20 | 09 | 2017

Preview Webcam and capture image

{jcomments on}The code below will show the webcams image into a picturebox and can be saved with the use of a savebutton.



Webcam Preview

'Impression of the preview screen'

Imports System.IO

Public Class FrmCap
'Create constant using attend in function of DLL file.

Const CAP As Short = &H400S
Const CAP_DRIVER_CONNECT As Integer = CAP + 10
Const CAP_EDIT_COPY As Integer = CAP + 30
Const CAP_SET_PREVIEW As Integer = CAP + 50
Const CAP_SET_PREVIEWRATE As Integer = CAP + 52
Const CAP_SET_SCALE As Integer = 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

Dim iDevice As Integer = 0 ' Normal device ID
Dim hHwnd As Integer ' Handle value to preview window

' Declare function from AVI capture DLL.

Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
ByVal lParam As Object) As Integer

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

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

Private Sub OpenForm()
Dim iHeight As Integer = picCapture.Height
Dim iWidth As Integer = picCapture.Width

' Open Preview window in picturebox .
' Create a child window with capCreateCaptureWindowA so you can display it in a picturebox.

hHwnd = capCreateCaptureWindowA(iDevice, WS_VISIBLE Or WS_CHILD, 0, 0, 640, _
480, picCapture.Handle.ToInt32, 0)
' Connect to device
If SendMessage(hHwnd, CAP_DRIVER_CONNECT, iDevice, 0) Then

' Set the preview scale
SendMessage(hHwnd, CAP_SET_SCALE, True, 0)

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

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

' Resize window to fit in picturebox
SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, picCapture.Width, picCapture.Height, _
' Error connecting to device close window

End If
End Sub

' Use SendMessage to copy the data to the clipboard Then transfer the image to the picture box.

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
Dim data As IDataObject
Dim bmap As Image
' Copy image to clipboard
SendMessage(hHwnd, 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)), Image)
picCapture.Image = bmap

Dim saveFileDialog1 As New SaveFileDialog()
saveFileDialog1.Filter = "Jpeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif"
saveFileDialog1.Title = "Save an Image File"
saveFileDialog1.FileName = "Image001"

' If the file name is not an empty string open it for saving.
If saveFileDialog1.FileName <> "" Then
' Saves the Image via a FileStream created by the OpenFile method.
Dim fs As System.IO.FileStream = CType _
(saveFileDialog1.OpenFile(), System.IO.FileStream)
picCapture.Image.Save(fs, System.Drawing.Imaging.ImageFormat.Jpeg)
End If

End If
End Sub

Private Sub frmcap_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Leave
' Disconnect from device
SendMessage(hHwnd, CAP_DRIVER_DISCONNECT, iDevice, 0)
' close window
End Sub

Private Sub FRMCAP_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
End Class

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