我正在尝试使用具有自动进纸器的扫描仪扫描多个页面。我的代码目前非常简单：
WIA.CommonDialog dialog = new WIA.CommonDialog();
WIA.Device device = dialog.ShowSelectDevice(WIA.WiaDeviceType.ScannerDeviceType);
WIA.Items items = dialog.ShowSelectItems(device);
foreach (WIA.Item item in items)
{
while (true)
{
try
{
WIA.ImageFile image = (WIA.ImageFile)dialog.ShowTransfer(item);
if (image != null && image.FileData != null)
{
dynamic binaryData = image.FileData.get_BinaryData();
if (binaryData is byte[])
using (MemoryStream stream = new MemoryStream(binaryData))
using (Bitmap bitmap = (Bitmap)Bitmap.FromStream(stream))
{
bitmap.Save(@"C:\Temp\scan.jpg", ImageFormat.Jpeg);
}
}
}
catch (COMException)
{
break;
}
}
}
我尝试查询WIA_DPS_DOCUMENT_HANDLING_STATUS属性以查看进纸器中是否有任何可用的页面，但是它总是返回1，所以如果我得到WIA_ERROR_PAPER_EMPTY，我会抓住一个COM异常，我知道送纸器是空的。
问题是这段代码只扫描第一页，当再次调用dialog.ShowTransfer方法时，我和E_FAIL HResult会出现异常，我无法扫描更多页面。奇怪的是，当我在调试器中单步执行此代码时，一切正常并且所有页面都被扫描。
我尝试通过Marshal.ReleaseComObject(image)和image = null释放图像对象，但这没有帮助。 this question的建议也没有。有没有什么我做错了导致这些错误？
E_FAIL，这需要几秒钟（它不是一个非常快的扫描仪）。所以，我添加了一个循环来继续尝试10秒，这是一个我不喜欢的解决方案，但似乎有效。
编辑2：这似乎与打印机的WIA驱动程序有关。我尝试使用不同品牌的打印机，但根本没有这个问题。
答案 0 :(得分：2)
我正在做同样的事情，并尝试使用此示例中的代码和代码：http://www.codeproject.com/Tips/792316/WIA-Scanner-in-Csharp-Windows-Forms
我在hp scanjet 5590上测试了你的代码，它只设法获得一个图像，即使我在调试器中单步执行代码。在第二次调用时，dialog.ShowTransfer抛出ArgumentException，并显示消息“Value不在预期范围内”。我设法通过重置“图像”和“对话框”对象以及设置显式传输格式ID来使其工作。您的代码也将图像写入同一文件。如果应用于您的代码，这对我有用：
WIA.CommonDialog dialog = new WIA.CommonDialog();
WIA.Device device = dialog.ShowSelectDevice(WIA.WiaDeviceType.ScannerDeviceType);
WIA.Items items = dialog.ShowSelectItems(device);
foreach (WIA.Item item in items)
{
while (true)
{
WIA.ImageFile image = null;
try
{
dialog = new WIA.CommonDialog();
image = (WIA.ImageFile)dialog.ShowTransfer(item,"{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}", false);
if (image != null && image.FileData != null)
{
dynamic binaryData = image.FileData.get_BinaryData();
if (binaryData is byte[])
using (MemoryStream stream = new MemoryStream(binaryData))
using (Bitmap bitmap = (Bitmap) Bitmap.FromStream(stream))
{
bitmap.Save(String.Format(@"C:\Temp\scan{0}.jpg", Path.GetRandomFileName()),
ImageFormat.Jpeg);
}
}
}
catch (COMException)
{
break;
}
finally
{
if (image != null)
Marshal.FinalReleaseComObject(image);
}
}
}
CodeProject示例也在我的硬件上失败，但相同的修复程序也有帮助。如果上面的代码仍然不适合您，请尝试使用此替换原始的扫描方法：
public static List<Image> Scan(string scannerId)
{
List<Image> images = new List<Image>();
// select the correct scanner using the provided scannerId parameter
WIA.DeviceManager manager = new WIA.DeviceManager();
WIA.Device device = null;
foreach (WIA.DeviceInfo info in manager.DeviceInfos)
{
if (info.DeviceID == scannerId)
{
// connect to scanner
device = info.Connect();
break;
}
}
// device was not found
if (device == null)
{
// enumerate available devices
string availableDevices = "";
foreach (WIA.DeviceInfo info in manager.DeviceInfos)
{
availableDevices += info.DeviceID + "\n";
}
// show error with available devices
throw new Exception("The device with provided ID could not be found. Available Devices:\n" + availableDevices);
}
WIA.Item item = null;
WIA.CommonDialog dialog = new WIA.CommonDialog();
WIA.Items items = dialog.ShowSelectItems(device);
if (items == null)
return images;
item = items[1];
bool hasMorePages = true;
while (hasMorePages)
{
try
{
// scan image
WIA.ICommonDialog wiaCommonDialog = new WIA.CommonDialog();
WIA.ImageFile image = (WIA.ImageFile)wiaCommonDialog.ShowTransfer(item, wiaFormatBMP, false);
// save to temp file
string fileName = Path.GetTempFileName();
File.Delete(fileName);
image.SaveFile(fileName);
try
{
Marshal.FinalReleaseComObject(image);
}
finally
{
image = null;
}
// add file to output list
images.Add(Image.FromFile(fileName));
}
finally
{
//determine if there are any more pages waiting
WIA.Property documentHandlingSelect = null;
WIA.Property documentHandlingStatus = null;
foreach (WIA.Property prop in device.Properties)
{
if (prop.PropertyID == WIA_PROPERTIES.WIA_DPS_DOCUMENT_HANDLING_SELECT)
documentHandlingSelect = prop;
if (prop.PropertyID == WIA_PROPERTIES.WIA_DPS_DOCUMENT_HANDLING_STATUS)
documentHandlingStatus = prop;
}
// assume there are no more pages
hasMorePages = false;
// may not exist on flatbed scanner but required for feeder
if (documentHandlingSelect != null)
{
// check for document feeder
if ((Convert.ToUInt32(documentHandlingSelect.get_Value()) & WIA_DPS_DOCUMENT_HANDLING_SELECT.FEEDER) != 0)
{
hasMorePages = ((Convert.ToUInt32(documentHandlingStatus.get_Value()) & WIA_DPS_DOCUMENT_HANDLING_STATUS.FEED_READY) != 0);
}
}
}
}
return images;
}
也可以用这个替换btn_scan_Click方法：
private void btn_scan_Click(object sender, EventArgs e)
{
try
{
//get list of devices available
List<string> devices = WIAScanner.GetDevices();
List<Image> images = null;
//check if device is not available
if (devices.Count == 0)
{
MessageBox.Show("You do not have any WIA devices.");
this.Close();
}
else
{
if (devices.Count == 1)
{
images = WIAScanner.Scan(devices[0]);
}
else
{
images = WIAScanner.Scan();
}
}
//get images from scanner
foreach (Image image in images)
{
var path = String.Format(@"C:\Temp\scan{0}_{1}.jpg", DateTime.Now.ToString("yyyy-MM-dd HHmmss"), Path.GetRandomFileName());
image.Save(path, ImageFormat.Jpeg);
}
}
catch (Exception exc)
{
MessageBox.Show(exc.Message);
}
}
答案 1 :(得分：-1)
此代码适用于我
try
{
// Create a DeviceManager instance
var deviceManager = new DeviceManager();
List<Image> ret = new List<Image>();
WIA.CommonDialog dialog = new WIA.CommonDialog();
WIA.Device device = dialog.ShowSelectDevice(WIA.WiaDeviceType.ScannerDeviceType);
WIA.Items items = dialog.ShowSelectItems(device);
foreach (WIA.Item item in items)
{
while (true)
{
try
{
WIA.ImageFile image = (WIA.ImageFile) dialog.ShowTransfer(item);
if (image != null && image.FileData != null)
{
var imageBytes = (byte[]) image.FileData.get_BinaryData();
var ms = new MemoryStream(imageBytes);
Image img = null;
img = Image.FromStream(ms);
ret.Add(img);
}
}
catch
{
break;
}
}
}
return ret;
}
catch (Exception)
{
return null;
}