we would like to build a screensaver that shows the desktop and the running applications but prevents user input by showing the login screen. The idea was to build a windows app with no window or a transparent window. However, as soon as the screensaver gets activated the desktop and all applications are hidden from the screen.
Is it possible to start the screensaver without hiding the desktop?
Thx,
bja
Is it possible for you to implement this as something other than a screensaver? I'm assuming that the Windows API does have a method that allows you to tell how long the computer has been idle (otherwise, how does the stuff that manages screensavers do it?), so if you use that you could just set up your application such that it's continuously running as a background process, and will pop up a modal dialog box (or your idea of a transparent window) or something that prompts for the user's login info when the computer has been idle for a certain amount of time.
Why can't you just grab an image of the screen when the SS kicks off. Then use that as the backdrop of your SS.
Vista has a bubbles screen saver that just starts putting bubbles on the screen. Not sure how they do it.
You are better off just creating a full-screen application with a transparent window that starts up on a timer like a screensaver. The screensaver functionality while similar to what you are doing, functions much differently.
As an alternative suggestion, you could always use a service (or background app) to gather the information you want these monitoring tools to display, or even just to grab periodic screenshots of the (hidden) desktop, and then have your screensaver query that app to get the data it needs to display.
That way, you get the benefit (the secure desktop, the usual Windows login sequence, etc.) of a screensaver, but still get to display what you need to.
Related
I'm writing a .NET 4.0 application that simply accepts input into a TextBox, processes it and then sends it off to a database. This app is intended to work with USB barcode scanners.
I have a requirement to ensure that the input from these barcode scans is processed by this app. I have been asked to ensure that this app stays activated and focused at all times as the laptop it will reside on has no other requirements other than to power and accept input from a USB barcode scanner.
I managed to achieve this myself by using a System.Windows.Forms.Timer that calls this.Activate() on a set interval, or better yet;
protected override void OnDeactivate(EventArgs e)
{
BeginInvoke((Action)this.Activate);
base.OnDeactivate(e);
}
Whilst these methods work fine on my Windows 8.1 Development machine, I can't get this same code to work on a Windows 7 OS (I've tried numerous boxes as well as VMs). For the Win7 machines I can see that this code is executed fine, but I just cannot get my app to Activate again.
Could anyone please advise as to why I'm seeing this behaviour?
Many thanks!
Windows only permits the application that owns the foreground window to bring another window into the foreground (either one of its own or belonging to another application). A background application can't bring itself into the foreground. This is a deliberate design choice (introduced circa Windows 98, as I recall) to prevent background applications from interrupting what the user is doing - particularly to ensure that keyboard input goes to the right place and doesn't accidentally fire actions that the user hadn't intended.
This constraint is documented in the SetForegroundWindow documentation:
The system restricts which processes can set the foreground window. A process can set the foreground window only if one of the following conditions is true:
• The process is the foreground process.
• The process was started by the foreground process.
• The process received the last input event.
• There is no foreground process.
• The process is being debugged.
• The foreground process is not a Modern Application or the Start Screen.
• The foreground is not locked (see LockSetForegroundWindow).
• The foreground lock time-out has expired (see SPI_GETFOREGROUNDLOCKTIMEOUT in SystemParametersInfo).
• No menus are active.
Source: SetForegroundWindow function (Windows)
If you need to be sure that input from a barcode scanner goes into a particular application, you should look into keyboard hooks, if the scanner is configured for keyboard emulation, or whether the scanner supports another API to allow direct control.
For example, the scanner may support the National Retail Federation's UnifiedPOS standard. Microsoft have provided a library, POS for .NET, which allows UnifiedPOS devices to be controlled from .NET.
That's an illegal action. You're stealing control from the user, which is forbidden in the desktop ecosystem. The user should always be the one in control. Windows Vista+ started paying a lot more attention to things like this.
The proper thing the OS is supposed to do is notify the user you want his attention (e.g. flashing the window in the taskbar), it must not actually activate your window. Every time the OS allows you to steal control from the user, it's considered to be a bug, and usually must be fixed.
Maybe you want to replace the default Windows shell instead? That will allow you to simply have just one application running anyway, and when it's closed, it will restart the machine...
Barcode scanners typically transfer their data as if some user would have typed it by using keyboard. This lead to a false assumption that you need to have focus and active window all the time.
However, you could use technique from stone age called keylogging (usually with the word trojan in front). This is achieved by setting keyboard hooks in windows based system. Then your application can have all the input.
It's done by using SetWindowsHookEx. I still have windows XP software which uses hooks and it seems to work under Window 8.
The problem to determine when it's a barcode scanner and when user is typing password into login form of another application I leave at your disposal =P.
I'd like to be able to stop a computer outputting to the display or be able to hide this output temporarily. I've used a VNC application called AnyPlace that allows the controlling computer to hide the output to the monitor and stop keyboard input, but I can't work out how they did this.
As you can still control the computer from the remote app I'm assuming they don't just load an application with a black screen. I thought about doing this but I can't guarantee I'll be the topmost application apparently.
I need to be able to hide the screen whilst I use a control system to close on application and open another in the background and then restore the output.
Some programs use DPMS to force the monitor into power-saving mode. Others might use a HUD overlay to draw on top of the screen without actually having a window (these are frequently used alongside volume control keys, etc). In Windows, you can use the "window station / desktop" GUI containment APIs to switch to a whole other desktop temporarily.
I want to create an alarm app for myself. On certain conditions (i need to poll websites) i want my app to inform me and make it HARD TO MISS. So i can take appropriate action or ignore it if i need to do something else.
I wrote a test app and using a BalloonTip (ShowBalloonTip with notifyIcon) isnt great. One of my previous apps brings the window in front of you and does a MessageBox however that doesnt always work or work well (if i somehow miss it or accidentally forget to click ok no futher messages will occur).
What are your suggestions?
You could also make it a system tray application and change the icon out if there is something which requires attention, a la a messenger application. That may not be "hard to miss" but I am trained (for better or worse) to look down at the icon tray when I see something blinking.
Where I work, we have a TimeTracker application (built in house) with which developers are supposed to log what we worked on and when. I am notorious for not using it. So, I wrote my own (Windows Forms) version for my own use which, every hour opens up and takes over my screen:
It is a frameless dialog which consumes the entire screen.
TopMost = True.
On resize, it sets WindowsState = Normal and resizes to fill the screen.
While it is open, it polls for taskmgr.exe and procexp.exe and kills them if found.
It disables the start menu to prevent cmd.exe commands from the menu in Windows 7.
The only way to close it is to enter a log, only then is the OK button shown!
So far, it's working out well - no one has been able to break it!
My less drastic suggestion would be to have a notification which pops up momentarily above the system tray. After a second or two, fade it out. Keep showing the notification every 30 seconds or so until it is dismissed.
Always-on-top window in the corner of the screen?
You could always set your window to be a top most window, make it full screen, and activate it. It would be very, very hard to miss...
Granted, it would also be very annoying, and not something I'd do to other users...
My "real" suggestion would be to use sound along with standard notification methods if this is going to be used by other people, as that's an easy way to grab attention without necessarily killing their workflow. A modeless window that appears in a corner of the screen, especially if combined with sound and color, can be very effective to grab attention.
The industry has been adopting these ambient orb devices and variations of it when such a hard-to-miss notification is required. It is used for tracking the stock-market and for broken-daily-builds.
http://www.ambientdevices.com/cat/orb/MAN_Ambient%20Orb_3-23-03.pdf
Regards
How can I print screen minimized windows? I believe it's possible, since Windows task-bar can create a preview of a window even if it is minimized.
This guy managed to do exactly what you are after: http://www.codeproject.com/Articles/20651/Capturing-Minimized-Window-A-Kid-s-Trick
I know this question is really old, but it can still be valid for someone.
I'm pretty confident that this is not possible, at least by an external application like yours. When an application window is minimized, the window cannot (and does not) receive WM_PAINT messages, meaning that it is impossible to ask the window to redraw itself while it is minimized (or, "take a picture of it"). This is a limitation (or a rule) of the Windows API.
The taskbar "gets around this" by displaying a cached image (which is the last snapshot the DWM took of the window before it was minimized) and so it is not in fact taking a current picture of the window. You can test this by running an application which periodically updates itself, and then minimizing it -- you will see that the preview image will not be updated until it is restored.
The only way you could get around this is to do what the taskbar does -- periodically take a picture of the window you want, and when it is minimized, use the cached image instead. Of course, this means your app will have had to have been following the target window some time in advance (this obviously won't work if the first time you want to take a snapshot of the window is while it is minimized).
In windows mobile PDA app is there anyway to show a form full screen, no other PDA system menus, just our form on top in fullscreen and make the user no exit from the form (there will be an exit button in form , they can exit through that) , Like locking a windows application showing in maximized with no titlebar, taskbar , not ctrl-alt-delete, alt-tab etc, as we did in win apps with APIs. I need the same thing in PDA.
Setting the WindowState to Maximized will make the form visually cover the full screen, but will not prevent the user to leave the screen using hardware buttons on the device.
If this is at bootup, try using a console app.
In addition if you happen to be using a symbol branded product download their appcenter from http://support.symbol.com
This gives you a lot of control over what the user can do with the system beyond just maxing out the screen, includes password protected settings.