[gegl] operation: add GeglOperationAreaFilter::get_abyss_policy() vfunc

[N/A <ell src gnome org>]

commit ad9790d6d28b0ac6ccf481260aca27f4dded74fe
Author: Ell <ell_se yahoo com>
Date:   Thu Apr 26 14:09:40 2018 -0400

    operation: add GeglOperationAreaFilter::get_abyss_policy() vfunc
    
    Add a GeglOperationAreaFilter::get_abyss_policy() virtual function,
    which subclasses can override to specify which abyss policy is used
    when reading the input buffer.
    
    Modify get_required_for_output() and get_invalidated_by_change() to
    take the abyss policy into account.  In particular, when using the
    LOOP abyss policy, wrap the rectangle around the input bounds, so
    that the correct input area is processed, and the correct output
    area is invalidated.

 gegl/operation/gegl-operation-area-filter.c |   89 +++++++++++++++++++++++++--
 gegl/operation/gegl-operation-area-filter.h |   11 +++-
 2 files changed, 92 insertions(+), 8 deletions(-)
---
diff --git a/gegl/operation/gegl-operation-area-filter.c b/gegl/operation/gegl-operation-area-filter.c
index 4a9733b..dc9c33e 100644
--- a/gegl/operation/gegl-operation-area-filter.c
+++ b/gegl/operation/gegl-operation-area-filter.c
@@ -113,6 +113,40 @@ get_required_for_output (GeglOperation        *operation,
       rect.y      -= area->top;
       rect.width  += area->left + area->right;
       rect.height += area->top + area->bottom;
+
+      /* wrap rectangle around the input bounds, if using a LOOP abyss policy */
+      if (GEGL_OPERATION_AREA_FILTER_GET_CLASS (area)->get_abyss_policy &&
+          GEGL_OPERATION_AREA_FILTER_GET_CLASS (area)->get_abyss_policy (
+            operation, input_pad) == GEGL_ABYSS_LOOP)
+        {
+          GeglRectangle *in_rect;
+
+          in_rect = gegl_operation_source_get_bounding_box (operation,"input");
+          g_return_val_if_fail (in_rect != NULL, rect);
+
+          rect.x      = in_rect->x + (rect.x - in_rect->x) % in_rect->width;
+          rect.y      = in_rect->y + (rect.y - in_rect->y) % in_rect->height;
+          rect.width  = rect.width;
+          rect.height = rect.height;
+
+          if (rect.x < in_rect->x)
+            rect.x += in_rect->width;
+
+          if (rect.y < in_rect->y)
+            rect.y += in_rect->height;
+
+          if (rect.x + rect.width > in_rect->x + in_rect->width)
+            {
+              rect.x      = in_rect->x;
+              rect.width  = in_rect->width;
+            }
+
+          if (rect.y + rect.height > in_rect->y + in_rect->height)
+            {
+              rect.y      = in_rect->y;
+              rect.height = in_rect->height;
+            }
+        }
     }
 
   return rect;
@@ -123,13 +157,56 @@ get_invalidated_by_change (GeglOperation        *operation,
                            const gchar         *input_pad,
                            const GeglRectangle *input_region)
 {
-  GeglOperationAreaFilter *area = GEGL_OPERATION_AREA_FILTER (operation);
-  GeglRectangle            retval;
+  GeglOperationAreaFilter *area   = GEGL_OPERATION_AREA_FILTER (operation);
+  GeglRectangle            retval = *input_region;
+
+  /* wrap rectangle around the input bounds, if using a LOOP abyss policy */
+  if (GEGL_OPERATION_AREA_FILTER_GET_CLASS (area)->get_abyss_policy &&
+      GEGL_OPERATION_AREA_FILTER_GET_CLASS (area)->get_abyss_policy (
+        operation, input_pad) == GEGL_ABYSS_LOOP)
+    {
+      GeglRectangle *in_rect;
+
+      in_rect = gegl_operation_source_get_bounding_box (operation,"input");
+
+      if (in_rect)
+        {
+          if (input_region->x -
+              in_rect->x      <
+              area->left + area->right)
+            {
+              retval.width = in_rect->width - (retval.x - in_rect->x);
+            }
+
+          if ((in_rect->x      + in_rect->width)      -
+              (input_region->x + input_region->width) <
+              area->right + area->left)
+            {
+              retval.width += retval.x - in_rect->x;
+              retval.x      = in_rect->x;
+            }
+
+          if (input_region->y -
+              in_rect->y      <
+              area->top + area->bottom)
+            {
+              retval.height = in_rect->height - (retval.y - in_rect->y);
+            }
+
+          if ((in_rect->y      + in_rect->height)      -
+              (input_region->y + input_region->height) <
+              area->bottom + area->top)
+            {
+              retval.height += retval.y - in_rect->y;
+              retval.y       = in_rect->y;
+            }
+        }
+    }
 
-  retval.x      = input_region->x      - area->right;
-  retval.y      = input_region->y      - area->bottom;
-  retval.width  = input_region->width  + area->right  + area->left;
-  retval.height = input_region->height + area->bottom + area->top;
+  retval.x      -= area->right;
+  retval.y      -= area->bottom;
+  retval.width  += area->right  + area->left;
+  retval.height += area->bottom + area->top;
 
   return retval;
 }
diff --git a/gegl/operation/gegl-operation-area-filter.h b/gegl/operation/gegl-operation-area-filter.h
index 789732d..38348f9 100644
--- a/gegl/operation/gegl-operation-area-filter.h
+++ b/gegl/operation/gegl-operation-area-filter.h
@@ -50,8 +50,15 @@ struct _GeglOperationAreaFilter
 typedef struct _GeglOperationAreaFilterClass GeglOperationAreaFilterClass;
 struct _GeglOperationAreaFilterClass
 {
-  GeglOperationFilterClass parent_class;
-  gpointer                 pad[4];
+  GeglOperationFilterClass    parent_class;
+
+  /* returns the abyss policy used when reading the input.  if not overridden,
+   * GEGL_ABYSS_NONE is assumed.
+   */
+  GeglAbyssPolicy          (* get_abyss_policy) (GeglOperation *operation,
+                                                 const gchar   *input_pad);
+
+  gpointer                    pad[3];
 };
 
 GType gegl_operation_area_filter_get_type (void) G_GNUC_CONST;