[RESOLVED] Minimum code to draw PNG? GDI+?

[DigiRev]

What's the minimum code I can use to draw a PNG with alpha transparency (of course) to a window/device context?

ಠ_ಠ

Edit: Let me add that I'm making a 2D side-scrolling game and want to be able to use PNGs. I might also have to have collision detection while taking alpha transparency into effect. Any ideas on this?

[LaVolpe]

Private Declare Function GdiplusStartup Lib "gdiplus" (Token As Long, inputbuf As GdiplusStartupInput, Optional ByVal outputbuf As Long = 0) As Long
Private Declare Function GdipLoadImageFromFile Lib "GdiPlus.dll" (ByVal mFilename As Long, ByRef mImage As Long) As Long
Private Declare Function GdipDeleteGraphics Lib "GdiPlus.dll" (ByVal mGraphics As Long) As Long
Private Declare Function GdipCreateFromHDC Lib "gdiplus" (ByVal hDC As Long, hGraphics As Long) As Long
Private Declare Function GdipDrawImage Lib "GdiPlus.dll" (ByVal mGraphics As Long, ByVal mImage As Long, ByVal mX As Single, ByVal mY As Single) As Long
Private Declare Function GdipDisposeImage Lib "gdiplus" (ByVal Image As Long) As Long
Private Declare Sub GdiplusShutdown Lib "gdiplus" (ByVal Token As Long)
Private Type GdiplusStartupInput
    GdiplusVersion           As Long
    DebugEventCallback       As Long
    SuppressBackgroundThread As Long
    SuppressExternalCodecs   As Long
End Type

Private Function RenderPNG(FileName As String, hDC As Long, X As Long, Y As Long) As Boolean
    On Error Resume Next
    Dim GDIsi As GdiplusStartupInput, gToken As Long, hGraphics As Long, hBitmap As Long
    GDIsi.GdiplusVersion = 1&
    GdiplusStartup gToken, GDIsi
    If Err Then
          Err.Clear
          Exit Function
    ElseIf gToken = 0& Then
         Exit Function
    End If
    On Error Goto 0
    Call GdipCreateFromHDC(hDC, hGraphics)
    If hGraphics Then
        Call GdipLoadImageFromFile(StrPtr(FileName), hBitmap)
        If hBitmap Then
            GdipDrawImage hGraphics, hBitmap, X, Y
            GdipDisposeImage hBitmap
            RenderPNG = True
        End If
        GdipDeleteGraphics hGraphics
    End If
    GdiplusShutdown gToken
    
End Function

The above code is about as basic is it gets. Not much room for customization. To render the image at different sizes, more API calls needed to get the image size and a different draw API needed to render at different sizes: GdipGetImageBounds & GdipDrawImageRectRectI APIs respectively

Other tips:
-- The gdi+ token, especially in a game, is best to be retrieved at form load and released in form terminate. You really don't want to take extra cpu cycles creating/destroying it every time you load/draw an image
-- The hBitmap should be cached too as long as the game piece is being moved; obviously loading the image every time you want to paint it is wasting time.

Worth bookmarking: http://www.jose.it-berater.org/gdiplus/iframe/index.htm

[DigiRev]

Thanks, LaVolpe. Figured you'd be the one to answer.

ಠ_ಠ

[koolsid]

Another interesting thread....

http://www.vbaccelerator.com/home/vb...on/article.asp

Edit:

Yeah LaVolpe is good with that

[LaVolpe]

Thanks, LaVolpe. Figured you'd be the one to answer.

ಠ_ಠ

You're welcome. I did add a worthwhile GDI+ bookmark to my reply and also turned off On Error Resume Next in the sample code. Never want to leave that on indefinitely

[whatsup]

btw: is there an API to saveimagefile ?
or i have to know the png format for example
and save it bit by bit ?

[LaVolpe]

btw: is there an API to saveimagefile ?
or i have to know the png format for example
and save it bit by bit ?

See this thread in the CodeBank section. You'll have to extract what you need or simply use it as a guide to rebuild the SaveAs routine you need. The thread has examples of saving as bitmap, jpg, png & tiff.

[makice]

I found this http://www.almostfreeware.com/prod/1001/index.php while searching for LaVolpe AlphaImage Control.
Is this commercial version of LaVolpe Control or somebody has older version and tries to make money from selling someone else's work?