Color -> Color pixel change (Fast, not loop)

[kb244]

I want to be able to have a sort of function, where I can type for example.

changeme(picture1, RGB1, RGB2)

and it would change all pixels matching RGB1 into RGB2, and it must be fast, looping thru each pixel is painstakinly slow.

[plenderj]

Dont put a DoEvents statement in your loops ...
I shall demonstrate ....

[plenderj]

This only takes a few seconds on my system :

Option Explicit

Private Declare Function GetPixel Lib "gdi32" (ByVal hDc As Long, ByVal x As Long, ByVal y As Long) As Long
Private Declare Function SetPixel Lib "gdi32" (ByVal hDc As Long, ByVal x As Long, ByVal y As Long, ByVal crColor As Long) As Long



Private Sub Form_Load()
    'draw some coloured pixels
    Dim i As Long
    For i = 0 To 10000
        Picture1.PSet (i * Rnd, i * Rnd), vbRed
    Next i
    
    Me.Show
    DoEvents
    
    'now do the change
    changeMe Picture1, RGB(255, 0, 0), RGB(0, 255, 0)
    
End Sub

Private Sub changeMe(xPictureBox As PictureBox, srcColour As Long, dstColour As Long)
    Dim i As Long
    Dim j As Long
    Dim nWidth As Long
    Dim nHeight As Long
    Dim hDc As Long
    nWidth = xPictureBox.ScaleWidth
    nHeight = xPictureBox.ScaleHeight
    hDc = xPictureBox.hDc
    
    xPictureBox.Visible = False
    DoEvents
    For i = 0 To nWidth
        For j = 0 To nHeight
            If (GetPixel(hDc, i, j) = srcColour) Then
                SetPixel hDc, i, j, dstColour
            End If
        Next j
    Next i
    DoEvents
    xPictureBox.Visible = True
End Sub

[kedaman]

Getpixel/Setpixel are freakingly slow, check out the DMA samples using safe arrays on unlimited realities [/B][/QUOTE] if that's not fast enough, you can code the algoritm in c++ with best performance.

[plenderj]

Pfff I think my idea's ok

[kedaman]

Nope, it really sucks screw RGB function

[plenderj]

Okay then how about this :

Private Function myRGB(nRed As Long, nGreen As Long, nBlue As Long) As Long
    myRGB = (nRed * 1) + (nGreen * 256) + (nBlue * 65536)
End Function

[kedaman]

worse... use the hex notation

[plenderj]

'twas a joke ked

oh yeah , and what was the thing about that number ?

[kedaman]

okay, since nobody'll never get it, i'll give you the last hint: base convertion

[plenderj]

What do you mean the last hint ?
You never game me any ****ing hints