How do replicate "RenderSurfaceWithinCorners" in my matrix calculation?

I would like to include an image perspective warping option in my existing matrix calculation ("DrawTo", stated at the end of this post).
A great example using RenderSurfaceWithinCorners is in this thread.

My problem is that I can not use RenderSurfaceWithinCorners, and I am looking for a way to transform a matrix (which I use to render an image using RC6) so that the image is render as if I was using RenderSurfaceWithinCorners.

The reason I can't utilize RenderSurfaceWithinCorners is that I need to maintain image centering while compensating for x and y offsets + scaling + rotating. Therefore, I'm seeking an alternative way to transform a matrix that I use with RC6 to render images similarly to how RenderSurfaceWithinCorners would.

How could I replicate such a perspective warping in the my "DrawTo" function?

Attachment 193845

This is the code that would do what I want (but which I can not use):

Code:

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Private Sub DrawRotated(Ang As Double, ByVal PerspectiveFactor As Double)
    Dim DeltaX    As Double
    Dim DeltaY    As Double
    Dim CenterX#
    Dim X1#, Y1#, X2#, Y2#
    Dim X3#, Y3#, X4#, Y4#

    Const kDeformY As Double = 55

    DeltaX = TargetWidth * 0.5 * Cos(-Ang * 3.14159265358979)
    DeltaY = kDeformY * Sin(-Ang * 3.14159265358979) * PerspectiveFactor

    CenterX = PIC.ScaleWidth * 0.5
    X1 = CenterX + DeltaX
    Y1 = kDeformY + DeltaY
    X2 = CenterX - DeltaX
    Y2 = kDeformY - DeltaY
    X3 = X2
    Y3 = TargetHeight - kDeformY + DeltaY
    X4 = X1
    Y4 = TargetHeight - kDeformY - DeltaY

    If Sgn(DeltaX) <> Sgn(OldDX) Then
        If CurrImg = "IMG1" Then CurrImg = "IMG2" Else: CurrImg = "IMG1"
        OldDX = DeltaX
    End If

    CC.SetSourceColor 0: CC.Paint
    CC.RenderSurfaceWithinCorners CurrImg, X1, Y1, X2, Y2, X3, Y3, X4, Y4

    Srf.DrawToDC PIC.hDC
    DoEvents
End Sub

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Code:

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Public Function DrawTo(ByRef uDestCC As cCairoContext, ByVal uLeft As Long, ByVal uTop As Long) As Boolean

    If m_Img Is Nothing Then
        Exit Function
    End If

    Dim dblOffx As Double: Dim dblOffy As Double
   
    Dim dblNewWidth As Double
    Dim dblNewHeight As Double
    dblNewWidth = (m_Img.Width * Me.ScaleFactorWidth)
    dblNewHeight = (m_Img.Height * Me.ScaleFactorHeight)

   
    If (dblNewWidth = 0) Or (dblNewHeight = 0) Or (m_dblAlpha < 0.05) Then
        Exit Function
    End If
   
  uDestCC.Save
        ' Calculate offsets based on alignment and scaling
        dblOffx = Me.AlignmentFactorX * (dblNewWidth / 2)
        dblOffy = Me.AlignmentFactorY * (dblNewHeight / 2)
       
        Dim dblNewX1 As Double:  Dim dblNewY1 As Double
        dblNewX1 = (uLeft + dblOffx)
        dblNewY1 = (uTop + dblOffy)
       
        Dim dblNewX2 As Double: Dim dblNewY2 As Double
        dblNewX2 = -(m_Img.Width / 2) - (Me.CenterOffsetX / 2)
        dblNewY2 = -(m_Img.Height / 2) - (Me.CenterOffsetY / 2)



        m_Matrix.TranslateCoords dblNewX1, dblNewY1
        m_Matrix.RotateCoordsDeg m_sngAngleDeg
        m_Matrix.SkewXDeg m_dblPerspectiveFactor * Me.ScaleFactorWidth
        m_Matrix.ScaleCoords Me.ScaleFactorWidth, Me.ScaleFactorHeight
        m_Matrix.TranslateCoords dblNewX2, dblNewY2

        ' Set the final transformation
        Set uDestCC.Matrix = m_Matrix
       
        ' Now draw the image with the same transformations
        uDestCC.RenderSurfaceContent m_Img, 0, 0, , , , m_dblAlpha
   
        Dim corners(3) As POINT  ' Array of points for 4 corners
        'Define rectangle corners using the "m_Img" surface dimensions
        corners(0).x = 0: corners(0).y = 0  ' Top Left
        corners(1).x = m_Img.Width: corners(1).y = 0 ' Top right
        corners(2).x = 0: corners(2).y = m_Img.Height ' Bottom left
        corners(3).x = m_Img.Width: corners(3).y = m_Img.Height ' Bottom right
   
        ' Transform each corner point
        Dim i As Integer
        For i = 0 To 3
            m_Matrix.CalculatePoint corners(i).x, corners(i).y
        Next
       
        'Determine the render rect
        Dim cornerTopLeft As POINT
        Dim cornerBottomRight As POINT
     
        'Start with "invalid" values
        cornerTopLeft.x = 999999
        cornerTopLeft.y = 999999
        cornerBottomRight.x = -999999
        cornerBottomRight.y = -999999
   
        For i = 0 To 3
            Dim n As POINT
            n = corners(i)
           
            'Search minimum "x" for TopLeft
            If n.x < cornerTopLeft.x Then
                cornerTopLeft.x = n.x
            End If
           
            'Search minimum "y" for TopLeft
            If n.y < cornerTopLeft.y Then
                cornerTopLeft.y = n.y
            End If
           
            'Search maximum "x" for BottomRight
            If n.x > cornerBottomRight.x Then
                cornerBottomRight.x = n.x
            End If
           
            'Search maximum "y" for BottomRight
            If n.y > cornerBottomRight.y Then
                cornerBottomRight.y = n.y
            End If
        Next
   
        'store the render corners
        m_TopX = cornerTopLeft.x
        m_TopY = cornerTopLeft.y
     
        m_BottomX = cornerBottomRight.x
        m_BottomY = cornerBottomRight.y

        ' Clear the path
        uDestCC.ClearPath False

        m_Matrix.ResetToIdentity

    uDestCC.Restore

    DrawTo = True

End Function

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I noticed that I put this thread into the wrong forum. Could an admin put it into the VB6 forum instead? Thank you very much!