redo subsample as a class

ChangeLog

@@ -4,7 +4,7 @@
 it's cheap so caching doesn't help anyway
 - auto rshift down to 8 bits on save, if necessary
 - im_gaussnoise(), im_copy_file(), im_grid(), im_scale(), im_scaleps(),
-  im_wrap(), im_rotquad(), im_zoom() redone as classes
+  im_wrap(), im_rotquad(), im_zoom(), im_subsample() redone as classes
 - add --angle option to dzsave
 
 14/5/13 started 7.32.4

libvips/conversion/Makefile.am

@@ -31,7 +31,7 @@ libconversion_la_SOURCES = \
 	grid.c \
 	scale.c \
 	wrap.c \
-	im_subsample.c \
+	subsample.c \
 	im_system.c \
 	im_system_image.c \
 	im_text.c \

libvips/conversion/conversion.c

@@ -130,6 +130,7 @@ vips_conversion_operation_init( void )
 	extern GType vips_scale_get_type( void ); 
 	extern GType vips_wrap_get_type( void ); 
 	extern GType vips_zoom_get_type( void ); 
+	extern GType vips_subsample_get_type( void ); 
 
 	vips_copy_get_type();
 	vips_tile_cache_get_type(); 
@@ -157,6 +158,7 @@ vips_conversion_operation_init( void )
 	vips_scale_get_type(); 
 	vips_wrap_get_type(); 
 	vips_zoom_get_type(); 
+	vips_subsample_get_type(); 
 }
 
 /* The common part of most binary conversion

libvips/conversion/im_subsample.c

@@ -1,254 +0,0 @@
-/* im_subsample
- *
- * 3/7/95 JC
- *	- adapted from im_shrink()
- * 3/8/02 JC
- *	- fall back to im_copy() for x/y factors == 1
- * 21/4/08
- * 	- don't fall back to pixel-wise shrinks for smalltile, it kills
- * 	  performance, just bring IM_MAX_WIDTH down instead
- * 1/2/10
- * 	- gtkdoc
- */
-
-/*
-
-    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 <stdlib.h>
-
-#include <vips/vips.h>
-
-/* Maximum width of input we ask for.
- */
-#define IM_MAX_WIDTH (100)
-
-/* Our main parameter struct.
- */
-typedef struct {
-	int xshrink;		/* Subsample factors */
-	int yshrink;
-} SubsampleInfo;
-
-/* Subsample a REGION. We fetch in IM_MAX_WIDTH pixel-wide strips, left-to-right
- * across the input.
- */
-static int
-line_shrink_gen( REGION *or, void *seq, void *a, void *b )
-{
-	REGION *ir = (REGION *) seq;
-	IMAGE *in = (IMAGE *) a;
-	SubsampleInfo *st = (SubsampleInfo *) b;
-	Rect *r = &or->valid;
-
-	int le = r->left;
-	int ri = IM_RECT_RIGHT( r );
-	int to = r->top;
-	int bo = IM_RECT_BOTTOM(r);
-
-	int ps = IM_IMAGE_SIZEOF_PEL( in );
-
-	int owidth = IM_MAX_WIDTH / st->xshrink;
-
-	Rect s;
-	int x, y;
-	int z, k;
-
-	/* Loop down the region.
-	 */
-	for( y = to; y < bo; y++ ) {
-		VipsPel *q = IM_REGION_ADDR( or, le, y );
-		VipsPel *p;
-
-		/* Loop across the region, in owidth sized pieces.
-		 */
-		for( x = le; x < ri; x += owidth ) {
-			/* How many pixels do we make this time?
-			 */
-			int ow = IM_MIN( owidth, ri - x );
-
-			/* Ask for this many from input ... can save a 
-			 * little here!
-			 */
-			int iw = ow * st->xshrink - (st->xshrink - 1);
-
-			/* Ask for input.
-			 */
-			s.left = x * st->xshrink;
-			s.top = y * st->yshrink;
-			s.width = iw;
-			s.height = 1;
-			if( im_prepare( ir, &s ) )
-				return( -1 );
-
-			/* Append new pels to output.
-			 */
-			p = IM_REGION_ADDR( ir, s.left, s.top );
-			for( z = 0; z < ow; z++ ) {
-				for( k = 0; k < ps; k++ )
-					q[k] = p[k];
-
-				q += ps;
-				p += ps * st->xshrink;
-			}
-		}
-	}
-
-	return( 0 );
-}
-
-/* Fetch one pixel at a time ... good for very large shrinks.
- */
-static int
-point_shrink_gen( REGION *or, void *seq, void *a, void *b )
-{
-	REGION *ir = (REGION *) seq;
-	IMAGE *in = (IMAGE *) a;
-	SubsampleInfo *st = (SubsampleInfo *) b;
-	Rect *r = &or->valid;
-
-	int le = r->left;
-	int ri = IM_RECT_RIGHT( r );
-	int to = r->top;
-	int bo = IM_RECT_BOTTOM(r);
-
-	int ps = IM_IMAGE_SIZEOF_PEL( in );
-
-	Rect s;
-	int x, y;
-	int k;
-
-	/* Loop down the region.
-	 */
-	for( y = to; y < bo; y++ ) {
-		VipsPel *q = IM_REGION_ADDR( or, le, y );
-		VipsPel *p;
-
-		/* Loop across the region, in owidth sized pieces.
-		 */
-		for( x = le; x < ri; x++ ) {
-			/* Ask for input.
-			 */
-			s.left = x * st->xshrink;
-			s.top = y * st->yshrink;
-			s.width = 1;
-			s.height = 1;
-			if( im_prepare( ir, &s ) )
-				return( -1 );
-
-			/* Append new pels to output.
-			 */
-			p = IM_REGION_ADDR( ir, s.left, s.top );
-			for( k = 0; k < ps; k++ )
-				q[k] = p[k];
-			q += ps;
-		}
-	}
-
-	return( 0 );
-}
-
-/**
- * im_subsample:
- * @in: input image
- * @out: output image
- * @xshrink: horizontal shrink factor
- * @yshrink: vertical shrink factor
- *
- * Subsample an image by an integer fraction. This is fast nearest-neighbour
- * shrink.
- *
- * See also: im_shrink(), im_affinei(), im_zoom().
- * 
- * Returns: 0 on success, -1 on error.
- */
-int 
-im_subsample( IMAGE *in, IMAGE *out, int xshrink, int yshrink )
-{
-	SubsampleInfo *st;
-
-	/* Check parameters.
-	 */
-	if( xshrink < 1 || yshrink < 1 ) {
-		im_error( "im_subsample", 
-			"%s", _( "factors should both be >= 1" ) );
-		return( -1 );
-	}
-	if( xshrink == 1 && yshrink == 1 ) 
-		return( im_copy( in, out ) );
-	if( im_piocheck( in, out ) ||
-		im_check_coding_known( "im_subsample", in ) )
-		return( -1 );
-
-	/* Prepare output. Note: we round the output width down!
-	 */
-	if( im_cp_desc( out, in ) )
-		return( -1 );
-	out->Xsize = in->Xsize / xshrink;
-	out->Ysize = in->Ysize / yshrink;
-	out->Xres = in->Xres / xshrink;
-	out->Yres = in->Yres / yshrink;
-	if( out->Xsize <= 0 || out->Ysize <= 0 ) {
-		im_error( "im_subsample", 
-			"%s", _( "image has shrunk to nothing" ) );
-		return( -1 );
-	}
-
-	/* Build and attach state struct.
-	 */
-	if( !(st = IM_NEW( out, SubsampleInfo )) )
-		return( -1 );
-	st->xshrink = xshrink;
-	st->yshrink = yshrink;
-
-	/* Set demand hints. We want THINSTRIP, as we will be demanding a
-	 * large area of input for each output line.
-	 */
-	if( im_demand_hint( out, IM_THINSTRIP, in, NULL ) )
-		return( -1 );
-
-	/* Generate! If this is a very large shrink, then it's
-	 * probably faster to do it a pixel at a time. 
-	 */
-	if( xshrink > 10 ) {
-		if( im_generate( out, 
-			im_start_one, point_shrink_gen, im_stop_one, in, st ) )
-			return( -1 );
-	}
-	else {
-		if( im_generate( out, 
-			im_start_one, line_shrink_gen, im_stop_one, in, st ) )
-			return( -1 );
-	}
-
-	return( 0 );
-}

libvips/conversion/subsample.c

@@ -0,0 +1,322 @@
+/* subsample
+ *
+ * 3/7/95 JC
+ *	- adapted from im_shrink()
+ * 3/8/02 JC
+ *	- fall back to im_copy() for x/y factors == 1
+ * 21/4/08
+ * 	- don't fall back to pixel-wise shrinks for smalltile, it kills
+ * 	  performance, just bring VIPS_MAX_WIDTH down instead
+ * 1/2/10
+ * 	- gtkdoc
+ * 1/6/13
+ * 	- redo 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 <stdlib.h>
+
+#include <vips/vips.h>
+
+#include "conversion.h"
+
+typedef struct _VipsSubsample {
+	VipsConversion parent_instance;
+
+	/* The input image.
+	 */
+	VipsImage *in;
+
+	int xfac;		/* Subsample factors */
+	int yfac;
+
+} VipsSubsample;
+
+typedef VipsConversionClass VipsSubsampleClass;
+
+G_DEFINE_TYPE( VipsSubsample, vips_subsample, VIPS_TYPE_CONVERSION );
+
+/* Maximum width of input we ask for.
+ */
+#define VIPS_MAX_WIDTH (100)
+
+/* Subsample a VipsRegion. We fetch in VIPS_MAX_WIDTH pixel-wide strips, 
+ * left-to-right across the input.
+ */
+static int
+vips_subsample_line_gen( VipsRegion *or, 
+	void *seq, void *a, void *b, gboolean *stop )
+{
+	VipsRegion *ir = (VipsRegion *) seq;
+	VipsSubsample *subsample = (VipsSubsample *) b;
+	VipsImage *in = (VipsImage *) a;
+	VipsRect *r = &or->valid;
+	int le = r->left;
+	int ri = VIPS_RECT_RIGHT( r );
+	int to = r->top;
+	int bo = VIPS_RECT_BOTTOM( r );
+	int ps = VIPS_IMAGE_SIZEOF_PEL( in );
+	int owidth = VIPS_MAX_WIDTH / subsample->xfac;
+
+	VipsRect s;
+	int x, y;
+	int z, k;
+
+	/* Loop down the region.
+	 */
+	for( y = to; y < bo; y++ ) {
+		VipsPel *q = VIPS_REGION_ADDR( or, le, y );
+		VipsPel *p;
+
+		/* Loop across the region, in owidth sized pieces.
+		 */
+		for( x = le; x < ri; x += owidth ) {
+			/* How many pixels do we make this time?
+			 */
+			int ow = VIPS_MIN( owidth, ri - x );
+
+			/* Ask for this many from input ... can save a 
+			 * little here!
+			 */
+			int iw = ow * subsample->xfac - (subsample->xfac - 1);
+
+			/* Ask for input.
+			 */
+			s.left = x * subsample->xfac;
+			s.top = y * subsample->yfac;
+			s.width = iw;
+			s.height = 1;
+			if( vips_region_prepare( ir, &s ) )
+				return( -1 );
+
+			/* Append new pels to output.
+			 */
+			p = VIPS_REGION_ADDR( ir, s.left, s.top );
+			for( z = 0; z < ow; z++ ) {
+				for( k = 0; k < ps; k++ )
+					q[k] = p[k];
+
+				q += ps;
+				p += ps * subsample->xfac;
+			}
+		}
+	}
+
+	return( 0 );
+}
+
+/* Fetch one pixel at a time ... good for very large shrinks.
+ */
+static int
+vips_subsample_point_gen( VipsRegion *or, 
+	void *seq, void *a, void *b, gboolean *stop )
+{
+	VipsRegion *ir = (VipsRegion *) seq;
+	VipsSubsample *subsample = (VipsSubsample *) b;
+	VipsImage *in = (VipsImage *) a;
+	VipsRect *r = &or->valid;
+	int le = r->left;
+	int ri = VIPS_RECT_RIGHT( r );
+	int to = r->top;
+	int bo = VIPS_RECT_BOTTOM(r);
+	int ps = VIPS_IMAGE_SIZEOF_PEL( in );
+
+	VipsRect s;
+	int x, y;
+	int k;
+
+	/* Loop down the region.
+	 */
+	for( y = to; y < bo; y++ ) {
+		VipsPel *q = VIPS_REGION_ADDR( or, le, y );
+		VipsPel *p;
+
+		/* Loop across the region, in owidth sized pieces.
+		 */
+		for( x = le; x < ri; x++ ) {
+			/* Ask for input.
+			 */
+			s.left = x * subsample->xfac;
+			s.top = y * subsample->yfac;
+			s.width = 1;
+			s.height = 1;
+			if( vips_region_prepare( ir, &s ) )
+				return( -1 );
+
+			/* Append new pels to output.
+			 */
+			p = VIPS_REGION_ADDR( ir, s.left, s.top );
+			for( k = 0; k < ps; k++ )
+				q[k] = p[k];
+			q += ps;
+		}
+	}
+
+	return( 0 );
+}
+
+static int
+vips_subsample_build( VipsObject *object )
+{
+	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
+	VipsConversion *conversion = VIPS_CONVERSION( object );
+	VipsSubsample *subsample = (VipsSubsample *) object;
+
+	VipsGenerateFn subsample_fn;
+
+	if( VIPS_OBJECT_CLASS( vips_subsample_parent_class )->build( object ) )
+		return( -1 );
+
+	g_assert( subsample->xfac > 0 ); 
+	g_assert( subsample->yfac > 0 ); 
+
+	if( subsample->xfac == 1 && 
+		subsample->yfac == 1 ) 
+		return( vips_image_write( subsample->in, conversion->out ) );
+	if( vips_image_pio_input( subsample->in ) || 
+		vips_check_coding_known( class->nickname, subsample->in ) )  
+		return( -1 );
+
+	/* Prepare output. Note: we round the output width down!
+	 */
+	if( vips_image_copy_fields( conversion->out, subsample->in ) )
+		return( -1 );
+	conversion->out->Xsize = subsample->in->Xsize / subsample->xfac;
+	conversion->out->Ysize = subsample->in->Ysize / subsample->yfac;
+	conversion->out->Xres = subsample->in->Xres / subsample->xfac;
+	conversion->out->Yres = subsample->in->Yres / subsample->yfac;
+	if( conversion->out->Xsize <= 0 || 
+		conversion->out->Ysize <= 0 ) {
+		vips_error( class->nickname, 
+			"%s", _( "image has shrunk to nothing" ) );
+		return( -1 );
+	}
+
+	/* Set demand hints. We want THINSTRIP, as we will be demanding a
+	 * large area of input for each output line.
+	 */
+	vips_demand_hint( conversion->out, 
+		VIPS_DEMAND_STYLE_THINSTRIP, subsample->in, NULL );
+
+	/* Generate! If this is a very large shrink, then it's
+	 * probably faster to do it a pixel at a time. 
+	 */
+	if( subsample->xfac > 10 ) 
+		subsample_fn = vips_subsample_point_gen;
+	else 
+		subsample_fn = vips_subsample_line_gen;
+	if( vips_image_generate( conversion->out, 
+		vips_start_one, subsample_fn, vips_stop_one,
+		subsample->in, subsample ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+/* xy range we sanity check on ... just to stop crazy numbers from divide by 0 
+ * etc. causing g_assert() failures later.
+ */
+#define RANGE (100000000)
+
+static void
+vips_subsample_class_init( VipsSubsampleClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
+	VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	vobject_class->nickname = "subsample";
+	vobject_class->description = _( "subsample an image" );
+	vobject_class->build = vips_subsample_build;
+
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
+
+	VIPS_ARG_IMAGE( class, "input", 0, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsSubsample, in ) );
+
+	VIPS_ARG_INT( class, "xfac", 2, 
+		_( "Xfac" ), 
+		_( "Horizontal subsample factor" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsSubsample, xfac ),
+		1, RANGE, 1 );
+
+	VIPS_ARG_INT( class, "yfac", 3, 
+		_( "Yfac" ), 
+		_( "Vertical subsample factor" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsSubsample, yfac ),
+		1, RANGE, 1 );
+
+}
+
+static void
+vips_subsample_init( VipsSubsample *subsample )
+{
+}
+
+/**
+ * vips_subsample:
+ * @in: input image
+ * @out: output image
+ * @xfac: horizontal shrink factor
+ * @yfac: vertical shrink factor
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Subsample an image by an integer fraction. This is fast, nearest-neighbour
+ * shrink.
+ *
+ * See also: vips_affine(), vips_shrink(), vips_zoom().
+ * 
+ * Returns: 0 on success, -1 on error.
+ */
+int
+vips_subsample( VipsImage *in, VipsImage **out, int xfac, int yfac, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, yfac );
+	result = vips_call_split( "subsample", ap, in, out, xfac, yfac );
+	va_end( ap );
+
+	return( result );
+}

libvips/deprecated/vips7compat.c

@@ -1581,6 +1581,22 @@ im_zoom( VipsImage *in, VipsImage *out, int xfac, int yfac )
 	return( 0 );
 }
 
+int 
+im_subsample( VipsImage *in, VipsImage *out, int xfac, int yfac )
+{
+	VipsImage *t;
+
+	if( vips_subsample( in, &t, xfac, yfac, NULL ) )
+		return( -1 );
+	if( vips_image_write( t, out ) ) {
+		g_object_unref( t );
+		return( -1 );
+	}
+	g_object_unref( t );
+
+	return( 0 );
+}
+
 static int
 vips__math( VipsImage *in, VipsImage *out, VipsOperationMath math )
 {

libvips/include/vips/conversion.h

@@ -196,6 +196,8 @@ int vips_wrap( VipsImage *in, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_zoom( VipsImage *in, VipsImage **out, int xfac, int yfac, ... )
 	__attribute__((sentinel));
+int vips_subsample( VipsImage *in, VipsImage **out, int xfac, int yfac, ... )
+	__attribute__((sentinel));
 
 int vips_cast( VipsImage *in, VipsImage **out, VipsBandFormat format, ... )
 	__attribute__((sentinel));
@@ -269,8 +271,6 @@ int im_text( VipsImage *out, const char *text, const char *font,
 
 int im_insertset( VipsImage *main, VipsImage *sub, VipsImage *out, int n, int *x, int *y );
 
-int im_subsample( VipsImage *in, VipsImage *out, int xshrink, int yshrink );
-
 int im_system( VipsImage *im, const char *cmd, char **out );
 VipsImage *im_system_image( VipsImage *im, 
 	const char *in_format, const char *out_format, const char *cmd_format, 

libvips/include/vips/vips7compat.h

@@ -716,6 +716,7 @@ int im_grid( VipsImage *in, VipsImage *out, int tile_height, int across, int dow
 int im_scale( VipsImage *in, VipsImage *out );
 int im_scaleps( VipsImage *in, VipsImage *out );
 int im_zoom( VipsImage *in, VipsImage *out, int xfac, int yfac );
+int im_subsample( VipsImage *in, VipsImage *out, int xshrink, int yshrink );
 
 int im_c2amph( VipsImage *in, VipsImage *out );
 int im_c2rect( VipsImage *in, VipsImage *out );

po/POTFILES.in

@@ -54,14 +54,14 @@ libvips/colour/dECMC.c
 libvips/colour/scRGB2sRGB.c
 libvips/conversion/flip.c
 libvips/conversion/bandmean.c
-libvips/conversion/im_zoom.c
+libvips/conversion/zoom.c
 libvips/conversion/im_system.c
 libvips/conversion/gaussnoise.c
 libvips/conversion/bandary.c
 libvips/conversion/cast.c
 libvips/conversion/conversion.c
 libvips/conversion/flatten.c
-libvips/conversion/im_subsample.c
+libvips/conversion/subsample.c
 libvips/conversion/grid.c
 libvips/conversion/extract.c
 libvips/conversion/bandjoin.c