I'm new to Windows 8 development and I'm stuck on the this question. Basically, I have main page and I want change its background image every time when application is started. Please help !!!!
Create a Uri in your ViewModel, and have your Background's ImageBrush bind to this Uri. Then, on app startup, have your app just change the Uri to whatever new image you want, using whatever logic you want.
Also, when using ImageSource as you mentioned in the comments, you should be using SetSource.
Related
In Android, it is quite easy to set a image placeholder for development purposes in an imageview.
All one would do is use the tools:src for the placeholder image during development so you could see it in your layout design preview and your actual image you would put into your android:src
. Frequently, you don't set the android:src put would populate that imageview with images that you download off the internet once you connect your app to the net:
<ImageView
android:layout_width="28dp"
android:layout_height="28dp"
android:src=#drawable/activated_icon"
tools:src="#mipmap/white_activated_icon" />
In Xamarin, you have this to display images:
<Image Source="http://lorempixel.com/1920/1080/nature/3" />
Once the app connects, the image is downloaded from the internet and displayed. How do I put in a placeholder image for development purposes (similar to the way you would do it through tools:src in android) so I can see it within the layout design previews?
I'm assuming you want to achieve this with Xamarin Forms, as you referring to XAML in the question title.
Or possibly you are referring to the Xamarin Forms Previewer? In that case, disregard the following answer. You can only use local images in the Previewer as far as I can tell.
Answer in case the question is related to runtime Xamarin Forms
There is no standard option to do this in Xamarin Forms. Take a look at this example suggested by Stephane Delcroix from the Xamarin Forums. The important part of this approach is to stack 2 images on top of each other in a grid. 1 is the placeholder that is placed beneath the image that is being loaded, like this:
var grid = new Grid();
grid.RowDefinitions.Add (new RowDefinition());
grid.Children.Add (image);
grid.Children.Add (placeholderImage);
As an alternative option, WebImage of Xamarin Forms Labs allows an option for a DefaultImage, but I'm not sure if that shows immediately. See this class for the code of the Web Image. Keep in mind that Xamarin Forms Labs is no longer under active maintenance.
Of course you can also write a custom renderer. Maybe based on the Xamarin Forms Labs example.
I use FFImageLoading for this Case.
Just install the Nuget Package and Use the "CachedImage" in XAML.
<ff:CachedImage Source="your url" Placeholder="placeholder while loading"/>
You don´t need to download (and cache) the Image manually then. It will automatically displayed when the download is done.
You can use local files (from Resources or Drawable) and files from HTTP/HTTPS.
I am new in Xcode and IOS development.
i have designed and finished my app and i connected with Parse for push notification and core data.
the problem is what i didn't understand is: if in future i want to change the background of my app or add new event or to change the palace of button my app, how can i do that? i have to rebuild and submit it again or there is any way to do by online a website like parse?
i couldn't find the answer any where, help please...
Thanks ,
If you had designed your app to load the background data from Parse, then you could just put the new background on Parse and your app would load it. There is no need to submit a new app to do that. If you did it this way, you'd want to have a default background in the case when the network is not available.
You can't add new code to your application with this method (that is not allowed), but you can add data such as images, text, etc. The key point here is that you have to design your app from the start to work this way, then it is simply a matter of putting the new data on Parse where your app can find it.
Expanding on #vacawama's very good answer:
For this version you are out of luck, since it sounds like you did not design it to use a background that is loaded from your Parse server.
What you need to do is to code an update to your app that has these new abilities, and submit that to the app store. Once that version is approved then you should be able to change the background from the server.
I am working on windows phone application in which i need to change ApplicationBarButton icon dinamically, for example to show current date like in default Windows Phone Calendar app. Regarding to this article, we can use only png images previously added to solution and reference to them with relative Uri.
It is not a problem for me to generate correct png image (this way and using ToolStack C# PNG Writer Library) and save it to isolated storage, but when i'm initializing AppBarButton with absolute Uri to this image and trying to add it to ApplicationBar, my app throws ArgumentException.
Am i doing something wrong or i just have to draw 366 icons and add them to my project? :)
Thanks in advance!
For one of my apps I'd like to send the app to snapped view after tapping a button. As far as I know there's no public API available to send a running application to snapped view. Did anyone find a workaround to do this?
Somehow it should be possible since you're able to do it in Windows 8 itself, and snap one of the running apps.
Update: Being able to trigger a Win+. might do the same trick, but the SendKeys API isn't available in WinRT either.
There is no way to force an application into snapped mode - it has to be a user initiated action.
An application can request to be unsnapped through:
Windows.UI.ViewManagement.ApplicationView.TryUnsnap();
Which tries to push the app into fill mode.
Windows 10 has a ApplicationView.TryResizeView method
So... to summarize the interesting WinRT journey:
Windows 8
Has a a 'Snapped' mode that a only a user can initiate. the developer can try to unsnap with the TryUnsnap method
Windows 8.1
Does not have Snapped mode, and TryUnsnap is deprecated. The dev can still listen for window size changes and know if the app view is in a smaller size as before.
Windows 10
Introduced the ApplicationView.TryResizeView method, where the dev can try to resize. Window size changed event is still there.
ApplicationView.GetForCurrentView().TryResizeView(new size(width, height)));
I have a Metro app using a WebView control. I'm using NavigateToString to load a html file which may contain hyperlinks. What I then want to do is detect when one of these hyperlinks is selected and, instead of allowing navigation within the WebView control, to launch IE and view the page there instead.
Is this possible within the WinRT constraints, and if so, how?
So far, I've tried capturing the WebView_LoadCompleted() event, but although it does fire at the right time, I can't see any details about the URI from the NavigationEventArgs.
Unfortunately this isn't possible directly because WebView does not include events like Navigating (which were present in Windows Phone).
Luckily Nick Randolph (brilliant Windows Phone and Windows 8 developer) has created a workaround using script events. He's got a great write up on his blog:
http://nicksnettravels.builttoroam.com/post/2012/04/21/Limitations-of-the-WebView-in-Windows-8-Metro-Apps.aspx