An easy question in DirectX(Direct Draw)

[007shahid]

I am a newbie in DX. While creating a surface from a picture file we use Set Surface=DirectDraw.CreateSurfaceFromFile().
My question is there is also a function DirectDraw.GetSurfaceFromDC() and I want to know how to use this. I tried getting the hDc of a picture box but no luck.

[PsychoMark]

Used this in Delphi a few days ago, don't quite remember the VB way, but since it's all just directx, it should be similar. Therefore, a little pseudo-code:

'// Set up a DDSURFACEDESC2 with the width & height and stuff,
'// then create an empty surface
Set Surface = DirectDraw.CreateSurface()
 
'// Get DC
DC = Surface.GetDC()
 
'// Draw from source DC onto surface DC
BitBlt(Source, 0, 0, Width, Height, DC, 0, 0, vbSrcCopy)
 
'// Release DC
Surface.ReleaseDC(DC)

Should work something like that


[edit]
oops, used Delphi-style comments
[/edit]

[Sastraxi]

I think you're trying to use it the wrong way- you're trying to get the picture from a DC into the Surface, while what that function does is allows you to use the surface in GDI operations. It returns the DC rather than setting it.

[PsychoMark]

*cough* I need a DC for the BitBlt operation


[edit]
I used this technique in Delphi, since a surface doesn't have a CreateFromFile function. I don't know if this is a bad translation of the C header files or that they added that function to the interface for VB... my point: this method is correct


Interesting, the text functions have disappeared too. I have to manually get the DC and draw the text using TextOut... I think that the VB import library does that too, every time you call it, that's why Surface.TextOut is slow
[/edit]

[007shahid]

Yeah I was trying to set the DC. Actually I tried using the mask technique to make an area invisible using BitBlt and then set that DC to the surface. I am just a newbie and don't know much in DX. Can anyone give some help.

[PsychoMark]

Use the SetColorKey function of the surface to get a color transparent


http://www.vbexplorer.com/directx4vb/ explains it quite good

[007shahid]

Thanks, I got it