OpenEuphoria

1. GDI Plus library

• Posted by LewisTownsend Jan 23, 2010
• 1455 views

Howdy folks,

long time no post.

I've been trying to work with Al Getz' GDI+ wrapper lib as a hopefully faster alternative to Win32lib graphics functions. However, before I can even tell if this is going to be faster, I have to figure out some of the undocumented functions. I have figured out several but I'm currently stumped at the draw polygon functions. I'm not a C programmer so I don't know how exactly to format the points data in memory so that the cfunc can use it. I've tried just about everything I can think of and have done some Google searching but so far haven't got it to work. I'm assuming that the points are stored in some kind of standard c-array format but I don't know what that is. I have at least one other thing I can think to try but I figured I should ask before banging my head against this any more.

I know this lib hasn't been modified recently and the most relevant discussion here seems to be a few years ago. http://oe.cowgar.com/forum/87068.wc#87068 For fast image copying and basic graphics functions; should I be using something else, like DirectDraw, etc? Please note I'm not sure I could write my own wrapper and would probably have the same problem with anything else in C.

thanks for any help or advice

Lewis Townsend

3. Re: GDI Plus library

• Posted by LewisTownsend Jan 26, 2010
• 1411 views

EDITED

Thanks ssallen,

I'm actually trying to edit the wrapper to make it easier to use. like making it do all the allocating and peeking and poking for you I've been able to figure out quite a bit and simplified it for my purposes but I'm still stuck on this points thing.

I think most Euphoria programmers like Euphoria because of it's simplicity. I think those same (most) probably couldn't use GDI+ because it returns the complexity of C

Ok, so I thought I might get more responses if I posted some code:

global procedure WrongDrawLinePolygon(atom p_graphics,atom p_pen, sequence points ) --,atom count) 
	-- points is a 1-dimensional sequence in the form of {x1,y1,x2,y2,x3,y3...} 
	atom status, p_points 
	integer count 
	sequence bytesAll,bytesPair 
	count = length(points)-- count is the number of x and y values 
	p_points = allocate( count*2 )-- allocate 4 bytes per pair which is just going to be another pointer 
	bytesAll = "" 
 
	for i = 1 to count-1 by 2 do 
		status = allocate(8) -- the pointer for a pair 
		bytesPair = ( int_to_bytes( points[i] ) ) 
		bytesPair &= ( int_to_bytes( points[i+1] ) ) 
		--bytesPair = bytesPair[1..2]&bytesPair[5..6] -- this is for if only using 2 bytes per integer 
 
		poke( status, (bytesPair)) --reverse 
 
		bytesAll &=  status  --& bytes 
 
	end for 
	poke( p_points, ( bytesAll ) ) 
 
	--(GpGraphics *graphics,GpPen *pen,GDIPCONST GpPointF *points,INT count) 
	if gdiplus>0 then 
		status = c_func(xGdipDrawPolygon,{p_graphics,p_pen,p_points,count/2}) 
	--else    status = 0 
	end if 
 
	puts(1, GetErrorString(status) & " " ) 
	--bytes = "" 
	for i = 1 to length( bytesAll ) do 
		status = peek4u( bytesAll[i]) 
		puts(1, "{"&sprint(status)&"," ) 
		status = peek4u( bytesAll[i]+4) 
		puts(1, sprint(status)&"}\t" ) 
		free( bytesAll[i] ) 
	end for 
	--print(1, bytes) 
	puts(1, '\n' ) 
	free( p_points ) 
end procedure 
 

5. Re: GDI Plus library

• Posted by LewisTownsend Jan 27, 2010
• 1331 views

Thanks Pete, The flat array doesn't seem to work either. That does make the most sense tho and it was the first thing I tried. I am tying my brain into knots trying to use pointers to pointers. Here is a simplified version that still doesn't work. Is this using the "(flat) array of 32-bit floats"?

global procedure DrawLinePolygon(atom p_graphics,atom p_pen, sequence points ) 
	-- points is a 1-dimensional sequence in the form of {x1,y1,x2,y2,x3,y3...} 
	atom status, p_points 
	integer count 
	count = length(points)-- count is the number of x and y values 
	p_points = allocate( count*4 )-- allocate 4 bytes per integer 
	poke4( p_points, points ) 
 
	--(GpGraphics *graphics,GpPen *pen,GDIPCONST GpPointF *points,INT count) 
	if gdiplus>0 then 
		status = c_func(xGdipDrawPolygon,{p_graphics,p_pen,p_points,count}) 
	end if 
 
	puts(1, GetErrorString(status) & "\t" & sprint(points) & "\n" ) 
	free( p_points ) 
end procedure 

I read somewhere that the first byte of an array identifies what kind of data it holds. Does this sound right? Any idea what byte value that would be?

7. Re: GDI Plus library

• Posted by LewisTownsend Jan 27, 2010
• 1339 views

Thanks Matt!

Your version gave me a machine-level exception on the c_func call but I switched back to using a plain integer for the count and it works now. Thanks much!

Here is my working version if anyone else cares:

global procedure DrawLinePolygon(atom p_graphics,atom p_pen, sequence points ) 
	-- points is a 1-dimensional sequence in the form of {x1,y1,x2,y2,x3,y3...} 
	atom status, p_points 
	integer count 
	sequence floats 
 
	count = length(points)-- count is the number of x and y values 
	p_points = allocate( (count)*4 )-- allocate 4 bytes per integer 
 
	floats = {} 
	for i = 1 to count do 
		floats &= atom_to_float32( points[i] ) 
	end for 
	poke( p_points , floats ) 
 
	--(GpGraphics *graphics,GpPen *pen,GDIPCONST GpPointF *points,INT count) 
	if gdiplus>0 then 
		status = c_func(xGdipDrawPolygon,{p_graphics, p_pen, p_points, count}) 
	end if 
 
	--puts(1, GetErrorString(status) & "\t" & sprint(points) & "\n" ) 
	free( p_points ) 
end procedure 

9. Re: GDI Plus library

• Posted by mattlewis (admin) Jan 28, 2010
• 1373 views

Yeah, obviously I didn't even look at the example. The header at koders appears to be from ReactOS, on closer inspection. It shows a pointer, just like the documentation:

Status DrawPolygon(const Pen *pen, const PointF *points, INT *count) 

A version of the actual header shows an integer:

    Status DrawPolygon(IN const Pen* pen, 
                       IN const PointF* points, 
                       IN INT count) 
 

Matt