form, and thought that enabling buttons would be just as easy, but when I am trying, I am either getting an "Object reference not set to an instance of an object" exception, or an "Exception has been thrown by the target of an invocation" exception (from the current version of code) with the InnerException being the Object reference exception. I am posting the portions of code related to the issue, then below it is the InnerException name and stack trace. Perhaps I am not using the Delegates correctly (since I still do not fully understand what can and can't be done using a Delegate.) Or there is a better way to do this.
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May 8, 2011
I have 10 PictureBox on a windows form (created in Design View) and a context menu strip is attached to each of them. I am trying to set the property of the PictureBox using the context menu.
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Nov 17, 2010
I have a mutex and threaded related question about = Run one or the other per call to routine
[Code]...
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Jul 23, 2009
how to re-write my application (http:[url]....) to be multi-threaded using the background worker. The use case is something like:
1. User opens a binary file, it can be several Gbytes in size so reading it into memory isn't practical.
2. User can then navigate through the file in 188byte chunks, data is read from disk, decoded, and displayed for each chunk in turn.
3. User may want to search for some data or build a report. This will involve repeating the read, decode, display, function multiple times. During this looping the GUI stops responding and there is no option to cancel so I want to make it multi-threaded. So, is it safe to open the file in the GUI thread and then read from the file in the background thread? I currently use something like this to open the file once:
Dim fi As New FileInfo(filepath)
fs = fi.OpenRead()
and then in a separate sub multiple calls to:[code]..........
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Dec 4, 2009
I have a console application (VB.NET). When it is started, it spawns worker threads to find work in the database and do the task, then look for the next task (A workflow basically).
The problem that I have is that I have my Event Handler in the main thread that spawns the worker threads. Those workers, if they error, raise an event to a public delegate. However my main thread is not detecting these events, and I cannot figure out how to make it. My intention is to do all logging (text/database), email alerts, and restarting the worker to find another task that is not errored. (This will be expanded in the LogErrorMessage routine and such, for now I am just keeping it a simple Console.Writeline so that I can see if the method is being fired or not)
Here is the code around what I am trying to do:
Logger Class:
Public Delegate Sub LogDelegateError(ByVal Ex As Exception)
Public Class EventLogger
Public Event EventError As LogDelegateError
[Code].....
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Apr 27, 2011
I'm making a control and I am trying to finalize my design time properties grid. I have several List(of Class) items as public properties and when I click on the design time menu (while testing the control) there is the word "Collection" and a button with an ellipsis (...) that brings up a neat pop up with the buttons Add/remove and all of the public properties of the collection's class on the right hand side. Basically for a non-collection instance of a class (with public properties) I'd like a similar button to show up. I know I could put all of the properties in the main control class and group them, but I like the pop up box feature. Anyway to duplicate this? (think font grid item etc.)
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Sep 1, 2009
How can I change system properties like: being able to see hidden files or being able to see System files?
So far I can only do that with Particular files
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fileDetail As IO.FileInfo = My.Computer.FileSystem.GetFileInfo("c:\users\owner
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Jul 24, 2009
I am trying to create a new thread that will import from an excel spreadsheet, because it was doing all the import before the form actually displayed to the screen. So the user never saw the form while it was importing..In the form's load event I create the thread and start it, but I get this large error:An error occurred creating the form. See Exception.InnerException for details. The error is: ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment.
I am using visual studio 2005 pro on Vista Business?
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Sep 17, 2010
I have a TableLayoutPanel with a Chart in the 2nd column and 3rd row, and it's ColumnSpan and RowSpan properties are set to 1 (the effect is that it takes up about a quarter of the screen). When I click the chart I want it to take up most of the screen. I was thinking that I would have to change it's Column/Row and ColumnSpan/RowSpan properties, but it might be easier to change the Column/Row values of the table itself. My main problem is that I'm just starting off on Visual Studio 2010 coming from VB6 and I have no idea where to access any of these properties.
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Jun 18, 2009
Changing datatypes of properties of serialized objects?
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Mar 6, 2009
I've got a groupbox on my form. I changed its font and fore color. The problem is that when I add a button or any other controls like a label, checkbox etc to the groupbox, the controls are automatically changing their fore color and font to that of the groupbox. How to prevent this?
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Nov 23, 2009
how to change the properties of control which are created at run time. The actual situation goes like this: I will be creating 4 picture boxes at runtime and assigning pictures to them. Now if i wanted to change those pictures, i am not getting how to call those picture boxes.
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Jan 26, 2010
change the character spacing of a string or textbox output? One possibility is by creating a custom font, but i am unsure if there is a property in one of the overloads that will allow me to change character spacing?!
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May 15, 2009
I have made a program wherein you the labels are dynamically created with a press of a button. if you press on the label, the label would then change color from white to blue. my problem is that how will you make the backcolor of the label change when the button3 is pressed.
here are the codes. placed the whole thing since I dunno if you guys would understand what I mean.
[code]...
PS here is the link to what my program looks like. link to my program . the button3 in the image is Reserve Seat.
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Oct 5, 2011
I have a problem with this program
Form1.vb
Imports System.ComponentModel<br/><br/>Public Class Form1
Public Delegate Sub updatePB(ByVal value As Integer)
Private bgworker As BackgroundWorker = New BackgroundWorker
[code]....
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Nov 6, 2008
I have my own class of graphic objects, and now I'd like to allow a user to right-click on one of those within the application and see a properties window. Is there a pre-built dialog or control for displaying properties at runtime? I'd like to have something just like the IDE properties window button for my application.
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Nov 25, 2009
What I've done is create a User Control Library (Project) and I've added a single User Control to that project. The control contains a single FlowLayoutPanel, and I created a Property on the control itself to pass the FlowDirection from the Control to its FlowLayoutPanel child.
Build, reference, component appears in the Toolbox and everything works fine, but the property on the control does not appear in the Properties window when I go to edit it at design time.
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Feb 16, 2011
I'm trying to make a program with transparent labels over pictureboxes and when I set the label Parent to the PictureBox the position of the label changes.
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Dec 11, 2009
I would like to be able to set Control visual properties such as color, boarder, flat style, etc. on the base class of the control so that as I add new instances of the control, each instance inherits the visual properties of the base. I have tried using Application Settings but it appears as though I need to reference an application setting manually each time I add the control to a form. This is a Windows Form question.
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Feb 28, 2011
I tried it and get an error but maybe I'm tring the wrong way. Can a usercontrol inherate an application defined class ie.. could you inheritance a classic rect class into a user control to add the hight and width properties to the control without having to do all the coding all over again? Currently I just declair a private instance of the class within the control and then encapsalate. It would be nice if I could just inherit all the functionality of my classes into controls designed to implament the classes.
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Feb 18, 2012
I've been trying make a mdi notepad that can start up new instances of a "note" which is unique from the other notes as in you can save/change/cut/ copy/ paste in the individual notes without changing the properties of the other notes..something like a tabbed notepad but instead of tab control i have a mdi container. but i can't make it work. [code] problem with it is that whatever you cut/copy/paste in one mdi container richtextbox, it automatically cuts/copies/pastes in the other richtextbox controls in the other containers..
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May 19, 2010
Is it possible to access Application Properties of my applicaiton in run time ? Please refer the below attached image (I want to access the Title and Category properties in my application)
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Jan 7, 2010
Im always using this code(Example):Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ToolStrip1.Parent = PictureBox1 End Sub To set the Parent Property of an Object. How can i change it from the "Properties Window"? Just to save 3 line of code.
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Dec 1, 2010
I am reasonable new to programing and have ventured in to using VB.net after creating macro's etc in excel, as this seemed to be the easiest transition into the world of programing.I am creating a application to work with an access database and before I submit the forms textboxs to the database, I check to make sure each field is filled in and if it isn't then I highlight the field by changing the label back colour to orangered.
What I have is a bunch of textboxes and a label above each saying what the field is. so for example the textbox name is txtBox1 and its label is lblBox1, txtBox2 - lblBox2 and so on.So what I thought I would try and do is, as the user leaves the txtBox after editing, the label background colour would be changed back to transparent.
As I have multiple txtbox's I thought I could do this using sender to get the name of the txtBox on leave, strip the first 3 letters txt and change them for lbl cast it as a label, then change the background color but I cant seem to convert my string to a label control. can someone help me with what am i missing or not doing.
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Dec 2, 2009
I need to allow the user to rotate a control (the control inherits from a TextBox) in 90 degree increments so the text can be read from either side, or even upside down.
I'm guessing I could override the control's paint event and just paint it in the orientation that I want, but I'm just wondering if there's a quicker/built-in way?
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Feb 2, 2011
I have added a few text boxes to my report in MS Datareport.I want to assign value from my variables to these controls.how to access and address these controls.In VB6, I could simply do it in the code part of the data report.
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Sep 17, 2009
I'm quite new at this but I'm trying to change the look of a tab control other than the options provided in the control's properties. In short I want to create a large tab that will fit a picture but I don't know how to change the size of the tab. I also want to make the control look somewhat different than what the control provided with VS.NET looks like.
What I need to know is how to create a custom control that operates the same as tabcontrol but looks different than the traditional control provided with VS. I tried looking up how to create a custom control but all I could find was how to create one programatically and I don't know how it would apply to a tab control. Maybe the only way to do it is programmatically but I would rather play with the control in the designer than having it appear only at runtime.
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Jun 23, 2010
Is there anyway that I can access all the properties of a control during runtime and
get their values. I dont want to specify the property name. I should get the all the
property names and their values. It is something like reflection namespace in VB.NEt
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Dec 30, 2008
I have a problem: I want to code a program which can get properties of controls in orther program or other project (VB.Net project). I don't know where to begin?
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Apr 6, 2009
i had designed a form with various controls added some days ago. Accordingly i had coded the controls. And today i didnt like the look and feel of the form, so i copied the controls for a while and then re-pasted it over a new control (panel). Now when i double click to see the underlying code of the control generates a new event. I mean i had a button as Button1 and its underlying code was under the Button1_Click event. But now its is like Button1_Click_1 which i dont understand. Is it due to formation of control array or what? I want the button to be remapped to Button1_Click event.
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