/// <summary>
/// Requests a new image and return it via the callback. If the image is in the cache, it is
/// returned from there. Otherwise we queue up the request and spin up a thread to retrieve the
/// image and invoke the callback from there.
/// </summary>
/// <param name="imageURL">The URL of the image</param>
/// <param name="maxWidth">The maximum width of the requested image</param>
/// <param name="maxHeight">The maximum height of the requested image</param>
/// <param name="callback">The callback</param>
/// <param name="callbackParameter">A user specified parameter for the callback</param>
/// <returns>An Image object that represents the specified image or null if it is not yet available</returns>
public Image NewRequest(string imageURL, int maxWidth, int maxHeight, ImageRetrieved callback, object callbackParameter)
{
if (_imageCache.ContainsKey(imageURL))
{
LogFile.WriteLine("Image {0} retrieved from cache", imageURL);
return((_imageCache[imageURL].Image != null) ? ScaleImage(_imageCache[imageURL].Image, maxWidth, maxHeight) : null);
}
// Spin up a new thread to obtain any images
Thread t = new Thread(() =>
{
try
{
LogFile.WriteLine("Requesting image {0}", imageURL);
// Convert Dropbox share URLs into raw links
string realImageURL = imageURL;
if (realImageURL.StartsWith("https://www.dropbox.com", StringComparison.Ordinal))
{
realImageURL += "?raw=1";
}
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(realImageURL);
webRequest.AllowWriteStreamBuffering = true;
webRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)";
using (WebResponse _WebResponse = webRequest.GetResponse())
{
Stream stream = _WebResponse.GetResponseStream();
if (stream != null)
{
Image _tmpImage = Image.FromStream(stream);
_imageCache[imageURL] = new ImageCacheEntry {
Image = _tmpImage, Timestamp = DateTime.Now
};
Image image = ScaleImage(_tmpImage, maxWidth, maxHeight);
callback(image, callbackParameter);
LogFile.WriteLine("Image {0} retrieved from server and cached", imageURL);
}
}
}
catch (Exception e)
{
LogFile.WriteLine("Failed to load {0}: {1}", imageURL, e.Message);
// Don't try and request this image again for a while.
_imageCache[imageURL] = new ImageCacheEntry {
Image = null, Timestamp = DateTime.Now
};
}
});
t.Start();
return(null);
}
/// <summary>
/// Requests a new image and return it via the callback. If the image is in the cache, it is
/// returned from there. Otherwise we queue up the request and spin up a thread to retrieve the
/// image and invoke the callback from there.
/// </summary>
/// <param name="imageURL">The URL of the image</param>
/// <param name="maxWidth">The maximum width of the requested image</param>
/// <param name="maxHeight">The maximum height of the requested image</param>
/// <param name="callback">The callback</param>
/// <param name="callbackParameter">A user specified parameter for the callback</param>
/// <returns>An Image object that represents the specified image or null if it is not yet available</returns>
public Image NewRequest(string imageURL, int maxWidth, int maxHeight, ImageRetrieved callback, object callbackParameter)
{
if (_imageCache.ContainsKey(imageURL))
{
LogFile.WriteLine("Image {0} retrieved from cache", imageURL);
return (_imageCache[imageURL].Image != null) ? ScaleImage(_imageCache[imageURL].Image, maxWidth, maxHeight) : null;
}
// Spin up a new thread to obtain any images
Thread t = new Thread(() =>
{
try
{
LogFile.WriteLine("Requesting image {0}", imageURL);
// Convert Dropbox share URLs into raw links
string realImageURL = imageURL;
if (realImageURL.StartsWith("https://www.dropbox.com", StringComparison.Ordinal))
{
realImageURL += "?raw=1";
}
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(realImageURL);
webRequest.AllowWriteStreamBuffering = true;
webRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)";
using (WebResponse _WebResponse = webRequest.GetResponse())
{
Stream stream = _WebResponse.GetResponseStream();
if (stream != null)
{
Image _tmpImage = Image.FromStream(stream);
_imageCache[imageURL] = new ImageCacheEntry { Image = _tmpImage, Timestamp = DateTime.Now };
Image image = ScaleImage(_tmpImage, maxWidth, maxHeight);
callback(image, callbackParameter);
LogFile.WriteLine("Image {0} retrieved from server and cached", imageURL);
}
}
}
catch (Exception e)
{
LogFile.WriteLine("Failed to load {0}: {1}", imageURL, e.Message);
// Don't try and request this image again for a while.
_imageCache[imageURL] = new ImageCacheEntry { Image = null, Timestamp = DateTime.Now };
}
});
t.Start();
return null;
}
