Windows 8 - Images and DPI

Windows 8 is DPI aware then the applications auto-scale images according to DPI and screen resolution:

• 100% when the scale is not applied.
• 140% when the screen resolution is 1920x1080 and for all devices with minimum 174 DPI.
• 180% when the screen resolution is 2560x1440 and for all devices with minimum 240 DPI.

The developer can use vectorial elements like SVG or XAML without problems.

Otherwise when the developer uses the images raw, bitmap, png or jpg, he needs to create a file for every case.

He can explicit the scale factor in the file extension:
\myLogo.scale-100.jpg
\myLogo.scale-140.jpg
\myLogo.scale-180.jpg

Or use the folder convention:
\scale-100\myLogo.jpg
\scale-140\myLogo.jpg
\scale-180\myLogo.jpg

When the application don't has static images, it's possible to create a logic to have the same result from code behind.

switch (DisplayProperties.ResolutionScale)
{
 case ResolutionScale.Scale100Percent:
  img.Source = new BitmapImage(new Uri("url?s=100"));
 break;
 case ResolutionScale.Scale140Percent:
  img.Source = new BitmapImage(new Uri("url?s=140"));
 break;
 case ResolutionScale.Scale180Percent:
  img.Source = new BitmapImage(new Uri("url?s=180"));
 break;

 default:
 // some exception
}

The class DisplayProperties has some event to help the developer:

• ColorProfileChanged: when the color profile changes.
• LogicalDpiChanged: when the the pixel per inches (PPI) changes.
• OrientationChanged: when device orientation changes.
• StereoEnabledChanged: when the property StereoEnabled changes (3D stereoscopic).

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Windows Phone - Localization

When you publish a Windows Phone application in the Marketplace, you have more visibility if you support the region language.

An easy way to build a localized app is to use resources file (.resx).

First of all remember to set the default "neutral" language in the project properties! This is an important step because the "AppResources.resx" file is used from all not specified languages.

Add new file, and name it "AppResources.resx" for default language. For a new language, just add a new resource named with the CultureInfo ISO letters:

• AppResources.it-IT.resx for italian language.
• AppResources.cs-CZ.resx for czech language.
• AppResources.fr-FR.resx for french language.
• etc..

Remember to set all resource files to the public access modifier.

Now unload your project and edit the csproj file to add your supported language:

<SupportedCultures>it-IT;en-US;cs-CZ;fr-FR</SupportedCultures>

Create a class to get your resources.

public class LocalizedStrings
    {
        private static AppResources localizedResources = new AppResources();

        public AppResources Strings
        {
            get
            {
                return localizedResources;
            }
        }
    }

In your xaml you need to declare your class as resource:

<phone:PhoneApplicationPage.Resources>
     <local:LocalizedStrings x:Key="LocalizedStrings"/>
 </phone:PhoneApplicationPage.Resources>

Now you can use your localized string like this:

Text="{Binding Strings.Loading, Source={StaticResource LocalizedStrings}}"

Or from code behind:

txtLoading.Text = AppResources.Loading;

To test your app you can insert this code in application launching event:

Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("it-IT");
Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("it-IT");

All CultureInfo codes here.

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Windows Phone - Get Album Art

When you use MediaPlayer class in Windows Phone, usually you want to get the album cover for the current song.
You can access the current track with the ActiveSong property. This property is exposed by the Queue of MediaPlayer. Then you can check out the album art.

This code is all you need:

if (MediaPlayer.Queue.ActiveSong.Album.HasArt)
{
 BitmapImage bmp = new BitmapImage();
 bmp.SetSource(MediaPlayer.Queue.ActiveSong.Album.GetAlbumArt());
 imgAlbum.Source = bmp;
}

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Equality Comparer with Lambda

Today, it's normal to write code with LINQ and Lambda Expressions.
But when you need to use IEqualityComparer, it's not possibile to use a lambda predicate.
The Interface needs a class, then you have to create a new type that inherit from IEqualityComparer.

You can use this workaround:

 
public class EqualityComparer<T> : IEqualityComparer<T>
{
   private Func<T, T, bool> _fnEquals;
   private Func<T, int> _fnGetHashCode;

   public EqualityComparer(Func<T, T, bool> fnEquals, Func<T, int> fnGetHashCode)
   {
      _fnEquals = fnEquals;
      _fnGetHashCode = fnGetHashCode;
   }

   public bool Equals(T x, T y)
   {
      return _fnEquals(x, y);
   }

   public int GetHashCode(T obj)
   {
      return _fnGetHashCode(obj);
   }
}

The simple usage is:

 
Dictionary<int, string> d = new Dictionary<int, string>() { { 1, "a" }, { 2, "a" }, { 3, "b" } };

var d2 = d.Distinct(new EqualityComparer<KeyValuePair<int, string>>((kvp1, kvp2) => kvp1.Value == kvp2.Value, kvp => kvp.Value.GetHashCode()));

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Windows Phone - Settings Page in 5 minutes

The best user experience for a settings page is: stay away from the save button.

People don't love to press the back button and lose all settings. Then it's better to save when the user does something.

Thanks to Jerry Nixon you can use this code and have a base framework for all your applications.

    public static bool EnableLocation
    {
        get { return Get("EnableLocation", false); }
        private set { Set("EnableLocation", value); }
    }

    public static event PropertyChangedEventHandler SettingChanged;

    private static T Get<T>(string key, T otherwise)
    {
        try
        {
            return (T)IsolatedStorageSettings.ApplicationSettings[key];
        }
        catch { return otherwise; }
    }

    private static void Set<T>(string key, T value)
    {
        IsolatedStorageSettings.ApplicationSettings[key] = value;
        if (SettingChanged != null)
            SettingChanged(null, new PropertyChangedEventArgs(key));
    }

The code is very easy:

• the "Get" function return the default value if the key don't exists.
• the "Set" function uses an event to immediatly reflect changes into your apps.
• the functions use "Generics".

Enjoy!

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myMoneyBook for Windows Phone

"myMoneyBook" is an easy way to manage your personal finances. You can customize catogories according to your needs, and set a monthly budget to keep track of what you spent. The dashboard summarize the balance with simple indicators and have two big tiles to speed up your operations.
All screens are in perfect Windows Phone style.
It's possible to set your privacy with a password.

There is a fast option to backup and restore all data via SkyDrive, and to export the records in file .csv.


The landscape mode show customizable and zoomable charts for detailed statistics.

"myMoneyBook" offers also customizable live tile:

• Change image
• Enable budget alert
• Show today balance
• Show monthly balance
• Show total balance

At moment myMoneyBook is translated in Italian, English and Czech language.

More screenshots:

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Windows Phone - Live Tiles with Telerik

The default Windows Phone framework offers a simple template for tiles:

• Static background image from application or from url.
• Title.
• Number (top right).
• A back message.

With Telerik RadControl for Windows Phone you have more power in your hands!



myWeather

"LiveTileHelper" class helps you to create dynamic live tiles with your own design and your own content.

The "RadExtendedTileData" extends the standard tile data with two properties VisualElement and BackVisualElement.
Now the amazing thing: this properties accept UIElement. Yes, UIElement!!

Now let's code...

LiveTileHelper.CreateOrUpdateTile( 
 new RadExtendedTileData() 
 { 
  Title = "My front title",
  VisualElement = new MyUserControl(),
  BackTitle = "My back title" 
  BackContent = "My back message", 
  BackVisualElement = new MyUserControl2(), 
 }, 
 new Uri("/MainPage.xaml?param=myparam", UriKind.RelativeOrAbsolute)
);

You can customize MyUserControl and MyUserControl2 as you want, the only limit is your imagination.

Then, why should you use this controls?

• Easyness
• More features
• Time saver
• Support and help

And remember this: a good app, has a good live tile.

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