vb.net - 使用 WIA 和 VB 从同一台计算机上的多个扫描仪自动扫描

Question

你好堆栈溢出！

我是编程的终极初学者。我在 php 和 vba 方面有一些经验，可以根据需要编写自己的脚本，尤其是在 excel 中。

最近，对于一个正在进行的项目，我需要能够从连接到同一台计算机的多台扫描仪（比如 2台）自动扫描（比如每 2 分钟）。我决定以这个项目为起点，让我感受一下 Visual Basic。所以我们开始吧，我安装了 Visual Studio Express 2010 并开始编写我的脚本，试图在这里和那里找到一些可以帮助我的代码。我发现 WIA 可以帮助解决这个问题（吐温也可以，但对于我这个新手来说似乎更晦涩难懂）

无论如何，我终于想出了一个应用程序，它能够在仅连接一个扫描仪时以设定的时间间隔自动扫描。当我连接多个扫描仪时，问题就来了。然后，第一次扫描正确发生（扫描仪 1 扫描，然后扫描仪 2 扫描），但是当第二次扫描应该开始时，什么也没有发生，并且扫描仪变得无法访问（忙碌）。我虽然可能忘记“释放”或“断开”最后使用的扫描仪。或者，扫描仪的缓冲存储器中还有一些东西？

在过去的 3 天里，我一直被困在这个问题上，不知道如何使它工作。

这是扫描的功能：（我没有超越其余部分，因为它是 UI 和文件夹管理）

 Public Sub scannerloop()

    'format constants
    Const wiaFormatBMP = "{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatPNG = "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatGIF = "{B96B3CB0-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatJPEG = "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}"
    Const wiaFormatTIFF = "{B96B3CB1-0728-11D3-9D7B-0000F81EF32E}"


    'file format
    Dim fileformat As String
    If Me.FileExt.SelectedItem = "TIF" Then fileformat = wiaFormatTIFF
    If Me.FileExt.SelectedItem = "JPEG" Then fileformat = wiaFormatJPEG
    If Me.FileExt.SelectedItem = "BMP" Then fileformat = wiaFormatBMP
    If Me.FileExt.SelectedItem = "PNG" Then fileformat = wiaFormatPNG
    If Me.FileExt.SelectedItem = "GIF" Then fileformat = wiaFormatGIF

    'colors
    Dim colorcode As Integer
    If Me.Colorbox.SelectedItem = "Black and white" Then colorcode = 4
    If Me.Colorbox.SelectedItem = "Greyscale" Then colorcode = 2
    If Me.Colorbox.SelectedItem = "Colour" Then colorcode = 1

    'Resolution
    Dim dpi As Integer
    dpi = Me.dpiBox.SelectedItem
    Dim horizextent = dpi * 8.2
    Dim vertextent = dpi * 11.6


    Dim j As String = 1
    Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager

    For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices

        If DeviceManager1.DeviceInfos(i).Type = 1 Then  'Select only scanners, not webcams etc...

            'startpoint to calculate how long it is to scan
            Dim ScanStart = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)


            'Directory + file
            Dim targetdir = Me.ProjectFolderBox.Text & "\scans\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
            Form2.CurrentActionLabel.Text = "Scanning from scanner #" & j


            Dim Scanner As WIA.Device = DeviceManager1.DeviceInfos(i).connect


            If IsNothing(Scanner) Then
                Log(Me.logfilename, Now & " | Scanner #" & j & " not found")
            Else
                Try
                    Dim Img As WIA.ImageFile

                    With Scanner.Items(1)
                        .Properties("6146").Value = colorcode '4 is Black-white,gray is 2, color 1 (Color Intent)
                        .Properties("6147").Value = dpi  'dots per inch/horizontal
                        .Properties("6148").Value = dpi 'dots per inch/vertical
                        .Properties("6149").Value = 0 'x point where to start scan
                        .Properties("6150").Value = 0 'y-point where to start scan

                        'Following is A4 paper size. (Not 100% accurate because real A4 Ht errors)
                        .Properties("6151").Value = horizextent 'horizontal exent DPI x inches wide
                        .Properties("6152").Value = vertextent 'vertical extent DPI x inches tall
                        '  .Properties("4104").Value = 8 'bits per pixel

                    End With

                    'transfer image
                    Img = Scanner.Items(1).Transfer(fileformat) 'scans the image.

                    'kill previous file if exists to avoid errors
                    If System.IO.File.Exists(targetdir) = True Then
                        Kill(targetdir)
                    End If

                    Img.SaveFile(targetdir)

                    'last scan
                    Form2.LastFileLabel.Text = "\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
                    Form2.LastScanLabel.Text = Now

                Catch ex As Exception
                    MsgBox(ex.Message)
                Finally

                    Scanner = Nothing
                End Try
            End If

            'End time for the scan
            Dim ScanEnd = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)

            'log
            Log(Me.logfilename, Now & " | Scanner #" & j & " | Scanned " & targetdir & " | duration: " & (ScanEnd - ScanStart))

            j = j + 1



    Next
    DeviceManager1 = Nothing


    Me.CurrFileIndex = Me.CurrFileIndex + 1

    Me.ScanCount = Me.ScanCount + 1
    Me.NextScan = DateAdd("n", Me.IntervalBox.Value, Now)

    Form2.ScanCountLabel.Text = Me.ScanCount
    Form2.NextScanLabel.Text = Me.NextScan
    Form2.CurrentActionLabel.Text = "Waiting..."

    'Increment next file index and update in config file
    Me.FileIndexBox.Value = Me.CurrFileIndex
    SaveCfg()

End Sub

请放纵我，我知道代码对于有很多坏东西的编程专业人员来说可能是一场噩梦，但它确实是我的第一个 VB 程序，我渴望学习。

所以基本上，程序的其余部分是一个表单，我在其中输入扫描的目标目录、文件名、分辨率等，当我点击“开始扫描”时，它 - 第一次运行scannerloop - 启动一个“scantimer”每次滴答声都会启动scannerloop。

正如我所说，它与 1 个扫描仪（按预期创建的文件、更新的日志文件等）完美配合，但只要我有 2 个扫描仪，只有第一次扫描有效，然后，当扫描仪#1 应该开始扫描时，它不会't 并且扫描仪#2 的 LED 开始闪烁（好像在扫描，但不是在扫描）

我希望有人能帮助我。

提前致谢。

文斯

---

更新 - 我尝试过的可能感兴趣的事情：我只是尝试添加一个 for 循环以使其从两个扫描仪扫描几次（因此，基本上独立于计时器和程序的其余部分）：

Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager
 For k = 1 To 3
            Dim j As String = 1
            For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
[...]
          Next i
        Next k
        DeviceManager1 = Nothing

这表明循环的第一次出现有效（从每个扫描仪扫描一次）但就是这样，扫描仪从不扫描第二次并开始闪烁，所以基本上完​​全相同的问题。我还尝试在新循环中包含 Devicemanager 声明：

 For k = 1 To 3 
Dim DeviceManager1 = CreateObject("WIA.DeviceManager")   'wia device manager
            Dim j As String = 1
            For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
[...]
          Next i
        DeviceManager1 = Nothing
        Next k

但它没有改变任何东西。

接下来我要做的是记录循环中的事件，以便我可以知道事情到底在哪里停止：

Dim DeviceManager1 = CreateObject("WIA.DeviceManager") 'wia 设备管理器 Dim j As String = 1

For i = 1 To DeviceManager1.DeviceInfos.Count 'loop through all devices
    If DeviceManager1.DeviceInfos(i).Type = 1 Then  'Select only scanners, not webcams etc...

        'startpoint to calculate how long it is to scan
        Dim ScanStart = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)


        'Directory + file
        Dim targetdir = Me.ProjectFolderBox.Text & "\scans\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
        Form2.CurrentActionLabel.Text = "Scanning from scanner #" & j


        Dim Scanner As WIA.Device = DeviceManager1.DeviceInfos(i).connect


        If IsNothing(Scanner) Then
            Log(Me.logfilename, Now & " | Scanner #" & j & " not found")
        Else
            Try
                Dim Img As WIA.ImageFile

                'log
                Log(Me.logfilename, Now & " | Scanner #" & j & " | Img initialized")

                With Scanner.Items(1)
                    .Properties("6146").Value = colorcode '4 is Black-white,gray is 2, color 1 (Color Intent)
                    .Properties("6147").Value = dpi  'dots per inch/horizontal
                    .Properties("6148").Value = dpi 'dots per inch/vertical
                    .Properties("6149").Value = 0 'x point where to start scan
                    .Properties("6150").Value = 0 'y-point where to start scan

                    'Following is A4 paper size. (Not 100% accurate because real A4 Ht errors)
                    .Properties("6151").Value = horizextent 'horizontal exent DPI x inches wide
                    .Properties("6152").Value = vertextent 'vertical extent DPI x inches tall
                    '  .Properties("4104").Value = 8 'bits per pixel

                End With

                'log
                Log(Me.logfilename, Now & " | Scanner #" & j & " | properties initialized")

                'transfer image
                Img = Scanner.Items(1).Transfer(fileformat) 'scans the image.

                'log
                Log(Me.logfilename, Now & " | Scanner #" & j & " |Transfer done")

                'kill previous file if exists to avoid errors
                If System.IO.File.Exists(targetdir) = True Then
                    Kill(targetdir)
                    'log
                    Log(Me.logfilename, Now & " | Scanner #" & j & " | deleted existing " & targetdir)

                End If

                Img.SaveFile(targetdir)
                'log
                Log(Me.logfilename, Now & " | Scanner #" & j & " | saved " & targetdir)

                'last scan
                Form2.LastFileLabel.Text = "\Scanner" & j & "\S" & j & "_" & Me.FilePrefix.Text & Me.CurrFileIndex & "." & Me.FileExt.SelectedItem
                Form2.LastScanLabel.Text = Now

            Catch ex As Exception
                MsgBox(ex.Message)
            Finally

                Scanner = Nothing
            End Try
        End If

        'End time for the scan
        Dim ScanEnd = DateAndTime.Second(Now) + (DateAndTime.Minute(Now) * 60) + (DateAndTime.Hour(Now) * 3600)

        'log
        Log(Me.logfilename, Now & " | Scanner #" & j & " | Scanned " & targetdir & " | duration: " & (ScanEnd - ScanStart))

        j = j + 1

    End If

Next i

这是生成的日志文件：

Scan starts 29/11/2012 9:24:31 AM | Interval :Start scanning with 5 min | Res:100 DPI | 
29/11/2012 9:24:31 AM | Scanner #1 | Img initialized
29/11/2012 9:24:31 AM | Scanner #1 | properties initialized
29/11/2012 9:24:49 AM | Scanner #1 |Transfer done
29/11/2012 9:24:49 AM | Scanner #1 | saved C:\__2\scans\Scanner1\S1_img_1.TIF
29/11/2012 9:24:49 AM | Scanner #1 | Scanned C:\__2\scans\Scanner1\S1_img_1.TIF | duration: 18
29/11/2012 9:24:49 AM | Scanner #2 | Img initialized
29/11/2012 9:24:49 AM | Scanner #2 | properties initialized
29/11/2012 9:25:08 AM | Scanner #2 |Transfer done
29/11/2012 9:25:08 AM | Scanner #2 | saved C:\__2\scans\Scanner2\S2_img_1.TIF
29/11/2012 9:25:08 AM | Scanner #2 | Scanned C:\__2\scans\Scanner2\S2_img_1.TIF | duration: 19
29/11/2012 9:25:08 AM | Scanner #1 | Img initialized
29/11/2012 9:25:08 AM | Scanner #1 | properties initialized

这条线似乎出了问题：

Img = Scanner.Items(1).Transfer(fileformat) 'scans the image.

看起来 WIA 很乐意从扫描仪 1 切换到扫描仪 2，但拒绝回到扫描仪 1 进行下一轮。另外，我应该准确地说，当应该进行第二次扫描时，扫描仪 #2 会闪烁（而不是 1 让我感到惊讶）。扫描仪#2 是否有可能被选为“默认扫描仪”或类似的东西，如果是这样，有没有办法恢复它？

感谢您的帮助

Answer 1

此代码用于扫描图像：“不要忘记将 wiaaut.DLL 从 windows\sys32 添加到解决方案参考。” 首先检查是否连接了扫描仪设备

Dim tempfile As String
Dim mydevice As WIA.Device
Dim item As WIA.Item
Dim imfile As WIA.ImageFile
Dim Commondialog1 As WIA.CommonDialog
sub check()
  On Error Resume Next
    Commondialog1 = New WIA.CommonDialog
    mydevice = Commondialog1.ShowSelectDevice
    MsgBox(mydevice.Type)

  On Error GoTo Err_btnTakePicture_click

end sub
'then connect to scanner

sub scan()
    'put the path and name for the location of your temp file here.
    tempfile = ("d:\filename.jpg")

    'the next 4 lines deletes the old temp file if it exists
    Dim filesystemobject = CreateObject("Scripting.FileSystemObject")
    If filesystemobject.fileExists(tempfile) Then
        Kill(tempfile)
    End If

    'the next two lines set up the configuration
    Dim Commondialog1 As New WIA.CommonDialog
    mydevice = Commondialog1.ShowSelectDevice

    Dim wiaFormatJPEG As String = "{B96B3CAE-0728-11D3-9D7B-0000F81EF32E}"

    item = mydevice.Items(1)


    imfile = DirectCast(Commondialog1.ShowTransfer(item, wiaFormatJPEG, False), WIA.ImageFile)

    'this line saves the picture to a specified file
    imfile.SaveFile(tempfile)


    MsgBox("Picture taken")
    PictureBox1.ImageLocation = tempfile

  Exit_btnTakePicture_click:
    mydevice = Nothing
    item = Nothing
    Exit Sub

  Err_btnTakePicture_click:
    MsgBox(Err.Description, vbOKOnly + vbCritical, "Error Taking Picture")
    Resume Exit_btnTakePicture_click
   end sub