how use CopyMemory() on VB6?

[Joaquim_5]

how can i use CopyMemory() on VB6?
i have these funcion:

Public Sub Clear(BGRColor As Long)
    Dim i As Long
    For i = 0 To (Width * Height) - 1
        CopyMemory ByVal PixelData(0) + (i * 4), vbGreen, 4
    Next i
End Sub

how can avoid the 'for' loop?
i tried:

Public Sub Clear2(BGRColor As Long)
    Dim i As Long
    i = ((Width * Height) - 1) * 4
    CopyMemory ByVal PixelData(0), vbGreen, i
End Sub

but seems that i fail on 'i' calculation(array size)... maybe because we have 4 bytes by a pixel?

[rproffitt]

From memory (pun unintended) I think you should think about using BitBlt. Read https://www.vbforums.com/showthread.php?271014-VB-6-BitBlt

[Joaquim_5]

the BitBlt() is for draw the image from 1 HDC to another HDC.

[rproffitt]

While I can't guess the intended use, read https://stackoverflow.com/questions/55909731/how-can-an-hdc-bitmap-be-copied-to-a-3-dimensional-array-quickly on how to go from an HDC to arrays.

[Joaquim_5]

on VB6 is more hard to use pointers.. it's possible, i know that, because i'm doing it, but we must know what we are doing, because it's pointers(like Multithread)...
but how can i fill a memory pointer that have 4 bytes by a pixel?(RGBA)

[Joaquim_5]

thank you so much for all to all

[Joaquim_5]

rproffitt my big goal, like others topics\questions, is using DIB's on VB6... but the pixel data be a pointer for change the pixel, using the pixel data array, directly on HDC\HBITMAP.
theres some ways:
http://www.vbaccelerator.com/home/VB/Code/vbMedia/DIB_Sections/Alpha_DIBSection/article.html
and: http://www.vbaccelerator.com/home/VB/Code/vbMedia/DIB_Sections/True_Colour_DIBSection/article.html
but i need learn use it. thanks for all

[Jane_11]

Working with pointers in VB6 can be more challenging, but it's certainly possible. It requires a thorough understanding of the concept, as dealing with pointers is akin to managing multithreading – precise knowledge is key. However, I'm intrigued by a specific aspect: how to effectively populate a memory pointer that accommodates 4 bytes for each pixel (representing RGBA). This indicates a nuanced exploration of memory management within VB6, demonstrating an advanced level of expertise. Could you kindly share your insights on accomplishing this task? Your experience could greatly benefit those navigating similar complexities.

[Joaquim_5]

i need some time.. but i will share it ;)

[Gulshan_6]

Well, script that you have tries have some issue, can you try below script.

   Public Sub Clear2(BGRColor As Long)
        Dim i As Long
        Dim dataSize As Long

        ' Calculate the total size of the array in bytes
        dataSize = (Width * Height) * 4

        ' Use CopyMemory to fill the entire array with the specified color
        CopyMemory ByVal PixelData(0), ByVal VarPtr(BGRColor), dataSize
    End Sub

Thanks