[gimp/gimp-2-10] app: align drawable undo rectangle to tile grid

[Ell <ell src gnome org>]

commit 782d54a615f3e8e841218eb46c2c9330dad67582
Author: Ell <ell_se yahoo com>
Date:   Sun Dec 2 02:36:17 2018 -0500

    app: align drawable undo rectangle to tile grid
    
    When creating a drawable undo from the drawable's buffer, align the
    copied rectangle to the buffer's tile grid, so that all the copied
    tiles are COWed, saving memory and gaining speed.
    
    Add applied_x and applied_y fields to GimpDrawableUndo, specifying
    the position at which to apply the applied_buffer, so that we apply
    it in the right place, even if the undo rect has changed due to
    alignment.
    
    (cherry picked from commit bb9dd049fb570353a7fc40e3af7d887d3a6be580)

 app/core/gimpdrawable.c     | 36 +++++++++++++++++++++++++++++++++---
 app/core/gimpdrawableundo.h |  2 ++
 app/core/gimpimage-fade.c   |  6 ++----
 3 files changed, 37 insertions(+), 7 deletions(-)
---
diff --git a/app/core/gimpdrawable.c b/app/core/gimpdrawable.c
index cb4dd55713..262d67ea5c 100644
--- a/app/core/gimpdrawable.c
+++ b/app/core/gimpdrawable.c
@@ -43,9 +43,11 @@
 #include "gimpdrawable-private.h"
 #include "gimpdrawable-shadow.h"
 #include "gimpdrawable-transform.h"
+#include "gimpdrawableundo.h"
 #include "gimpfilterstack.h"
 #include "gimpimage.h"
 #include "gimpimage-colormap.h"
+#include "gimpimage-undo.h"
 #include "gimpimage-undo-push.h"
 #include "gimpmarshal.h"
 #include "gimppickable.h"
@@ -859,14 +861,32 @@ gimp_drawable_real_push_undo (GimpDrawable *drawable,
                               gint          width,
                               gint          height)
 {
+  GimpImage        *image;
+  GimpDrawableUndo *undo;
+  gint              applied_x = x;
+  gint              applied_y = y;
+
   if (! buffer)
     {
+      GeglBuffer    *drawable_buffer = gimp_drawable_get_buffer (drawable);
+      GeglRectangle  drawable_rect;
+
+      gimp_gegl_rectangle_align_to_tile_grid (
+        &drawable_rect,
+        GEGL_RECTANGLE (x, y, width, height),
+        drawable_buffer);
+
+      x      = drawable_rect.x;
+      y      = drawable_rect.y;
+      width  = drawable_rect.width;
+      height = drawable_rect.height;
+
       buffer = gegl_buffer_new (GEGL_RECTANGLE (0, 0, width, height),
                                 gimp_drawable_get_format (drawable));
 
       gimp_gegl_buffer_copy (
-        gimp_drawable_get_buffer (drawable),
-        GEGL_RECTANGLE (x, y, width, height), GEGL_ABYSS_NONE,
+        drawable_buffer,
+        &drawable_rect, GEGL_ABYSS_NONE,
         buffer,
         GEGL_RECTANGLE (0, 0, 0, 0));
     }
@@ -875,10 +895,20 @@ gimp_drawable_real_push_undo (GimpDrawable *drawable,
       g_object_ref (buffer);
     }
 
-  gimp_image_undo_push_drawable (gimp_item_get_image (GIMP_ITEM (drawable)),
+  image = gimp_item_get_image (GIMP_ITEM (drawable));
+
+  gimp_image_undo_push_drawable (image,
                                  undo_desc, drawable,
                                  buffer, x, y);
 
+  undo = GIMP_DRAWABLE_UNDO (gimp_image_undo_get_fadeable (image));
+
+  if (undo)
+    {
+      undo->applied_x = applied_x;
+      undo->applied_y = applied_y;
+    }
+
   g_object_unref (buffer);
 }
 
diff --git a/app/core/gimpdrawableundo.h b/app/core/gimpdrawableundo.h
index d87fd1f4c4..9e67327273 100644
--- a/app/core/gimpdrawableundo.h
+++ b/app/core/gimpdrawableundo.h
@@ -43,6 +43,8 @@ struct _GimpDrawableUndo
 
   /* stuff for "Fade" */
   GeglBuffer             *applied_buffer;
+  gint                    applied_x;
+  gint                    applied_y;
   GimpLayerMode           paint_mode;
   GimpLayerColorSpace     blend_space;
   GimpLayerColorSpace     composite_space;
diff --git a/app/core/gimpimage-fade.c b/app/core/gimpimage-fade.c
index 6fd60ea749..462d03126d 100644
--- a/app/core/gimpimage-fade.c
+++ b/app/core/gimpimage-fade.c
@@ -58,9 +58,7 @@ gimp_image_fade (GimpImage   *image,
       gimp_image_undo (image);
 
       gimp_drawable_apply_buffer (drawable, buffer,
-                                  GEGL_RECTANGLE (0, 0,
-                                                  gegl_buffer_get_width (undo->buffer),
-                                                  gegl_buffer_get_height (undo->buffer)),
+                                  gegl_buffer_get_extent (buffer),
                                   TRUE,
                                   gimp_object_get_name (undo),
                                   gimp_context_get_opacity (context),
@@ -69,7 +67,7 @@ gimp_image_fade (GimpImage   *image,
                                   GIMP_LAYER_COLOR_SPACE_AUTO,
                                   gimp_layer_mode_get_paint_composite_mode (
                                     gimp_context_get_paint_mode (context)),
-                                  NULL, undo->x, undo->y);
+                                  NULL, undo->applied_x, undo->applied_y);
 
       g_object_unref (buffer);
       g_object_unref (undo);