问题
I try to take a picture from a webcam with WIA 2.0, C#, .net 4.0 on Windows 7. I tried many different samples, but nothing works. I always get this Exception: "ComException was unhandled" Exception from HRESULT: 0x80210015". The code is WIA_S_NO_DEVICE_AVAILABLE. I checked, if WIA-Service is running and if the cam shows up in Scanners and Camera. I have no idea whats wrong here! Can anybody help?
Exception is thrown on this line:
Device d = class1.ShowSelectDevice(WiaDeviceType.CameraDeviceType, true, false);:
Here the code
string DeviceID;
const string wiaFormatBMP = "{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}";
const string wiaFormatPNG = "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}";
const string wiaFormatGIF = "{B96B3CB0-0728-11D3-9D7B-0000F81EF32E}";
const string wiaFormatJPEG = "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}";
const string wiaFormatTIFF = "{B96B3CB1-0728-11D3-9D7B-0000F81EF32E}";
class WIA_DPS_DOCUMENT_HANDLING_SELECT
{
public const uint FEEDER = 0x00000001;
public const uint FLATBED = 0x00000002;
}
class WIA_DPS_DOCUMENT_HANDLING_STATUS
{
public const uint FEED_READY = 0x00000001;
}
class WIA_PROPERTIES
{
public const uint WIA_RESERVED_FOR_NEW_PROPS = 1024;
public const uint WIA_DIP_FIRST = 2;
public const uint WIA_DPA_FIRST = WIA_DIP_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
public const uint WIA_DPC_FIRST = WIA_DPA_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
//
// Scanner only device properties (DPS)
//
public const uint WIA_DPS_FIRST = WIA_DPC_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
public const uint WIA_DPS_DOCUMENT_HANDLING_STATUS = WIA_DPS_FIRST + 13;
public const uint WIA_DPS_DOCUMENT_HANDLING_SELECT = WIA_DPS_FIRST + 14;
}
class WIA_ERRORS
{
public const uint BASE_VAL_WIA_ERROR = 0x80210000;
public const uint WIA_ERROR_PAPER_EMPTY = BASE_VAL_WIA_ERROR + 3;
}
public void ADFScan()
{
//Choose Scanner
CommonDialogClass class1 = new CommonDialogClass();
Device d = class1.ShowSelectDevice(WiaDeviceType.CameraDeviceType, true, false);
if (d != null)
{
this.DeviceID = d.DeviceID;
}
else
{
//no scanner chosen
return;
}
WIA.CommonDialog WiaCommonDialog = new CommonDialogClass();
bool hasMorePages = true;
int x = 0;
int numPages = 0;
while (hasMorePages)
{
//Create DeviceManager
DeviceManager manager = new DeviceManagerClass();
Device WiaDev = null;
foreach (DeviceInfo info in manager.DeviceInfos)
{
if (info.DeviceID == this.DeviceID)
{
WIA.Properties infoprop = null;
infoprop = info.Properties;
//connect to scanner
WiaDev = info.Connect();
break;
}
}
//Start Scan
WIA.ImageFile img = null;
WIA.Item Item = WiaDev.Items[1] as WIA.Item;
try
{
img = (ImageFile)WiaCommonDialog.ShowTransfer(Item, wiaFormatJPEG, false);
//process image:
//one would do image processing here
//
//Save to file
string varImageFileName = "c:\\test" + x.ToString() + ".jpg";
if (File.Exists(varImageFileName))
{
//file exists, delete it
File.Delete(varImageFileName);
}
img.SaveFile(varImageFileName);
numPages++;
img = null;
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
finally
{
Item = null;
//determine if there are any more pages waiting
Property documentHandlingSelect = null;
Property documentHandlingStatus = null;
foreach (Property prop in WiaDev.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;
}
hasMorePages = false; //assume there are no more pages
if (documentHandlingSelect != null)
//may not exist on flatbed scanner but required for feeder
{
//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);
}
}
x++;
}
}
}
Thanks for any help!
回答1:
This is a typical example of non-documented error from Microsoft... The error code simply means that no device has been found, either not connected or not-WIA recognized.
回答2:
Try to add a method like CameraTest to test, if there is a camera connected:
bool CameraTest()
{
bool present = false;
try
{
Device d = class1.ShowSelectDevice(WiaDeviceType.CameraDeviceType, true, false);
present = true;
}
catch (Exception ex)
{}
return present;
}
回答3:
Try the code below:
class WIAScanner
{
const string wiaFormatBMP = "{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}";
class WIA_DPS_DOCUMENT_HANDLING_SELECT
{
public const uint FEEDER = 0x00000001;
public const uint FLATBED = 0x00000002;
}
class WIA_DPS_DOCUMENT_HANDLING_STATUS
{
public const uint FEED_READY = 0x00000001;
}
class WIA_PROPERTIES
{
public const uint WIA_RESERVED_FOR_NEW_PROPS = 1024;
public const uint WIA_DIP_FIRST = 2;
public const uint WIA_DPA_FIRST = WIA_DIP_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
public const uint WIA_DPC_FIRST = WIA_DPA_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
//
// Scanner only device properties (DPS)
//
public const uint WIA_DPS_FIRST = WIA_DPC_FIRST + WIA_RESERVED_FOR_NEW_PROPS;
public const uint WIA_DPS_DOCUMENT_HANDLING_STATUS = WIA_DPS_FIRST + 13;
public const uint WIA_DPS_DOCUMENT_HANDLING_SELECT = WIA_DPS_FIRST + 14;
}
/// <summary>
/// Use scanner to scan an image (with user selecting the scanner from a dialog).
/// </summary>
/// <returns>Scanned images.</returns>
public static List<Image> Scan()
{
WIA.ICommonDialog dialog = new WIA.CommonDialog();
WIA.Device device = dialog.ShowSelectDevice(WIA.WiaDeviceType.UnspecifiedDeviceType, true, false);
if (device != null)
{
return Scan(device.DeviceID);
}
else
{
throw new Exception("You must select a device for scanning.");
}
}
/// <summary>
/// Use scanner to scan an image (scanner is selected by its unique id).
/// </summary>
/// <param name="scannerName"></param>
/// <returns>Scanned images.</returns>
public static List<Image> Scan(string scannerId)
{
List<Image> images = new List<Image>();
bool hasMorePages = true;
while (hasMorePages)
{
// 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 = device.Items[1] as WIA.Item;
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);
image = null;
// add file to output list
images.Add(Image.FromFile(fileName));
}
catch (Exception exc)
{
throw exc;
}
finally
{
item = null;
//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;
}
/// <summary>
/// Gets the list of available WIA devices.
/// </summary>
/// <returns></returns>
public static List<string> GetDevices()
{
List<string> devices = new List<string>();
WIA.DeviceManager manager = new WIA.DeviceManager();
foreach (WIA.DeviceInfo info in manager.DeviceInfos)
{
devices.Add(info.DeviceID);
}
return devices;
}
}
来源：https://stackoverflow.com/questions/5830223/camera-capture-with-wia-c-sharp-and-win-7