I have developed an application that needs to read an extensive list of files (loading images) before it starts running. With UWP, the user has to wait with the window in the foreground until everything is loaded because it is in suspended state when not in the foreground.
After much reading, I'm trying to decide which route to take. I could use the "Extended Execution" approach or start a background task.
Anyone could point me on the plus and minuses of each approach, or any other recommendation?
Just show a wait message as the window content. Show a nice company logo and 'Please wait, initialising' as a message. Even better, show a percentage indicator so the user gets a feel for how long it will take to complete. When finished you replace the window content with the real content of the application.
I found a very good explanation here:
https://msdn.microsoft.com/en-us/magazine/mt590969.aspx
Very useful. Thanks Phil for pointing me in the right direction. It's working great.
Related
I’m developing a screen saver in C# .NET4.0 on VS2010 which needs to do a fair bit of processing before it actually shows screens (fairly complex database access). This is fine because the user is unaware that this processing is going on and then the full screen forms kick in when everything is ready. That is, unless we are running on Windows 8.
Searching on the Microsoft Community (http://answers.microsoft.com/en-us/windows/forum/windows_8-desktop/bubbles-screensaver-has-black-background/e0807324-5ca6-4abe-b6ba-716848b41ff5?page=4) reveals that a design change was made in Windows 8 that prevents screensavers from drawing over an image of the desktop. Any screensaver that previously drew over the desktop will instead draw over a plain background using your chosen “metro” background colour. Experimenting reveals that this background kicks in immediately the .scr file launches i.e. before any forms can be displayed. Hence tricks like displaying forms minimised or with 0% opacity don’t work because this simply reveals the plain background underneath.
The best I’ve been able to come up with is to display full screen plain black forms as first action when my code starts i.e. before any database processing or other screen construction takes place. Why try to replace a plain screen with another plain screen? Well, because the default Windows background colour seems to be blue. That’s blue as in BSOD blue which looks kind of alarming when it kicks in. So the best I can do for a Windows 8 user experience is a quick flicker of blue followed by 3-4 seconds of plain black before screens are populated with something meaningful.
This new behaviour from Microsoft is apparently “by design”. The fact that it doesn’t manifest itself in Preview mode is apparently an error which one supposes MS will tidy up later.
So my question is does anyone know any way around this so that I can continue to have the desktop showing until screensaver forms are ready to kick in?
I struggled quite a lot with a similar problem regarding this awkward design decision in win8.
I the end had to compromise but my search continues for a a bullet proof solution, when I have time.
Now what I ended up with is running a batch file after the monitoring system starts and have thread detect idle time and run that batch again.
#start /wait Bubbles.scr /s & rundll32 user32.dll,LockWorkStation
What this does is:
starts screensaver preview in fullscreen (this works in win8) and waits
on user action lock screen is show and user prompted for password
As I said it's a compromise until a find something better. Hope it helps
Updated to win10; try to use that cool scr and found same issue;
Try to trick ms restriction and found only one very long solution:
enable logging of screensaver invoked events;
here instruction via gpedit: https://superuser.com/questions/538146/run-a-batch-cmd-upon-screensaver
now you will able to start other comand or app when screensaver starting;
goto C:\Windows\System32
copy Bubbles.scr and rename to Bubbles.exe
then config task to run C:\Windows\System32\Bubbles.exe with argument /s (administration->taskcheduler)
use some windows screensaver and config to use 1 min or more; (or use 'runsarver' with empty options from upper link or create your own empty.exe and rename to .scr and install with right menu, etc)
Found cool app to customize hidden screensaver features: http://winaero.com/download.php?view.8
(work with small bugs but work as needed under win10)
All work fine one cons checkbox to lock PC must be unchecked;
If needed create own app to run Bubbles and on exit lock PC or bat file as above, etc;
hope people will have fun with my solution :)
I have a Windows Form Application that reads a barcode from a Web Cam.
Everything is running smooth but I still need to implement a function to the application to keep listening my keyboard inputs and be able to read the barcodes and put the reading in the clipboard.
In other words, do the stuff that my program has to do but in the background.
I searched a lot in the internet but I couldn't find any good answer to my problem.
Can you guys help me?
Thank you a lot!
There's more than one way to perform this.
So the problem is that your application doesn't have focus, and so doesn't get keyboard/mouse input passed to it. To work around that you can use Keyboard hooks.
Alternatively, you can perform polling. That is, run your 'scan' periodically - quickly enough that the user doesn't need to enter keyboard input, they just put something in front of the web cam for a second, and it scans.
You need to use a background worker to read the barcode so the main thread is not locked up. Below is a microsoft example:
http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx
I’ve got a process which will take a little under 5 seconds to complete. The user will most likely notice the program flicker for a few seconds after pushing the “go” button.
My question is:
Is this something that would normally be dumped onto a background worker, or is there another .NET method for handling small tasks, or is this something that shouldn’t be a concern?
FYI:
The process opens a user specified excel file, processes an unknown number of lines (max 1.5 million due to excel I believe), and queries a database (very quick query). So at the worst case scenario the user uploads a 1.5 million row excel file and is running on a very slow internet connection.
If you don't want the user to be able to do anything while the file is being uploaded, then you don't need to put it on a different thread.
If you want the user to be able to go on to other tasks while the file is uploading, put it on a different thread.
As a general rule of thumb, if I have a situation where I absolutely don't want the user to do anything while a long-running process is going, I disable the controls on the form until the task is complete, and usually use a status indicator to show that progress is happening.
My personal guideline for whether or not to allow user interaction is if the results of a process could be altered by a user action in mid-stream.
For example, one program that we have parses a bunch of queries on a highly normalized database (normalized to the point where reporting is sloooow) into "reportable" tables, and I don't want the user altering data in one of the source tables while the query is running, because it will give goofy results.
If there is no harm in allowing user interaction while the process is occuring, then put it in another thread.
Edit
Actually, on reading #UrbanEsc and #archer's comments, I agree with them. Still put it on a different thread and freeze the controls (and include a progress indicator where possible).
I would push this to a background worker. Doing so will keep the UI responsive. If the process ever does lag for more than a few seconds, users start getting nervous ...especially when the lagging process causes the UI to be 'frozen'.
From a user experience point of view it might be best to hand the job over to a different thread or an asynchronous worker and tell the user that his request is being processed in the background. Once the worker finishes, a success/failure message can be handled and shown to the user as required.
The cheapest way to handle the problem is to turn the cursor into an hourglass during the processing. That tells user please wait, I'm busy.
According to the budget (time and/or effort) you're willing to throw in it, using a backgroundworker and some reporting GUI is certainly a plus. But it's up to you according to your app.
For example, I'm currently modifying an in-house app that has 3 users. In that case, the hourglass is OK: All 3 of them will quickly learn they just have to wait. Don't get me wrong: this app is damn important. Without it, the small company that uses it would just die. But if I ask them for 2 hours of extra budget for a nice and tested little GUI, background thread, blah vs an hourglass, what do you think they'll say?
On the other hand, if it's an important operation in your flagship product, of course be nice to your users! Don't hesitate: background thread. Especially if the operation may actually take much longer than those 5 seconds.
Conclusion: Be pragmatic!
I would put it into a background worker or fire of a task if you are in .NET 4.0, for example:
void OnButtonClick(...)
{
new TaskFactory().StartNew(() => { /* your excel and query code */ });
}
I'll vote for the background worker process, since a frozen UI is like a frozen application, and most of users will think your application isn't doing anything at all.
UI thread for a progress bar or some animation, info text noticing what's going on + background worker thread = win
I think every process not related with the UI itself should be started as a separate thred or, in this case, as a bg worker. This will help to maintain the app healthy and easy to improve/fix in the future.
Also, as a user or tester, I really hate flicking and freezing windows...
Regards.
A general rule of thumb is any operation that takes a second or longer to complete requires some form of feedback to the user. This can be a progress bar, message, etc. Anything longer then that then the user becomes frustrated (not sure if they did something wrong, hate waiting, etc).
For operations like this that can take longer based on the environment (number of apps, available memory, data size, hard drive speed, etc) they should ALWAYS be put on a background thread and pipe messages back to the UI. I love the BackGroundWorker for this.
I'm looking for some ideas for alerting a user when a long running process has completed from a winforms application. The process could take a couple minutes or a couple hours depending on their inputs, and more than likely they'll just minimize the application and work on something else in the meantime. I know I can do something like playing a windows sound like this:
System.Media.SystemSounds.Exclamation.Play();
But most users here in the office don't have speakers so I don't think it would be very effective.
What are some other techniques I could do to tell the user, "Wake up!!! Your data is ready for you, finally!!!!"
Thanks!
Some ideas:
Animated or changed system tray icon
"Toaster" popup from the system tray (like Outlook, messenger, or some AV apps use)
Blinking alert in taskbar
Send an e-mail
Play a sound/audio alert
Message box
Have an indicator in the status bar at the bottom of your app
Of these, I like the system tray icon + toaster pop up the best. Blinking alert in the taskbar is too demanding, e-mail has too much latency and requires too much configuration, audio alerts have the issues you mentioned in the question, message box blocks execution of it's thread, and a status bar indicator is too subtle.
This sounds like an ideal use case for a notification in the taskbar's Notification Area.
This has the advantage of alerting the user immediately without relying on things like sound that may or may not be available on the user's computer and without the invasiveness of a message box.
...except you might say "Process completed" instead :-)
Open a Message Box.. if the app is minimized it will flash on the start bar.
How about blinking the form in the taskbar similar to how most IM programs blink when a new message is received. You'll need to P/Invoke to get that functionality, but it's actually very easy:
http://pietschsoft.com/post/2009/01/26/CSharp-Flash-Window-in-Taskbar-via-Win32-FlashWindowEx.aspx
You don't need speakers to do the console beep...
Console.Beep();
You can allow the user to customise how they want to be notified if you've got the dev. time.
I have a windows form application which needs to be the TopMost. I've set my form to be the TopMost and my application works as I'd like it to except for in one case.
There is a 3rd party application (referred to as player.exe) that displays SWF movie files on a portion of the screen that popup on top of my application.
Using Process Monitor I determined that player.exe application calls
flash.exe <PositionX> <PositionY> <Width> <Height> <MovieFile>
in my case:
flash.exe 901 96 379 261 somemovie.swf
Since flash.exe is being spawned in a new process after my form has been set to the TopMost it is appearing on top of my application.
First thing I did was make my application minimize the player.exe main application window hoping that this would prevent the Flash from appearing also. But, unfortunately it doesn't... even with the window minimized whenever the flash movie starts it shows up at the pixel location (901,96). I then tried creating a timer to keep setting the form.TopMost property to true every 10ms. This sort of works but you still see a very quick blip of the swf file.
Is there some type of Windows API call which can be used to temporarily prevent player.exe from spawning child processes which are visible? I admit it sounds a little far fetched. But, curious if anyone else has had a similar problem.
Addendum:
This addendum is to provide a reply to some of the suggestions layed out in Mathew's post below.
For the emergency situation described in the comments, I would look at possible solutions along these lines:
1) How does the third party application normally get started and
stopped? Am I permitted to close it
the same way? If it is a service, the
Service Control Manager can stop it.
If it is a regular application,
sending an escape keystroke (with
SendInput() perhaps) or WM_CLOSE
message to its main window may work.
Easiest way to close the app is to CTRL-ALT-DEL, then kill process. -OR-
The proper way is to Hold ESC while clicking the left mouse button... then input your username and password, navigate some menu's to stop the player.
There is no PAUSE command... believe it or not.
I don't think using WM_CLOSE will help since minimizing the application doesn't. Would that kill the process also? If not, how do you reopen it.
2) If I can't close it nicely, am I permitted to kill it? If so,
TerminateProcess() should work.
I can't kill the process for two reasons. 1) Upon relaunch you need to supply username/password credentials... There may be a way to get around this since it doesn't prompt when the machine is rebooted but... 2) Whenever I kill the process in task manager it doesn't die gracefully and asks if you want to send an error report.
3) If I absolutely have to leave the other process running, I would try
to see if I can programmatically
invoke fast user switching to take me
to a different session (in which there
will be no competing topmost windows).
I don't know where in the API to start
with this one. (Peter Ruderman
suggests SwitchDesktop() for this
purpose in his answer.)
I got really excited by this idea... I found this article on CodeProject which provides a lot of the API Wrapper methods. I stopped implementing it because I think that in order for desktop's to work you must have explorer.exe running (which I do not).
EDIT2: On second thought... maybe explorer.exe isn't needed. I'll give it a try and report back.
Edit3: Was unable to get the code in that article working. Will have to put this on hold for a moment.
Answer Summary
As one might have expected, there is no simple answer to this problem. The best solution would be to problematically switch to a different desktop when you need to guarantee nothing will appear over it. I was unable to find a simple C# implementation of desktop switching that worked and I had a looming doubt that I would just be opening a whole new set of worms once it was implemented. Therefore, I decided not to implement the desktop switching. I did find a C++ Implementation that works well. Please post working C# virtual desktop implementations for others.
Setting the TopMost property (or adding the WS_EX_TOPMOST style to a window) does not make it unique in the system. Any number of topmost windows may be created by any number of applications; the only guarantee is that all topmost windows will be drawn 'above' all non-topmost windows. If there are two or more topmost windows, the Z-order still applies. From your description, I suspect that flash.exe is also creating a topmost window.
Aside from periodically forcing your window to the top of the Z-order, I think there is little you can do. Be warned, however, that this approach is dangerous: if two or more windows are simultaneously trying to force themselves to the top of the Z-order, the result will be a flickering mess that the user will likely have to use the task manager to escape.
I recommend that your program not attempt to meddle with other processes on the computer (unless that is its explicit purpose, e.g. a task manager clone). The computer belongs to the user, and he may not value your program more highly than all others.
Addendum:
For the emergency situation described in the comments, I would look at possible solutions along these lines:
How does the third party application normally get started and stopped? Am I permitted to close it the same way? If it is a service, the Service Control Manager can stop it. If it is a regular application, sending an escape keystroke (with SendInput() perhaps) or WM_CLOSE message to its main window may work.
If I can't close it nicely, am I permitted to kill it? If so, TerminateProcess() should work.
If I absolutely have to leave the other process running, I would try to see if I can programmatically invoke fast user switching to take me to a different session (in which there will be no competing topmost windows). I don't know where in the API to start with this one. (Peter Ruderman suggests SwitchDesktop() for this purpose in his answer.)
You can use the Process class to start flash.exe directly - and use an appropriate ProcessStartInfo settings to show the window in a hidden state - or with a WindowStyle of hidden or minimized.
You could also consider using the SetWindowsHookEx API to intercept the process start API calls, and when the process is flash.exe run some code to restore you window to top-most status.
Matthew's answer is excellent, but I suspect you may be asking the wrong question. Why does your application need to be topmost? If you're trying to create a kiosk or some such, then topmost is not the way to go.
Edit: After reading your response to Matthew's comment, I'd suggest creating a new desktop and switching to it before displaying your alert. (See CreateDesktop and SwitchDesktop in MSDN.)