Re: FAO Andy P, SDL2 library.
- Posted by ghaberek (admin) Mar 28, 2021
- 944 views
Hi Andy.
Playing with your SDL2 library now, got it working with Phix, apart from font colouring which I am tearing my hair out at.
See the FontTest.exw, I have fiddled, so the line numbers may not be exact, lines 39 40
atom h = TTF_RenderText_Solid(f,"Hello World",255,0,0,100) --<--colour set here to red, alpha 100 atom ht = SDL_CreateTextureFromSurface(ren,h)
atom h = TTF_RenderText_Solid(f,"Hello World",0,255,0,100) --<--colour set here to green, alpha 100 --but this doesn't work, text now black. --in fact setting the red channel to anything, only shows the --strength of that red atom ht = SDL_CreateTextureFromSurface(ren,h)
I've done lots of reading of the SDL2 docs, the SDL2TTF docs, and I can't see what I'm missing. I've also tried setTextureColorMod to change the color chanels of ht, but again only the red channel was modified.
Any ideas?
I think the root problem here may be that SDL2 passes structs by value and not by pointer. TTF_RenderText_Solid expects an SDL_Color struct which is four UInt8 (or C_UCHAR in std/dll.e) values but Andy's wrapper is just passing them as four separate C_UINT values: https://github.com/gAndy50/EuSDL2/blob/master/EuSDLTTF.ew#L270. But we should be able to pack the four values into a single unsigned int and pass it that way instead. (Also the fourth value should be "a" for alpha, not "u"). I haven't tested this but I can at least confirm that sizeof(SDL_Color) is 4 which means the values are indeed each a single byte. Give this a shot and see how it goes:
public constant xTTF_RenderText_Solid = define_c_func(ttf,"+TTF_RenderText_Solid",{C_POINTER,C_POINTER,C_UINT},C_POINTER) --SDLColor is a struct of four UInt8 values, so pack them into a single unsigned int. public function TTF_RenderText_Solid(atom font,sequence text,atom r,atom g,atom b,atom a) atom str = allocate_string(text,1) atom color = bytes_to_int({r,g,b,a}) return c_func(xTTF_RenderText_Solid,{font,str,color}) end function
-Greg
