VB6 - Capture any Window, even in background, with WinRT / Windows.Graphics.Capture

[Maatooh]

Certainly For the implementation of vb6 it is really a marvel.
I remember starting this thread: https://www.vbforums.com/showthread....nd-PrintWindow

But I ended up using PrintWindow. Now I'd like to use Windows.Graphics.Capture, which is great for reducing CPU load.

Do you think you could help me organize a .dll file to properly encapsulate this application? In fact, I created one with PrintWindow that creates a hidden picturebox at runtime. When I call a function, I capture the window image using Hwnd at that instant and can easily export it to another picturebox for easy scaling and cropping if needed.

Although in this case, I'd like to implement continuous capture, As you have done in your project. Doing this repeatedly with standard timers causes the yellow frame to flicker, which is a bit annoying on Windows 10.

Public CVHwnd As Long
Public CVCapture As PictureBox
Private CVForm As Form

'---------------------------------------------------------------
Private Declare Function GetDesktopWindow Lib "user32" () As Long
Private Declare Function GetWindowDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long
Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type
Private Declare Function PrintWindow Lib "User32.dll" (ByVal hwnd As Long, ByVal hdcBlt As Long, ByVal nFlags As Long) As Long
Private Declare Function GetWindowRect Lib "user32" (ByVal hwnd As Long, lpRect As RECT) As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
'----------------------------------------------------------------

Public Function SetupCapture(GHwnd As Long, ByRef GForm As Object)
On Error GoTo QH
    CVHwnd = GHwnd
    Set CVForm = GForm
    Set CVCapture = CVForm.Controls.Add("VB.PictureBox", "MainCaptureCV")
QH:
End Function

Public Function GetCapture(SMode As Long, Optional SWidth As Long, Optional SHeight As Long)
    Dim Calc_hWnd As Long
    Dim Calc_Rect As RECT
    
    CVForm.ScaleMode = vbPixels
    CVCapture.ScaleMode = vbPixels
    CVCapture.AutoRedraw = True
    ' Get Handle to windows calculator
    Calc_hWnd = CVHwnd
    
    ' get size of windows calculator
    If Calc_hWnd Then
        GetWindowRect Calc_hWnd, Calc_Rect
        ' size temp destination to calc
        If SWidth = 0 Then
        CVCapture.Width = (Calc_Rect.Right - Calc_Rect.Left)
        Else
        CVCapture.Width = SWidth
        End If
        
        If SHeight = 0 Then
        CVCapture.Height = (Calc_Rect.Bottom - Calc_Rect.Top)
        Else
        CVCapture.Height = SHeight
        End If
        
        ' capture it
        PrintWindow Calc_hWnd, CVCapture.hdc, SMode 'PW_CLIENTONLY Or PW_RENDERFULLCONTENT
        CVCapture.Refresh
        BitBlt CVCapture.hdc, 0, 0, _
                            CVCapture.ScaleWidth, _
                            CVCapture.ScaleHeight, _
                            CVCapture.hdc, 0, 0, vbSrcCopy
        CVCapture.Picture = CVCapture.Image
    Else
    'Msgbox "Err Cap"
    End If
    
End Function