A few of my users are experiencing a strange bug. I have a simple WPF window that contains a few textblocks and buttons. After a short time using my application successfully the users that experience the problem report that the window's content becomes empty and only the border of the window is visible.
After remoting onto their machines I have confirmed that it looks like the content of the window is frozen. When the window first opens it appears like its see through and displays whatever is behind it. If I move the window around the same frozen image of what was behind the window when it opened stays there. If I bring something in front of the Windows (such as a browser) the "frozen image" in the contents will change to a frozen image of whatever was in front of it. I have discovered that the buttons are still active and clickable in the window, so it's not completely frozen it just seems not to be drawing the content properly.
The issue only seems to affect a small percentage of my users and I cannot recreate this issue on any of my test machines. Any ideas about what is happening would be greatly appreciated.
If you have a user that's willing to experiment to find a solution, have them Disable Hardware Acceleration in WPF. If this fixes the issue, then it's most likely a graphics driver problem.
Related
I have a problem that appears to be new to Windows 10.
I want to create a form that is visible to the user, but with no task bar icon and that does not appear in Alt+Tab.
This is perfectly doable if one is happy to sacrifice the normal styling of a window by following the accepted solutions here for either WPF or Windows Forms.
The general advice for both WPF and Windows Forms is:
Set ShowInTaskbar to false
Enable the ToolWindow styling (either through setting the border style in WinForms or the WindowStyle in WPF)
However, this has a new, practical problem in Windows 10 when using Virtual Desktops: the moment you do the above, the WPF or WinForms window will appear in every virtual desktop. See my example application with a red background:
This affects both the Task View switching screen and the actual desktop itself. No matter where you go, the form is there!
Is there any way to show a form - or even just a bitmap - on Windows without anything appearing in the taskbar, without anything appearing in Alt+Tab and without duplicating the window on every virtual desktop?
I have spent two days researching every possible option, trying every example online, reading MSDN documentation on window styles etc. but all resort to the same method, either through P/Invoke calls or directly, but either way the result is the same.
I'm not sure that's the right way to say it, but what I want is to for my wpf main window to have it's own bar that will behave like a taskbar, and any children windows that will be open from the main one will be placed in that bar in a similar way like the taskbar works in windows - a rectangle showing the window name for example, on click it opens you the window, if you click minimize it will minimize it to the bar, and with some option, to get it out of the main window and move it to the real windows taskbar, with another option for putting it back in. The problem is I don't know if this is even possible, and I don't know the name of such an element, so if anyone can give me any tips I'll be really thankful.
I worked on an application years ago (.NET 3.0: first WPF release!) that did exactly that. We ran into a lot of issues getting it to work, but we were pretty successful in the end. One thing we didn't support was moving it to the Windows taskbar.
The best option would be to set an attached property on each Window. This would register a Window with your custom taskbar, so if you wanted to move the Window out of your custom bar, you'd set the property to false. Setting the property to true would add it to the collection of application windows, as well as register event handlers to track the state of the Window.
One of the major pain points for us was getting the Window animations correct. If you're not running in XP, this probably less of an issue, as the animations in Vista (or is it 7?) and above aren't really showing where a Window is going on minimize. In the end, we had to do a lot of low level Win32 (p/Invoke) work for this.
Take a look at AvalonDock and WPF MDI:
http://avalondock.codeplex.com/
http://wpfmdi.codeplex.com/
Im beginning in my journey of learning WPF. After a few days of coding I see that whenever I resize any WPF form I get a black border on the bottom and right while resizing, like an artifact, as if the screen is too slow. When working with winforms I never noticed this.
Like so :
Is this a known problem? any simple workaround?
EDIT 1:
Seems its related to the graphics driver, I only work on laptops with weakish gfx cards, so does anyone else have this issue? (Im also using Win7 SP1)
It's a known problem, and it's unlikely that it will be fixed. There is a work-around that reduces the impact of this problem if your background is sufficiently uniform: https://stackoverflow.com/a/14309002/33080
My understanding of the underlying cause is that WPF controls lag behind on resizes: WPF draws them in the "wrong" location briefly. See the linked question for a demonstration.
If you resize a window it has to redraw. This takes some time and also it occurs after the window manager already resized your window and shows it; in that case you'll get a black border in WPF and one with the normal window background (grey, usually) in Windows Forms.
Usually all you can hope for there is that the computer is fast enough with the redraw to not show it.
We've been working on an application for the last few months that's aimed at Windows 7 tablet PCs. So we've used the Surface 2 SDK for most controls and it's all touch-happy.
I have noticed recently, though, that one of our custom controls isn't working as it should. This control provides popout menus, and these are achieved through the Popup control. On a developer's laptop, this works fine and the menus vanish when you click away from them. I've noticed, though, that on our test tablet they have a tendency to stay open.
I found that there was a SurfacePopup in the first Surface SDK, but I can't find one in the Surface 2 SDK. Did they get rid of it? Is there a 'best practice' approach?
If there's no simple solution, I may have to go old-school and add a window-sized hidden SurfaceButton below the menu when it appears, that hides itself and the menu when clicked or touched.
Beyond that I've noticed that sometimes the SurfaceScrollViewer within the popups won't work. I'm guessing this is because it's not picking up touch events properly. I tried adding this extension method to the window..
this.EnableSurfaceInput();
..but I get a NullReferenceException on System.Windows.Input.Mouse.get_LeftButton() which bizarrely suggests that it can only enable surface inputs for controls when there's a mouse plugged in.
Any ideas? They'll all be welcomed with open arms!
There's no SurfacePopup in the Surface SDK 2.0, however you can use a normal WPF popup. Then you need to make sure that it receives Touch Events by using the extension method you suggested above on the popup, not the window:
((HwndSource)HwndSource.FromVisual(popup)).EnableSurfaceInput();
Edit: As I just found out, this only works when the popup is initially open. To get it to work when the popup is opened later on, you don't need to use the popup, but the parent of it's child (see this question).
For the benefit of Daniel, and anyone else who needs a solution to this, I'll try to cast my mind back two years and explain how we got this working.
As far as I can remember, the answer was to use an adorner layer instead of a popup. Basically, every WPF control has an adorner layer, which sits above the control's UI stack. By default it contains nothing, but you can add whatever you like to it.
I got this all working by writing a custom control that allows you to place that control, with content, in the XAML and then show and hide it whenever you need to. When it's shown, it moves its contents into the adorner layer of the containing window, and when it's hidden it moves the contents back into the control itself, which is hidden from the user.
Afraid I can't go into any more detail than that, but as far as I can remember this was the ultimate solution; replacing popups (which never quite worked very well) with a custom control that uses the adorner layer.
Hope that helps!
I'm not sure if what I want to do is appropriate, so I'll explain a little.
We've got a large application that takes a while to load. So we have a splash screen.
The Splash screen causes excessive load time on Remote Desktop (terminal server).
So to alleviate this, we want to hide the splash screen when loading on RDP.
But we still need to at least show the user that the application is loading.
So, I was thinking perhaps just show something in the Taskbar (not the system tray), as it will disappear once the application is fully loaded (and be replaced by the main form's Task icon).
However any WPF solution I've looked at, requires a visible form/window to go with the Taskbar status.
Is there any way of showing something in the Taskbar without showing a WPF window?
Or is there another way of showing application load status without something on the screen?
We had same problem.
On remote desktop, we did following steps...
We configured the Splash window to not allow resizing and have only Minimize and Close button.
We removed WindowStyle=None setting so that title bar of the Splash window appeared
We made the Splash window's width and height zero. This way all you see on screen is a small blue rectangle of the title bar with Text "Loading... Please Wait ..." and minimize and Close button.
We used Window's kernel calls to disable title bar's Close button too. This way user was not able to cancel the Splash window.
So all a user could do is to minimize or restore from taskbar.
When restored, all he sees is a title bar's blue rectangle with "Loading..." text. This way the window also claimed its place on the task bar but hid its splash animation and user is also aware that the splash screen is loading. For this you can also update the Title bar's text by appending more fullstops ...
Loading. Please Wait..
Loading. Please Wait...
Loading. Please Wait....
Loading. Please Wait..
I do think you need to look into the root cause of your issue. Possibly looking at threading and parallelism.
However, a simple solution to what you are asking would be to just create a hidden window. One that is transparent, no borders or anything. It could even bet set to a size of 0, 0. That way you would be able to get the taskbar item that you require.