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Flip Mirror & Rotate

Flip Mirror & Rotate

API Declarations



' add three command buttons and two pictureboxes. Load a bitmap into picture1 in design
' mode. Set both box to the same size. Routines execute 3 times faster than routines
' found in Microsoft's Knowledge Base.




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(1(1 Vote))

               'Const Pi = 3.14159265359
               'private Declare Function SetPixel Lib "GDI32" (ByVal hDC As Integer, ByVal X As Integer, ByVal Y As Integer, ByVal crColor As Long) As Long
               'private Declare Function GetPixel Lib "GDI32" (ByVal hDC As Integer, ByVal X As Integer, ByVal Y As Integer) As Long
               'private Declare Function StretchBlt% Lib "GDI32" (ByVal hDC%, ByVal X%, ByVal Y%, ByVal nWidth%, ByVal nHeight%, ByVal hSrcDC%, ByVal XSrc%, ByVal YSrc%, ByVal nSrcWidth%, ByVal nSrcHeight%, ByVal dwRop&)

               'Sub Form_Load ()
                picture1.ScaleMode = 3
                picture2.ScaleMode = 3
               'End Sub


               'Sub Command1_Click ()
               'flip horizontal
                picture2.Cls
                px% = picture1.ScaleWidth
                py% = picture1.ScaleHeight
                retval% = StretchBlt(picture2.hDC, px%, 0, -px%, py%, picture1.hDC, 0, 0, px%, py%, SRCCOPY)
               'End Sub


               'Sub Command2_Click ()
                'flip vertical
                picture2.Cls
                px% = picture1.ScaleWidth
                py% = picture1.ScaleHeight
                retval% = StretchBlt(picture2.hDC, 0, py%, px%, -py%, picture1.hDC, 0, 0, px%, py%, SRCCOPY)
               'End Sub

               'Sub Command3_Click ()
                'rotate 45 degrees
                picture2.Cls
                Call bmp_rotate(picture1, picture2, 3.14 / 4)
               'End Sub


               'Sub bmp_rotate (pic1 As PictureBox, pic2 As PictureBox, ByVal theta!)
                ' bmp_rotate(pic1, pic2, theta)
                ' Rotate the image in a picture box.
                '   pic1 is the picture box with the bitmap to rotate
                '   pic2 is the picture box to receive the rotated bitmap
                '   theta is the angle of rotation
                Dim c1x As Integer, c1y As Integer
                Dim c2x As Integer, c2y As Integer
                Dim a As Single
                Dim p1x As Integer, p1y As Integer
                Dim p2x As Integer, p2y As Integer
                Dim n As Integer, r   As Integer

                c1x = pic1.ScaleWidth \ 2
                c1y = pic1.ScaleHeight \ 2
                c2x = pic2.ScaleWidth \ 2
                c2y = pic2.ScaleHeight \ 2

                If c2x < c2y Then n = c2y Else n = c2x
                n = n - 1
                pic1hDC% = pic1.hDC
                pic2hDC% = pic2.hDC

                For p2x = 0 To n
                  For p2y = 0 To n
                    If p2x = 0 Then a = Pi / 2 Else a = Atn(p2y / p2x)
                    r = Sqr(1& * p2x * p2x + 1& * p2y * p2y)
                    p1x = r * Cos(a + theta!)
                    p1y = r * Sin(a + theta!)
                    c0& = GetPixel(pic1hDC%, c1x + p1x, c1y + p1y)
                    c1& = GetPixel(pic1hDC%, c1x - p1x, c1y - p1y)
                    c2& = GetPixel(pic1hDC%, c1x + p1y, c1y - p1x)
                    c3& = GetPixel(pic1hDC%, c1x - p1y, c1y + p1x)
                    If c0& <> -1 Then xret& = SetPixel(pic2hDC%, c2x + p2x, c2y + p2y, c0&)
                    If c1& <> -1 Then xret& = SetPixel(pic2hDC%, c2x - p2x, c2y - p2y, c1&)
                    If c2& <> -1 Then xret& = SetPixel(pic2hDC%, c2x + p2y, c2y - p2x, c2&)
                    If c3& <> -1 Then xret& = SetPixel(pic2hDC%, c2x - p2y, c2y + p2x, c3&)
                  Next
                  t% = DoEvents()
                Next
               'End Sub