/// <summary>
/// Updates the image set.
/// </summary>
/// <remarks>
/// This fetches the list of files from Dropbox and, for each file that is an image
/// ensures that it is in the <see cref="Images"/> property. This method contains
/// logic to handle removing and updating files that have been deleted or updated
/// respectively.
/// </remarks>
/// <returns>An asynchronous task.</returns>
public async Task UpdateImageSet()
{
var initiallyEmpty = this.Images.Count == 0;
var client = this.App.DropboxClient;
if (client == null)
{
return;
}
var list = await client.Files.ListFolderAsync(string.Empty);
var previous = this.Images.Select(i => i.Name).ToList();
foreach (var entry in list.Entries.Where(e => e.IsFile))
{
var ext = Path.GetExtension(entry.Name).ToLowerInvariant();
if (!IsImageExtension(ext))
{
continue;
}
var rev = entry.AsFile.Rev;
var existing = this.Images.FirstOrDefault(i => i.Name == entry.Name);
if (existing == null)
{
var image = new AppImage(entry.Name, rev);
this.Images.Add(image);
}
else if (existing.Rev != entry.AsFile.Rev)
{
existing.UpdateRev(rev);
}
previous.Remove(entry.Name);
}
if (initiallyEmpty && this.Images.Count > 0)
{
this.DoChangeImage(0);
}
else if (previous.Count > 0)
{
foreach (var name in previous)
{
var existing = this.Images.FirstOrDefault(i => i.Name == name);
if (existing != null)
{
this.Images.Remove(existing);
}
}
this.DoChangeImage(0);
}
}
/// <summary>
/// Handles the event raised when <see cref="App.DropboxClient"/> changes.
/// </summary>
/// <remarks>If the client is <c>null</c>, then this clears all data.</remarks>
/// <param name="sender">The sender.</param>
/// <param name="args">The <see cref="EventArgs"/> instance containing the event data.</param>
private void AppDropboxClientChanged(object sender, EventArgs args)
{
if (this.App.DropboxClient == null)
{
this.CurrentImage = null;
this.PreviousImage = null;
this.NextImage = null;
this.Images.Clear();
this.NotifyPropertyChanged();
}
else
{
var t = this.UpdateImageSet();
}
}
/// <summary>
/// Changes the currently selected image, or if no image is currently selected,
/// selects the first.
/// </summary>
/// <param name="increment">The amount to change the current index by.</param>
private void DoChangeImage(int increment)
{
int index = 0;
if (this.CurrentImage == null)
{
if (this.Images.Count == 0)
{
return;
}
}
else
{
index = this.Images.IndexOf(this.CurrentImage);
if (index == -1)
{
index = 0;
}
index = (index + this.Images.Count + increment) % this.Images.Count;
}
this.CurrentImage = this.Images[index];
this.NotifyPropertyChanged("CurrentImage");
this.PreviousImage = this.Images[(index - 1 + this.Images.Count) % this.Images.Count];
this.NotifyPropertyChanged("PreviousImage");
this.NextImage = this.Images[(index + 1) % this.Images.Count];
this.NotifyPropertyChanged("NextImage");
var task = this.InvokeAsync(async() =>
{
await this.CurrentImage.Update();
await this.NextImage.Update();
await this.PreviousImage.Update();
});
}
/// <summary>
/// Updates the image set.
/// </summary>
/// <remarks>
/// This fetches the list of files from Dropbox and, for each file that is an image
/// ensures that it is in the <see cref="Images"/> property. This method contains
/// logic to handle removing and updating files that have been deleted or updated
/// respectively.
/// </remarks>
/// <returns>An asynchronous task.</returns>
public async Task UpdateImageSet()
{
var initiallyEmpty = this.Images.Count == 0;
var client = this.App.DropboxClient;
if (client == null)
{
return;
}
var list = await client.Files.ListFolderAsync(string.Empty);
var previous = this.Images.Select(i => i.Name).ToList();
foreach (var entry in list.Entries.Where(e => e.IsFile))
{
var ext = Path.GetExtension(entry.Name).ToLowerInvariant();
if (!IsImageExtension(ext))
{
continue;
}
var rev = entry.AsFile.Rev;
var existing = this.Images.FirstOrDefault(i => i.Name == entry.Name);
if (existing == null)
{
var image = new AppImage(entry.Name, rev);
this.Images.Add(image);
}
else if (existing.Rev != entry.AsFile.Rev)
{
existing.UpdateRev(rev);
}
previous.Remove(entry.Name);
}
if (initiallyEmpty && this.Images.Count > 0)
{
this.DoChangeImage(0);
}
else if (previous.Count > 0)
{
foreach (var name in previous)
{
var existing = this.Images.FirstOrDefault(i => i.Name == name);
if (existing != null)
{
this.Images.Remove(existing);
}
}
this.DoChangeImage(0);
}
}
/// <summary>
/// Changes the currently selected image, or if no image is currently selected,
/// selects the first.
/// </summary>
/// <param name="increment">The amount to change the current index by.</param>
private void DoChangeImage(int increment)
{
int index = 0;
if (this.CurrentImage == null)
{
if (this.Images.Count == 0)
{
return;
}
}
else
{
index = this.Images.IndexOf(this.CurrentImage);
if (index == -1)
{
index = 0;
}
index = (index + this.Images.Count + increment) % this.Images.Count;
}
this.CurrentImage = this.Images[index];
this.NotifyPropertyChanged("CurrentImage");
this.PreviousImage = this.Images[(index - 1 + this.Images.Count) % this.Images.Count];
this.NotifyPropertyChanged("PreviousImage");
this.NextImage = this.Images[(index + 1) % this.Images.Count];
this.NotifyPropertyChanged("NextImage");
var task = this.InvokeAsync(async () =>
{
await this.CurrentImage.Update();
await this.NextImage.Update();
await this.PreviousImage.Update();
});
}
/// <summary>
/// Handles the event raised when <see cref="App.DropboxClient"/> changes.
/// </summary>
/// <remarks>If the client is <c>null</c>, then this clears all data.</remarks>
/// <param name="sender">The sender.</param>
/// <param name="args">The <see cref="EventArgs"/> instance containing the event data.</param>
private void AppDropboxClientChanged(object sender, EventArgs args)
{
if (this.App.DropboxClient == null)
{
this.CurrentImage = null;
this.PreviousImage = null;
this.NextImage = null;
this.Images.Clear();
this.NotifyPropertyChanged();
}
else
{
var t = this.UpdateImageSet();
}
}