I have a Windows app that basically calls other classes and within thise stored procedures and ultimately creates a csv file of a lot of info. I need a progress bar that just runs until its done so the user can see something is happening. I have scoured the internet and cant seem to get this to work. I just want the bar to start running on a button click. Why does this seem so difficult? The closest I got is just starting the bar in marquee but it wont "start" until after the object has been filled which does me no good, I need it to start while the object is being filled. This is being done in C#. Any ideas?
You need to run the long running task in a separate thread so that the UI can update while the task runs.
See Windows Forms ProgressBar: Easiest way to start/stop marquee? for an example of setting this up.
Related
I am working on Windows Forms application, that needs to start a big amount of async tasks. In other words, a small control panel, that will start and monitor the process (Task), started from this UI control panel.
But, after some researches, I realized, that there is no easy way to monitor variables' values from inside the Task.
Currently, I am looking for any way of monitoring progress in Task<>. Thinked, that I might start minimized process (Just basically copy&paste the whole code from task, that I need to start to a ConsoleApp, but, as always, that is not easy to catch the data from variables).
Any thoughts, how to do it correctly?
And found IProgress interface, but I didn't actually get the idea how it works. Just no examples.
My app consists of 3 tabs, each tab has a DGV, tab 1 and 2 do not contain that much data within the DGV but in tab 3 it can be between 100-5000 rows
The problem im having is that when i start my app, and move to tab 3 it takes a while before anything is displayed..
Im looking for a way to display a loading form to the user while the data is being added to the DGV..
How would i accomplish something like this?
Start loading data on a background thread and monitor the progress(displayed as progress bar).If you are doing it on main thread than you'll hang your interface.
Theres one good article but it is in VB.
Long running operations should be running in a seperate worker thread, commonly BackgroundWorker class. This prevents the UI from locking up during said operation. You can also choose to display a loading dialogue while this thread runs.
The other answers here are correct. But since you specifically asked about a loading window, I remembered a very nice example in Code Project.
In a project I was involved with, we took this example and made it independent. We added static methods called Start and Stop, and the Start method would create a thread, and then load the window, while the Stop method signaled the form it needs to close gracefully.
Hope this helps!
I'm writing a c# application that requires user authentication.
When the user hits the log in button, quite a bit of stuff is done in the background, but I'm having trouble informing the user that something is happening, and that the program isn't just frozen.
I have some hidden text fields that I would like to have show up after they log in, while this stuff is running, but I can't seem to get it to show up.
Basically, when the user hits the log in button, it checks to see if their credentials are correct, then the messages should show up, and then either some other functions might run, followed by a different form being shown.
After the credentials are checked, and I know that the user is valid, I tried running this:
please_wait.Visible = true;
But it doesn't change when it gets to that point in the code.
I've tried threading it, to see if that would help. Instead of calling the above line, I just start a thread that does it.
That doesn't work either. The field still doesn't show up.
If I return out of the function right after I either start the thread or change the Visible property, it works just fine.
How do I get it to work fine and have more code run after the change?
The problem isn't that you need to update the UI from a background thread. Rather, it's that you should be performing your long-running task in a background thread and marshalling updates to the foreground. This is frequently done via a BackgroundWorker with progress notification (on a progressbar, for example).
Basically, your UI foreground thread is either loaded or blocked doing work, so it isn't handling messages in its message queue to update your user interface.
Along with what Greg recommends (which is certainly the first step if you're not already doing it) you may also need to give up some quantum.
If you are taxing the scheduler, it's possible that the UI updates (which are pretty low priority) may be getting preempted until your worker is complete. Adding an Application.DoEvents (or maybe Thread.Sleep(1) in the background thread) could give the UI a little scheduler time to paint.
Have you tried adding a call to Application.DoEvents()? It's a hack, but it's all you sometimes need.
I want to have my own progress bar in .net compact framework, instead of default wait cursor.
I have tried with a form, having only a progress bar, and showing and hiding the form when I want to show some background activity running, but that does not update the progress bar.
I have found out that it needs to be on different thread. I am quite weak at threads, I cant get it working.
Please help me out.
Thanks in advance.
A cheap way of doing this would be to use Application.DoEvents(); within your "background work"... This would allow the screen to update whilst your application is busy.
I do not recommend doing this though.
I suggest you learn how to start and use BackgroundWorkers. They should provide the functionality you are looking for. Note you will not be able to alter the progress bar directly from the new thread, so will have to use an event or delegate.
I'm building a UI for a program, and I can't figure out why my progress bar won't become visible after the convert button is clicked.
private void convertButton_Click(object sender, EventArgs e)
{
toolStripProgressBar.Visible = true;
...
toolStripProgressBar.Visible = false;
}
I ran into a similar problem with tkinter in Python, and I had to call a function to update the idle tasks. Is there a way to do this with windows forms without using threads?
Edit: On a side note, this is a progress bar in a toolStrip that also contains a label that gets updated with status bar text. Is there any way to get the label on the left side and the progress bar on the other instead of right next to each other on the left?
Well, there is a way to do this without using threads (Application.DoEvents) but I strongly recommend against you using it. Re-entrancy is nasty, and you really don't want the UI thread tied up at all.
Use BackgroundWorker instead - it's easy, and it's pretty much designed for progress bars. It takes the hassle out of using a separate thread and reporting progress back to the UI thread. No need for Control.Invoke etc - it takes care of that for you.
There are lots of tutorials for BackgroundWorker - it shouldn't take you too long to get going with it.
Per the question you asked for the way to do this WITHOUT threads, that is to do it with Application.DoEvents();. (Just add that call right after setting the progress bar as visible.)
Now I do agree with Jon Skeet though that BackgroundWorker is a better way of doing this, but it does use a separate thread.
You need to execute your process in a thread separate from the UI thread, and then have it periodically report back to the UI thread with it's progress. If your convert operation is working inside the UI thread, it will simply go unresponsive until the operation is complete.
The progress bar can only become visible when it is allowed to paint which occurs during the processing of messages. Message processing cannot normally happen while you are in the middle of an event handler. If you want the progress bar to show up you will have to set the visiblitity to true, start a background thread to complete the work and return from the handler.
I'm guessing the problem is that the "..." in your code is a long-running process. UI updates are not instantaneous, but must run through the message queue in windows and then be painted to the screen. The queue is pumped and painting takes place in the same thread as your events.
As a result, any long-running tasks need to be moved to a different thread. More than that, your line line of code needs to called after that thread terminates. Otherwise you set the progress bar and then immediately turn it off again.
One way to do that is with a BackgroundWorker control.
Here go two links trying to explain you how things work:
(1) (2)
Now, I will try to explain it as shortly as I can. Most of what happens inside a windows forms application happens in a single thread, usually the same thread Main() runs in. If you open Program.cs, you will see that Main() has a line that looks like the following:
Application.Run(new Form1());
If you debug the application at any moment and examine the call stack, you will see it will trace back to that Run method. This means that a Windows Forms application is in fact a continuous run of the Run method. So, what is Run doing? Run is eating a message queue through which Windows sends messages to it. Run then dispatches those messages to the correct controls, which themselves do things like add text which corresponds to the key being pressed, redraw themselves, etc. Notice that all this happens during and endless loop running alongside a single thread, so weather you are typing or simply moving the window around, loads of those messages are being passed onto the application, which in turn is processing them and reacting accordingly, all in that single thread. Controls can also send messages to themselves through the queue and even you can place messages in the pump via Control.BeginInvoke. One of the things those controls do is to raise events according to what happens. So, if you click a button, the code you've written to handle that click will ultimately and indirectly be run by the Application.Run method.
Now, what is happening with your code is that even though you are changing the visible status of your progress bar to visible and then updating its Value, you are then changing its visibility to false, all in the same method. This means that only after you leave the method, will Application.Run() be able to continue iterating and consuming the message queue, effectively asking the progress bar to update its display. When that happens, you've already left the progress bar's visibility to false, the last thing you did before exiting the method. DoEvents() is a quick and dirty workaround to your problem as it reads the messages in the queue and processes them. I don't really feel comfortable using it as it can bring reentrancy problems.
Using threads is a good solution, but I would recommend using a ThreadPool thread instead of a custom thread in this kind of situation, as I tend to use custom threads only in cases where I have a limited number of long lived threads and I need to control their life cycles. The easiest and most practical way to use threads is to use the BackgroundWorker component, even though I would recommend going through the pains of understanding how to do Windows Forms multithreading with delegates if you want to really understand what is going on.
My solution is to call refresh on the status strip.
I believe this causes the UI thread to repaint the status strip.
toolStripStatusBar1.PerformStep();
statusStrip1.Refresh();
This is for .NET 4.0. Even though this question is old it was the first I found on googling this issue.