I'm building a windows phone 8.1 application. My home page has some user controls on it. For some reasons user controls are released during forward navigation. So when I navigate back to my home page, user controls are created again. How can I avoid this?
public partial sealed MyUserControl : UserControl
{
myVM MyViewModel;
public MyUserControl()
{
myVM = new MyViewModel(new Composites(new DataAccessRest()));
}
}
I would be very glad if someone can point me in the right direction. Thanks in advance
By default, pages are trashed, once you navigated away (unless you are navigating to the same page your are already on). This is a point where the 8.1 RT app model differs from Silverlight.
The Frame handles caching for you using the NavigationCacheMode property of the page. Setting it to Enabled or Required, the Frame will cache the page and reuse it when you navigate to it.
As caching uses a lot of memory, handle cache with care to keep your app from getting closed once in background.
Also: The frames default Cache size is 1. Set it to an appropriate number for you app. Pages with NavigationCacheMode required do not count towards the cache size and are always cached.
Related
I need to pin AIR application over other windows, I mean, regardless if AIR application is in focus or not, it must not hide, it always must be shown, whatever other program I activate or work with, AIR application must be over every window always. Is it possible? If it is, please show me the function (example code will be better :) ) which does it, incase if AS3 has one.
You're looking for the alwaysInFront property of the NativeWindow class:
The alwaysInFront property specifies whether this window will always be in front of other windows (including those of other applications).
The following example forces a window to be displayed in front of all
other windows (that are not similarly forced to the front):
windowObj.alwaysInFront = true;
Another example with a reference to a display object on the window stage:
displayObject.stage.nativeWindow.alwaysInFront=true;
I have a page in a WP8 application, that every time I navigate to it, the constructor is called.
From what I know, the constructor of a page called only once at the first time the page loaded. my page is very heavy, and every construction takes wasted time..
this my navigation code, usual one:
NavigationService.Navigate(new Uri("/Views/Pages/ContentControlNew.xaml", UriKind.Relative));
and this is the constructor of the page:
public ContentControlNew()
{
InitializeComponent();
}
Not special.. is it normal that the constructor is called every time? Please tell me if you need more details because I don't know what else to say about this subject.
Yes this is normal because whenever you use NavigationService.Navigate it always creates a new page object and adds that (pushes it) to the navigation stack. For example when you use GoBack() it pops it out of the stack and destroys it, but when it gets back to the previous page it doesn't call the constructor since that one was already in the stack and does not have to be recreated.
If you don't want to create a page every time you navigate to it, you should look into Navigation Models for Windows Phone for some ideas on how you can tackle this.
I've added the Share Target declaration to my app for the data format WebLink and everything works as expected. However, when I add a JumpListItemBackgroundConverter or JumpListItemForegroundConverter anywhere in the app, the app hangs on the splash screen when you enter the app using the Share from IE. No exception, no crash, the debugger doesn't even stop. All I get is a cryptic error in the output window, "The program '...' has exited with code -1073741819 (0xc0000005) 'Access violation'." The documentation for those converters say they're fine with universal apps, just that they've been moved to a different namespace. Has anyone been able to get these two things to work in the same app? If so, where did I go wrong? Or is there something better than those two converters to get the LongListSelector look and feel?
Steps to reproduce:
Create a new universal app. I chose hub.
Add a share target of format WebLink to the appxmanifest declarations.
Add a new page to point the share contract to.
Add the OnShareTargetActivated code to app.xaml.cs to open the new page. See code below
Add a JumpListItemBackgroundConverter to the resources of the main page of the app. You don't need to apply it to anything, just declaring it is enough to break the sharing.
Go to IE and share a link. It should hang on the splash screen.
Code for app.xaml.cs:
protected override async void OnShareTargetActivated(ShareTargetActivatedEventArgs args)
{
// Replace SharePage with the name of the share target page
var rootFrame = new Frame();
rootFrame.Navigate(typeof(SharePage), args.ShareOperation);
Window.Current.Content = rootFrame;
Window.Current.Activate();
}
It turns out this is a bug in the emulator. It works if you test on a physical device.
MSDN Forum - JumpListItemBackgroundConverter and Share Target in Windows Phone 8.1
I'm having a problem getting bing.com to load in a WebBrowser control on Windows Phone 8. It seems that doing that will launch the WP8 Search App (same as pressing the Search button on the phone). The problem is, once you click a result in that search app, it doesn't take you back to your original app - it goes to IE to show the result. This isn't going to work for me and seems to be a massive flaw (IMO) in the WebBrowser behavior.
There does seem to be a few apps out there that have succeeded in being able to show bing.com without launching the phone's search app - for example Image Downloader Free. There was another one, but I can't remember what it was...
After some research, I've found that the WebBrowser_Navigating event gets fired 3 times when going to bing.com: first request to the user-entered URL (www.bing.com), it then gets redirected to http://wp.m.bing.com/?mid=10006, then it redirects to bing://home/?mid=10006.
Preventing it from forwarding to the Bing search app is quite simple, just add this to the Navigating event:
e.Cancel = (e.Uri.Scheme == "bing");
The problem is, it then only shows the Bing search page place holder which says "Bing Search" and has a link that says "Back to Bing search" which does nothing (it would typically relaunch the Bing Search app).
I have a few thoughts, but I'm not sure how feasible they are.
In the WP8 WebBrowser control, is it possible to fake the User Agent?
Can one of the items in the WebBrowser.Uri.Flags property be removed or added to affect the way Bing.com handles the request?
If none of those work, I can simply create a dummy page on my web server, redirect all bing.com requests to it, and have it grab the m.bing.com front page with a card-coded user-agent. I really would like to avoid having to do this option though. From an End-User perspective, they would never know, but I just added a whole new layer of overhead, maintenance and resource-wise.
If you're interested, attached are the diff's for the EventArgs object between the 3 requests that occur in the WebBrowser.Navigating event:
Request 1 (bing.com) -> Request 2 (forwarded to wp.m.bing.com/?mid=10006)
Request 2 (forwarded to wp.m.bing.com/?mid=10006) -> Request 3 (forwarded to bing://home/?mid=10006)
tl;dr Does anyone know of a way to prevent www.bing.com from causing the search app to launch in the WebBrowser control in my application?
Thank you!
I don't know if there's a better way to handle this, but I found a solution. I haven't gotten it to work perfectly when the back button is clicked, so I will update my answer if/when I found a more solid solution. I still think this is a big flaw in the WebBrowser control in WP8.
Here is the code:
private bool _customHeaderRequest = false;
private void MainBrowser_Navigating(object sender, NavigatingEventArgs e)
{
string host = e.Uri.Host.ToLowerInvariant().Trim();
if ((host == "bing.com" || host.EndsWith(".bing.com")) && !_customHeaderRequest)
{
e.Cancel = true;
Dispatcher.BeginInvoke(() =>
MainBrowser.Navigate(e.Uri, null,
"User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows Phone OS 7.5; Trident/5.0; IEMobile/9.0; NOKIA; Lumia 710)\r\n"));
_customHeaderRequest = true;
return;
}
_customHeaderRequest = false;
}
private void MainBrowser_Navigated(object sender, NavigationEventArgs e)
{
_customHeaderRequest = false;
}
I don't have access to my emulator, but I tried it on my phone, and:
The redirect doesn't happen when you "Prefer desktop version" and open m.bing.com. Warning: The mobile version isn't very pretty.
Try disabling scripts on your WebBrowser, that could stop the redirect from happening.
Any chance you could just use Google?
I want to write a Windows Store App that can capture video (without any sound) and take pictures. Imagine a digital camera: you can preview the picture on the screen of your device before pushing the button which takes the pic.
The problem I'm facing now is the fact that the Windows.Media.Capture namespace has only classes for objects that capture video with sound (CameraCaptureUI, MediaCapture). I'm not troubled by the objects' capabilities, but by the fact that I will have to include in the manifest of the app the Microphone capability and it does not make sense for the app to use it. I need a class that uses only the Webcam capability.
Any ideas?
I found the answer and I thought I should share it. I'm sorry for answering my own question, but here goes:
One can specify in the settings of the MediaCapture object, when initializing it, that it will use only the Video part:
var mediaCaptureMgr = new MediaCapture();
var captureSettings = new MediaCaptureInitializationSettings();
captureSettings.StreamingCaptureMode = StreamingCaptureMode.Video;
await mediaCaptureMgr.InitializeAsync(captureSettings);
RTFM!