I have a value on screen1 which keeps on incrementing from 0 and when I navigate to screen2 it has to stop. When I navigate back it has to start incrementing from the stopped value.
How do I catch the current page change in Xamarin C# like wise OnAppearing and OnDisappearing for the app
Thanks!
Do you use NavigationPage?
If yes, you can use its Pushed and Popped events.
If no, please describe how exactly you implement your navigation.
Related
I have made a custom MessageBox for my application and it launches as a UserControl. I have two buttons inside it and I would like to allow users to press Tab to switch between Buttons. However, since it's a UserControl overlaying the content, Pressing tab more than twice makes the focus go in the background on elements that aren't supposed to be tabbed at.
I can't figure out a good idea how to prevent this, I've thought of making a method that will select all elements and make their IsTabStop values to false and then restore them later, but I think that would be more of a problem then a solution.
Is there a way around this to limit tabbing only to the UserControl?
I would also appreciate advice on working with the message box.. the whole messagebox is an async function that has an infinitive loop until the answer is given. Is there another way to stop the application until one of the message box options was selected?
Crowcoder's reference has lead to correct MSDN page where I found my solution:
dialog = new UCMessageBox("Are you sure you want to exit the application?", MBType.YesNo);
AppMessageBox.Children.Add(dialog);
KeyboardNavigation.SetTabNavigation(dialog, KeyboardNavigationMode.Cycle);
The key was to call .SetTabNavigation function and direct it to my dialog (custom UserControl for the message box) and setting the KeyboardNavigationMode to Cycle.
After closing the UC rest of the application continued normally regarding navigation.
I have a problem with Bing Maps control I use in my WP7 application.
When I'm navigated to the page with map control, it starts the GeoCoordinateWatcher. When GeoCoordinateWatcher has some location data for me, it calls a SetView() method to center the map at current location. There is also a button on ApplicationBar that's also starting the GeoCoordinateWatcher.
Now, the thing is, when I first navigate to this page, all works fine: GeoCoordinateWatcher starts, gives me the location data after some time, calls SetView() and the map centers when I need it too. The same with the button.
But if I press the Back button to get back to the main page and then try to navigate again to the map page, SetView() stops working. In debugging I see that the code surrounding it works as expected and the data passed to SetView() is correct, but nothing happens with the control and events for changing view don't fire either.
I'm assuming there may be something wrong with map initialization (or disposing on navigating from), but I don't know where to dig.
Edit:
I've tried changing Map.Center directly and it doesn't work in exactly the same way the SetView() doesn't: it works fine the first time page is navigated to and doesn't work on the other times.
Edit 2:
Ok, it gets weirder. In debugging I see that my map's center actually gets set to a correct value. But an actual control shows absolutely different location and me, moving map around, doesn't change the value that I see from code.
Edit 3:
I've added a button to ApplicationBar that just calls SetView() and it works fine. Apparently, the problem appears when I call SetView() as a result of GeoCoordinateWatcher.PositionChanged event raising. How could I work around that?
Try using map.Center = loc.CoOrdinates;
I've found the solution.
In my original code I've subscribed to the GeoCoordinateWatcher.Position property change event in the page constructor: App.PropertyChanged += AtmInfoPageOnAppPropertyChanged
All I had to do was to move that to the OnNavigatedTo event handler and add App.PropertyChanged -= AtmInfoPageOnAppPropertyChanged to the OnNavigatedFrom event handler.
I think, the problem was that keeping the old page subscribed to the event didn't allow it to be disposed, and at the same time didn't allow the new page to subscribe to that same event, thus causing the code to be called for the different page and different map control than the one displayed on the screen.
How to make a touchable notice top bar in windows phone ?
I am new to C# and windows phone world.So may be my question has a simple
way to solve,but I google a lot ,and didn't work out.
here is my purpose: I have a timer running throughout my app,it request a
service for notice info every one hour, and show a "notice bar" on the top of
screen.
it is easy to get the information ,but when I want to show them to the Page,
here is my problem:
1.
I used system tray to show my info.
It works,but then I found there is no touch or click event for Progress
Indication bar.
I even add an event to Touch.FrameReported in App.xaml.cs , but still ,
when i touch the system tray area, the event doesn't fire.
2.
Then I want to use a Dynamic way to achieve it: add a text block to the
current page
I got the current page handler ,but case I only know the current page
handler's type is PhoneApplicationPage, I can't get my Root UI element
(all my page has a root element named "LayoutRoot")
And when I try to use reflect method to get the "LayoutRoot" property,
the return value is null.
The code looks like this :
Type type = PhoneApplicationPageHandler.getType()<
//I checked,the type is my page's type
type.getProperty("LayoutRoot") or type.getField("LayoutRoot")
//they all return null
BTW: LayoutRoot is a grid, and it is described in my page's .xmal file.
Now My option is to make all my page inherit a defalut page ,in this page ,I will
implement a method to fulfill my second way to simulate a "touchable top bar".
but I think this coding is ugly .
So, can anyone tell me :
1.how to add touch event to a SystemTray
or
2.how to get a handler of an ui element which is described in xaml, while I only have a PhoneApplicationPage type handler of that page.
You may use
1) a toast prompt described here http://windowsphonegeek.com/articles/WP7-Toast-Prompt-in-depth
2)or shell toast described here http://www.c-sharpcorner.com/UploadFile/ae35ca/working-with-toast-notification-in%C2%A0windows-phone-7/ according to what suits your requirement the best. 3)You may also create a custom control which you may place on the top on your mainPage and handle its tap event accordingly.
Hi I just found out that my application was crashing when returning from tombstoning. I was able to target the problem here inside the constructor of my page:
RadPhoneApplicationFrame frame = App.Current.RootVisual as RadPhoneApplicationFrame;
frame.PageTransitionCompleted +=
new EventHandler<EventArgs>(frame_PageTransitionCompleted);
Everytime the app is Re-Activated the RootVisual is setting the frame to null. I'm wondering if there is a casting issue here because before I used this code my tombstoning was working perfectly and I was able to navigate freely throughout the app. Any ideas on what might be causing this? Or maybe a work around?
You should move this code from page constructor to OnNavigatedTo method override in your page. Reason is that RootVisual is probably set in RootFrame.Navigated event handler which is generated after page is constructed, not before (this depends of implementation in your App.xaml.cs).
Of course because OnNavigatedTo method may be runned more that once for a page, you should make sure that PageTransitionCompleted event handler is not assigned two times (just use -= before +=).
Another option is to move this code to App.xaml.cs. This makes sense most to me, because that PageTransitionCompleted event is related to whole app, not a single page.
Please guide me as how to save/discard values of controls of a form, upon pressing Ok/Cancel button accordingly in Visual Studio C#?
Controls in a form include TablelayoutPanel(TextBoxes), NumericUpDown.
Need your expert guidance
Regards
Asad
With both of your buttons, inside the "onclick" event, call a function that will save the content of the form. You also need this call in the "onclose" event of the form, in case the user presses the top-right X button (or not, if you dont want data to be saved at that moment)
Inside that function, you will need some code that will save data to the registry.
Writing in the registry is easy. This webpage also explain how to get the data back. The values you will write will be the textbox.Value and such
The question isn't clear, but in a WinForm you can call
this.Close()
on the Click event of your Close button.
Every object or variable used by the form will be destroyed. Be careful! running background threads will still be alive until they terminate.
About saving the status of your variables it completely depends on what you need to with them after; you can either keep them in memory and pass them around like parameters or write on a disk (maybe with serialization?).
We need to know more.
edit
You may want to take a look at Application Configuration ( http://msdn.microsoft.com/en-us/library/ms184658(VS.80).aspx ).