/// <summary>
/// Asynchronously returns a byte array containing the thumbnail image.
/// </summary>
/// <param name="uri">The image uri.</param>
/// <returns>A byte array containing the thumbnail image.</returns>
public static async Task <byte[]> GetThumbnailAsync(Uri uri)
{
try
{
var file = await StorageFile.GetFileFromApplicationUriAsync(uri)
.AsTask()
.ConfigureAwait(false);
using (var fileStream = await file.OpenReadAsync().AsTask().ConfigureAwait(false))
{
BitmapDecoder decoder = await BitmapDecoder
.CreateAsync(fileStream)
.AsTask()
.ConfigureAwait(false);
using (var imageStream = await decoder.GetThumbnailAsync().AsTask().ConfigureAwait(false))
using (var readStream = imageStream.AsStream())
{
byte[] thumbnail = new byte[readStream.Length];
await readStream.ReadAsync(thumbnail, 0, thumbnail.Length)
.ConfigureAwait(false);
return(thumbnail);
}
}
}
catch (Exception)
{
return(null);
}
}
public static async Task <BitmapImage> GetThumbnail(StorageFile file)
{
BitmapImage bi = null;
using (var sourceStream = await file.OpenAsync(FileAccessMode.Read))
{
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(sourceStream);
var stream = await decoder.GetThumbnailAsync();
bi = new BitmapImage();
bi.SetSource(stream);
}
return(bi);
}
/// <summary>
/// Asynchronously returns a byte array containing the thumbnail image.
/// </summary>
/// <param name="stream">The image stream.</param>
/// <returns>A byte array containing the thumbnail image.</returns>
public static async Task <byte[]> GetThumbnailAsync(IRandomAccessStream stream)
{
try
{
BitmapDecoder decoder = await BitmapDecoder
.CreateAsync(stream)
.AsTask()
.ConfigureAwait(false);
using (var imageStream = await decoder.GetThumbnailAsync().AsTask().ConfigureAwait(false))
using (var readStream = imageStream.AsStream())
{
byte[] thumbnail = new byte[readStream.Length];
await readStream.ReadAsync(thumbnail, 0, thumbnail.Length)
.ConfigureAwait(false);
return(thumbnail);
}
}
catch (Exception)
{
return(null);
}
}
/// <summary>
/// Create a thumbnail image from the input. The thumbnail is taken from the image file in the case that the file has one.
/// Otherwise it will be a new image that is created from the image file.
/// </summary>
/// <param name="decoder">Bitmap decoder.</param>
/// <param name="expectedWidth"> Expected width.</param>
/// <param name="expectedHeight">Expected height.</param>
/// <returns>a new image with smallest size that is larger than the input dimension.</returns>
public static async Task <SoftwareBitmap> CreateThumbnail(BitmapDecoder decoder, uint expectedWidth, uint expectedHeight)
{
BitmapDecoder decoder2;
try
{
var thumbnail = await decoder.GetThumbnailAsync();
decoder2 = await BitmapDecoder.CreateAsync(thumbnail);
}
catch
{
decoder2 = null;
}
if (decoder2 == null)
{
try
{
var preview = await decoder.GetPreviewAsync();
decoder2 = await BitmapDecoder.CreateAsync(preview);
}
catch
{
decoder2 = null;
}
}
if (decoder2 == null)
{
decoder2 = decoder;
}
return(await CreateResizedBitmap(decoder2, expectedWidth, expectedHeight, BitmapInterpolationMode.Linear));
}
