Develop Reference

Initialize topmost UWP window from the constructor

Weird issue.
I'm trying to build a desktop app that has an option to open a second "window".
So Foo opens Bar.
Only Bar should, by default, be a topmost window.
The below method works just fine, when called by a button click.
private async Task<bool> MakeTopMost()
{
await ApplicationView.GetForCurrentView().TryEnterViewModeAsync(ApplicationViewMode.CompactOverlay);
}
However, when called from the page constructor, via an Action,
new Action(async () => await MakeTopMost())();
...
Lo and behold. Nothing happens. I've tried the Loaded event also. No dice.
What am I missing?
Edit:
A workaround would be the button clicked to open a new app also makes the app topmost. Like so:
private async void ShowCompactView()
{
var compactViewId = ApplicationView.GetForCurrentView().Id;
await CoreApplication.CreateNewView().Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var frame = new Frame();
frame.Navigate(typeof(BAR));
Window.Current.Content = frame;
Window.Current.Activate();
ApplicationView.GetForCurrentView().Title = "CompactOverlay Window";
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsViewModeAsync(compactViewId, ApplicationViewMode.CompactOverlay);
}
But that makes the whole app topmost (not just a page).

What I basically did in the method posted last in the question was
Get the id of the application page currently displayed
Open a new page.
Compact overlay the id. Which was the main page. So basically the entire app was set as topmost.
So, by using a variable to hold the id of the newly opened page, the BAR, we can open a page from FOO that's automatically set as topmost.
private int _barID;
private async void ShowCompactView()
{
await CoreApplication.CreateNewView().Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var frame = new Frame();
frame.Navigate(typeof(Bar));
_barID = ApplicationView.GetForCurrentView().Id;
Window.Current.Content = frame;
Window.Current.Activate();
ApplicationView.GetForCurrentView().Title = "CompactOverlay Window";
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsViewModeAsync(sliderID, ApplicationViewMode.CompactOverlay);
}
it should have been obvious.

Bring the UWP app to the front of current window

How can i use
await Windows.System.Launcher.LaunchUriAsync(new Uri("protocol://"));
to navigate to specific view of uwp application.
Is there any way to bring the app in front of the screen, if app was minimized or hidden behind other apps?
Thanks in advance

How can i use await Windows.System.Launcher.LaunchUriAsync(new Uri("protocol://")); to navigate to specific view of uwp application
For this, firstly you need to add the Protocol declaration in your Package.appxmanifest file . (Go to declarations tab and add Protocol from the available protocols). ( MSDN Doc )
Here i am using "app-protocol" as the protocol name.
Once this is done, you need to override the OnActivated() method in your App.xaml.cs. This method will be called when the app is launched using the protocol.
The arguments that we pass when calling the protocol can be retrieved here and based on that you can show your page or maybe pass that parameter to your page and let it handle the navigation .
For instance, if our Uri is app-protocol:login?param1=true, when you receive the ProtocolActivatedEventArgs eventArgs in the onActivated() method you will have access to the whole Uri.
You can use eventArgs.Uri to access all the Uri properties.
In any case your code should look something like this :
C#
protected override void OnActivated(IActivatedEventArgs args)
{
if (args.Kind == ActivationKind.Protocol)
{
ProtocolActivatedEventArgs eventArgs = args as ProtocolActivatedEventArgs;
// Get the root frame
Frame rootFrame = Window.Current.Content as Frame;
// Do not repeat app initialization when the Window already has content,
// just ensure that the window is active
if (rootFrame == null)
{
// Create a Frame to act as the navigation context and navigate to the first page
rootFrame = new Frame();
rootFrame.NavigationFailed += OnNavigationFailed;
if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
//TODO: Load state from previously suspended application
}
// Place the frame in the current Window
Window.Current.Content = rootFrame;
}
//URI : app-protocol:login?param1=true
//Logic for showing different pages/views based on parameters passed
if (eventArgs.Uri.PathAndQuery != string.Empty)//PathAndQuery:login?param1=true
{
var absolutePath = eventArgs.Uri.AbsolutePath;//AbsolutePath:login
if (absolutePath.Equals("login"))
{
rootFrame.Navigate(typeof(LoginPage));
}
else
{
rootFrame.Navigate(typeof(MainPage));
}
}
else
{
rootFrame.Navigate(typeof(MainPage));
}
}
// Ensure the current window is active
Window.Current.Activate();
}
Is there any way to bring the app in front of the screen, if app was minimized or hidden behind other apps?
We are calling Window.Current.Activate(); to ensure this.

To bring any UWP window to the front use this snippet (works if window with given viewId was already created and is either minimized or behind other windows:
private async Task TryActivateViewAsync(viewId)
{
if (Window.Current.Dispatcher != null)
{
await Window.Current.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
{
if (await ApplicationViewSwitcher.TryShowAsStandaloneAsync(viewId))
{
await ApplicationViewSwitcher.SwitchAsync(viewId);
}
});
}
}
Just as a reminder, viewId is an Identifier of a window which you can get when you create that window using:
var coreView = CoreApplication.CreateNewView(); // creates new view
await coreView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
_someViewId = ApplicationView.GetForCurrentView().Id; // gets that view's id
}

How can I hide a window WITHOUT Visibility property?

I have an application that has a lot of modal popup windows. Some are custom windows displayed with .ShowDialog(), other are generic message boxes using a 3rd party tool (DXMessageBox.Show(...)), and others are system dialogs such as an OpenFileDialog. If the user leaves the application running long enough, it should time out and show a "Session Locked" screen and prevent users from seeing or interacting with the application until they login again. This is problematic because of the modal dialogs.
My current solution is to host the Relogin screen in the current modal window if there is one, and hide all other windows. The problem is that if I set Visibility = Hidden on any window I have called using .ShowDialog(), it treats that dialog as having received a result and processes the code that handles the dialog result. They are also no longer modal after they are re-shown.
So my current attempt is to try to hide the window using something other than Visibility, and prevent it from being activated. The closest I've come is by setting Minimized=true and ShowInTaskbar=false, but this results in an undesirable minimized titlebar above my taskbar.
Is there a way to prevent this from happening, or alternatively is there another way to hide a window and prevent it's activation without causing .ShowDialog to return?
Here's some code to re-create a sample application to test this with. Just add a button to launch the ShowLock_Click event handler.
private readonly Dictionary<System.Windows.Window, WindowStyle> _hiddenWindows = new Dictionary<System.Windows.Window, WindowStyle>();
// Create a button to launch this for testing
private void ShowLock_Click(object sender, RoutedEventArgs e)
{
// Will show another window with .ShowDialog, then 2s timeout will trigger lock window
using (new System.Threading.Timer(OnLockTimerElapsed, null, 2000, System.Threading.Timeout.Infinite))
{
ShowTestDialog();
}
}
private void OnLockTimerElapsed(object state)
{
_hiddenWindows.Clear();
Application.Current.Dispatcher.BeginInvoke(
DispatcherPriority.Background,
new Action(() =>
{
var mainWindow = Application.Current.MainWindow;
Window host = null;
foreach (Window win in Application.Current.Windows)
{
if (IsModalDialog(win))
host = win;
_hiddenWindows.Add(win, win.WindowStyle);
// Been testing various ways to hide window without using Visibility
win.ShowInTaskbar = false;
win.WindowStyle = WindowStyle.None;
win.WindowState = WindowState.Minimized;
win.Opacity -= 1;
win.IsHitTestVisible = false;
}
ShowLockScreen(host);
}));
}
private void ShowLockScreen(Window owner = null)
{
var lockScreen = new Window
{
Title = "Relogin Window",
Content = "This is a test Relogin Window. Close Window via X to continue",
WindowStartupLocation = WindowStartupLocation.CenterScreen
};
if (owner != null)
lockScreen.Owner = owner;
lockScreen.ShowDialog();
// Once that window closes, restore other windows
RestoreSession();
}
private void RestoreSession()
{
Application.Current.Dispatcher.BeginInvoke(
DispatcherPriority.Background,
new Action(() =>
{
foreach (var win in _hiddenWindows.Keys)
{
win.ShowInTaskbar = true;
win.WindowStyle = _hiddenWindows[win];
win.WindowState = WindowState.Normal;
win.IsHitTestVisible = true;
win.Opacity += 1;
}
}));
}
private void ShowTestDialog()
{
var test = new Window
{
Title = "Test Modal Dialog",
Content = "This is a test Modal Dialog. Close window via X to continue.",
Height = 100,
Width = 350,
WindowStartupLocation = WindowStartupLocation.CenterOwner,
Owner = this
};
var result = test.ShowDialog();
// This code gets run if I set Visibility=Hidden. I do not want that.
MessageBox.Show($"Test Dialog result returned. Result : {result}. This should ONLY happen when you click X on the dialog window");
}
private static bool IsModalDialog(Window window)
{
return (bool)typeof(System.Windows.Window)
.GetField("_showingAsDialog", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)
.GetValue(window);
}

How get navigation control from a button?

I know if I used a view controller I can use this:
var scanner = new MobileBarcodeScanner(this.NavigationController);
How do I know what navigation I am using inside of button I need use?
public class BarReaderButtonRenderer : ButtonRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
{
base.OnElementChanged(e);
// I tried this but don't worked
var scanner = new MobileBarcodeScanner(this.NavigationController);
// I tried this but do
var scanner = new MobileBarcodeScanner(this);
Element.Clicked += async(s_, e_) => {
// Setup our button
// Tell our scanner to use the default overlay
scanner.UseCustomOverlay = false;
//We can customize the top and bottom text of the default overlay
scanner.TopText = "Hold camera up to barcode to scan";
scanner.BottomText = "Barcode will automatically scan";
//Start scanning
var result = await scanner.Scan ();
HandleScanResult(result);
};
}
}
I can't use this code inside a button render. Or did someone this before?
The project is a shared application for iOS and Android.

The code for creating the scanner should stay inside the view controller/activity/page. You can still use the custom button and add the code you need to the Clicked event handler.
var myCustomButton = new BarReaderButton();
myCustomButton.Clicked += async(s, e) => {
var scanner = new MobileBarcodeScanner();
scanner.UseCustomOverlay = false;
//Start scanning
var result = await scanner.Scan ();
//Do something with the result
};
If this is Xamarin.Forms you will also have to use platform specific code inside the Page code as the barcode reader requires a Context on Android:
#if __IOS__
var scanner = new MobileBarcodeScanner();
#elif __ANDROID__
var scanner = new MobileBarcodeScanner(Forms.Context);
#endif

How can I create a shelltoast?

In my application I want to notify the user with the ShellToast.
Just by running...
var toast = new ShellToast
{
Title = "Nom nom nom!",
Content = "More! More! Keep feeding me!",
};
toast.Show();
...makes nothing happen, and as I understand it needs to be run from a ScheduledTaskAgent. But how do I run this on command, and make sure it only run once?

You can't use a ShellToast while the app is the foreground app. It's meant to be invoked from a background service while the app isn't the foreground app.
If you want to have a UX similar to that of ShellToast use the Coding4fun toolkit ToastPrompt control. Here's a code snippet showing how to use it:
private void ToastWrapWithImgAndTitleClick(object sender, RoutedEventArgs e)
{
var toast = GetToastWithImgAndTitle();
toast.TextWrapping = TextWrapping.Wrap;
toast.Show();
}
private static ToastPrompt GetToastWithImgAndTitle()
{
return new ToastPrompt
{
Title = "With Image",
TextOrientation = System.Windows.Controls.Orientation.Vertical,
Message = LongText,
ImageSource = new BitmapImage(new Uri("../../ApplicationIcon.png", UriKind.RelativeOrAbsolute))
};
}
Running this code snippet shows the following:

Just a small update: using ShellToast when the app is in foreground, is now possible, when using Windows Phone 8 Update 3. Though, they are obscured by other activity such as a phone call or the lock screen. Source