Rotate image???

[laura]

Ok, I saw many demo and project on rotate a picture. But all of them seem to be slow. Does anyone has a real fast one??

[HeSaidJoe]

it's all in the processor but most are slow because of the calculations needed...Just a thought, you could use an animated gif to get the same effect.

Look Here




[Edited by HeSaidJoe on 09-22-2000 at 01:56 PM]

[Jop]

I don't know if you used API for the processing, but I'm sure it's quite fast (can't test it tho)

Const SRCCOPY = &HCC0020 
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 As Long) 
'// 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 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

To Flip, rotate and mirror a picture.
Hope it's fast!