From 7164a2abec3c5f4b178729a62c814f93dba4ce49 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Tue, 29 Sep 2009 13:45:58 +0000
Subject: [PATCH] added im_segment()

---
 ChangeLog                          |  1 +
 libvips/include/vips/proto.h       |  5 ++--
 libvips/inplace/im_flood_other.c   | 48 ++++++++++++++++++++++++++++--
 libvips/inplace/inplace_dispatch.c | 32 ++++++++++++++++++++
 4 files changed, 81 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 28ee3924..f80a3510 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -49,6 +49,7 @@
   and else parts
 - better im_check() functions
 - added im_flood_other() as start of simple segmentation operator
+- added im_segment() 
 
 25/3/09 started 7.18.0
 - revised version numbers
diff --git a/libvips/include/vips/proto.h b/libvips/include/vips/proto.h
index e66b2863..8c38e8bc 100644
--- a/libvips/include/vips/proto.h
+++ b/libvips/include/vips/proto.h
@@ -620,8 +620,9 @@ int im_flood( IMAGE *, int, int, PEL *, Rect * );
 int im_flood_blob( IMAGE *, int, int, PEL *, Rect * );
 int im_flood_blob_copy( IMAGE *in, IMAGE *out, int x, int y, PEL *ink );
 int im_flood_other( IMAGE *mask, IMAGE *test, int x, int y, int serial );
-int im_flood_other_copy( IMAGE *mask, IMAGE *out, 
-	IMAGE *test, int x, int y, int serial );
+int im_flood_other_copy( IMAGE *mask, IMAGE *test, IMAGE *out, 
+	int x, int y, int serial );
+int im_segment( IMAGE *test, IMAGE *mask, int *segments );
 int im_lineset( IMAGE *in, IMAGE *out, IMAGE *mask, IMAGE *ink,
 	int n, int *x1v, int *y1v, int *x2v, int *y2v );
 
diff --git a/libvips/inplace/im_flood_other.c b/libvips/inplace/im_flood_other.c
index 164bb247..4518cf8b 100644
--- a/libvips/inplace/im_flood_other.c
+++ b/libvips/inplace/im_flood_other.c
@@ -275,7 +275,7 @@ im_flood_other( IMAGE *mask, IMAGE *test, int x, int y, int serial )
 	if( im_check_known_coded( "im_flood_other", test ) ||
 		im_check_uncoded( "im_flood_other", mask ) ||
 		im_check_mono( "im_flood_other", mask ) ||
-		im_check_int( "im_flood_other", mask ) ||
+		im_check_format( "im_flood_other", mask, IM_BANDFMT_INT ) ||
 		im_check_same_size( "im_flood_other", test, mask ) )
 		return( -1 );
 
@@ -315,8 +315,8 @@ im_flood_other( IMAGE *mask, IMAGE *test, int x, int y, int serial )
  * automatically. Maybe nip could do it if it sees a RW image argument?
  */
 int
-im_flood_other_copy( IMAGE *mask, IMAGE *out, 
-	IMAGE *test, int x, int y, int serial )
+im_flood_other_copy( IMAGE *mask, IMAGE *test, IMAGE *out, 
+	int x, int y, int serial )
 {
 	IMAGE *t;
 
@@ -329,4 +329,46 @@ im_flood_other_copy( IMAGE *mask, IMAGE *out,
 	return( 0 );
 }
 
+/* Now: segment with im_flood_other(). 
+ */
+int
+im_segment( IMAGE *test, IMAGE *mask, int *segments )
+{
+	IMAGE *t[2];
+	int serial;
+	int x, y;
+
+	/* Create the mask image.
+	 */
+	if( im_open_local_array( mask, t, 2, "im_segment", "p" ) ||
+		im_black( t[0], test->Xsize, test->Ysize, 1 ) ||
+		im_clip2fmt( t[0], t[1], IM_BANDFMT_INT ) ) 
+		return( 0 );
+
+	/* Search the mask image, flooding as we find zero pixels.
+	 */
+	if( im_incheck( t[1] ) )
+		return( -1 );
+	serial = 0;
+	for( y = 0; y < test->Ysize; y++ )
+		for( x = 0; x < test->Xsize; x++ ) {
+			int *m = (int *) t[1]->data + x + y * test->Ysize;
+
+			if( !*m ) {
+				if( im_flood_other( t[1], test, x, y, serial ) )
+					return( -1 );
+
+				serial += 1;
+			}
+		}
+
+	/* Copy result to mask.
+	 */
+	if( im_copy( t[1], mask ) )
+		return( -1 );
+	if( segments )
+		*segments = serial;
+
+	return( 0 );
+}
 
diff --git a/libvips/inplace/inplace_dispatch.c b/libvips/inplace/inplace_dispatch.c
index 18871f0c..53fe72cc 100644
--- a/libvips/inplace/inplace_dispatch.c
+++ b/libvips/inplace/inplace_dispatch.c
@@ -295,6 +295,37 @@ static im_function flood_other_copy_desc = {
 	flood_other_copy_args 	/* Arg list */
 };
 
+/* Args for im_segment().
+ */
+static im_arg_desc segment_args[] = {
+	IM_INPUT_IMAGE( "test" ),
+	IM_OUTPUT_IMAGE( "mask" ),
+	IM_OUTPUT_INT( "segments" )
+};
+
+/* Call im_segment() via arg vector.
+ */
+static int
+segment_vec( im_object *argv )
+{
+	IMAGE *test = argv[1];
+	IMAGE *mask = argv[0];
+	int *serial = (int *) argv[5];
+
+	return( im_segment( test, mask, serial ) );
+}
+
+/* Description of im_segment().
+ */ 
+static im_function segment_desc = {
+	"im_segment",		/* Name */
+	"number continuous regions in an image",
+	0,			/* Flags */
+	segment_vec, 		/* Dispatch function */
+	IM_NUMBER( segment_args ),/* Size of arg list */
+	segment_args 		/* Arg list */
+};
+
 /* To do:
  * these all need some kind of pel type
  *
@@ -313,6 +344,7 @@ static im_function *inplace_list[] = {
 	&circle_desc,
 	&flood_blob_copy_desc,
 	&flood_other_copy_desc,
+	&segment_desc,
 	&insertplace_desc,
 	&line_desc,
 	&lineset_desc