private IScannedImage TransferImage(WiaBackgroundEventLoop eventLoop, int pageNumber)
{
try
{
using (var stream = wiaTransfer.Transfer(pageNumber, eventLoop, WiaApi.Formats.BMP))
{
if (stream == null)
{
// User cancelled
return(null);
}
using (Image output = Image.FromStream(stream))
{
double scaleFactor = 1;
if (!ScanSettings.UseNativeUI)
{
scaleFactor = ScanSettings.AfterScanScale.ToIntScaleFactor();
}
using (var result = ImageScaleHelper.ScaleImage(output, scaleFactor))
{
ScanBitDepth bitDepth = ScanSettings.UseNativeUI ? ScanBitDepth.C24Bit : ScanSettings.BitDepth;
return(scannedImageFactory.Create(result, bitDepth, ScanSettings.MaxQuality));
}
}
}
}
catch (COMException e)
{
if ((uint)e.ErrorCode == WiaApi.Errors.OUT_OF_PAPER)
{
if (ScanSettings.PaperSource != ScanSource.Glass && pageNumber == 1)
{
throw new NoPagesException();
}
return(null);
}
else if ((uint)e.ErrorCode == WiaApi.Errors.OFFLINE)
{
throw new DeviceOfflineException();
}
else
{
throw new ScanDriverUnknownException(e);
}
}
}
protected override IEnumerable <IScannedImage> ScanInternal()
{
var session = new TwainSession(TwainAppId);
var twainForm = formFactory.Create <FTwainGui>();
var images = new List <IScannedImage>();
Exception error = null;
bool cancel = false;
DataSource ds = null;
session.TransferReady += (sender, eventArgs) =>
{
if (cancel)
{
eventArgs.CancelAll = true;
}
};
session.DataTransferred += (sender, eventArgs) =>
{
using (var output = Image.FromStream(eventArgs.GetNativeImageStream()))
{
double scaleFactor = 1;
if (!ScanSettings.UseNativeUI)
{
scaleFactor = ScanSettings.AfterScanScale.ToIntScaleFactor();
}
using (var result = ImageScaleHelper.ScaleImage(output, scaleFactor))
{
var bitDepth = output.PixelFormat == PixelFormat.Format1bppIndexed
? ScanBitDepth.BlackWhite
: ScanBitDepth.C24Bit;
images.Add(scannedImageFactory.Create(result, bitDepth, ScanSettings.MaxQuality));
}
}
};
session.TransferError += (sender, eventArgs) =>
{
error = eventArgs.Exception;
cancel = true;
twainForm.Close();
};
session.SourceDisabled += (sender, eventArgs) => twainForm.Close();
twainForm.Shown += (sender, eventArgs) =>
{
try
{
ReturnCode rc = session.Open(new WindowsFormsMessageLoopHook(DialogParent.Handle));
if (rc != ReturnCode.Success)
{
twainForm.Close();
return;
}
ds = session.FirstOrDefault(x => x.Name == ScanDevice.ID);
if (ds == null)
{
throw new DeviceNotFoundException();
}
rc = ds.Open();
if (rc != ReturnCode.Success)
{
twainForm.Close();
return;
}
ConfigureDS(ds);
var ui = ScanSettings.UseNativeUI ? SourceEnableMode.ShowUI : SourceEnableMode.NoUI;
rc = ds.Enable(ui, true, twainForm.Handle);
if (rc != ReturnCode.Success)
{
twainForm.Close();
}
}
catch (Exception ex)
{
error = ex;
twainForm.Close();
}
};
twainForm.ShowDialog(DialogParent);
if (ds != null && session.IsSourceOpen)
{
ds.Close();
}
if (session.IsDsmOpen)
{
session.Close();
}
if (error != null)
{
if (error is ScanDriverException)
{
throw error;
}
throw new ScanDriverUnknownException(error);
}
return(images);
}