/**
* Creates the list of ImageViewModels of the photos in this gallery. Once the list is created, loads
* their thumbnails asynchronously.
*/
private void InitAndLoadAllImages()
{
_images.Clear();
// Initialize all the image vms first without loading the images. This way,
// the whole gallery will be available and navigatable to in the slideshow
// view.
for (int i = 0; i < _gallery.Count; i++)
{
// 2nd argument is 0 so that it only loads the image once
ImageViewModel vm = new ImageViewModel(_gallery[i], 0, ThumbnailHeight);
_images.Add(vm);
}
LoadAllImages();
}
/**
* Initializes the cache of images as an array. Initially, the index of the current image is the 2nd position
* in the array. As the user moves left & right through the slideshow, the index will move left & right along
* with it, wrapping at the end as with a circular buffer. The cached images nearby the current image will be
* in the same relative position to the current image's position in the array.
*/
private void InitCache()
{
int cacheIndex = 0;
// Create each cache position for images before the current one
for (int i = 1; i <= BACK_CACHE_NUM; i++)
{
// Which image in the gallery do we load into the cache
int galleryIndex = CurrentIndex - i;
if (galleryIndex < 0)
{
galleryIndex += _galleryItems.Count();
}
// Create the VM which holds the image & subscribe to property change events
_imageCache[cacheIndex] = new ImageViewModel(_galleryItems[galleryIndex], 256, 0);
_imageCache[cacheIndex].PropertyChanged += new PropertyChangedEventHandler(Child_OnPropertyChanged);
cacheIndex++;
}
// Create a cache position for the current image
_imageCacheCurrIndex = cacheIndex;
// Create the VM which holds the image & subscribe to property change events
_imageCache[cacheIndex] = new ImageViewModel(_galleryItems[CurrentIndex], 256, 0);
_imageCache[cacheIndex].PropertyChanged += new PropertyChangedEventHandler(Child_OnPropertyChanged);
cacheIndex++;
// Create each cache position for images after the current one
for (int i = 1; i <= FORWARD_CACHE_NUM; i++)
{
// Which image in the gallery do we load into the cache
int galleryIndex = CurrentIndex + i;
if (galleryIndex >= _galleryItems.Count())
{
galleryIndex -= _galleryItems.Count();
}
// Create the VM which holds the image & subscribe to property change events
_imageCache[cacheIndex] = new ImageViewModel(_galleryItems[galleryIndex], 256, 0);
_imageCache[cacheIndex].PropertyChanged += new PropertyChangedEventHandler(Child_OnPropertyChanged);
cacheIndex++;
}
}
/// <summary>
/// Opens the given Photo in a new page.
/// </summary>
/// <param name="parameter">The Photo instance to open.</param>
public void OpenImage(object parameter)
{
Photo p = parameter as Photo;
// Get a list of all the currently visible images
List <ImageViewModel> list = ImagesView.OfType <ImageViewModel>().ToList();
List <Photo> photos = ImageViewModel.GetPhotoList(list);
// Get the clicked on photo's index in the list of Photos
int index = 0;
for (int i = 0; i < list.Count; i++)
{
if (p == list[i].Photo)
{
index = i;
}
}
// Create a new page to view the clicked image
ImageSlideshowViewModel imagePage = new ImageSlideshowViewModel(photos, index);
_navigator.NewPage(imagePage);
}