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Crop Image

x50Fade
x50Fade asked
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Last Modified: 2012-08-14
Ok. Using a webcam to capture a pic of a client.

The web cam's orientation is landscape, I need to capture a portrait. So I make the picturebox the right size. I then want to capture what I see in the picture box. (top left of the webcam feed). The picbox however saves the whole feed, not just the part that is visible to me.

I have tried to use this, but cannot get it to work effectively.

            bmpImage = New Bitmap(picCapture.Image)
            recCrop = New Rectangle(0, 0, 96, 120)
            bmpCrop = New Bitmap(recCrop.Width, recCrop.Height, bmpImage.PixelFormat)
            gphCrop = Graphics.FromImage(bmpCrop)
            recDest = New Rectangle(0, 0, 96, 120)
            gphCrop.DrawImage(bmpImage, recDest, recCrop.X, recCrop.Y, recCrop.Width, recCrop.Height, GraphicsUnit.Pixel)



            bmpCrop.Save(Application.StartupPath & "\tmp.jpg", Imaging.ImageFormat.Jpeg)

Depending on the size of recCrop, I either get a very small top left part of the pic, (pic dimensions of 96x120), but really its a VERY small part of the top left corner. If I make recCrop 640x480, I get a 640x480 pic with the top left the piece that I want.???

PLease help.
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CERTIFIED EXPERT
Most Valuable Expert 2012
Top Expert 2008

Commented:
I don't understand what you are looking for.

Bob
High School Computer Science, Computer Applications, Digital Design, and Mathematics Teacher
CERTIFIED EXPERT
Top Expert 2009
Commented:
Here is a different approach...we simply take a screen cap of your picturebox:

    Private Const SRCCOPY = &HCC0020

    Private Declare Function CreateDC Lib "gdi32" Alias "CreateDCA" (ByVal lpDriverName As String, ByVal lpDeviceName As String, ByVal lpOutput As String, ByVal lpInitData As String) As Integer
    Private Declare Function CreateCompatibleDC Lib "GDI32" (ByVal hDC As Integer) As Integer
    Private Declare Function CreateCompatibleBitmap Lib "GDI32" (ByVal hDC As Integer, ByVal nWidth As Integer, ByVal nHeight As Integer) As Integer
    Private Declare Function SelectObject Lib "GDI32" (ByVal hDC As Integer, ByVal hObject As Integer) As Integer
    Private Declare Function BitBlt Lib "GDI32" (ByVal hDestDC As Integer, ByVal X As Integer, ByVal Y As Integer, ByVal nWidth As Integer, ByVal nHeight As Integer, ByVal hSrcDC As Integer, ByVal SrcX As Integer, ByVal SrcY As Integer, ByVal Rop As Integer) As Integer
    Private Declare Function DeleteObject Lib "GDI32" (ByVal hObj As Integer) As Integer
    Private Declare Function DeleteDC Lib "GDI32" (ByVal hDC As Integer) As Integer

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ' convert PictureBox rectangle coordinates to screen coordinates
        Dim r As Rectangle = Me.RectangleToScreen(New Rectangle(Me.picCapture.Location, Me.picCapture.Size))
        ' grab the image of the PictureBox
        Dim bmp As Bitmap = GetScreen(r.X, r.Y, r.Width, r.Height)
        ' do something with it...
        bmp.Save(Application.StartupPath & "\tmp.jpg", Imaging.ImageFormat.Jpeg)
    End Sub

    Private Function GetScreen(ByVal X As Integer, ByVal Y As Integer, ByVal Width As Integer, ByVal Height As Integer) As Bitmap
        Dim hDeskDC As Integer
        Dim hTempDC As Integer
        Dim hBitmap As Integer
        Dim hTempBmp As Integer
        Dim desktopArea As Bitmap

        hDeskDC = CreateDC("DISPLAY", "", "", "")
        If hDeskDC Then
            hTempDC = CreateCompatibleDC(hDeskDC)
            If hTempDC Then
                hBitmap = CreateCompatibleBitmap(hDeskDC, Width, Height)
                If hBitmap Then
                    hTempBmp = SelectObject(hTempDC, hBitmap)
                    BitBlt(hTempDC, 0, 0, Width, Height, hDeskDC, X, Y, SRCCOPY)
                    desktopArea = Bitmap.FromHbitmap(New IntPtr(hBitmap))
                    DeleteObject(SelectObject(hTempDC, hTempBmp))
                End If
                DeleteDC(hTempDC)
            End If
            DeleteDC(hDeskDC)
        End If
        Return desktopArea
    End Function

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