text: /*
   * art_rgba.c: Functions for manipulating RGBA pixel data.
   *
   * Libart_LGPL - library of basic graphic primitives
   * Copyright (C) 2000 Raph Levien
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Library General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Library General Public License for more details.
   *
   * You should have received a copy of the GNU Library General Public
   * License along with this library; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 02111-1307, USA.
   */
  
  #include "config.h"
  #include "art_rgba.h"
  
  #define ART_OPTIMIZE_SPACE
  
  #ifndef ART_OPTIMIZE_SPACE
  #include "art_rgba_table.c"
  #endif
  
  /**
   * art_rgba_rgba_composite: Composite RGBA image over RGBA buffer.
   * @dst: Destination RGBA buffer.
   * @src: Source RGBA buffer.
   * @n: Number of RGBA pixels to composite.
   *
   * Composites the RGBA pixels in @dst over the @src buffer.
   **/
  void
  art_rgba_rgba_composite (art_u8 *dst, const art_u8 *src, int n)
  {
    int i;
  #ifdef WORDS_BIGENDIAN
    art_u32 src_rgba, dst_rgba;
  #else
    art_u32 src_abgr, dst_abgr;
  #endif
    art_u8 src_alpha, dst_alpha;
  
    for (i = 0; i < n; i++)
      {
  #ifdef WORDS_BIGENDIAN
        src_rgba = ((art_u32 *)src)[i];
        src_alpha = src_rgba & 0xff;
  #else
        src_abgr = ((art_u32 *)src)[i];
        src_alpha = (src_abgr >> 24) & 0xff;
  #endif
        if (src_alpha)
  	{
  	  if (src_alpha == 0xff ||
  	      (
  #ifdef WORDS_BIGENDIAN
  	       dst_rgba = ((art_u32 *)dst)[i],
  	       dst_alpha = dst_rgba & 0xff,
  #else
  	       dst_abgr = ((art_u32 *)dst)[i],
  	       dst_alpha = (dst_abgr >> 24),
  #endif
  	       dst_alpha == 0))
  #ifdef WORDS_BIGENDIAN
  	    ((art_u32 *)dst)[i] = src_rgba;
  #else
  	    ((art_u32 *)dst)[i] = src_abgr;
  #endif
  	  else
  	    {
  	      int r, g, b, a;
  	      int src_r, src_g, src_b;
  	      int dst_r, dst_g, dst_b;
  	      int tmp;
  	      int c;
  
  #ifdef ART_OPTIMIZE_SPACE
  	      tmp = (255 - src_alpha) * (255 - dst_alpha) + 0x80;
  	      a = 255 - ((tmp + (tmp >> 8)) >> 8);
  	      c = ((src_alpha << 16) + (a >> 1)) / a;
  #else
  	      tmp = art_rgba_composite_table[(src_alpha << 8) + dst_alpha];
  	      c = tmp & 0x1ffff;
  	      a = tmp >> 24;
  #endif
  #ifdef WORDS_BIGENDIAN
  	      src_r = (src_rgba >> 24) & 0xff;
  	      src_g = (src_rgba >> 16) & 0xff;
  	      src_b = (src_rgba >> 8) & 0xff;
  	      dst_r = (dst_rgba >> 24) & 0xff;
  	      dst_g = (dst_rgba >> 16) & 0xff;
  	      dst_b = (dst_rgba >> 8) & 0xff;
  #else
  	      src_r = src_abgr & 0xff;
  	      src_g = (src_abgr >> 8) & 0xff;
  	      src_b = (src_abgr >> 16) & 0xff;
  	      dst_r = dst_abgr & 0xff;
  	      dst_g = (dst_abgr >> 8) & 0xff;
  	      dst_b = (dst_abgr >> 16) & 0xff;
  #endif
  	      r = dst_r + (((src_r - dst_r) * c + 0x8000) >> 16);
  	      g = dst_g + (((src_g - dst_g) * c + 0x8000) >> 16);
  	      b = dst_b + (((src_b - dst_b) * c + 0x8000) >> 16);
  #ifdef WORDS_BIGENDIAN
  	    ((art_u32 *)dst)[i] = (r << 24) | (g << 16) | (b << 8) | a;
  #else
  	    ((art_u32 *)dst)[i] = (a << 24) | (b << 16) | (g << 8) | r;
  #endif	      
  	    }
  	}
  #if 0
        /* it's not clear to me this optimization really wins */
        else
  	{
  	  /* skip over run of transparent pixels */
  	  for (; i < n - 1; i++)
  	    {
  #ifdef WORDS_BIGENDIAN
  	      src_rgba = ((art_u32 *)src)[i + 1];
  	      if (src_rgba & 0xff)
  		break;
  #else
  	      src_abgr = ((art_u32 *)src)[i + 1];
  	      if (src_abgr & 0xff000000)
  		break;
  #endif
  	    }
  	}
  #endif
      }
  }
  
  /**
   * art_rgba_fill_run: fill an RGBA buffer a solid RGB color.
   * @buf: Buffer to fill.
   * @r: Red, range 0..255.
   * @g: Green, range 0..255.
   * @b: Blue, range 0..255.
   * @n: Number of RGB triples to fill.
   *
   * Fills a buffer with @n copies of the (@r, @g, @b) triple, solid
   * alpha. Thus, locations @buf (inclusive) through @buf + 4 * @n
   * (exclusive) are written.
   **/
  void
  art_rgba_fill_run (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, int n)
  {
    int i;
  #ifdef WORDS_BIGENDIAN
    art_u32 src_rgba;
  #else
    art_u32 src_abgr;
  #endif
  
  #ifdef WORDS_BIGENDIAN
    src_rgba = (r << 24) | (g << 16) | (b << 8) | 255;
  #else
    src_abgr = (255 << 24) | (b << 16) | (g << 8) | r;
  #endif
    for (i = 0; i < n; i++)
      {
  #ifdef WORDS_BIGENDIAN
        ((art_u32 *)buf)[i] = src_rgba;
  #else
        ((art_u32 *)buf)[i] = src_abgr;
  #endif
      }    
  }
  
  /**
   * art_rgba_run_alpha: Render semitransparent color over RGBA buffer.
   * @buf: Buffer for rendering.
   * @r: Red, range 0..255.
   * @g: Green, range 0..255.
   * @b: Blue, range 0..255.
   * @alpha: Alpha, range 0..255.
   * @n: Number of RGB triples to render.
   *
   * Renders a sequential run of solid (@r, @g, @b) color over @buf with
   * opacity @alpha. Note that the range of @alpha is 0..255, in contrast
   * to art_rgb_run_alpha, which has a range of 0..256.
   **/
  void
  art_rgba_run_alpha (art_u8 *buf, art_u8 r, art_u8 g, art_u8 b, int alpha, int n)
  {
    int i;
  #ifdef WORDS_BIGENDIAN
    art_u32 src_rgba, dst_rgba;
  #else
    art_u32 src_abgr, dst_abgr;
  #endif
    art_u8 dst_alpha;
    int a;
    int dst_r, dst_g, dst_b;
    int tmp;
    int c;
  
  #ifdef WORDS_BIGENDIAN
    src_rgba = (r << 24) | (g << 16) | (b << 8) | alpha;
  #else
    src_abgr = (alpha << 24) | (b << 16) | (g << 8) | r;
  #endif
    for (i = 0; i < n; i++)
      {
  #ifdef WORDS_BIGENDIAN
        dst_rgba = ((art_u32 *)buf)[i];
        dst_alpha = dst_rgba & 0xff;
  #else
        dst_abgr = ((art_u32 *)buf)[i];
        dst_alpha = (dst_abgr >> 24) & 0xff;
  #endif
        if (dst_alpha)
  	{
  #ifdef ART_OPTIMIZE_SPACE
  	  tmp = (255 - alpha) * (255 - dst_alpha) + 0x80;
  	  a = 255 - ((tmp + (tmp >> 8)) >> 8);
  	  c = ((alpha << 16) + (a >> 1)) / a;
  #else
  	  tmp = art_rgba_composite_table[(alpha << 8) + dst_alpha];
  	  c = tmp & 0x1ffff;
  	  a = tmp >> 24;
  #endif
  #ifdef WORDS_BIGENDIAN
  	  dst_r = (dst_rgba >> 24) & 0xff;
  	  dst_g = (dst_rgba >> 16) & 0xff;
  	  dst_b = (dst_rgba >> 8) & 0xff;
  #else
  	  dst_r = dst_abgr & 0xff;
  	  dst_g = (dst_abgr >> 8) & 0xff;
  	  dst_b = (dst_abgr >> 16) & 0xff;
  #endif
  	  dst_r += (((r - dst_r) * c + 0x8000) >> 16);
  	  dst_g += (((g - dst_g) * c + 0x8000) >> 16);
  	  dst_b += (((b - dst_b) * c + 0x8000) >> 16);
  #ifdef WORDS_BIGENDIAN
  	  ((art_u32 *)buf)[i] = (dst_r << 24) | (dst_g << 16) | (dst_b << 8) | a;
  #else
  	  ((art_u32 *)buf)[i] = (a << 24) | (dst_b << 16) | (dst_g << 8) | dst_r;
  #endif
  	}
        else
  	{
  #ifdef WORDS_BIGENDIAN
  	  ((art_u32 *)buf)[i] = src_rgba;
  #else
  	  ((art_u32 *)buf)[i] = src_abgr;
  #endif
  	}
      }
  }
  