I just put a button and a textbox on a form to try and learn to multi thread, i think i've done it correctly. but it still appears to freeze for a little bit just before it attempts to display the data. i think it's the invoking. Is it normal / have a done something wrong?
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I'm making a small version of Spy++ and i would like to recreate the function that finds windows by dragging your mouse over it. Now that is pretty easy but one little annoyance is some windows minimize or loose focus ect when you bring the mouse pointer over them.
I would like to know if you can stop a program from gaining focus or minimizing. And i know i can get the handles of open windows by the EnumWindows function?
my program freezes untill the loading has finished.Is this normal? And if it is then how can I prevent my program from not allowing me to go back to the other form untill the loading has completed?I'm using this url as a start up page for my custom browser;so can I prevent my program from freezing or not ?It looks as if my custom browser form keeps demanding focu
View 5 RepliesI am trying to get my program to read async so it doesn't just freeze up while it fetches the data. I have:
SR = New StreamReader(WC.OpenReadAsync(New Uri(url)))
Dim html = SR.ReadToEnd.ToString
It keeps throwing the error "does not produce an expression". I remember trying this in the past, only to have the same error.
I'm using the WIA Aut. Library [URL] , trying to capture photos from 5 digital cameras (Nikon D90) USB-connected to my pc. Now, I partially achieved my goal, what I do is:
- loop through the attached devices, connecting to every camera;
- fotocamera.ExecuteCommand (WIA.CommandID.wiaCommandTakePicture) ;
- other image processing operations...
Everything works fine but... the workflow is camera1 -> connect -> grab pic. => camera 2 -> connect -> grab pic. => camera 3.....
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Sub Main() Try'process i files on their own thread
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I'm running into a problem when I stop the debugger, the console window stays open, and I can't kill it via task manager.
explain to me why the 1st example gives me an error complaining about cross thread yada yada....but the second doesn't, and works? this is inside a worker thread function
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I understand the concept of needing delegates and all that jazz when working with multiple threads, but why give me an error if there's no invoke required anyway?
I am developing a software that catches streaming data. Unfortunately, there is no pattern or sequence on how this data comes in. So what I have initially done is to catch then write to my MS Access DB. Unfortunately, while writing to the DB, I am missing some data that is streaming since writing takes a little bit of time before it goes back to the catching syntax.
I am planning to multithread the DB writing then just call it from my main program. Do guys know any website/tutorial where I can learn the basics for multithreading? I am using Visual Studio 2010. Or if ever, does any one of you have a sample program where I can just learn from?
I'm trying to execute a sub with multiple parameters on a separate thread, but I just can't get it to work, Here's my code
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I'm writing a really simple file updater which downloads files off from a website and saves them. The download routine is working well, except that it freezes the project while attempting to connect to the host. Easily solved with threading except now when I try to access other form items such as text boxes, labels, form caption, it says I am not doing it in a safe manner and prompts an interrupt in debug. I did some reading on it and I'm still not sure what to do, I'm very new to vbnet and it is still a little confusing to me.
Error: Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on.
Imports System.Threading
Imports System.Net
Imports System.IO
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I've got 4 projects all running very similar multi-threading HTTPListener stuff.I wanted to make these functions common - in some module - but I'm having a hard time getting the AddressOf the "callback" passed in.This was the code in one of the 4 projects
Private Sub StartRequests(ByVal prefixes() As String)
If Not System.Net.HttpListener.IsSupported Then
DisplayInfo( _
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The error occurs at: For i As Integer = 0 To txt_load.Lines.Count - 1..The project exists of 2 rtb's. One with a list of lines. The other will be filled with the converted lines. The main reason that I use it is that I want to use the app during the conversion. The second is that I want to learn how this works.[code]
View 9 RepliesRight now I have a Email class that has all the properties of an email to send it, and then a SendEmail function which takes those properties and uses them in the following
Public Function SendEmail()
'Exception handling
Try
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The loop goes through each email in the array to process its email, however with the multithreaded function I cannot call
"EmailArray(i).ThreadSendBatchEmail()"
So how do I call an objects method when its on a different thread?
And I'm making it multithreaded so I can easily pause the process, and because the program freezes when the send() function is working, this would resolve that.
I'm using loop to read data from sql and then make some calculations then save it again to another table but when application loop for 3 or 4 times it's freeze but the job is done but if loop = 10 or more then it is freeze and hangup for long time .i need to learn how to make my application working better and never freeze and make application working with any count for loop without freeze .
View 7 RepliesI have a dgv, I populate it, and I insert a row at the pos 0. And I want to freeze this row even when the user sorts the dgv.
How can I make this? The frozen property alone seems to be not enough.
Currently I have to retrieve over 2000 records from DB and bind with combobox. and then follow with another 3 retrieving (less than 20 records)
My problem is when I call this function, my GUI became freeze.
I try to use Application.DoEvents() method but it still didn't work.I read some post and pages, they mention about BackGroundWorker and .Net 2.0. But what i use it MS 2003 with 1.1 so i think i can't access BackGroundWorker.
I am attempting to freeze the top pane of an excel spreadsheet, which I have opened via my application. The most used method from various internet sources is: [code]
View 2 Repliesok i have this code for a banner changer i wrote for an app but i have an issue the code works it gets the banner url from the mysql database useing this code[CODE]......
so im at at loss how do i get it to work so the GUI is still useable while it gets the banner ?
Using DataGridView with VB.Net 2008.I would like to freeze the left column so that when/if scrolled this column still remains in place.
View 1 RepliesI use these codes to download/upload to my FTP host , they work perfectly but since i have to handles few download/upload , sometimes the application freeze during download
'Upload :
Try
' set up request...
Dim clsRequest As System.Net.FtpWebRequest = _
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Is it possible to freeze a remote computer? thru the ip address.
freeze computer meaning temporarily disable the mouse and keyboard of that remote computer
My following code hangs my VB IDE. What could be the reason. I am of the opinion that by 'sleep' I am avoiding a tight loop and so the program should not freeze. What should I do?
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I'm experiencing an error which complexity and way to approach I can't quite understand.. It looks like two threads not able to work simultaneously.The first thread is the normal program thread, and the problem occurs when the user clicks a button. This sends some messages through a method (PlaceOrder) of an API library object. This method is called 2-3 times in a loop. Handlers have also been added (on program startup) to receive callbacks on events raised by that object, and this is the 2nd thread that contributes to the error.
The error seems to occur when the PlaceOrder method is called while receiving an event from this same object.The result is that the UI freezes. I can trace the error in two places. If I trace the first thread (which is the initial program thread); the freeze occurs when reaching the lock(this) line, in the API-object class. If I trace the callback event, the handlers of this event try to invoke a RichTextBox on the form, and the freeze occurs on the line <RichTextBox>.Invoke(....), as indicated below.
The thing is that when pushing the button, there is a loop which calls the method of the API-object 2-3 times. And the first time succeeds, but the 2nd time it seems to crash in some way with the callback. It would be nice if I had made some silly mistake with the invoke code, but I don't think I have, as it updates fine prior to the error.. I'm not sure, but it may be relevant that it's in fact the same object, so early in my program I add this event listener (which is the one that updates the RichTextBox):
AddHandler ibclient.Error, New EventHandler(Of ErrorEventArgs)(AddressOf client_Error)
..while later, related to the freeze, I have:
ibClient.PlaceOrder(....)
But I'm handling a lot of calls forth and back other than these, and haven't experienced any problem before.it doesn't give any exception or error message, it just freezes.The invoke stuff in the form code, which should be as per trusted examples: (Freeze occurs at blue highlight)
Private Delegate Sub SetRichTextBoxInvoker(ByVal message As String)
Private Sub OnLogUpdate(ByVal message As String)
If Me.rtbTwsMessages.InvokeRequired Then[code]........
First off I'm using aspx pages with Visual Basic .net 2008 for the code behind.
I'm using a FileUpload control on an aspx web page to upload files to the server.
When I click on the Browse button I get a dialog box to select the file. I select the file and click the Open button and the entire file path populates the textbox portion of the control, just as it should.
However, when I use the same process to select a second file, after clicking the Open button it takes over 2 minutes for it to populate the textbox portion.
I have a RichTextBox (txtCustomDict) ... and i am invoking it like so from another thread:
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EDIT: Just checked and it does the same thing if i split it into 2 differently named subs then invoke the other sub
I have an app with which I populate a DataGridView named data. I have implemented threading in this app. Now both in debug mode (run through VS 2008 Express Edition), and without threading implemented the app works smoothly as it should. With threading and as a standalone .exe however, it freezes up. Not just anywhere, but as soon as 6 items are filled in the DataGridView (the top of the last one is only slightly visible). I have synclocked everything relating to the DGV, and am completely stumped.
View 7 RepliesI am new to LINQ to SQL and I try to Edit and Add a New item on a Windows Form in VB.Net, the form freezes? By example, when I try to select a value from a combobox the prompt get stuck (it enters in Enter event) and it cannot exit, then the form froze.
View 3 RepliesI have problem with multiple webbrowsers on form so i created simple form with 10 browsers in it and 1 button: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
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When I click button and try to drag form1 everything is none or slow responding.I see web site loading in browsers but nothing is responding on screen until loading of pages is finished. In the meantime my processor it goes to 90-100%I tested exe on my laptop and is working same.
I'm trying to make the classic Snake game in VB.NET, but if I hold a key (any key) during the game, after a few seconds the game freezes until I release the key. I've tried lots to fix this, but nothing works, maybe because I don't understand the problem.I'm assuming that when I hold down a key, the Form1_KeyDown function gets called, and when, after a few seconds, the key goes into "I'm being held down" mode, that function is constantly called, so the timers don't get a chance to update. But like I said, I'm probably wrong.
I've been struggling with this for a while. I think this is all the necessary code, please let me know if it isn't.
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Problem: Need to get a picturebox to display four images, one after each other. But in a way in which during runtime the changes can be seen.
So I figured if after every image is changed for example if I had some sort of timer, then during runtime the image will be shown, then after a certain period the next one would be shown and etc. I tried doing this using a timer and then a stopwatch but both time's no change can be seen in runtime and there is a small wait before the last image comes up.
I then also, tried using sleep, but that also showed no changes. Underneath is a quick piece of coding of what I'm trying to achieve, but instead of textboxs, for the sake of what I'm trying to do I will be using pictureboxs.
CODE:
Question: I've tried all I know in regards to timers and so on with no luck.