public static ImageSource SaveThumbnail(ThumbnailOptions options)
{
// Make sure this method runs in the UI thread.
if (!Deployment.Current.Dispatcher.CheckAccess())
{
return(Deployment.Current.Dispatcher.Invoke <ImageSource>(() =>
{
return SaveThumbnail(options);
}));
}
// Gets the images.
WriteableBitmap preferedImage = GetBitmapSource(options.PreferedMedia);
WriteableBitmap fallbackImage = GetBitmapSource(options.FallbackMedia);
// Determines which image needs to be saved.
WriteableBitmap targetImage = preferedImage;
if (preferedImage == null)
{
// Use the fallback image if the prefered image does not exist.
targetImage = fallbackImage;
}
else if (fallbackImage != null && options.MinWidth > -1 && preferedImage.PixelWidth < options.MinWidth && preferedImage.PixelWidth < fallbackImage.PixelWidth)
{
// Use the fallback image if its width is bigger than the prefered image's width, the latter being
// smaller than the min width.
targetImage = fallbackImage;
}
// No image? Return.
if (targetImage == null)
{
return(null);
}
// Gets the dimensions of the target image.
int targetWidth = (int)Math.Max(options.MinWidth, targetImage.PixelWidth);
double sourcePixelRatio = targetImage.PixelWidth / (double)targetImage.PixelHeight;
int targetHeight = (int)Math.Floor(targetWidth / sourcePixelRatio);
// Blurs the image if needed.
ExtendedImage targetExtendedImage = null;
if (options.Blur)
{
// Converts the image to an ImageTools image.
targetExtendedImage = targetImage.ToImage();
// Resizes the image if it can help decreasing the time needed to blur it.
// The image is only resized if the target size is less than the original size.
// Otherwise it means that the original image is smaller than the target size, in which case we blur it
// as it is and let WP scale up the blurred image later.
if (targetExtendedImage.PixelHeight * targetExtendedImage.PixelWidth > targetWidth * targetHeight)
{
targetExtendedImage = ExtendedImage.Resize(targetExtendedImage, targetWidth, targetHeight, new ImageTools.Filtering.NearestNeighborResizer());
}
// Inits the blur filter if needed and runs it.
if (_gaussianBlurFilter == null)
{
_gaussianBlurFilter = new ImageTools.Filtering.GaussianBlur()
{
Variance = 2d
};
}
targetExtendedImage = ExtendedImage.ApplyFilters(targetExtendedImage, _gaussianBlurFilter);
}
// Crops the image if needed.
if (options.CropRectangle.HasValue)
{
if (targetExtendedImage == null)
{
// Converts the image to an ImageTools image.
targetExtendedImage = targetImage.ToImage();
}
// Computes the downscaled crop rectangle.
// We're downscaling the crop rectangle instead of upscaling the image and then cropping it,
// in order to save some time.
// WP will upscale the cropped image later on.
int conformedCropWidth = Math.Min(options.CropRectangle.Value.Width, targetWidth);
int conformedCropHeight = Math.Min(options.CropRectangle.Value.Height, targetHeight);
double scaleFactor = (double)targetExtendedImage.PixelWidth / (double)targetWidth;
Rectangle crop = options.CropRectangle.Value;
crop.Width = (int)(conformedCropWidth * scaleFactor);
crop.Height = (int)(conformedCropHeight * scaleFactor);
crop.X = (int)((double)crop.X * scaleFactor);
crop.Y = (int)((double)crop.Y * scaleFactor);
// Crops the image.
if (crop.Width > 0 && crop.Height > 0)
{
targetExtendedImage = ExtendedImage.Crop(targetExtendedImage, crop);
}
// Stores the final dimensions of the image for later scaling.
targetWidth = conformedCropWidth;
targetHeight = conformedCropHeight;
}
if (targetExtendedImage != null)
{
targetImage = targetExtendedImage.ToBitmap();
}
// Saves the image.
try
{
if (targetWidth > 0 && targetHeight > 0)
{
using (IsolatedStorageFileStream stream = options.IsoStoreFile.OpenFile(options.Filename, FileMode.Create, FileAccess.ReadWrite))
{
targetImage.SaveJpeg(stream, targetWidth, targetHeight, 0, 100);
}
}
}
catch (IsolatedStorageException ex)
{
// Nothing to do, let's just dump this for further analysis.
DebugUtils.DumpException(ex, string.Format("OpenFile(f:{0})", options.Filename), true);
}
catch (ArgumentException ex)
{
// Nothing to do, let's just dump this for further analysis.
DebugUtils.DumpException(ex, string.Format("SaveJpeg(w:{0},h:{1})", targetWidth, targetHeight), true);
}
// Returns the image.
return(targetImage);
}