[gegl] samplers: rename inverse_jacobian to scale

[Ãyvind KolÃs <ok src gnome org>]

commit 1726d5b36815b7a1727efd6696b468f988abc301
Author: Ãyvind KolÃs <pippin gimp org>
Date:   Sun Jul 3 02:34:10 2011 +0100

    samplers: rename inverse_jacobian to scale

 gegl/buffer/gegl-buffer-access.c    |    7 +++----
 gegl/buffer/gegl-sampler.c          |   25 +++++++++++++++----------
 gegl/buffer/gegl-sampler.h          |   10 ++++++----
 gegl/gegl-plugin.h                  |   34 ++++++++++++++++++----------------
 gegl/gegl-utils.h                   |    3 ---
 operations/workshop/fractal-trace.c |   32 +++++++++++++++++---------------
 6 files changed, 59 insertions(+), 52 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index 3614a86..620737c 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -339,7 +339,6 @@ gegl_buffer_iterate (GeglBuffer          *buffer,
   gint  buffer_abyss_y = buffer->abyss.y + buffer_shift_y;
   gint  abyss_x_total  = buffer_abyss_x + buffer->abyss.width;
   gint  abyss_y_total  = buffer_abyss_y + buffer->abyss.height;
-  gint  i;
   gint  factor         = 1<<level;
 
   /* roi specified, override buffers extent */
@@ -1069,7 +1068,7 @@ void
 gegl_buffer_sample2 (GeglBuffer       *buffer,
                      gdouble           x,
                      gdouble           y,
-                     GeglMatrix2      *inverse_jacobian,
+                     GeglMatrix2      *scale,
                      gpointer          dest,
                      const Babl       *format,
                      GeglInterpolation interpolation)
@@ -1105,8 +1104,8 @@ gegl_buffer_sample2 (GeglBuffer       *buffer,
       buffer->sampler_format = format;
       gegl_sampler_prepare (buffer->sampler);
     }
-  if (inverse_jacobian)
-    gegl_sampler_set_inverse_jacobian (buffer->sampler, inverse_jacobian);
+  if (scale)
+    gegl_sampler_set_scale (buffer->sampler, scale);
 
   gegl_sampler_get (buffer->sampler, x, y, dest);
 }
diff --git a/gegl/buffer/gegl-sampler.c b/gegl/buffer/gegl-sampler.c
index 9d45e49..ce0c2ad 100644
--- a/gegl/buffer/gegl-sampler.c
+++ b/gegl/buffer/gegl-sampler.c
@@ -42,7 +42,7 @@ enum
   PROP_BUFFER,
   PROP_FORMAT,
   PROP_CONTEXT_RECT,
-  PROP_INVERSE_JACOBIAN,
+  PROP_SCALE,
   PROP_LAST
 };
 
@@ -103,10 +103,15 @@ gegl_sampler_class_init (GeglSamplerClass *klass)
 
   g_object_class_install_property (
                  object_class,
-                 PROP_INVERSE_JACOBIAN,
-                 g_param_spec_pointer ("inverse_jacobian",
-                                       "Inverse Jacobian",
-                                       "Inverse Jacobian matrix, for certain samplers.",
+                 PROP_SCALE,
+                 g_param_spec_pointer ("scale",
+                                       "Scale",
+"An approximation of the extent of pixels sampled in source for a pixel. "
+"The property can be varied per sampled pixel, avoid setting it if it is "
+"constant for the entire buffer; if setting it for every pixel using the "
+"C function gegl_sampler_set_scale is more efficient. "
+"Mostly the scaling factors for sampling does not need to be set if the "
+"transformation is rotating or only scaling up.",
                                        G_PARAM_READWRITE | G_PARAM_CONSTRUCT));
 }
 
@@ -500,7 +505,7 @@ get_property (GObject    *object,
         g_value_set_pointer (value, self->format);
         break;
 
-      case PROP_INVERSE_JACOBIAN:
+      case PROP_SCALE:
         g_value_set_pointer (value, self->inverse_jacobian);
         break;
 
@@ -527,7 +532,7 @@ set_property (GObject      *object,
         self->format = g_value_get_pointer (value);
         break;
 
-      case PROP_INVERSE_JACOBIAN:
+      case PROP_SCALE:
         self->inverse_jacobian = g_value_get_pointer (value);
         break;
 
@@ -591,8 +596,8 @@ gegl_sampler_type_from_interpolation (GeglInterpolation interpolation)
     }
 }
 
-void  gegl_sampler_set_inverse_jacobian (GeglSampler *self,
-                                         GeglMatrix2 *inverse_jacobian)
+void  gegl_sampler_set_scale (GeglSampler *self,
+                              GeglMatrix2 *scale)
 {
-  self->inverse_jacobian = inverse_jacobian;
+  self->inverse_jacobian = scale;
 }
diff --git a/gegl/buffer/gegl-sampler.h b/gegl/buffer/gegl-sampler.h
index 0568e6a..65e2189 100644
--- a/gegl/buffer/gegl-sampler.h
+++ b/gegl/buffer/gegl-sampler.h
@@ -48,7 +48,10 @@ struct _GeglSampler
   GeglRectangle  context_rect[GEGL_SAMPLER_MIPMAP_LEVELS];
   gpointer       sampler_buffer[GEGL_SAMPLER_MIPMAP_LEVELS];
   GeglRectangle  sampler_rectangle[GEGL_SAMPLER_MIPMAP_LEVELS];
-  GeglMatrix2   *inverse_jacobian;
+  GeglMatrix2   *inverse_jacobian; /* scale - which could be the inverse
+                                      inverse jacobian matrix or some other
+                                      approximation of the extent of the region
+                                      being sampled.  */
   gdouble        x; /* mirrors the currently requested */
   gdouble        y; /* coordinates in the instance     */
 };
@@ -73,14 +76,13 @@ void  gegl_sampler_prepare     (GeglSampler *self);
 void  gegl_sampler_set_buffer  (GeglSampler *self,
                                 GeglBuffer  *buffer);
 
+void  gegl_sampler_set_scale   (GeglSampler *self,
+                                GeglMatrix2 *scale);
 void  gegl_sampler_get         (GeglSampler *self,
                                 gdouble      x,
                                 gdouble      y,
                                 void        *output);
 
-void  gegl_sampler_set_inverse_jacobian (GeglSampler *self,
-                                         GeglMatrix2 *inverse_jacobian);
-
 gfloat * gegl_sampler_get_from_buffer (GeglSampler *sampler,
                                        gint         x,
                                        gint         y);
diff --git a/gegl/gegl-plugin.h b/gegl/gegl-plugin.h
index 68881ff..3fec394 100644
--- a/gegl/gegl-plugin.h
+++ b/gegl/gegl-plugin.h
@@ -96,25 +96,27 @@ const gchar   * gegl_extension_handler_get_saver   (const gchar         *extensi
  * transform this is massive computational overhead that can
  * be skipped by passing NULL to the sampler.
  *
- * #define inverse_map(x,y,dx,dy) { dx=x; dy=y; }
+ * #define gegl_unmap(x,y,dx,dy) { dx=x; dy=y; }
  *
- * gegl_compute_jacobian(matrix, x, y);
- * inverse_map(x,y,sample_x,sample_y);
+ * gegl_sampler_compute_scale (scale, x, y);
+ * gegl_unmap(x,y,sample_x,sample_y);
+ * gegl_buffer_sample (buffer, sample_x, sample_y, scale, dest, format,
+ *                     GEGL_INTERPOLATION_LOHALO);
  *
- * #undef inverse_map      // IMPORTANT undefine map macro
+ * #undef gegl_unmap      // IMPORTANT undefine map macro
  */
-#define gegl_compute_inverse_jacobian(matrix, x, y) \
-  { \
-    float ax, ay, bx, by;            \
-    inverse_map(x + 0.5, y, ax, ay); \
-    inverse_map(x - 0.5, y, bx, by); \
-    matrix.coeff[0][0] = ax - bx;    \
-    matrix.coeff[1][0] = ay - by;    \
-    inverse_map(x, y + 0.5, ax, ay); \
-    inverse_map(x, y - 0.5, bx, by); \
-    matrix.coeff[0][1] = ax - bx;    \
-    matrix.coeff[1][1] = ay - by;    \
-  }
+#define gegl_sampler_compute_scale (matrix, x, y) \
+{                                       \
+  float ax, ay, bx, by;                 \
+  gegl_inverse_map(x + 0.5, y, ax, ay); \
+  gegl_inverse_map(x - 0.5, y, bx, by); \
+  matrix.coeff[0][0] = ax - bx;         \
+  matrix.coeff[1][0] = ay - by;         \
+  gegl_inverse_map(x, y + 0.5, ax, ay); \
+  gegl_inverse_map(x, y - 0.5, bx, by); \
+  matrix.coeff[0][1] = ax - bx;         \
+  matrix.coeff[1][1] = ay - by;         \
+}
 
 #include <glib-object.h>
 #include <babl/babl.h>
diff --git a/gegl/gegl-utils.h b/gegl/gegl-utils.h
index 3a56b99..f22db42 100644
--- a/gegl/gegl-utils.h
+++ b/gegl/gegl-utils.h
@@ -22,9 +22,6 @@
 
 G_BEGIN_DECLS
 
-
-
-
 /***
  * GeglRectangle:
  *
diff --git a/operations/workshop/fractal-trace.c b/operations/workshop/fractal-trace.c
index 22436f3..e5f3958 100644
--- a/operations/workshop/fractal-trace.c
+++ b/operations/workshop/fractal-trace.c
@@ -116,11 +116,13 @@ fractaltrace (GeglBuffer          *input,
               BackgroundType       background_type,
               Babl                *format)
 {
-  GeglMatrix2    inverse_jacobian;
-  gint           x, i, offset;
-  gdouble        scale_x, scale_y;
-  gdouble        bailout2;
-  gfloat         dest[4];
+  GeglMatrix2  scale;        /* a matrix indicating scaling factors around the
+                                current center pixel.
+                              */
+  gint         x, i, offset;
+  gdouble      scale_x, scale_y;
+  gdouble      bailout2;
+  gfloat       dest[4];
 
   scale_x = (o->X2 - o->X1) / picture->width;
   scale_y = (o->Y2 - o->Y1) / picture->height;
@@ -138,7 +140,7 @@ fractaltrace (GeglBuffer          *input,
       switch (fractal_type)
         {
         case FRACTAL_TYPE_JULIA:
-#define inverse_map(u,v,ud,vd) {\
+#define gegl_inverse_map(u,v,ud,vd) {\
        gdouble rx, ry;\
        cx = o->X1 + ((u) - picture->x) * scale_x; \
        cy = o->Y1 + ((v) - picture->y) * scale_y; \
@@ -146,13 +148,13 @@ fractaltrace (GeglBuffer          *input,
        ud = (rx - o->X1) / scale_x + picture->x;\
        vd = (ry - o->Y1) / scale_y + picture->y;\
       }
-      gegl_compute_inverse_jacobian (inverse_jacobian, x, y);
-      inverse_map(x,y,px,py);
-#undef inverse_map
+      gegl_sampler_compute_scale (scale, x, y);
+      gegl_inverse_map(x,y,px,py);
+#undef gegl_inverse_map
           break;
 
         case FRACTAL_TYPE_MANDELBROT:
-#define inverse_map(u,v,ud,vd) {\
+#define gegl_inverse_map(u,v,ud,vd) {\
            gdouble rx, ry;\
            cx = o->X1 + ((u) - picture->x) * scale_x; \
            cy = o->Y1 + ((v) - picture->y) * scale_y; \
@@ -160,9 +162,9 @@ fractaltrace (GeglBuffer          *input,
            ud = (rx - o->X1) / scale_x + picture->x;\
            vd = (ry - o->Y1) / scale_y + picture->y;\
          }
-      gegl_compute_inverse_jacobian (inverse_jacobian, x, y);
-      inverse_map(x,y,px,py);
-#undef inverse_map
+      gegl_compute_inverse_jacobian (scale, x, y);
+      gegl_inverse_map(x,y,px,py);
+#undef gegl_inverse_map
           break;
 
         default:
@@ -171,7 +173,7 @@ fractaltrace (GeglBuffer          *input,
 
       if (0 <= px && px < picture->width && 0 <= py && py < picture->height)
         {
-          gegl_buffer_sample2 (input, px, py, &inverse_jacobian, dest, format,
+          gegl_buffer_sample2 (input, px, py, &scale, dest, format,
                                GEGL_INTERPOLATION_LOHALO);
         }
       else
@@ -204,7 +206,7 @@ fractaltrace (GeglBuffer          *input,
                     py = picture->height - 1.0;
                 }
 
-              gegl_buffer_sample2 (input, px, py, &inverse_jacobian, dest, format,
+              gegl_buffer_sample2 (input, px, py, &scale, dest, format,
                                    GEGL_INTERPOLATION_LOHALO);
               break;