[SDL] Font color gradients

[Justin Davis]

I myself have actually been doing a lot of thorough research on this
topic for my project OpenRPGMaker and I've found that a quick and dirty
method of doing it would be to use TTF_RenderText_Solid() then make a
new SDL_Surface of the same width and height (bpp can be whatever you
want) and then go through each RGB pixel values and compare them with
the text's RGB color. If they are the same then place the color value of
the current x and y coordinate on you gradient (using the modulus
operator on the coordinate to allow tiling of the gradient) onto the
newly created surface, otherwise if they are not the same then simply
place a pre-chosen color to place instead and then use
SDL_SetColorKey(newsurface, SDL_SRCCOLORKEY,
(Uint32)chosen_transparent_color) on the surface after it's finished
rendering. The original surface can then be freed and the new one can be
used in its place.

On Sat, 2008-04-05 at 15:02 -0700, Mason Wheeler wrote:

> Interesting.  Is there a way to create an alpha-only surface?  (No color information, only an alpha channel.)  I could render the font onto that and then do a bit of creative blitting...
> 
> ----- Original Message ----
> From: David Olsen <jolynsbass at gmail.com>
> To: A list for developers using the SDL library. (includes SDL-announce) <sdl at lists.libsdl.org>
> Sent: Saturday, April 5, 2008 2:36:51 PM
> Subject: Re: [SDL] Font color gradients
> 
> I would think that using the output from SDL_TTF(Blended - the one that 
> gives you a per-pixel alpha image), you could blit the text onto a 
> predefined surface which contains a color gradient, and you should get a 
> resulting image of the sort you want. (Oh, first you must have SRCALPHA 
> turned on in both surfaces, or it won't act as a mask. Look at the 
> documentation of the SDL_SetAlpha function) I might have the surface order 
> reversed... you might need to blit the colored gradient surface onto the 
> rendered text surface. But a little experimentation along those lines should 
> get you set up.
> -Dave
> 
> 
> ----- Original Message ----- 
> From: "Mason Wheeler" <masonwheeler at yahoo.com>
> To: <sdl at lists.libsdl.org>
> Sent: Saturday, April 05, 2008 7:12 AM
> Subject: [SDL] Font color gradients
> 
> 
> > I've been looking through SDL_TTF, and it looks like the only option 
> > available is to render a font in a single, solid color.  How would I do 
> > gradients and other custom colorations?  The ideal way would be to use the 
> > glyph shapes as "cutouts" in an existing graphic from an SDL_Surface, 
> > which would allow custom colors to be defined beforehand.  If this isn't 
> > feasible, I'd like to be able to define multiple foreground colors and 
> > create a gradient from them.
> >
> > How would I go about doing something like this?
> >
> >
> > _______________________________________________
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> > SDL at lists.libsdl.org
> > http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org 
> 
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