Question

一个VB制作摄像头拍照的问题

在网上找到一个VB制作摄像头拍照的源码，如下：
Private Declare Function capCreateCaptureWindow Lib "avicap32.dll" _
Alias "capCreateCaptureWindowA" ( _
ByVal lpszWindowName As String, _
ByVal dwStyle As Long, _
ByVal x As Long, _
ByVal y As Long, _
ByVal nWidth As Long, _
ByVal nHeight As Long, _
ByVal hWndParent As Long, _
ByVal nID As Long) As Long
Private Const WS_CHILD = &H40000000
Private Const WS_VISIBLE = &H10000000
Private Const WM_USER = &H400
Private Const WM_CAP_START = &H400
Private Const WM_CAP_EDIT_COPY = (WM_CAP_START + 30)
Private Const WM_CAP_DRIVER_CONNECT = (WM_CAP_START + 10)
Private Const WM_CAP_SET_PREVIEWRATE = (WM_CAP_START + 52)
Private Const WM_CAP_SET_OVERLAY = (WM_CAP_START + 51)
Private Const WM_CAP_SET_PREVIEW = (WM_CAP_START + 50)
Private Const WM_CAP_DRIVER_DISCONNECT = (WM_CAP_START + 11)
Private Preview_Handle As Long
Private Declare Function SendMessage Lib "user32" _
Alias "SendMessageA" ( _
ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long
Private Function CapturePicture(nCaptureHandle As Long) As StdPicture
Clipboard.Clear
SendMessage nCaptureHandle, WM_CAP_EDIT_COPY, 0, 0
Set CapturePicture = Clipboard.GetData
End Function

Private Sub cmdCap_Click()
Picture1.Picture = CapturePicture(Preview_Handle)
End Sub

Private Sub cmdSave_Click()
On Error Resume Next
SavePicture Picture1.Picture, "C:\" & Format(Date, "dd-MM-yyyy") & " " & Format(Time, "hh-mm-ss") & ".bmp"
End Sub

Private Sub Form_Load()
Preview_Handle = capCreateCaptureWindow("Video", WS_CHILD + WS_VISIBLE, 2, 2, 320, 240, Me.hwnd, 1)
SendMessage Preview_Handle, WM_CAP_DRIVER_CONNECT, 0, 0
SendMessage Preview_Handle, WM_CAP_SET_PREVIEWRATE, 1, 0
SendMessage Preview_Handle, WM_CAP_SET_PREVIEW, 1, 0
End Sub

Private Sub Form_Unload(Cancel As Integer)
SendMessage Preview_Handle, WM_CAP_DRIVER_DISCONNECT, 0, 0
End Sub
预览的画面如果没有设置成使用的摄像头的分辨率的话，没有办法预览全部的图像，请大家看看，能不能改改。
不要改动Form_Load里面的320x240。

Answer 1

Preview_Handle = capCreateCaptureWindow("Video", WS_CHILD + WS_VISIBLE, 2, 2, 320, 240, Me.hwnd, 1)

320.240改