[gimp/goat-invasion: 394/526] app: add gimp-gegl-loops.[ch] which for now contains a convolve function

[Michael Natterer <mitch src gnome org>]

commit dbb203c9f0c9efc789438667ef13608944513bb2
Author: Michael Natterer <mitch gimp org>
Date:   Mon Apr 2 00:11:58 2012 +0200

    app: add gimp-gegl-loops.[ch] which for now contains a convolve function

 app/gegl/Makefile.am       |    2 +
 app/gegl/gimp-gegl-loops.c |  191 ++++++++++++++++++++++++++++++++++++++++++++
 app/gegl/gimp-gegl-loops.h |   39 +++++++++
 3 files changed, 232 insertions(+), 0 deletions(-)
---
diff --git a/app/gegl/Makefile.am b/app/gegl/Makefile.am
index 665a8e3..f445f88 100644
--- a/app/gegl/Makefile.am
+++ b/app/gegl/Makefile.am
@@ -22,6 +22,8 @@ libappgegl_a_sources = \
 	gimp-gegl.h				\
 	gimp-gegl-config-proxy.c		\
 	gimp-gegl-config-proxy.h		\
+	gimp-gegl-loops.c			\
+	gimp-gegl-loops.h			\
 	gimp-gegl-nodes.c			\
 	gimp-gegl-nodes.h			\
 	gimp-gegl-utils.c			\
diff --git a/app/gegl/gimp-gegl-loops.c b/app/gegl/gimp-gegl-loops.c
new file mode 100644
index 0000000..9b26af2
--- /dev/null
+++ b/app/gegl/gimp-gegl-loops.c
@@ -0,0 +1,191 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-gegl-loops.c
+ * Copyright (C) 2012 Michael Natterer <mitch gimp org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "gimp-gegl-types.h"
+
+#include "gimp-gegl-loops.h"
+
+
+void
+gimp_gegl_convolve (GeglBuffer          *src_buffer,
+                    const GeglRectangle *src_rect,
+                    GeglBuffer          *dest_buffer,
+                    const GeglRectangle *dest_rect,
+                    const gfloat        *matrix,
+                    gint                 size,
+                    gdouble              divisor,
+                    GimpConvolutionType  mode,
+                    gboolean             alpha_weighting)
+{
+  GeglBufferIterator *iter;
+  GeglRectangle      *src_roi;
+  GeglRectangle      *dest_roi;
+  const Babl         *src_format;
+  const Babl         *dest_format;
+  gint                src_bpp;
+  gint                dest_bpp;
+
+  src_format  = gegl_buffer_get_format (src_buffer);
+  dest_format = gegl_buffer_get_format (dest_buffer);
+
+  src_bpp  = babl_format_get_bytes_per_pixel (src_format);
+  dest_bpp = babl_format_get_bytes_per_pixel (dest_format);
+
+  iter = gegl_buffer_iterator_new (src_buffer, src_rect, 0, NULL,
+                                   GEGL_BUFFER_READ, GEGL_ABYSS_NONE);
+  src_roi = &iter->roi[0];
+
+  gegl_buffer_iterator_add (iter, dest_buffer, dest_rect, 0, NULL,
+                            GEGL_BUFFER_WRITE, GEGL_ABYSS_NONE);
+  dest_roi = &iter->roi[1];
+
+  while (gegl_buffer_iterator_next (iter))
+    {
+      /*  Convolve the src image using the convolution matrix, writing
+       *  to dest Convolve is not tile-enabled--use accordingly
+       */
+      const guchar *src       = iter->data[0];
+      guchar       *dest      = iter->data[1];
+      const gint    bytes     = src_bpp;
+      const gint    a_byte    = bytes - 1;
+      const gint    rowstride = src_bpp * src_roi->width;
+      const gint    margin    = size / 2;
+      const gint    x1        = src_roi->x;
+      const gint    y1        = src_roi->y;
+      const gint    x2        = src_roi->x + src_roi->width  - 1;
+      const gint    y2        = src_roi->y + src_roi->height - 1;
+      gint          x, y;
+      gint          offset;
+
+      /*  If the mode is NEGATIVE_CONVOL, the offset should be 128  */
+      if (mode == GIMP_NEGATIVE_CONVOL)
+        {
+          offset = 128;
+          mode = GIMP_NORMAL_CONVOL;
+        }
+      else
+        {
+          offset = 0;
+        }
+
+      for (y = 0; y < dest_roi->height; y++)
+        {
+          guchar *d = dest;
+
+          if (alpha_weighting)
+            {
+              for (x = 0; x < dest_roi->width; x++)
+                {
+                  const gfloat *m                = matrix;
+                  gdouble       total[4]         = { 0.0, 0.0, 0.0, 0.0 };
+                  gdouble       weighted_divisor = 0.0;
+                  gint          i, j, b;
+
+                  for (j = y - margin; j <= y + margin; j++)
+                    {
+                      for (i = x - margin; i <= x + margin; i++, m++)
+                        {
+                          gint          xx = CLAMP (i, x1, x2);
+                          gint          yy = CLAMP (j, y1, y2);
+                          const guchar *s  = src + yy * rowstride + xx * bytes;
+                          const guchar  a  = s[a_byte];
+
+                          if (a)
+                            {
+                              gdouble mult_alpha = *m * a;
+
+                              weighted_divisor += mult_alpha;
+
+                              for (b = 0; b < a_byte; b++)
+                                total[b] += mult_alpha * s[b];
+
+                              total[a_byte] += mult_alpha;
+                            }
+                        }
+                    }
+
+                  if (weighted_divisor == 0.0)
+                    weighted_divisor = divisor;
+
+                  for (b = 0; b < a_byte; b++)
+                    total[b] /= weighted_divisor;
+
+                  total[a_byte] /= divisor;
+
+                  for (b = 0; b < bytes; b++)
+                    {
+                      total[b] += offset;
+
+                      if (mode != GIMP_NORMAL_CONVOL && total[b] < 0.0)
+                        total[b] = - total[b];
+
+                      if (total[b] < 0.0)
+                        *d++ = 0;
+                      else
+                        *d++ = (total[b] > 255.0) ? 255 : (guchar) ROUND (total[b]);
+                    }
+                }
+            }
+          else
+            {
+              for (x = 0; x < dest_roi->width; x++)
+                {
+                  const gfloat *m        = matrix;
+                  gdouble       total[4] = { 0.0, 0.0, 0.0, 0.0 };
+                  gint          i, j, b;
+
+                  for (j = y - margin; j <= y + margin; j++)
+                    {
+                      for (i = x - margin; i <= x + margin; i++, m++)
+                        {
+                          gint          xx = CLAMP (i, x1, x2);
+                          gint          yy = CLAMP (j, y1, y2);
+                          const guchar *s  = src + yy * rowstride + xx * bytes;
+
+                          for (b = 0; b < bytes; b++)
+                            total[b] += *m * s[b];
+                        }
+                    }
+
+                  for (b = 0; b < bytes; b++)
+                    {
+                      total[b] = total[b] / divisor + offset;
+
+                      if (mode != GIMP_NORMAL_CONVOL && total[b] < 0.0)
+                        total[b] = - total[b];
+
+                      if (total[b] < 0.0)
+                        *d++ = 0.0;
+                      else
+                        *d++ = (total[b] > 255.0) ? 255 : (guchar) ROUND (total[b]);
+                    }
+                }
+            }
+
+          dest += dest_roi->width * dest_bpp;
+        }
+    }
+}
diff --git a/app/gegl/gimp-gegl-loops.h b/app/gegl/gimp-gegl-loops.h
new file mode 100644
index 0000000..6c49216
--- /dev/null
+++ b/app/gegl/gimp-gegl-loops.h
@@ -0,0 +1,39 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimp-gegl-loops.h
+ * Copyright (C) 2012 Michael Natterer <mitch gimp org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_GEGL_LOOPS_H__
+#define __GIMP_GEGL_LOOPS_H__
+
+
+/*  this is a pretty stupid port of concolve_region() that only works
+ *  on a linear source buffer
+ */
+void   gimp_gegl_convolve (GeglBuffer          *src_buffer,
+                           const GeglRectangle *src_rect,
+                           GeglBuffer          *dest_buffer,
+                           const GeglRectangle *dest_rect,
+                           const gfloat        *matrix,
+                           gint                 size,
+                           gdouble              divisor,
+                           GimpConvolutionType  mode,
+                           gboolean             alpha_weighting);
+
+
+#endif /* __GIMP_GEGL_LOOPS_H__ */