start vips_ismonotonic()

TODO

@@ -1,3 +1,5 @@
+- finish hist_ismonotonic()
+
 - need to do im_profile() before we can finish hist_percent()
 
 - try:

libvips/histogram/hist_ismonotonic.c

@@ -0,0 +1,157 @@
+/* test for monotonicity
+ *
+ * Author: John Cupitt
+ * Written on: 18/7/1995
+ * 17/9/96 JC
+ *	- restrictions on Ps, Pm, Ph relaxed
+ *	- restrictions on S, M, H relaxed
+ * 25/7/01 JC
+ *	- patched for im_extract_band() change
+ * 11/7/04
+ *	- generalised to im_tone_build_range() ... so you can use it for any
+ *	  image, not just LabS
+ * 26/3/10
+ * 	- cleanups
+ * 	- gtkdoc
+ * 20/9/13
+ * 	- redone as a class
+ */
+
+/*
+
+    This file is part of VIPS.
+    
+    VIPS is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 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 Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <stdio.h>
+
+#include <vips/vips.h>
+
+typedef struct _VipsHistIsmonotonic { 
+	VipsOperation parent_instance;
+
+	VipsImage *in;
+
+	int *monotonic;
+} VipsHistIsmonotonic;
+
+typedef VipsOperationClass VipsHistIsmonotonicClass;
+
+G_DEFINE_TYPE( VipsHistIsmonotonic, vips_hist_ismonotonic, VIPS_TYPE_OPERATION );
+
+static int
+vips_hist_ismonotonic_build( VipsObject *object )
+{
+	VipsHistIsmonotonic *ismonotonic = (VipsHistIsmonotonic *) object; 
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 4 );
+
+	if( VIPS_OBJECT_CLASS( vips_hist_ismonotonic_parent_class )->
+		build( object ) )
+		return( -1 );
+
+	if( im_check_hist( "im_ismonotonic", lut ) ||
+		im_open_local_array( lut, t, 2, "im_ismonotonic", "p" ) )
+		return( -1 );
+
+	if( lut->Xsize == 1 ) 
+		mask = im_create_imaskv( "im_ismonotonic", 1, 2, -1, 1 );
+	else 
+		mask = im_create_imaskv( "im_ismonotonic", 2, 1, -1, 1 );
+	if( !(mask = im_local_imask( lut, mask )) )
+		return( -1 );
+	mask->offset = 128;
+
+	/* We want >=128 everywhere, ie. no -ve transitions.
+	 */
+	if( im_conv( lut, t[0], mask ) ||
+		im_moreeqconst( t[0], t[1], 128 ) ||
+		im_min( t[1], &m ) )
+		return( -1 );
+
+	*out = m;
+
+	return( 0 );
+}
+
+static void
+vips_hist_ismonotonic_class_init( VipsHistIsmonotonicClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	object_class->nickname = "hist_ismonotonic";
+	object_class->description = _( "test for monotonicity" );
+	object_class->build = vips_hist_ismonotonic_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistIsmonotonic, in ) );
+
+	VIPS_ARG_INT( class, "monotonic", 2, 
+		_( "Monotonic" ), 
+		_( "non-zero if in is monotonic" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsHistIsmonotonic, monotonic ),
+		0, 1, 0 );
+
+}
+
+static void
+vips_hist_ismonotonic_init( VipsHistIsmonotonic *ismonotonic )
+{
+}
+
+/**
+ * im_ismonotonic:
+ * @lut: lookup-table to test
+ * @out: set non-zero if @lut is monotonic 
+ *
+ * Test @lut for monotonicity. @out is set non-zero if @lut is monotonic.
+ *
+ * See also: im_tone_build_range().
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int 
+vips_hist_ismonotonic( VipsImage *in, int *monotonic, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, monotonic );
+	result = vips_call_split( "hist_ismonotonic", ap, in, monotonic );
+	va_end( ap );
+
+	return( result );
+}