Background:
I'm trying to add an animation to a splash screen window in my WPF project. (Not using the actual SplashScreen control. I use a window.)
My reason for implementing the splash screen is beacuse there's a slight delay when the application is opened, due to the loading of data. Obviously, the splash screen's purpose is to aid the user experience, so the user knows the application has been executed.
Here's the idea behind my current approach:
Instantiate the splashscreen window at the beginning of the
constructor.
InitializeComponent() is called.
Close the splashscreen window.
Unfortunately, the animation in the splash screen doesn't start until after the InitializeComponent() method of the the main parent window is called; this occurs basically when I'd WANT TO close the splashscreen window anyway. Hence the animation is useless and doesn't start until it's too late.
My question:
Why does it not animate until after InitializeComponent() is called?
My current theory for why this happens is that it's because the splash
screen is being opened on the main UI thread. Am I correct?
Are there any workarounds that don't involve hijacking control of
the program and spawning the splashscreen in a new thread? (I don't want a solution that hackish)
And yes, I did browse this site for quite awhile and was unable to find a viable solution.
Processing time on the UI thread blocks the animation. No real way around it.
The best approach is to NOT spend so much time loading and blocking on the UI thread. I suggest that you could delay the loading of the data bound to your UI elements until after the initial load. That way, the InitializeComponents() should not take so long.
Basically, all your bindings should return no data to the controls until AFTER you initialize. This data initialization would preferably happen on a separate thread, and then notification would occur after the data has been loaded.
This would allow your splash screen to animate and you will have much more joy.
There are a few approaches that I've taken to handle this in the past, though #HighCore is right in the comments as well about your current problem
Use the SplashScreen class in the VisualBasic assembly
Use the WPF Splash Screen class
Regardless, these solutions boil down to threading, since the UI pipeline needs to render and you can't inherently do these things on the UI thread without blocking, particularly if you want animation.
Related
I have a WinForms application, and wanted to add some nice WPF controls, one of them being an 'indeterminate' progress bar.. which just animates nicely until I tell it to stop.
I have done this, and was racking my brains as to why it wasn't animating (changing the value of the progress bar).
I eventually tried showing my form (containing the ElementHost) modally, and hey presto, it animates, but I want to show the form non-modally, as I want to continue processing behind the scenes.
Is there some kind of setting that tells the ElementHost window to continue 'animating'?
Thanks
Rich.
There are many ways to do this , the simplest one is to use a backgroundworker for the lengthy task. The Backgroundworker has an event to report progress. Handle this event and in the handler change your progressbar's value. Just having an animation in the main thread while still doing work on the main thread will not work right ...
One other aproach you may try (though is not what I would recommend for a healty app) is to implement a DoEvents function and call it in the main thread when you want the progress bar to get updated ... Here is the link for the DoEvents implementation:
MSDN DoEvents sugestion
I would Strongly recommend the first approach though
As I mention in my comment above, the solution is to run the processing in a separte thread, which allows the .net Main GUI thread do its stuff, and animate the progress bar.
I need to create loading window. Some splash screen that appears while main window is initializing and loading.
But my loading window contain animations and so on. So, everything, and from ctor too I need to make through Dispatcher. And as a result - system wait while main window is loaded than show loading window for a moment and then show main window....
And there is no sense in loading window at all :)
So, how to make my loading window in right way?
Thanks a lot!
You might need to use Multi-threading. Here is msdn on threads
http://msdn.microsoft.com/en-us/library/798axes2.aspx
and a tutorial:
http://msdn.microsoft.com/en-us/library/aa645740%28v=vs.71%29.aspx
and another one specifically for this:
http://msdn.microsoft.com/en-us/library/aa446493.aspx
I am new to C# but I have been programming with VB6 for a long time. I have a very simple project that runs without any errors. There is one problem however and it has to do with the Windows itself. If I open up any Window (from any other program) and that window overlaps my application...the moment I close that "other window", my application's Window does not repaint the portion that was overlapped by the "other window".
The same thing happens whenever the Bubbles screensaver comes on for Windows Vista. When I jiggle the mouse to cancel the screen saver, guess what??? I have bubbles scattered all over my Window. In VB, we had a simple "Window.Refresh" and voila! In C# however, this does not work. I have scoured the forum(s) and there seems to be a mention of "refreshing a thread". I'm kind of confused at this point. Why can't things be simple??
You can call Form.Invalidate to invalidate the client area of the form. That will cause it to receive a paint message, and redraw itself.
This is similar to the VB6 Refresh method.
However, this should happen automatically. If your application is doing some processing in the UI thread, however, it will prevent it from processing its messages until the work is completed. If this is the case, you should consider using BackgroundWorker (or some other method) to push the work onto a background thread.
There is nothing special you should need to do to redraw the Form in C# (Form should redraw fine when you bring the window back to the top).
Do you have any third party controls in play? Control.Refresh() does exist in C#, should you should be able to call it from the Form itself (usually this.Refresh() in your Form's codebehind), or any Control which has children (like Panel).
hey,
i've got a wpf application that have a doubleanimation used for scrolling text and images (scrollbar) from the left side of the screen, to the right, and a movie playing, in the same window.
everytime a video ends, and a new video loads, the doubleanimation get stuck/hangs for a second, then it continues normally. i assume it's the control blocking the ui thread while loading the video. i've tried to create a seperate UI thread for the scrolling bar but i didn't solve the problem. i've tried using MediaElement, MediaPlayer and MediaUriElement control with no success.
any help would be appreciated.
That's a known issue with MediaElement. You pretty much have to preload your videos...which means block the UI thread no, or later ;).
You can also try my MediaUriElement in my WPF MediaKit project. I did as much as possible off thread so this wouldn't happen.
http://wpfmediakit.codeplex.com
I have multiple forms that popup during an intensive operation. For example, when a form popups asking user for something, and the user clicks OK, the form's graphics stay on the main screen, even though it is closed. How can I make it so that these graphics disappear completely?
I would recommend performing the heavy work in the background (using a BackgroundWorker for instance), so that the GUI thread is not blocked. That way, the forms will be able to peform screen updates while the work is going on.
It sounds like perhaps you are doing intensive processing on your main thread, which is the thread that processes events like painting windows. Instead you should spawn a separate thread for doing your computations/tasks so that your main thread can continue.
Alternatively you can call DoEvents() periodically while doing your processing to allow the form to refresh, but using DoEvents is kind of a cludge in my opinion.
You can call the Refresh() method on the main screen form, which will force a graphics repaint.