Develop Reference

SystemMediaControls.ButtonPressed event fires twice

I want to add a media player control to SystemMediaControls. But, I have an issue here. When you pressed it, it occurs twice. Please see code below:
using Windows.Media;
using . . .
public class Main{
public static SystemMediaTransportControls systemMediaControls;
public Main(){
this.InitializeComponent();
systemMediaControls = SystemMediaTransportControls.GetForCurrentView();
int num = 0;
systemMediaControls.ButtonPressed += async (SystemMediaTransportControls sender, SystemMediaTransportControlsButtonPressedEventArgs e) =>
{
num++;
Debug.WriteLine($"Event number: {num}");
};
}
}
I proved it with debug logs, and the debug logs are:
Event number: 1
Event number: 1
Event number: 2
Event number: 2
Event number: 3
Event number: 3
I have no idea where's the problem is.

This is my fault. I put event on MainPage main function. The mistake is, I call MainPage more than once in the App.cs. For example:
void LaunchApp() {
new MainPage();
...
rootFrame.Navigate(typeof(MainPage));
}
So it initializes twice. That's why the event also fires twice. I have resolved my issue.

SystemMediaControls.ButtonPressed event fires twice
I have tested with official code sample here. Unfortunately, we can't reproduce this problem, Derive official tutorial, if you want to custom SystemMediaTransportControls, we need to sync playback status To MediaPlayerState at fist. and control the media player in button pressed event.
switch (mediaPlayer.PlaybackSession.PlaybackState)
{
case MediaPlaybackState.None:
systemMediaControls.PlaybackStatus = MediaPlaybackStatus.Closed;
break;
case MediaPlaybackState.Opening:
// This state is when new media is being loaded to the MediaPlayer [ie.
// Source]. For this sample the design is to maintain the previous playing/pause
// state before the new media is being loaded. So we'll leave the PlaybackStatus alone
// during loading. This keeps the system UI from flickering between displaying a "Play"
// vs "Pause" software button during the transition to a new media item.
break;
case MediaPlaybackState.Buffering:
// No updates in MediaPlaybackStatus necessary--buffering is just
// a transitional state where the system is still working to get
// media to start or to continue playing.
break;
case MediaPlaybackState.Paused:
if (mediaPlayer.PlaybackSession.Position == TimeSpan.Zero)
systemMediaControls.PlaybackStatus = MediaPlaybackStatus.Stopped;
else
systemMediaControls.PlaybackStatus = MediaPlaybackStatus.Paused;
break;
case MediaPlaybackState.Playing:
systemMediaControls.PlaybackStatus = MediaPlaybackStatus.Playing;
break;
}
For more detail please refer Manual control of the System Media Transport Controls

UWP multiple views not closing

PROBLEM
I am using a secondary view to run my media files, but When I close my secondary view with close button on it ( while media is still playing ) the secondary view/window closes but the media somehow keeps playing because I can hear the sound and source of sound seems to be the primary view ( main app window ). how can I completely terminate the secondary window when I close it?
TRIED
I followed windows samples multiple views and was able to complete all steps, I copied the ViewLifetimeControl.cs file from the sample and used it in my project. the code runs fine until it reaches Windows.Current.Close() in released event of the secondary view.
Then it gives an exception when it tries "Window.Current.Close()" with in the released event. according to documentation exception occurs due to any on going changes ( which might be because of media file playing ), but I need to force close the window even when media file is playing how can I do that? btw here is the exception :
Message = "COM object that has been separated from its underlying RCW cannot be used."
Code to Create and Show secondary view
internal static async Task CompactOpen(string Title, string caption)
{
ViewLifetimeControl viewControl = null;
await CoreApplication.CreateNewView().Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
viewControl = ViewLifetimeControl.CreateForCurrentView();
viewControl.Title = Title;
viewControl.StartViewInUse();
var frame = new Frame();
frame.MinHeight = 200;
frame.MinWidth = 200;
frame.Navigate(typeof(CompactNowPlayingPage), new object[] { viewControl,caption});
Window.Current.Content = frame;
Window.Current.Activate();
ApplicationView.GetForCurrentView().Title = viewControl.Title;
});
((App)App.Current).SecondaryViews.Add(viewControl);
var selectedView = viewControl;
var sizePreference = new SizePreferenceString() { Title = "SizePreference", Preference = ViewSizePreference.Default };
var anchorSizePreference = new SizePreferenceString() { Title = "AnchorSizePreference", Preference = ViewSizePreference.Default };
if (selectedView != null && sizePreference != null && anchorSizePreference != null)
{
try
{
selectedView.StartViewInUse();
var viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(
selectedView.Id,
sizePreference.Preference,
ApplicationView.GetForCurrentView().Id,
anchorSizePreference.Preference);
if (!viewShown)
{
// The window wasn't actually shown, so release the reference to it
// This may trigger the window to be destroyed
}
// Signal that switching has completed and let the view close
selectedView.StopViewInUse();
}
catch (InvalidOperationException)
{
// The view could be in the process of closing, and
// this thread just hasn't updated. As part of being closed,
// this thread will be informed to clean up its list of
// views (see SecondaryViewPage.xaml.cs)
}
}
}
Released Event
private async void ViewLifetimeControl_Released(Object sender, EventArgs e)
{
((ViewLifetimeControl)sender).Released -= ViewLifetimeControl_Released;
// The ViewLifetimeControl object is bound to UI elements on the main thread
// So, the object must be removed from that thread
await mainDispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
((App)App.Current).SecondaryViews.Remove(thisViewControl);
});
// The released event is fired on the thread of the window
// it pertains to.
//
// It's important to make sure no work is scheduled on this thread
// after it starts to close (no data binding changes, no changes to
// XAML, creating new objects in destructors, etc.) since
// that will throw exceptions
Window.Current.Close(); //this is where that exception occurs
}
Note : both of above methods and even all the related variables, all of them I have followed the guidelines within the uwp sample for multiple views.
Thanks in advance, any help would be really appreciated, I only want to force close the secondary view ( If that's possible )

Is this in the editor or the app? If it's in your debug or build of the app, the secondary view is most likely still open but hidden. You may be using a custom close button which doesn't perform its job well enough. Instead of putting down SecondaryViews.Remove you should do what you had originally written and try StopViewInUse. It may not work, I'm not used to this kind of thing.

How to avoid multiple event fire when WPF page is opened again?

I have a frame and few pages in my WPF application.
My navigation is controlled by buttons. On each button I have click handler that creates new page with some parameters:
private void ButtonProductionAuto_OnClick(ref TechModbus, RoutedEventArgs e)
{
FrameMain.Content = new PageProductionAuto(someobject, this);
}
private void ButtonProductionManual_OnClick(ref TechModbus, RoutedEventArgs e)
{
FrameMain.Content = new PageProductionManual(someobject, this);
}
When I'm switching between pages - previous pages still exist in memory and they react on some custom events.
(edit)
This is my code related with events:
public PageProductionAuto(ref TechModbus modbus, MainWindow wnd)
{
// ...
wnd.KeyDown += Wnd_KeyDown;
wnd.KeyUp += Wnd_KeyUp;
m.OnReadFinished += Modbus_OnReadFinished;
// ...
}
How can I dispose these pages or how can I avoid double-fire on my events when page is opened second time?

You should unregister the events on leaving the page.
GarbageCollector will then "dispose" (it's actually not a dispose) by itsself when there are no more references on those objects(PageProductionAuto and PageProductionManual).
Quoting MS:
The reason WPF controls don't implement IDisposable is because they have nothing to dispose. They have no handle to clean up, and no unmanaged resources to release. To ensure your memory is cleaned up, just make sure nothing has a reference to the controls once you're finished with them.

Your question is incomplete. But I can answer the question about "how to avoid multiple instances" part of it. To dispose your pages, you have to detach your events, remove them from the "openedPages" collection, and dispose where possible.
List<object> openedPages = new List<object>();
private void ButtonProductionAuto_OnClick(object sender, RoutedEventArgs e)
{
var page = openedPages.FirstOrDefault(p => p.GetType().Equals(typeof(PageProductionAuto)));
if(page == null)
{
page = new PageProductionAuto(someobject, this);
opendPages.Add(page);
}
else
{
page.SetObjects(someobject, this); // create a method to set "someObject" to your page.
}
FrameMain.Content = page;
}

What I did to avoid this was I have a window with 2 frames in it. I placed one of each source XAML in each frame so frame 1 was XAML 1 and frame 2 was XAML 2. Then I just edited the visibility to collapsed and visible. Then you don't have any page changes or instances getting created. You just create the original 2 instances.

Handler fires to early

I have an device with an integrated bixolon printer in it. I want to create an app to print on the printer. My OnCreate method looks as follow:
protected override void OnCreate(Bundle bundle){
base.OnCreate(bundle);
SetContentView(Resource.Layout.Main);
printer = new BixolonPrinter(this, new MyHandler(), Looper.MainLooper);
printer.FindUsbPrinters();
//button connect
Button button = FindViewById<Button>(Resource.Id.buttonConnect);
button.Click += delegate {
printer.ConnectUsb();//in the brackets I would need the value of the Handler back once it is available
}; }
My Handler is as follow:
private class MyHandler : Handler
{
public override void HandleMessage(Message msg)
{
switch (msg.What)
{
case BixolonPrinter.MessageUsbDeviceSet:
Console.WriteLine("U S B device::: " + msg.Obj);
//can not return the msg.Obj back to the button event
break;
}
}
}
The problem is the once the instance of the BixolonPrinter is created it immediately fires the Handler. There is no way to bring back the result of the Handler to the button event. To make that problem a litte bit more complicated, the BixolonPrinter is a Java .jar file. So how can I get the result back to the event button?

When you use MainLooper, everything will be executed on main thread. Create HandlerThread for interaction instead. To postpone execution, use Handler.postDelayed() method, or, what is better, use RxJava library

How to Capture 'Send' button event for Outlook using UI Automation in C#?

I want to capture 'Send' button event of outlook using UI Automation.
Right now i am able to get 'Focus Change Event' like whenever iam minimizing or maximizing the WINWORD window the the event is raised instead of that i want to get the event on Send button click.
private void SendButtonInvoke()
{
Process[] processes = Process.GetProcessesByName("WINWORD");
AutomationElement aeOutLook = null;
foreach (var item in processes)
{
aeOutLook = AutomationElement.FromHandle(item.MainWindowHandle);
}
//AutomationElement outlookelm = AutomationElement.FromHandle(processName.MainWindowHandle);
AutomationElement buttonAddInstance = aeOutLook.FindFirst(TreeScope.Descendants,
new PropertyCondition(AutomationElement.NameProperty, "Send"));
if (buttonAddInstance == null)
{
MessageBox.Show("Add button instance not found");
}
else
{
AutomationPropertyChangedEventHandler ButtonEvent =
new AutomationPropertyChangedEventHandler(ButtonChecked_EventHandler);
//Attaching the EventHandler
Automation.AddAutomationPropertyChangedEventHandler(buttonAddInstance, TreeScope.Children,
ButtonEvent, AutomationElement.NameProperty);
}
}
private void ButtonChecked_EventHandler(object sender, AutomationEventArgs e)
{
AutomationElement ar = sender as AutomationElement;
MessageBox.Show("Button Clicked Sucessfully.");
}

You have to specifiy the EventHandler for the involved UIA Pattern. (For your case it's likely to be the InvokePattern):
Automation.AddAutomationEventHandler(InvokePattern.InvokedEvent, AutomationElement buttonAddInstance ,TreeScope.Element, new AutomationEventHandler(OnStartInvoke));
private static void OnStartInvoke(object src, AutomationEventArgs e)
{
//logic
}

I wrote and tested the code below and it seems to work for me.
private void AddEmailSendEvent()
{
// Find the new email window
PropertyCondition newEmailWindowCondition = new PropertyCondition(AutomationElement.NameProperty, "Untitled - Message (HTML) ");
AutomationElement NewEmailWindow = AutomationElement.RootElement.FindFirst(TreeScope.Children, newEmailWindowCondition);
// Find the Send Button
PropertyCondition sendEmailButtonCondition = new PropertyCondition(AutomationElement.NameProperty, "Send");
AutomationElement sendButton = NewEmailWindow.FindFirst(TreeScope.Descendants, sendEmailButtonCondition);
// If supported, add the invoke event
if (sendButton.GetSupportedPatterns().Any(p => p.Equals(InvokePattern.Pattern)))
Automation.AddAutomationEventHandler(InvokePattern.InvokedEvent, sendButton, TreeScope.Element, handler);
}
private void handler(object sender, AutomationEventArgs e)
{
// Do whatever is needed, for testing this just adds a message to my forms Main UI
AddMessage("Invoke event occured");
}
I should note that I'm using the .Net 4.0 automation libs. I've found the older ones don't always work the way I want them. I also tested this with Outlook 2013, and both outlook and the new email message were already open when I tested this. It doesn't handle waiting for them to appear.
Just so your aware, these events don't always work for all controls. Some custom controls are made in such a way the invoke events are not reported to the UI in a way the event can register. With that said, from my testing you should be able to use this method on the send button.
Invoking vs mouse clicks: Just to add a little more detail, the standard control causes the invoke event to fire when a user clicks it. "Invoke" is just the standard event fired on clickable controls. The only time a click wouldn't fire the same invoke is if the developer decided to intercept the click somehow and redirect it elsewhere. I've seen this a lot when people build there own custom controls.
If your not sure about whether a control using/firing the invoke event or not you can get use the Accessible Event Watcher to watch a control as you click it. You can get more information on the tool here: https://msdn.microsoft.com/en-us/library/windows/desktop/dd317979(v=vs.85).aspx