OpenEuphoria

2. Re: WebCam with wxEuphoria

• Posted by mattlewis (admin) Mar 25, 2011
• 1354 views

image = {{{R,G,B},{R,G,B},{R,G,B},{R,G,B}}, 
         {{R,G,B},{R,G,B},{R,G,B},{R,G,B}}, 
         {{R,G,B},{R,G,B},{R,G,B},{R,G,B}}} 

I suppose there are a few ways to go here. It's hard to say which will be best, since I'm not sure what all you need to do.

1. Looking at the OpenCV docs, you could use cvSaveImage(), and then load it from your code. This is probably the easiest, but also likely the slowest.
2. You could encode it on the fly as an XPM, and pass that to the constructor.
3. You could create a bitmap in memory, use a wxMemoryDC, and use draw_point.

I suspect that #2 may be the fastest, but it's hard to say.

Matt

4. Re: WebCam with wxEuphoria

• Posted by raseunew Mar 27, 2011
• 1356 views

I have been able to successfully map from an SDL image buffer
to a wxWidgets buffer and display images.

See below for code snippets.

wxWidgets requires images to be in BGR format, where
the list of bytes is a single sequence buffer.

so, an image buffer of

image = {{{R,G,B},{R,G,B},{R,G,B},{R,G,B}},  
         {{R,G,B},{R,G,B},{R,G,B},{R,G,B}},  
         {{R,G,B},{R,G,B},{R,G,B},{R,G,B}}} 

would need to be 'flattened'. I think eu4 standard library
has a flatten() function

if your opencv image is RGB it will
need to be converted.

 
--// Convert SDL surface from RGB to BGR 
public enum 
		ofsRED   = 1, 
		ofsGREEN, 
		ofsBLUE, 
		ofsALPHA 
 
public function RGBtoBGR(sequence rgbbuf, integer bytesPerPixel=3) 
	--// swap B with R 
	sequence bgrbuf = {} 
	sequence rgb    = {} 
	integer  l = length(rgbbuf) 
	for i = 1 to l by bytesPerPixel do 
		rgb = rgbbuf[i..(i + (bytesPerPixel - 1))] 
		bgrbuf &= { rgb[ofsBLUE], rgb[ofsGREEN], rgb[ofsRED] } 
	end for 
	--// return buffer 
	atom bgr = allocate(length( rgbbuf )) 
	poke(bgr, bgrbuf) 
	return bgr 
end function 
 

something similar to the following will display
a BGR buffer to a wxWidgets DC.

--// convert sdl surface into wx compatible buffer 
-- atom bgr = RGBtoBGR(sdlcanvas, 3) 
 
/* 

    you would probably need to flatten your image  
    here and create your bgr surface 
*/ 
 
atom bgr = RGBtoBGR( flatten(openCVImage), 3)     
 
--// create image from converted bgr surface 
atom img = wx:create(wxImage, { openCVImageWidth, openCVImageHeight, bgr }) 
--// free converted bgr surface 
free(bgr) 
 
--// create bitmap from image 
atom bmp = wx:create(wxBitmap,{ BM_FROM_IMAGE, img, -1 }) 
 
--// update client DC 
atom clientDC = wx:create(wxClientDC, this) 
wx:begin_drawing(clientDC) 
wx:draw_bitmap(clientDC, bmp, 0, 0, true) 
wx:end_drawing(clientDC) 
 
--// clean up 
wx:delete_instance(clientDC) 
wx:delete_instance(bmp) 
wx:delete_instance(img) 
 

HTH

6. Re: WebCam with wxEuphoria

• Posted by mattlewis (admin) Mar 28, 2011
• 1272 views

There might be some ways to speed it up. For instance, since you're capturing video, many of the pixels may not be changing in each frame. You could possibly skip updating those. You might also detect if you have the same color pixel multiple times, and use draw_line() to reduce the number of calls. There might also be some micro optimizations possible in your euphoria code. Finally, you might compare the difference interpreted vs translated.

--// create image from converted bgr surface 
atom img = wx:create(wxImage, { openCVImageWidth, openCVImageHeight, bgr }) 
--// free converted bgr surface 
free(bgr) 
 
--// create bitmap from image 
atom bmp = wx:create(wxBitmap,{ BM_FROM_IMAGE, img, -1 }) 

I'm really surprised that works at all. The "data" parameter is supposed to be XPM data. If you're not familiar with XPM, there are several used in the demos. When they're created, the wxEuphoria library converts the euphoria sequences into "raw" xpm char data. It's basically an array of pointers to C strings.

You can pass the euphoria sequence versions to the wxBitmap constructor, and the library converts it, or you can convert it yourself and pass it to the wxImage constructor.

Matt