public static LoadCommandArgs FromJSON(string json)
{
LoadCommandArgs loadArgs = new LoadCommandArgs();
loadArgs.Uri = new Uri(DemoUtils.JsonStringToString(json, "uri"));
loadArgs.StartPage = DemoUtils.JsonStringToInteger(json, "startPage");
loadArgs.EndPage = DemoUtils.JsonStringToInteger(json, "endPage");
loadArgs.Resolution = DemoUtils.JsonStringToInteger(json, "resolution");
loadArgs.BitsPerPixel = DemoUtils.JsonStringToInteger(json, "bitsPerPixel");
return(loadArgs);
}
/// <summary>
/// Run the load command.
/// </summary>
/// <param name="id">Scanning session id.</param>
/// <param name="service">Twain scanning service handle.</param>
/// <param name="args">Load command arguments.</param>
public static void Run(string id, TwainScanningService service, LoadCommandArgs args)
{
if (args.Uri == null)
{
throw new ArgumentNullException("Uri");
}
if (args.StartPage < 0)
{
throw new ArgumentOutOfRangeException("StartPage", "must be a value greater than or equal to 1");
}
if (args.Resolution < 0)
{
throw new ArgumentOutOfRangeException("Resolution", "must be a value greater than or equals to 0");
}
// Force the uri to be fully qualified, reject everything else for security reasons
if (args.Uri.IsFile || args.Uri.IsUnc)
{
throw new ArgumentException("URL cannot be local file or UNC path.");
}
// Use a temp file, much faster than calling Load/Info from a URI directly
// In a production service, you might want to create a caching mechanism
string tempFile = Path.GetTempFileName();
try
{
// Download the file
using (WebClient client = new WebClient())
client.DownloadFile(args.Uri, tempFile);
using (RasterCodecs codecs = new RasterCodecs())
{
DemoUtils.InitCodecs(codecs, args.Resolution);
CodecsImageInfo info = codecs.GetInformation(tempFile, true);
if ((args.EndPage < 0) || (args.EndPage > info.TotalPages))
{
args.EndPage = info.TotalPages;
}
for (int pageNumber = args.StartPage; pageNumber <= args.EndPage; pageNumber++)
{
using (RasterImage image = codecs.Load(tempFile, args.BitsPerPixel, CodecsLoadByteOrder.BgrOrGray, pageNumber, pageNumber))
{
service.AddPage(id, image);
}
}
}
}
finally
{
if (File.Exists(tempFile))
{
try
{
File.Delete(tempFile);
}
catch
{
// Do nothing.
}
}
}
}