Use Webbrowser In Multithread?
Sep 5, 2010
I'm working on a project. It is a windows form app which has a webbrowser. The app navigates to a url automatically, checks the url's document, and jumps to another url (depends on the document). It works fine. But, now, the problem is the project needs check many urls, so, I'm trying to make it as a MDI form project. when the start button clicked, it create a control thread, in the thread, it launchs 10 MDI forms (within main form), each form does the work for different urls. once done, then launch the next 10 urls.
It works. However, I noticed that, although 10 MDI forms are open, the navigating part in their webbrowser seems run in sequencial. I thought these 10 MDI forms will load 10 urls at the same time, do the work at the same time, but I found that it seems they do load urls one by one, not at the same time.
so, I did some research, it seems webbrowser can only be run STA mode. does it mean I can not use multithread to load different urls at the same time?
basically, I want to have a multi tab webbrowser, and navigate to different urls in these tabs at the same time.
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Feb 23, 2011
I'm making a type of download manager which downloads parts of a file using HTTPREQUEST.addrange. The parts download without a problem and currently I use 5 instances of the same class to download the parts simultaneously each one downloading a different section of the file. Now my problem is that I don't want to save each part as a file then merge them later, I want to use a singular filestream and append everything asynchronously. In the code below I attempted to use the seek method but it feels like it changes the seek for all of the other parts as well.
[Code]...
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Nov 17, 2011
how do I multithread using timers. For instance 3 picture boxes that change ever 3 seconds?
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Feb 24, 2011
I have client/server app.I have a class for the tcpclient and a class for the tcplistenerIn my tcpclient class I have a system.timers.timerThe timer elapsed event fires a public event(in the tcpclient class) which the tcplistener class handles.During debugging I see the timer firing its elapsed event and calling raiseevent on the public method, yet the event is never fired in my tcplistener class.
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Mar 4, 2011
the differences between multi threading and background worker and when I should be using either.
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Mar 3, 2009
On this piece Of code I want to multithread, beginning where the for loop takes the data out of the array arydata. The threads would all do the same task.
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Aug 10, 2009
VB and programming on Windows as such. Mostly c++/gcc/linux. I am trying to build this VB app that shows a streaming video from a camera and that needs to be overlaid with some custom graphics and text. I used the code published here: [URL] to get the capture part to work. It essentially uses the avicap32.dll that most of you would probably know.
My plan:
1) Capture frames using SendMessage(windowHandle, WM_CAP_EDIT_COPY, 0, 0) and then copy from clipboard.
2) Do whatever graphics/text overlay on the obtained bitmap
3) send it to some picturebox on some form that is being shown
4) Do step 1 to 3 in a loop by a spawned worker thread.
Firstly is this a reasonable way to do what I want? or is there a much more efficient/easier way to about?
Now the specific problem: From my main thread directly if I do step 1 to 3 once UIComponent.DrawImage(VideoComponent.GetBitmap()) It shows me once captured image as it should and all is good.
Just to clarify: UIComponent is an object/instance that launches the Form and owns the picturebox I want to display on. VideoComponent is an object/instance that has started the videocapture and owns the picturebox to which the video is being captured. But if I wrap the same call above in a function and launch a thread that would start with that function as its starting point, I see a blank screen. Again, for testing purpose, I am only doing step 1 through 3 just once.
The thread part of the code is like this:
Private drawthread As Thread
public sub main()
drawthread = New Thread(AddressOf threadfunc)
[CODE]........
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Nov 25, 2009
I have this situation: a Form with a System.Timer in it (with AutoReset = False). The form has its main thread and the timer its own thread too (nothing new here). When the user press a button I need to stop the timer, wait until the timer thread has stopped its execution and do something more.
On the other side, the timer updates an item at the form so BeginInvoke is used. The code looks like this:
Button Code: Private Sub ButtonStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonStop.Click
[Code]...
The point is that I wait the main thread to let the timer thread to end its work.The problem is that this code deadlocks when the user clicks the button when the BeginInvoke is going to be called. How a simple thing like this one can be done? Looks like I cannot find a good solution to this problem
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Aug 9, 2009
SERVER
Im using this code:
Imports System.Threading
Imports System.Net.Sockets
[code]....
but when i tried to run the application, it hangs even if i wait several minutes.., is there something wrong with the code..
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Apr 30, 2011
I have a multithread program and in a thread i read a stram from ftp server and write them to a file and close it and in another thread open saved file and read it for process.but sometime when i want to open saved file i receive a error that say : cannot open file , because another user open it .i create 2 filter that surly file saved and closed , but i don't success.
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Jan 21, 2010
I have a program with 3 forms; each has a different role behind them. Form 1 loads when the program executes and the other 2 load by clicking on buttons from form 1. I would like to implement a multithreaded approach where even after clicking on form2 and form 3 I can still execute other form 1 options while form2 and form 3 contents execute. I read through some tutorials and still not to sure how to implement. I figured I need to create instances of the forms 2 and 3 but how to call the threads and control them? I did try a simple one and had some error concerning delegates.
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May 18, 2011
The server connects, the clients connect, one client sends a message to the server, and the server broadcasts it to the other clients. But what I want to do now is to also have the server communicate with the clients. But when I click on the server form, it freezes, and I cant do nothing.
I think this is because of me not creating a thread for the communication(I saw this on another forum), but I dont know how to do that. I copied basically all the chat program code from a site, and I dont know much of sockets and what not.
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May 18, 2011
i'm doing a chat for a project, and it works like this. The server connects, the clients connect, one client sends a message to the server, and the server broadcasts it to the other clients. But what I want to do now is to also have the server communicate with the clients. But when I click on the server form, it freezes, and I cant do nothing. I think this is because of me not creating a thread for the communication(I saw this on another forum), but I dont know how to do that. I copied basically all the chat program code from a site, and I dont know much of sockets and what not.
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Nov 15, 2011
How can I use a text box on a multithreaded client so that it will appear in the command line of the multithreaded server?We were given this code to work around/tear apart:
Imports System.Net.Sockets
Imports System.Text
Module Module1
[code]....
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Jun 27, 2011
i am new with multithreading in vbnet. i got this error.Cross-thread operation not valid: Control 'lvSample' accessed from a thread other than thethread it was created on.this is my code.
Private Sub xFormLoad(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim t As Threading.Thread
[code].....
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Jan 21, 2010
I have a thread executing the following:
vb
Do UpdateVis()
System.Threading.Thread.Sleep(Interval)
Loop
UpdateVis is as follows:
[Code]...
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May 27, 2009
I am trying to successfully multithread a piece of software I have been working on. I have an array of threads 'gen' already working, calling to a method taking a single integer as a parameter (done via typecasting).Now in this thread, when the function gets processed (for each thread a roughly 500 iteration while loop) the index seems to be getting mixed up. As far as I can tell, my threads are messing with eachother and warping values. Now this is happening in locally declared variables inside this function, not global variables.It may be useful to know that I am using a WebRequest via a call to another method. Don't know if that makes a difference or not.
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Jul 7, 2009
I'm trying to manipulate something that is in a different thread, and I know I need to do something by the way of Invoked procedure, but I'm unclear on how. I looked up some examples here on the forums and tried to follow the basic template, but I continue to have the same problem. how to use invoke correctly.
Private Sub getMessage()
For Me.infiniteCounter = 1 To 2
'Try
[CODE]...........................
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Aug 16, 2009
I currently have a browser go through the same list of sites one by one and gather updates. The problem though this takes awhile. Can a browser be multithreaded, (so it could visit several sites at a time) and if so would this take up a lot of server resources?
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Aug 31, 2009
I am doing this within a thread:For Each item As ListViewItem In lvUsers.Items and I am getting: Cross-thread operation not valid: Control 'lvUsers' accessed from a thread other than the thread it was created on.I have been able to adjust a control in a way using something like:
Public Delegate Sub ListAddNameInvoker(ByVal text As String)
Public Sub ListAddName(ByVal text As String)
If lvUsers.InvokeRequired Then
[code]....
But how do I get data from a control and pass it to another thread?
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Sep 3, 2009
I have simple ASP.net web form. With a simple click on a button i need to call a the Multithread process in order to execute my querry in SQL Server DB. I know that my querry willl take up to 45 min to be executed. While the process is running i need to display some status information like: Starting time, Time elapsed, % of completed...So after running the process i got the following error message: "Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding."So i have 2 problems to fix:
Avoid getting timeout while processing/calling the stored procedure. I tried to add cmd.CommandTimeout = 1000 but it didn't work out!
Display correctly Time elapsed and % Completed while processing.
Here's my code in the main form:
Imports System
Imports System.Data
Imports System.Configuration
[code]....
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Feb 28, 2010
how can i make my webbrowser open up a new link in my same webbrowser or in another form? basically what im saying is i dont want it opening links in internet explorer.
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Apr 18, 2011
I use webbrowser as File Explorer.
If you click folder it opens new folder contents in WB window but if you click html document it opens in EXTERNAL viewer.
How do you get html document to open in WB while exploring ?
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Aug 10, 2010
I am writing a few web based apps which will require a webbrowser extension. I have already used the IE webbrowser control that uses the trident web rendering engine. I believe this is MSHTML.DLL? Anyway, some of the users of my programs have complained of a few things. Particularily,
1. It seems to be a slow browser, at least compared to other rendering engines out there (webkit and gecko are 2 known ones).
2. On the developer side, it seems to be low in features. The features are sufficient in most cases, but there are some "special" things that I need.
3. It has VERY low HTML (and especially HTML5) compliance.
My question is, how much work would it take to use a different engine (such as webkit .net, which I HAVE heard of) and be able to distribute it easily. Or, if you guys feel ambitious, we could try writing a brand new engine ourselves. I know how big of a job it is, and frankly, I have no clue where to begin. I would just like your thoughts and opinions on the matter.
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Oct 1, 2009
I am utilizing a webbrowser control in vb.net 2005 to display excel workbooks
We are using this control to open excel documents. Webbrowser.ShowSaveAsDialog() allows the user to save the excel workbook open at any location he wants
However, I don't want the user to decide where to save. Is there any way to save an excel document from the webbrowser control without going through the ShowSaveAsDialog?
On closing of webbrowser, a simple prompt to user whether he/she would like to save changes should be fine enough
As of now, I can close webbrowser control and it does not prompt the user to save the changes. Actually, all changes are lost until and unless I perform a save (Ctrl+S) manually
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Mar 18, 2011
i have created an app to load an access database into a datagridview, which contains web urls. When button is clicked it webbrowser1 navigates to each url and each webpages document.inertext is put into textbox. This all work fine but after a while the webbrowser navigation becomes increasingly slower.
For Each RW As DataGridViewRow In Me.DataGridView1.SelectedRows
'''''''''''#######cell values into strings ########''''''''''''''
If RW.Selected = True Then
Dim domain As String
[code]....
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May 6, 2011
I want to make a webbrowser, but only have it show one specific thing and not the whole page. The thing I want it to show and only show is in about the middle. How would I frame the page, and put it on the webbrowser?
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Nov 5, 2009
Is it possible to add tabs to a normal webbrowser without using a tabbed webbrowser ?
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Jan 1, 2011
Ive tried to edit option on the webbrowser control, example javascript enable/disable. but found out that it uses IE's option and cannot be changed.So my question is: Is there a way to do a "webbrowser" without using the WEbbrowser control that is based on internetexplorer? If it is, can i change option example flash and so on?
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Oct 30, 2011
i have two browsers. And one browser makes some occasional popups. I want the popups to open in a new webbrowser (webbrowser2). I don't want to kill them, only to open them in the second webbrowser. Where do i start from? what code should i use? right now I can't figure out anything, i even GOOGLED the stuff.
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