update Changes

[imager.git] / render.im

diff --git a/render.im b/render.im
index 54d47dfdf748413f6aebe9dc3fbf719ea8483a59..947dcb211ac7688160522fea57f02434fd91d9d8 100644 (file)
--- a/render.im
+++ b/render.im
@@ -5,12 +5,16 @@ Render utilities
 
 #define RENDER_MAGIC 0x765AE
 
 
 #define RENDER_MAGIC 0x765AE
 

-typedef void (*render_color_f)(i_render *, int, int, int, unsigned char const *src, i_color const *color);
+typedef void (*render_color_f)(i_render *, i_img_dim, i_img_dim, i_img_dim, unsigned char const *src, i_color const *color);
+
+#define i_has_alpha(channels) ((channels) == 2 || (channels) == 4)
+
+#define i_color_channels(channels) (i_has_alpha(channels) ? (channels)-1 : (channels))

 
 #code
 
 
 #code
 

-static void IM_SUFFIX(render_color_alpha)(i_render *r, int x, int y, int width, unsigned char const *src, i_color const *color);
-static void IM_SUFFIX(render_color_13)(i_render *r, int x, int y, int width, unsigned char const *src, i_color const *color);
+static void IM_SUFFIX(render_color_alpha)(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width, unsigned char const *src, i_color const *color);
+static void IM_SUFFIX(render_color_13)(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width, unsigned char const *src, i_color const *color);

 
 static render_color_f IM_SUFFIX(render_color_tab)[] =
   {
 
 static render_color_f IM_SUFFIX(render_color_tab)[] =
   {


@@ -21,32 +25,189 @@ static render_color_f IM_SUFFIX(render_color_tab)[] =
     IM_SUFFIX(render_color_alpha),
   };
 
     IM_SUFFIX(render_color_alpha),
   };
 

+static void IM_SUFFIX(combine_line_noalpha)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count);
+static void IM_SUFFIX(combine_line_alpha)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count);
+/* the copy variant copies the source alpha to the the output alpha channel */
+static void IM_SUFFIX(combine_line_alpha_na)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count);
+
+static void IM_SUFFIX(combine_line)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count);
+static void IM_SUFFIX(combine_line_na)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count);
+

 #/code
 
 #/code
 

+/* 
+=item i_render_new(im, width)
+=category Blit tools
+
+Allocate a new C<i_render> object and initialize it.
+
+=cut
+*/
+
+i_render *
+i_render_new(i_img *im, i_img_dim width) {
+  i_render *r = mymalloc(sizeof(i_render));
+
+  i_render_init(r, im, width);
+
+  return r;
+}
+
+/*
+=item i_render_delete(r)
+=category Blit tools
+
+Release an C<i_render> object.
+
+=cut
+*/
+

 void
 void

-i_render_init(i_render *r, i_img *im, int width) {
+i_render_delete(i_render *r) {
+  i_render_done(r);
+  myfree(r);
+}
+
+void
+i_render_init(i_render *r, i_img *im, i_img_dim width) {

   r->magic = RENDER_MAGIC;
   r->im = im;
   r->magic = RENDER_MAGIC;
   r->im = im;

-  r->width = width;
+  r->line_width = width;

   r->line_8 = NULL;
   r->line_double = NULL;
   r->line_8 = NULL;
   r->line_double = NULL;

-#code im->bits <= 8
-    r->IM_SUFFIX(line) = mymalloc(sizeof(i_fcolor) * width);
-#/code
+  r->fill_width = width;
+  r->fill_line_8 = NULL;
+  r->fill_line_double = NULL;

 }
 
 void
 i_render_done(i_render *r) {
   if (r->line_8)
     myfree(r->line_8);
 }
 
 void
 i_render_done(i_render *r) {
   if (r->line_8)
     myfree(r->line_8);

-  else
+  if (r->line_double)

     myfree(r->line_double);
     myfree(r->line_double);

+  if (r->fill_line_8)
+    myfree(r->fill_line_8);
+  if (r->fill_line_double)
+    myfree(r->fill_line_double);

   r->magic = 0;
 }
 
   r->magic = 0;
 }
 

+static void
+alloc_line(i_render *r, i_img_dim width, i_img_dim eight_bit) {
+  if (width > r->line_width) {
+    i_img_dim new_width = r->line_width * 2;
+    if (new_width < width)
+      new_width = width;
+
+    if (eight_bit) {
+      if (r->line_8)
+       r->line_8 = myrealloc(r->line_8, sizeof(i_color) * new_width);
+      else
+       r->line_8 = mymalloc(sizeof(i_color) * new_width);
+      if (r->line_double) {
+       myfree(r->line_double);
+       r->line_double = NULL;
+      }
+    }
+    else {
+      if (r->line_double)
+       r->line_double = myrealloc(r->line_double, sizeof(i_fcolor) * new_width);
+      else
+       r->line_double = mymalloc(sizeof(i_fcolor) * new_width);
+      if (r->line_8) {
+       myfree(r->line_8);
+       r->line_double = NULL;
+      }
+    }
+
+    r->line_width = new_width;
+  }
+  else {
+    if (eight_bit) {
+      if (!r->line_8)
+       r->line_8 = mymalloc(sizeof(i_color) * r->line_width);
+      if (r->line_double) {
+       myfree(r->line_double);
+       r->line_double = NULL;
+      }
+    }
+    else {
+      if (!r->line_double)
+       r->line_double = mymalloc(sizeof(i_fcolor) * r->line_width);
+      if (r->line_8) {
+       myfree(r->line_8);
+       r->line_8 = NULL;
+      }
+    }
+  }
+}
+
+static void
+alloc_fill_line(i_render *r, i_img_dim width, int eight_bit) {
+  if (width > r->fill_width) {
+    i_img_dim new_width = r->fill_width * 2;
+    if (new_width < width)
+      new_width = width;
+
+    if (eight_bit) {
+      if (r->line_8)
+       r->fill_line_8 = myrealloc(r->fill_line_8, sizeof(i_color) * new_width);
+      else
+       r->fill_line_8 = mymalloc(sizeof(i_color) * new_width);
+      if (r->fill_line_double) {
+       myfree(r->fill_line_double);
+       r->fill_line_double = NULL;
+      }
+    }
+    else {
+      if (r->fill_line_double)
+       r->fill_line_double = myrealloc(r->fill_line_double, sizeof(i_fcolor) * new_width);
+      else
+       r->fill_line_double = mymalloc(sizeof(i_fcolor) * new_width);
+      if (r->fill_line_8) {
+       myfree(r->fill_line_8);
+       r->fill_line_double = NULL;
+      }
+    }
+
+    r->fill_width = new_width;
+  }
+  else {
+    if (eight_bit) {
+      if (!r->fill_line_8)
+       r->fill_line_8 = mymalloc(sizeof(i_color) * r->fill_width);
+      if (r->fill_line_double) {
+       myfree(r->fill_line_double);
+       r->fill_line_double = NULL;
+      }
+    }
+    else {
+      if (!r->fill_line_double)
+       r->fill_line_double = mymalloc(sizeof(i_fcolor) * r->fill_width);
+      if (r->fill_line_8) {
+       myfree(r->fill_line_8);
+       r->fill_line_8 = NULL;
+      }
+    }
+  }
+}
+
+/*
+=item i_render_color(r, x, y, width, source, color)
+=category Blit tools
+
+Render the given color with the coverage specified by C<source[0]> to
+C<source[width-1]>.
+
+Renders in normal combine mode.
+
+=cut
+*/
+

 void
 void

-i_render_color(i_render *r, int x, int y, int width, unsigned char const *src,
-               i_color const *color) {
+i_render_color(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width,
+              unsigned char const *src, i_color const *color) {

   i_img *im = r->im;
   if (y < 0 || y >= im->ysize)
     return;
   i_img *im = r->im;
   if (y < 0 || y >= im->ysize)
     return;


@@ -73,43 +234,258 @@ i_render_color(i_render *r, int x, int y, int width, unsigned char const *src,
   if (!width)
     return;
 
   if (!width)
     return;
 

-  /* make sure our line buffer is big enough */
-  if (width > r->width) {
-    int new_width = r->width * 2;
-    if (new_width < width)
-      new_width = width;
+  alloc_line(r, width, r->im->bits <= 8);
+
+#code r->im->bits <= 8
+  /*if (r->IM_SUFFIX(line) == NULL)
+    r->IM_SUFFIX(line) = mymalloc(sizeof(IM_COLOR) * r->width);*/
+  (IM_SUFFIX(render_color_tab)[im->channels])(r, x, y, width, src, color);
+#/code
+}
+
+/*
+=item i_render_fill(r, x, y, width, source, fill)
+=category Blit tools
+
+Render the given fill with the coverage in C<source[0]> through
+C<source[width-1]>.
+
+=cut
+*/

 
 

-    if (r->line_8)
-      r->line_8 = myrealloc(r->line_8, sizeof(i_color) * new_width);
-    else
-      r->line_double = myrealloc(r->line_double, sizeof(i_fcolor) * new_width);
+void
+i_render_fill(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width,
+             unsigned char const *src, i_fill_t *fill) {
+  i_img *im = r->im;
+  int fill_channels = im->channels;
+  
+  if (fill_channels == 1 || fill_channels == 3)
+    ++fill_channels;
+
+  if (y < 0 || y >= im->ysize)
+    return;
+  if (x < 0) {
+    width += x;
+    src -= x;
+    x = 0;

   }
   }

+  if (x + width > im->xsize) {
+    width = im->xsize - x;
+  }
+  if (x >= im->xsize || x + width <= 0 || width <= 0)
+    return;

 
 

-#code r->im->bits <= 8
-    (IM_SUFFIX(render_color_tab)[im->channels])(r, x, y, width, src, color);
+  if (src) {
+    /* avoid as much work as we can */
+    while (width > 0 && *src == 0) {
+      --width;
+      ++src;
+      ++x;
+    }
+    while (width > 0 && src[width-1] == 0) {
+      --width;
+    }
+  }
+  if (!width)
+    return;
+
+  alloc_line(r, width, r->im->bits <= 8 && fill->f_fill_with_color != NULL);
+  alloc_fill_line(r, width, r->im->bits <= 8 && fill->f_fill_with_color != NULL);
+
+#code r->im->bits <= 8 && fill->f_fill_with_color
+  if (IM_FILL_COMBINE(fill)) {
+    IM_COLOR *srcc = r->IM_SUFFIX(fill_line);
+    IM_COLOR *destc = r->IM_SUFFIX(line);
+    IM_FILL_FILLER(fill)(fill, x, y, width, fill_channels, r->IM_SUFFIX(fill_line));
+    if (src) {
+      unsigned char const *srcc = src;
+      IM_COLOR *fillc = r->IM_SUFFIX(fill_line);
+      i_img_dim work_width = width;
+      while (work_width) {
+       if (*srcc == 0) {
+         fillc->channel[fill_channels-1] = 0;
+       }
+       else if (*srcc != 255) {
+         fillc->channel[fill_channels-1] =
+           fillc->channel[fill_channels-1] * *srcc / 255;
+       }
+       --work_width;
+       ++srcc;
+       ++fillc;
+      }
+    }
+    IM_GLIN(r->im, x, x+width, y, r->IM_SUFFIX(line));
+    IM_FILL_COMBINE(fill)(destc, srcc, r->im->channels, width);
+  }
+  else {
+    if (src) {
+      i_img_dim work_width = width;
+      IM_COLOR *srcc = r->IM_SUFFIX(fill_line);
+      IM_COLOR *destc = r->IM_SUFFIX(line);
+      int ch;
+
+      IM_FILL_FILLER(fill)(fill, x, y, width, fill_channels, r->IM_SUFFIX(fill_line));
+      IM_GLIN(r->im, x, x+width, y, r->IM_SUFFIX(line));
+      while (work_width) {
+       if (*src == 255) {
+         /* just replace it */
+         *destc = *srcc;
+       }
+       else if (*src) {
+         for (ch = 0; ch < im->channels; ++ch) {
+           IM_WORK_T work = (destc->channel[ch] * (255 - *src)
+                             + srcc->channel[ch] * *src) / 255.0;
+           destc->channel[ch] = IM_LIMIT(work);
+         }
+       }
+       
+       ++srcc;
+       ++destc;
+       ++src;
+       --work_width;
+      }
+    }
+    else { /* if (src) */
+      IM_FILL_FILLER(fill)(fill, x, y, width, fill_channels, r->IM_SUFFIX(line));
+    }
+  }
+  IM_PLIN(im, x, x+width, y, r->IM_SUFFIX(line));

 #/code
 }
 
 #/code
 }
 

+#if 0
+
+/* for debuggin */
+

 static void
 static void

-dump_src(const char *note, unsigned char const *src, int width) {
-  int i;
-  printf("%s - %p/%d\n", note, src, width);
+dump_src(const char *note, unsigned char const *src, i_img_dim width) {
+  i_img_dim i;
+  printf("%s - %p/%" i_DF "\n", note, src, i_DFc(width));

   for (i = 0; i < width; ++i) {
     printf("%02x ", src[i]);
   }
   putchar('\n');
 }
 
   for (i = 0; i < width; ++i) {
     printf("%02x ", src[i]);
   }
   putchar('\n');
 }
 

+#endif
+

 #code
 
 #code
 

+/*
+=item i_render_line(r, x, y, width, source, fill)
+=category Blit tools
+
+Render the given fill with the coverage in C<source[0]> through
+C<source[width-1]>.
+
+=cut
+
+=item i_render_linef(r, x, y, width, source, fill)
+=category Blit tools
+
+Render the given fill with the coverage in C<source[0]> through
+C<source[width-1]>.
+
+=cut
+*/
+
+void
+IM_RENDER_LINE(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width,
+              const IM_SAMPLE_T *src, IM_COLOR *line,
+              IM_FILL_COMBINE_F combine) {
+  i_img *im = r->im;
+  int src_chans = im->channels;
+
+  /* src must always have an alpha channel */
+  if (src_chans == 1 || src_chans == 3)
+    ++src_chans;
+
+  if (y < 0 || y >= im->ysize)
+    return;
+  if (x < 0) {
+    src -= x;
+    line -= x;
+    width += x;
+    x = 0;
+  }
+  if (x + width > im->xsize)
+    width = r->im->xsize - x;
+
+#ifdef IM_EIGHT_BIT
+  alloc_line(r, width, 1);
+#else
+  alloc_line(r, width, 0);
+#endif
+
+  if (combine) {
+    if (src) {
+      i_img_dim work_width = width;
+      IM_COLOR *linep = line;
+      const IM_SAMPLE_T *srcp = src;
+      int alpha_chan = src_chans - 1;
+      
+      while (work_width) {
+       if (*srcp) {
+         if (*srcp != IM_SAMPLE_MAX) 
+           linep->channel[alpha_chan] = 
+             linep->channel[alpha_chan] * *srcp / IM_SAMPLE_MAX;
+       }
+       else {
+         linep->channel[alpha_chan] = 0;
+       }
+       --work_width;
+       ++srcp;
+       ++linep;
+      }
+    }
+    IM_GLIN(im, x, x+width, y, r->IM_SUFFIX(line));
+    combine(r->IM_SUFFIX(line), line, im->channels, width);
+    IM_PLIN(im, x, x+width, y, r->IM_SUFFIX(line));
+  }
+  else {
+    if (src) {
+      i_img_dim work_width = width;
+      IM_COLOR *srcc = line;
+      IM_COLOR *destc = r->IM_SUFFIX(line);
+
+      IM_GLIN(im, x, x+width, y, r->IM_SUFFIX(line));
+      while (work_width) {
+       if (*src == 255) {
+         /* just replace it */
+         *destc = *srcc;
+       }
+       else if (*src) {
+         int ch;
+         for (ch = 0; ch < im->channels; ++ch) {
+           IM_WORK_T work = (destc->channel[ch] * (IM_SAMPLE_MAX - *src)
+                             + srcc->channel[ch] * *src) / IM_SAMPLE_MAX;
+           destc->channel[ch] = IM_LIMIT(work);
+         }
+       }
+       
+       ++srcc;
+       ++destc;
+       ++src;
+       --work_width;
+      }
+      IM_PLIN(im, x, x+width, y, r->IM_SUFFIX(line));
+    }
+    else {
+      IM_PLIN(im, x, x+width, y, line);
+    }
+  }
+}
+

 static
 void
 static
 void

-IM_SUFFIX(render_color_13)(i_render *r, int x, int y, int width, 
-                unsigned char const *src, i_color const *color) {
+IM_SUFFIX(render_color_13)(i_render *r, i_img_dim x, i_img_dim y,
+                          i_img_dim width, unsigned char const *src,
+                          i_color const *color) {

   i_img *im = r->im;
   IM_COLOR *linep = r->IM_SUFFIX(line);
   int ch, channels = im->channels;
   i_img *im = r->im;
   IM_COLOR *linep = r->IM_SUFFIX(line);
   int ch, channels = im->channels;

-  int fetch_offset;
+  i_img_dim fetch_offset;
+  int color_alpha = color->channel[im->channels];

 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)
 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)


@@ -123,17 +499,19 @@ IM_SUFFIX(render_color_13)(i_render *r, int x, int y, int width,
 #endif
  
   fetch_offset = 0;
 #endif
  
   fetch_offset = 0;

-  while (fetch_offset < width && *src == 0xFF) {
-    *linep++ = STORE_COLOR;
-    ++src;
-    ++fetch_offset;
+  if (color_alpha == 0xFF) {
+    while (fetch_offset < width && *src == 0xFF) {
+      *linep++ = STORE_COLOR;
+      ++src;
+      ++fetch_offset;
+    }

   }
   IM_GLIN(im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT
   }
   IM_GLIN(im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT

-    IM_WORK_T alpha = *src++;
+    IM_WORK_T alpha = *src++ * color_alpha / 255;

 #else
 #else

-    IM_WORK_T alpha = *src++ / 255.0;
+    IM_WORK_T alpha = *src++ * color_alpha / (255.0 * 255.0);

 #endif
     if (alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;
 #endif
     if (alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;


@@ -151,12 +529,14 @@ IM_SUFFIX(render_color_13)(i_render *r, int x, int y, int width,
 
 static
 void
 
 static
 void

-IM_SUFFIX(render_color_alpha)(i_render *r, int x, int y, int width, 
-                unsigned char const *src, i_color const *color) {
+IM_SUFFIX(render_color_alpha)(i_render *r, i_img_dim x, i_img_dim y,
+                             i_img_dim width, unsigned char const *src,
+                             i_color const *color) {

   IM_COLOR *linep = r->IM_SUFFIX(line);
   int ch;
   int alpha_channel = r->im->channels - 1;
   IM_COLOR *linep = r->IM_SUFFIX(line);
   int ch;
   int alpha_channel = r->im->channels - 1;

-  int fetch_offset;
+  i_img_dim fetch_offset;
+  int color_alpha = color->channel[alpha_channel];

 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)
 #undef STORE_COLOR
 #ifdef IM_EIGHT_BIT
 #define STORE_COLOR (*color)


@@ -170,17 +550,19 @@ IM_SUFFIX(render_color_alpha)(i_render *r, int x, int y, int width,
 #endif
 
   fetch_offset = 0;
 #endif
 
   fetch_offset = 0;

-  while (fetch_offset < width && *src == 0xFF) {
-    *linep++ = STORE_COLOR;
-    ++src;
-    ++fetch_offset;
+  if (color->channel[alpha_channel] == 0xFF) {
+    while (fetch_offset < width && *src == 0xFF) {
+      *linep++ = STORE_COLOR;
+      ++src;
+      ++fetch_offset;
+    }

   }
   IM_GLIN(r->im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT
   }
   IM_GLIN(r->im, x+fetch_offset, x+width, y, linep);
   while (fetch_offset < width) {
 #ifdef IM_EIGHT_BIT

-    IM_WORK_T src_alpha = *src++;
+    IM_WORK_T src_alpha = *src++ * color_alpha / 255;

 #else
 #else

-    IM_WORK_T src_alpha = *src++ / 255.0;
+    IM_WORK_T src_alpha = *src++ * color_alpha / (255.0 * 255.0);

 #endif
     if (src_alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;
 #endif
     if (src_alpha == IM_SAMPLE_MAX)
       *linep = STORE_COLOR;


@@ -199,6 +581,733 @@ IM_SUFFIX(render_color_alpha)(i_render *r, int x, int y, int width,
     ++fetch_offset;
   }
   IM_PLIN(r->im, x, x+width, y, r->IM_SUFFIX(line));
     ++fetch_offset;
   }
   IM_PLIN(r->im, x, x+width, y, r->IM_SUFFIX(line));

+#undef STORE_COLOR
+}
+
+/* combine a line of image data with an output line, both the input
+   and output lines include an alpha channel.
+
+   Both input and output lines have I<channels> of data, channels
+   should be either 2 or 4.
+*/
+
+static void
+IM_SUFFIX(combine_line_alpha)(IM_COLOR *out, IM_COLOR const *in, 
+                             int channels, i_img_dim count) {
+  int ch;
+  int alpha_channel = channels - 1;
+  
+  while (count) {
+    IM_WORK_T src_alpha = in->channel[alpha_channel];
+      
+    if (src_alpha == IM_SAMPLE_MAX)
+      *out = *in;
+    else if (src_alpha) {
+      IM_WORK_T remains = IM_SAMPLE_MAX - src_alpha;
+      IM_WORK_T orig_alpha = out->channel[alpha_channel];
+      IM_WORK_T dest_alpha = src_alpha + (remains * orig_alpha) / IM_SAMPLE_MAX;
+       
+      for (ch = 0; ch < alpha_channel; ++ch) {
+       out->channel[ch] = ( src_alpha * in->channel[ch]
+                            + remains * out->channel[ch] * orig_alpha / IM_SAMPLE_MAX
+                            ) / dest_alpha;
+      }
+      out->channel[alpha_channel] = dest_alpha;
+    }
+
+    ++out;
+    ++in;
+    --count;
+  }
+}
+
+/* combine a line of image data with an output line.  The input line
+   includes an alpha channel, the output line has no alpha channel.
+   
+   The input line has I<channels>+1 of color data.  The output line
+   has I<channels> of color data.
+*/
+
+static void
+IM_SUFFIX(combine_line_noalpha)
+     (IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count) {
+  int ch;
+
+  while (count) {
+    IM_WORK_T src_alpha = in->channel[channels];
+    
+    if (src_alpha == IM_SAMPLE_MAX)
+      *out = *in;
+    else if (src_alpha) {
+      IM_WORK_T remains;
+      
+      remains = IM_SAMPLE_MAX - src_alpha;
+      for (ch = 0; ch < channels; ++ch) {
+       out->channel[ch] = ( in->channel[ch] * src_alpha
+                            + out->channel[ch] * remains) / IM_SAMPLE_MAX;
+      }
+    }
+    
+    ++out;
+    ++in;
+    --count;
+  }

 }
 
 }
 

+/* combine a line of image data with an output line, both the input
+   and output lines include an alpha channel.
+
+   Both input and output lines have I<channels> of data, channels
+   should be either 2 or 4.
+
+   This variant does not modify the output alpha channel.
+*/
+
+static void
+IM_SUFFIX(combine_line_alpha_na)(IM_COLOR *out, IM_COLOR const *in, 
+                                  int channels, i_img_dim count) {
+  int ch;
+  int alpha_channel = channels - 1;
+  
+  while (count) {
+    IM_WORK_T src_alpha = in->channel[alpha_channel];
+      
+    if (src_alpha == IM_SAMPLE_MAX)
+      *out = *in;
+    else if (src_alpha) {
+      IM_WORK_T remains = IM_SAMPLE_MAX - src_alpha;
+      IM_WORK_T orig_alpha = out->channel[alpha_channel];
+      IM_WORK_T dest_alpha = src_alpha + (remains * orig_alpha) / IM_SAMPLE_MAX;
+       
+      for (ch = 0; ch < alpha_channel; ++ch) {
+       out->channel[ch] = ( src_alpha * in->channel[ch]
+                            + remains * out->channel[ch] * orig_alpha / IM_SAMPLE_MAX
+                            ) / dest_alpha;
+      }
+    }
+
+    ++out;
+    ++in;
+    --count;
+  }
+}
+
+static void
+IM_SUFFIX(combine_line)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count) {
+  if (channels == 2 || channels == 4)
+    IM_SUFFIX(combine_line_alpha)(out, in, channels, count);
+  else
+    IM_SUFFIX(combine_line_noalpha)(out, in, channels, count);
+}
+
+static void
+IM_SUFFIX(combine_line_na)(IM_COLOR *out, IM_COLOR const *in, int channels, i_img_dim count) {
+  if (channels == 2 || channels == 4)
+    IM_SUFFIX(combine_line_alpha_na)(out, in, channels, count);
+  else
+    IM_SUFFIX(combine_line_noalpha)(out, in, channels, count);
+}
+
+static void IM_SUFFIX(combine_alphablend)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_mult)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_dissolve)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_add)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_subtract)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_diff)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_darken)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_lighten)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_hue)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_sat)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_value)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+static void IM_SUFFIX(combine_color)(IM_COLOR *, IM_COLOR *, int, i_img_dim);
+
+static const IM_FILL_COMBINE_F IM_SUFFIX(combines)[] =
+{
+  NULL,
+  IM_SUFFIX(combine_alphablend),
+  IM_SUFFIX(combine_mult),
+  IM_SUFFIX(combine_dissolve),
+  IM_SUFFIX(combine_add),
+  IM_SUFFIX(combine_subtract),
+  IM_SUFFIX(combine_diff),
+  IM_SUFFIX(combine_lighten),
+  IM_SUFFIX(combine_darken),
+  IM_SUFFIX(combine_hue),
+  IM_SUFFIX(combine_sat),
+  IM_SUFFIX(combine_value),
+  IM_SUFFIX(combine_color)
+};
+
+#/code
+
+/*
+=item i_get_combine(combine, color_func, fcolor_func)
+
+=cut
+*/
+
+void i_get_combine(int combine, i_fill_combine_f *color_func, 
+                   i_fill_combinef_f *fcolor_func) {
+  if (combine < 0 || combine > sizeof(combines_8) / sizeof(*combines_8))
+    combine = 0;
+
+  *color_func = combines_8[combine];
+  *fcolor_func = combines_double[combine];
+}
+
+#code
+
+/*
+  Three good references for implementing combining modes:
+
+  http://www.w3.org/TR/2004/WD-SVG12-20041027/rendering.html
+  referenced as [svg1.2]
+
+  http://gimp-savvy.com/BOOK/index.html?node55.html
+  ("The Blending Modes", if it changes)
+  referenced as [savvy]
+
+  http://www.pegtop.net/delphi/articles/blendmodes/
+  referenced as [pegtop]
+
+  Where differences exist, I follow the SVG practice, the gimp
+  practice, and lastly pegtop.
+*/
+
+
+static void 
+IM_SUFFIX(combine_alphablend)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  IM_SUFFIX(combine_line)(out, in, channels, count);
+}
+
+/*
+Dca' = Sca.Dca + Sca.(1 - Da) + Dca.(1 - Sa)
+Da'  = Sa.Da + Sa.(1 - Da) + Da.(1 - Sa)
+     = Sa + Da - Sa.Da
+
+When Da=1
+
+Dc' = Sc.Sa.Dc + Dc.(1 - Sa)
+ */
+static void
+IM_SUFFIX(combine_mult)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int ch;
+  IM_COLOR *inp = in;
+  IM_COLOR *outp = out;
+  i_img_dim work_count = count;
+  int color_channels = i_color_channels(channels);
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T orig_alpha = outp->channel[color_channels];
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      
+      if (src_alpha) {
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha 
+         - (src_alpha * orig_alpha) / IM_SAMPLE_MAX;
+       
+       for (ch = 0; ch < color_channels; ++ch) { 
+         outp->channel[ch] = 
+           (inp->channel[ch] * src_alpha * outp->channel[ch] / IM_SAMPLE_MAX
+            * orig_alpha
+            + inp->channel[ch] * src_alpha * (IM_SAMPLE_MAX - orig_alpha)
+            + outp->channel[ch] * orig_alpha * (IM_SAMPLE_MAX - src_alpha))
+           / IM_SAMPLE_MAX / dest_alpha;
+       }
+       outp->channel[color_channels] = dest_alpha;
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      IM_WORK_T remains = IM_SAMPLE_MAX - src_alpha;
+      
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) { 
+         outp->channel[ch] = 
+           (src_alpha * inp->channel[ch] * outp->channel[ch] / IM_SAMPLE_MAX
+            + outp->channel[ch] * remains) / IM_SAMPLE_MAX;
+       }
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+}
+
+static void 
+IM_SUFFIX(combine_dissolve)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int color_channels = i_color_channels(channels);
+  int ch;
+
+  if (i_has_alpha(channels)) {
+    while (count--) {
+      if (in->channel[channels-1] > rand() * ((double)IM_SAMPLE_MAX / RAND_MAX)) {
+       for (ch = 0; ch < color_channels; ++ch) {
+         out->channel[ch] = in->channel[ch];
+       }
+       out->channel[color_channels] = IM_SAMPLE_MAX;
+      }
+      ++out;
+      ++in;
+    }
+  }
+  else {
+    while (count--) {
+      if (in->channel[channels] > rand() * ((double)IM_SAMPLE_MAX / RAND_MAX)) {
+       for (ch = 0; ch < color_channels; ++ch) {
+         out->channel[ch] = in->channel[ch];
+       }
+      }
+      ++out;
+      ++in;
+    }
+  }
+}
+
+/*
+Dca' = Sca.Da + Dca.Sa + Sca.(1 - Da) + Dca.(1 - Sa)
+     = Sca + Dca
+Da'  = Sa.Da + Da.Sa + Sa.(1 - Da) + Da.(1 - Sa)
+     = Sa + Da
+*/
+
+static void
+IM_SUFFIX(combine_add)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int ch;
+  int color_channels = i_color_channels(channels);
+  i_img_dim work_count = count;
+  IM_COLOR *inp = in;
+  IM_COLOR *outp = out;
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       IM_WORK_T orig_alpha = outp->channel[color_channels];
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha;
+       if (dest_alpha > IM_SAMPLE_MAX)
+         dest_alpha = IM_SAMPLE_MAX;
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T total = (outp->channel[ch] * orig_alpha + inp->channel[ch] * src_alpha) / dest_alpha;
+         if (total > IM_SAMPLE_MAX)
+           total = IM_SAMPLE_MAX;
+         outp->channel[ch] = total;
+       }
+       outp->channel[color_channels] = dest_alpha;
+      }
+      
+      ++outp;
+      ++inp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T total = outp->channel[ch] + inp->channel[ch] * src_alpha / IM_SAMPLE_MAX;
+         if (total > IM_SAMPLE_MAX)
+           total = IM_SAMPLE_MAX;
+         outp->channel[ch] = total;
+       } 
+      }
+      
+      ++outp;
+      ++inp;
+    }
+  }
+}
+
+/* 
+   [pegtop] documents this as max(A+B-256, 0) while [savvy] documents
+   it as max(A-B, 0). [svg1.2] doesn't cover it.
+
+   [savvy] doesn't document how it works with an alpha channel.  GIMP
+   actually seems to calculate the final value then use the alpha
+   channel to apply that to the target.
+ */
+static void
+IM_SUFFIX(combine_subtract)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int ch;
+  IM_COLOR const *inp = in;
+  IM_COLOR *outp = out;
+  i_img_dim work_count = count;
+  int color_channels = i_color_channels(channels);
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       IM_WORK_T orig_alpha = outp->channel[color_channels];
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha;
+       if (dest_alpha > IM_SAMPLE_MAX)
+         dest_alpha = IM_SAMPLE_MAX;
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T total = 
+           (outp->channel[ch] * orig_alpha - inp->channel[ch] * src_alpha) 
+           / dest_alpha;
+         if (total < 0)
+           total = 0;
+         outp->channel[ch] = total;
+       }
+       outp->channel[color_channels] = dest_alpha;
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T total = outp->channel[ch] - inp->channel[ch] * src_alpha / IM_SAMPLE_MAX;
+         if (total < 0)
+           total = 0;
+         outp->channel[ch] = total;
+       } 
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+}
+
+#ifdef IM_EIGHT_BIT
+#define IM_abs(x) abs(x)
+#else
+#define IM_abs(x) fabs(x)
+#endif
+
+/*
+Dca' = abs(Dca.Sa - Sca.Da) + Sca.(1 - Da) + Dca.(1 - Sa)
+     = Sca + Dca - 2.min(Sca.Da, Dca.Sa)
+Da'  = Sa + Da - Sa.Da 
+*/
+static void
+IM_SUFFIX(combine_diff)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int ch;
+  IM_COLOR const *inp = in;
+  IM_COLOR *outp = out;
+  i_img_dim work_count = count;
+  int color_channels = i_color_channels(channels);
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       IM_WORK_T orig_alpha = outp->channel[color_channels];
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha 
+         - src_alpha * orig_alpha / IM_SAMPLE_MAX;
+       for (ch = 0; ch < color_channels; ++ch) {
+         IM_WORK_T src = inp->channel[ch] * src_alpha;
+         IM_WORK_T orig = outp->channel[ch] * orig_alpha;
+         IM_WORK_T src_da = src * orig_alpha;
+         IM_WORK_T dest_sa = orig * src_alpha;
+         IM_WORK_T diff = src_da < dest_sa ? src_da : dest_sa;
+         outp->channel[ch] = (src + orig - 2 * diff / IM_SAMPLE_MAX) / dest_alpha;
+       }
+       outp->channel[color_channels] = dest_alpha;
+      }
+      ++inp;
+      ++outp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) {
+         IM_WORK_T src = inp->channel[ch] * src_alpha;
+         IM_WORK_T orig = outp->channel[ch] * IM_SAMPLE_MAX;
+         IM_WORK_T src_da = src * IM_SAMPLE_MAX;
+         IM_WORK_T dest_sa = orig * src_alpha;
+         IM_WORK_T diff = src_da < dest_sa ? src_da : dest_sa;
+         outp->channel[ch] = (src + orig - 2 * diff / IM_SAMPLE_MAX) / IM_SAMPLE_MAX;
+       }
+      }
+      ++inp;
+      ++outp;
+    }
+  }
+}
+
+#undef IM_abs
+
+/*
+  Dca' = min(Sca.Da, Dca.Sa) + Sca.(1 - Da) + Dca(1 - Sa)
+  Da' = Sa + Da - Sa.Da
+
+  To hoist some code:
+
+  Dca' = min(Sc.Sa.Da, Dc.Da.Sa) + Sca - Sca.Da + Dca - Dca.Sa
+       = Sa.Da.min(Sc, Dc) + Sca - Sca.Da + Dca - Dca.Sa
+
+  When Da=1:
+
+  Dca' = min(Sca.1, Dc.1.Sa) + Sca.(1 - 1) + Dc.1(1 - Sa)
+       = min(Sca, Dc.Sa) + Dc(1-Sa)
+       = Sa.min(Sc, Dc) + Dc - Dc.Sa
+  Da'  = Sa + 1 - Sa.1
+       = 1
+ */
+static void 
+IM_SUFFIX(combine_darken)(IM_COLOR *out, IM_COLOR *in, int channels, 
+                         i_img_dim count) {
+  int ch;
+  IM_COLOR const *inp = in;
+  IM_COLOR *outp = out;
+  i_img_dim work_count = count;
+  int color_channels = i_color_channels(channels);
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+
+      if (src_alpha) {
+       IM_WORK_T orig_alpha = outp->channel[color_channels];
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha 
+         - src_alpha * orig_alpha / IM_SAMPLE_MAX;
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T Sca = inp->channel[ch] * src_alpha;
+         IM_WORK_T Dca = outp->channel[ch] * orig_alpha;
+         IM_WORK_T ScaDa = Sca * orig_alpha;
+         IM_WORK_T DcaSa = Dca * src_alpha;
+         IM_WORK_T minc = ScaDa < DcaSa ? ScaDa : DcaSa;
+         outp->channel[ch] = 
+           ( 
+            minc + (Sca + Dca) * IM_SAMPLE_MAX
+            - ScaDa - DcaSa
+            ) / (IM_SAMPLE_MAX * dest_alpha);
+       } 
+       outp->channel[color_channels] = dest_alpha;
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T minc = outp->channel[ch] < inp->channel[ch]
+           ? outp->channel[ch] : inp->channel[ch];
+         outp->channel[ch] = 
+           ( 
+            src_alpha * minc + 
+            outp->channel[ch] * ( IM_SAMPLE_MAX - src_alpha )
+            ) / IM_SAMPLE_MAX;
+       } 
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+}
+
+static void 
+IM_SUFFIX(combine_lighten)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  int ch;
+  IM_COLOR const *inp = in;
+  IM_COLOR *outp = out;
+  i_img_dim work_count = count;
+  int color_channels = i_color_channels(channels);
+
+  if (i_has_alpha(channels)) {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+
+      if (src_alpha) {
+       IM_WORK_T orig_alpha = outp->channel[color_channels];
+       IM_WORK_T dest_alpha = src_alpha + orig_alpha 
+         - src_alpha * orig_alpha / IM_SAMPLE_MAX;
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T Sca = inp->channel[ch] * src_alpha;
+         IM_WORK_T Dca = outp->channel[ch] * orig_alpha;
+         IM_WORK_T ScaDa = Sca * orig_alpha;
+         IM_WORK_T DcaSa = Dca * src_alpha;
+         IM_WORK_T maxc = ScaDa > DcaSa ? ScaDa : DcaSa;
+         outp->channel[ch] = 
+           ( 
+            maxc + (Sca + Dca) * IM_SAMPLE_MAX
+            - ScaDa - DcaSa
+            ) / (IM_SAMPLE_MAX * dest_alpha);
+       } 
+       outp->channel[color_channels] = dest_alpha;
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+  else {
+    while (work_count--) {
+      IM_WORK_T src_alpha = inp->channel[color_channels];
+
+      if (src_alpha) {
+       for (ch = 0; ch < color_channels; ++ch) { 
+         IM_WORK_T maxc = outp->channel[ch] > inp->channel[ch]
+           ? outp->channel[ch] : inp->channel[ch];
+         outp->channel[ch] = 
+           ( 
+            src_alpha * maxc + 
+            outp->channel[ch] * ( IM_SAMPLE_MAX - src_alpha )
+            ) / IM_SAMPLE_MAX;
+       } 
+      }
+      ++outp;
+      ++inp;
+    }
+  }
+}
+
+#if IM_EIGHT_BIT
+#define IM_RGB_TO_HSV i_rgb_to_hsv
+#define IM_HSV_TO_RGB i_hsv_to_rgb
+#else
+#define IM_RGB_TO_HSV i_rgb_to_hsvf
+#define IM_HSV_TO_RGB i_hsv_to_rgbf
+#endif
+
+static void 
+IM_SUFFIX(combine_hue)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  if (channels > 2) {
+    IM_COLOR *inp = in;
+    IM_COLOR const *outp = out;
+    i_img_dim work_count = count;
+
+    if (i_has_alpha(channels)) {
+      while (work_count--) {
+       IM_COLOR c = *inp;
+       IM_RGB_TO_HSV(&c);
+       /* only transfer hue if there's saturation */
+       if (c.channel[1] && inp->channel[3] && outp->channel[3]) {
+         *inp = *outp;
+         IM_RGB_TO_HSV(inp);
+         /* and no point in setting the target hue if the target has no sat */
+         if (inp->channel[1]) {
+           inp->channel[0] = c.channel[0];
+           IM_HSV_TO_RGB(inp);
+           inp->channel[3] = c.channel[3];
+         }
+         else {
+           inp->channel[3] = 0;
+         }
+       }
+       else {
+         inp->channel[3] = 0;
+       }
+       
+       ++outp;
+       ++inp;
+      }
+    }
+    else {
+      while (work_count--) {
+       IM_COLOR c = *inp;
+       IM_RGB_TO_HSV(&c);
+       /* only transfer hue if there's saturation */
+       if (c.channel[1] && inp->channel[3]) {
+         *inp = *outp;
+         IM_RGB_TO_HSV(inp);
+         /* and no point in setting the target hue if the target has no sat */
+         if (inp->channel[1]) {
+           inp->channel[0] = c.channel[0];
+           IM_HSV_TO_RGB(inp);
+           inp->channel[3] = c.channel[3];
+         }
+       }
+       else {
+         inp->channel[3] = 0;
+       }
+       
+       ++outp;
+       ++inp;
+      }
+    }
+
+    IM_SUFFIX(combine_line_na)(out, in, channels, count);
+  }
+}
+
+static void
+IM_SUFFIX(combine_sat)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  if (channels > 2) {
+    IM_COLOR *inp = in;
+    IM_COLOR const *outp = out;
+    i_img_dim work_count = count;
+
+    while (work_count--) {
+      IM_COLOR c = *inp;
+      *inp = *outp;
+      IM_RGB_TO_HSV(&c);
+      IM_RGB_TO_HSV(inp);
+      inp->channel[1] = c.channel[1];
+      IM_HSV_TO_RGB(inp);
+      inp->channel[3] = c.channel[3];
+      ++outp;
+      ++inp;
+    }
+
+    IM_SUFFIX(combine_line_na)(out, in, channels, count);
+  }
+}
+
+static void 
+IM_SUFFIX(combine_value)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  if (channels > 2) {
+    IM_COLOR *inp = in;
+    IM_COLOR const *outp = out;
+    i_img_dim work_count = count;
+
+    while (work_count--) {
+      IM_COLOR c = *inp;
+      *inp = *outp;
+      IM_RGB_TO_HSV(&c);
+      IM_RGB_TO_HSV(inp);
+      inp->channel[2] = c.channel[2];
+      IM_HSV_TO_RGB(inp);
+      inp->channel[3] = c.channel[3];
+      ++outp;
+      ++inp;
+    }
+  }
+
+  /* all images have a "value channel" - for greyscale it's the only
+     colour channel */
+  IM_SUFFIX(combine_line_na)(out, in, channels, count);
+}
+
+static void 
+IM_SUFFIX(combine_color)(IM_COLOR *out, IM_COLOR *in, int channels, i_img_dim count) {
+  if (channels > 2) {
+    IM_COLOR *inp = in;
+    IM_COLOR const *outp = out;
+    i_img_dim work_count = count;
+
+    while (work_count--) {
+      IM_COLOR c = *inp;
+      *inp = *outp;
+      IM_RGB_TO_HSV(&c);
+      IM_RGB_TO_HSV(inp);
+      inp->channel[0] = c.channel[0];
+      inp->channel[1] = c.channel[1];
+      IM_HSV_TO_RGB(inp);
+      inp->channel[3] = c.channel[3];
+      ++outp;
+      ++inp;
+    }
+
+    IM_SUFFIX(combine_line_na)(out, in, channels, count);
+  }
+}
+
+#undef IM_RGB_TO_HSV
+#undef IM_HSV_TO_RGB
+

 #/code
 #/code