Windows Phone 实用开发技巧（27）：创建透明Tile

 I have talked about how to create custom Live Tile in 《Windows Phone 实用开发技巧（17）：自定义应用程序的Tile》. Today let’s dig a little bit deeper.

What do you see in this image shown below ?

Do you see the same tile with different background called accent color in windows phone . So how can we create such tile . One simplest way is we replace ApplicationIcon.png with a transparent png file. But as we know it is just main tile of our app. Can we create own tile since we can pin what we want to start ?

Yes, we can do that. All we need to do is to create a transparent png file and save it to Isolated.

Maybe you have already know, we can save jpg file to Iso with following code:

WriteableBitmap bit = new WriteableBitmap();
bit.SaveJpeg(stream, 480, 800, 0, 100);

or

Extensions.SaveJpeg(WriteableBitmap, stream, 480, 800, 0, 100);

But jpg can not be transparent. So we need some extra library to help us create transparent png images. Here I use the famous open souce ImageTools.

We can use two differernt ways to dynamic create images. One way I have post here.

//add encoder for png image Encoders.AddEncoder<PngEncoder>();

StandardTileData std = new StandardTileData {
    BackgroundImage = new Uri(CreateBackground()),
    Title = "Tile Test",
    BackTitle = "Secondary",
    BackBackgroundImage = new Uri(CreateBackground())
};
ShellTile.Create(new Uri("/MainPage.xaml?type=1", UriKind.Relative), std);
sw.Stop();
Debug.WriteLine("Tranditonal method took time :" + sw.ElapsedMilliseconds);

Here is CreateBackground method looks like:

public static string CreateBackground()
{
    Grid grid = new Grid     {
        Background = new ImageBrush         {
            ImageSource = new BitmapImage             {
                UriSource = new Uri("/mangTile;component/Images/1.png", UriKind.Relative),
                CreateOptions = BitmapCreateOptions.IgnoreImageCache
            }
        },
        Width = 173,
        Height = 173
    };
    TextBlock tb = new TextBlock     {
        Text = "Hello world",
        Foreground = new SolidColorBrush(Colors.Red),
        FontSize = 32,
    };
    grid.Children.Add(tb);
    grid.Arrange(new Rect(0d, 0d, 173, 173));
    WriteableBitmap wbmp = new WriteableBitmap(grid, null);

    ExtendedImage extendImage = wbmp.ToImage();

    using (var store = IsolatedStorageFile.GetUserStoreForApplication())
    {
        if (!store.DirectoryExists(tiledirectory))
        {
            store.CreateDirectory(tiledirectory);
        }
        using (var stream = store.OpenFile(fullPath, System.IO.FileMode.OpenOrCreate))
        {
            extendImage.WriteToStream(stream, fullPath);
        }
    }
    return "isostore:/" + fullPath;
}

Another way is just render it within ImageOpened event:

public static void CreateTile(Uri imageUri, string temperature, string timeOfDay)
{
    var source = new BitmapImage(imageUri)
        {
            CreateOptions = BitmapCreateOptions.IgnoreImageCache,
        };
    
    string fullPath = tiledirectory + @"/" + timeOfDay + ".png";

    // This is important. The image can't be rendered before it's loaded.     source.ImageOpened += (sender, e) =>
    {
        // Create our image as a control, so it can be rendered to the WriteableBitmap.         var cloudImage = new Image { Source = source, Width = 173, Height = 173 };

        // TextBlock for the time of the day.         TextBlock tbTemperature = new TextBlock         {
            Text = temperature + '°',
            FontSize = 36,
            Foreground = new SolidColorBrush(Colors.White),
            FontFamily = new FontFamily("Segoe WP"),
        };

        using (IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication())
        {
            if (!store.DirectoryExists(tiledirectory))
            {
                store.CreateDirectory(tiledirectory);
            }

            var bitmap = new WriteableBitmap(173, 173);

            // Render our background. Remember the renders are in the same order as XAML,             // so whatever is rendered first, is rendered behind the next element.              // Render our cloud image             bitmap.Render(cloudImage, new TranslateTransform());

            // Render the temperature text.             bitmap.Render(tbTemperature, new TranslateTransform()
            {
                X = 124,
                Y = 63
            });
            bitmap.Invalidate();
            ExtendedImage extendImage = bitmap.ToImage();
            using (var stream = store.OpenFile(fullPath, System.IO.FileMode.OpenOrCreate))
            {
                extendImage.WriteToStream(stream, fullPath);
            }
            StandardTileData std = new StandardTileData             {
                BackgroundImage = new Uri("isostore:/" + fullPath),
                Title = "Tile Test22",
                BackTitle = "Secondary",
                BackBackgroundImage = new Uri("isostore:/" + fullPath)
            };
            ShellTile.Create(new Uri("/MainPage.xaml?type=2", UriKind.Relative), std);
        }

    };

}

I have a test on it(Conculsion is prefer to use second way as it’s faster and more stable! )

Tranditonal took 239 ms, Image size 6.11kb 
Render took 10 ms, Image size 5.24kb.

You can find demo source code here. Hope that helps, .

     本文转自xshf12345 51CTO博客，原文链接：http://blog.51cto.com/alexis/706532，如需转载请自行联系原作者