Windows 8 Tablet上的圖像捕獲

Question

我正在使用戴爾Latitude ST2平板電腦。 它在Intel Atom處理器上運行Windows 8 Pro。

我正試圖從前后攝像頭同時拍攝圖像。 我在這里亂碼： http : //www.codeproject.com/Articles/18511/Webcam-using-DirectShow-NET

我只能得到后置攝像頭，即使這樣，圖像捕捉也不起作用。 流很好。 （不太關心這個，而不是我的雙流。）

平板電腦中的兩個圖像傳感器是OV8830和OV2720。

另外，是否有更好的API或方法，而不是使用DirectShow來實現我想要完成的任務？

謝謝！

編輯：我忘了提到我在VB工作。 我更喜歡堅持使用Windows窗體應用程序。

Answer 1

我在前一天嘗試過這種方法，對代碼進行了少量修改。對我來說，圖像流以及捕獲工作都很好。我會將代碼放在這里。您可以對應用程序進行修改以便為您工作。

 Imports System.Runtime.InteropServices
Imports System.IO

Public Class FrmCam
    Const WM_CAP As Short = &H400S
    Const WM_CAP_DRIVER_CONNECT As Integer = WM_CAP + 10
    Const WM_CAP_DRIVER_DISCONNECT As Integer = WM_CAP + 11
    Const WM_CAP_EDIT_COPY As Integer = WM_CAP + 30
    Public Const WM_CAP_GET_STATUS As Integer = WM_CAP + 54
    Public Const WM_CAP_DLG_VIDEOFORMAT As Integer = WM_CAP + 41
    Const WM_CAP_SET_PREVIEW As Integer = WM_CAP + 50
    Const WM_CAP_SET_PREVIEWRATE As Integer = WM_CAP + 52
    Const WM_CAP_SET_SCALE As Integer = WM_CAP + 53
    Const WS_CHILD As Integer = &H40000000
    Const WS_VISIBLE As Integer = &H10000000
    Const SWP_NOMOVE As Short = &H2S
    Const SWP_NOSIZE As Short = 1
    Const SWP_NOZORDER As Short = &H4S
    Const HWND_BOTTOM As Short = 1
    Private DeviceID As Integer = 0 ' Current device ID
    Private hHwnd As Integer ' Handle to preview window
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
        (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
        ByRef lParam As CAPSTATUS) As Boolean
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
       (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Boolean, _
       ByRef lParam As Integer) As Boolean
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
         (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
         ByRef lParam As Integer) As Boolean
    Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Integer, _
        ByVal hWndInsertAfter As Integer, ByVal x As Integer, ByVal y As Integer, _
        ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer) As Integer

    Declare Function DestroyWindow Lib "user32" (ByVal hndw As Integer) As Boolean
    Structure POINTAPI
        Dim x As Integer
        Dim y As Integer
    End Structure
    Public Structure CAPSTATUS
        Dim uiImageWidth As Integer                    '// Width of the image
        Dim uiImageHeight As Integer                   '// Height of the image
        Dim fLiveWindow As Integer                     '// Now Previewing video?
        Dim fOverlayWindow As Integer                  '// Now Overlaying video?
        Dim fScale As Integer                          '// Scale image to client?
        Dim ptScroll As POINTAPI                    '// Scroll position
        Dim fUsingDefaultPalette As Integer            '// Using default driver palette?
        Dim fAudioHardware As Integer                  '// Audio hardware present?
        Dim fCapFileExists As Integer                  '// Does capture file exist?
        Dim dwCurrentVideoFrame As Integer             '// # of video frames cap'td
        Dim dwCurrentVideoFramesDropped As Integer     '// # of video frames dropped
        Dim dwCurrentWaveSamples As Integer            '// # of wave samples cap'td
        Dim dwCurrentTimeElapsedMS As Integer          '// Elapsed capture duration
        Dim hPalCurrent As Integer                     '// Current palette in use
        Dim fCapturingNow As Integer                   '// Capture in progress?
        Dim dwReturn As Integer                        '// Error value after any operation
        Dim wNumVideoAllocated As Integer              '// Actual number of video buffers
        Dim wNumAudioAllocated As Integer              '// Actual number of audio buffers
    End Structure
    Declare Function capCreateCaptureWindowA Lib "avicap32.dll" _
         (ByVal lpszWindowName As String, ByVal dwStyle As Integer, _
         ByVal x As Integer, ByVal y As Integer, ByVal nWidth As Integer, _
         ByVal nHeight As Short, ByVal hWndParent As Integer, _
         ByVal nID As Integer) As Integer
    Declare Function capGetDriverDescriptionA Lib "avicap32.dll" (ByVal wDriver As Short, _
        ByVal lpszName As String, ByVal cbName As Integer, ByVal lpszVer As String, _
        ByVal cbVer As Integer) As Boolean
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadDeviceList()
        If Not Directory.Exists(Application.StartupPath & "\Images") Then
            Directory.CreateDirectory(Application.StartupPath & "\Images")
        End If
        If lstDevices.Items.Count > 0 Then
            btnStart.Enabled = True
            lstDevices.SelectedIndex = 0
            btnStart.Enabled = True
        Else
            lstDevices.Items.Add("No Capture Device")
            btnStart.Enabled = False
        End If
        Me.AutoScrollMinSize = New Size(100, 100)
        btnStop.Enabled = False
        btnSave.Enabled = False
        'picCapture.SizeMode = PictureBoxSizeMode.StretchImage
    End Sub
    Private Sub LoadDeviceList()
        Dim strName As String = Space(100)
        Dim strVer As String = Space(100)
        Dim bReturn As Boolean
        Dim x As Short = 0
        ' 
        ' Load name of all avialable devices into the lstDevices
        '
        Do
            '
            '   Get Driver name and version
            '
            bReturn = capGetDriverDescriptionA(x, strName, 100, strVer, 100)
            '
            ' If there was a device add device name to the list
            '
            If bReturn Then lstDevices.Items.Add(strName.Trim)
            x += CType(1, Short)
        Loop Until bReturn = False
    End Sub

    Private Sub OpenPreviewWindow()
        Dim iHeight As Integer = Piccapture.Height
        Dim iWidth As Integer = Piccapture.Width
        '
        ' Open Preview window in picturebox
        '
        hHwnd = capCreateCaptureWindowA(DeviceID.ToString, WS_VISIBLE Or WS_CHILD, 0, 0, 1280, _
            1024, Piccapture.Handle.ToInt32, 0)
        '
        ' Connect to device
        '
        If SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, DeviceID, 0) Then
            '
            'Set the preview scale
            '
            SendMessage(hHwnd, WM_CAP_SET_SCALE, True, 0)

            '
            'Set the preview rate in milliseconds
            '
            SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0)

            '
            'Start previewing the image from the camera
            '
            SendMessage(hHwnd, WM_CAP_SET_PREVIEW, True, 0)

            '
            ' Resize window to fit in picturebox
            '
            SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, Piccapture.Width, Piccapture.Height, _
                    SWP_NOMOVE Or SWP_NOZORDER)

            btnSave.Enabled = True
            btnStop.Enabled = True
            btnStart.Enabled = False
        Else
            '
            MsgBox("No Device Connected", MsgBoxStyle.Information, "RStar")
            ' 
            DestroyWindow(hHwnd)
            btnSave.Enabled = False
        End If
    End Sub
    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        DeviceID = lstDevices.SelectedIndex
        'If DeviceID = 0 Then
        '    MsgBox("No Device Found", MsgBoxStyle.Information, "RStar")
        '    Exit Sub
        'End If
        OpenPreviewWindow()
        Dim bReturn As Boolean
        Dim s As CAPSTATUS
        bReturn = SendMessage(hHwnd, WM_CAP_GET_STATUS, Marshal.SizeOf(s), s)
        Debug.WriteLine(String.Format("Video Size {0} x {1}", s.uiImageWidth, s.uiImageHeight))
    End Sub
    Private Sub ClosePreviewWindow()
        '
        ' Disconnect from device
        '
        SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, DeviceID, 0)
        '
        ' close window
        '
        DestroyWindow(hHwnd)
    End Sub
    Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
        ClosePreviewWindow()
        btnSave.Enabled = False
        btnStart.Enabled = True
        btnStop.Enabled = False

    End Sub
    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Dim data As IDataObject
        Dim bmap As Bitmap
        Dim filepath As String

        '
        ' Copy image to clipboard
        '
        SendMessage(hHwnd, WM_CAP_EDIT_COPY, 0, 0)
        '
        ' Get image from clipboard and convert it to a bitmap
        '
        data = Clipboard.GetDataObject()
        If data.GetDataPresent(GetType(System.Drawing.Bitmap)) Then
            bmap = CType(data.GetData(GetType(System.Drawing.Bitmap)), Bitmap)
            Piccapture.Image = bmap
            ClosePreviewWindow()
            btnSave.Enabled = False
            btnStop.Enabled = False
            btnStart.Enabled = True
            Trace.Assert(Not (bmap Is Nothing))
            filepath = Application.StartupPath & "\Images\" & frmChartOfAccounts.txtAcName.Text & frmChartOfAccounts.txtRegNo.Text & ".jpeg"
            bmap.Save(filepath)
            frmChartOfAccounts.txtimg.Text = filepath
        End If
    End Sub
    Private Sub Form1_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
        If btnStop.Enabled Then
            ClosePreviewWindow()
        End If
    End Sub
    Private Sub btnInfo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
        'SendMessage(hHwnd, WM_CAP_DLG_VIDEOFORMAT, 0&, 0&)
    End Sub

    Private Sub cmdExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdExit.Click
        Close()
    End Sub
    End Class

希望它會對你有所幫助。