help learn from example

[busta]

I can't figure out how something so simple was done..

http://www.Planet-Source-Code.com/vb...50597&lngWId=1

I was interested in this code and noticed something very simple that I notice in alot of VB projects from PLC... the background of the images are already transparent/\.. or just the same color as the form.. I couldn't figure out how this was done... Can someone please explain it to me?

[RhinoBull]

Hi and welcome to our forums!

It looks to me that those images are small (32x32) icons which support transparency.

[Jacob Roman]

Yeah, you need two of the same image. One is the actual image with a black background, and the othe is the mask, which is the same image only with a white background and the image itself is all black. Then you do this:

Const SRCCOPY = &HCC0020         ' (DWORD) dest = source
Const SRCPAINT = &HEE0086        ' (DWORD) dest = source OR dest
Const SRCAND = &H8800C6          ' (DWORD) dest = source AND dest
Const SRCINVERT = &H660046       ' (DWORD) dest = source XOR dest
Const SRCERASE = &H440328        ' (DWORD) dest = source AND (NOT dest )
Const NOTSRCCOPY = &H330008      ' (DWORD) dest = (NOT source)
Const NOTSRCERASE = &H1100A6     ' (DWORD) dest = (NOT src) AND (NOT dest)
Const DSTINVERT = &H550009       ' (DWORD) dest = (NOT dest)
 
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hsrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
 
Private Sub Command1_Click()
 
BitBlt picDest.hdc, 0, 0, 60, 46, picMask.hdc, 60, 0, SRCAND 
BitBlt picDest.hdc, 0, 0, 60, 46, picSprite.hdc, 60, 0, SRCPAINT 
 
End Sub

[RhinoBull]

Nope, you don't need two images - all you need is an icon editor to create icon type file with transparent background.

There are plenty of free icon editors but master of all is of course Microangelo (not free though).

[busta]

ok thanks for the info. I was messing with photoshop and found out why. I was saving the pics in bmp which dont support transparent background apparently.. neither do jpegs.. but when I tried gif it worked so I'm good to go. thanks again people.

[RhinoBull]

GIFs do support trans but VB has a problem with refreshing these type images - you may experience flickering effect so try to convert then to icons.

[Jacob Roman]

What if you don't want icons and need images. Aren't images the standard when making games?

[RhinoBull]

There are many types of images and icons are one of them.
Windows icons are small images that support transparency.
Their sizes are vary between 16 and 128 pixels but majority of icon editors support only upto 64x64.
When you need to use small images in your app - icons are the best.
GIFs and JPGs are ok but flicker on every refresh so your screen looks like ... well you know.
VB is best with BMPs but those don't support transparency and are much larger files.

[busta]

so the best thing to do when making games with larger images is to use bitblt trans on bmp pics?

[RhinoBull]

Why not - works fine for me and more important no flickering.