fix demand hints for shrink

"vips shrink" was broken due to wonky demand hints, thanks Jan

ChangeLog

@@ -1,6 +1,7 @@
 12/3/13 started 7.32.2
 - removed some left-over debugging code from configure.ac
 - better error messages from vips.c
+- fix demand hints so "vips shrink" works again, thanks Jan
 
 6/2/13 started 7.32.1
 - fix --without-lcms, thanks speckins

libvips/foreign/jpeg2vips.c

@@ -746,7 +746,7 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
 		interpretation,
 		xres, yres );
 
-	vips_demand_hint( out, VIPS_DEMAND_STYLE_FATSTRIP, NULL );
+	vips_demand_hint( out, VIPS_DEMAND_STYLE_THINSTRIP, NULL );
 
 	/* Interlaced jpegs need lots of memory to read, so our caller needs
 	 * to know.

libvips/foreign/vipspng.c

@@ -318,9 +318,10 @@ png2vips_header( Read *read, VipsImage *out )
 		VIPS_CODING_NONE, interpretation, 
 		Xres, Yres );
 
-	/* We're always supposed to set dhint.
+	/* Sequential mode needs thinstrip to work with things like
+	 * vips_shrink().
 	 */
-        vips_demand_hint( out, VIPS_DEMAND_STYLE_FATSTRIP, NULL );
+        vips_demand_hint( out, VIPS_DEMAND_STYLE_THINSTRIP, NULL );
 
 	/* Fetch the ICC profile. @name is useless, something like "icc" or
 	 * "ICC Profile" etc.  Ignore it.

libvips/iofuncs/generate.c

@@ -84,6 +84,7 @@
 
 /*
 #define VIPS_DEBUG
+#define DEBUG
  */
 
 #ifdef HAVE_CONFIG_H

libvips/iofuncs/image.c

@@ -539,8 +539,10 @@ vips_image_preeval_cb( VipsImage *image, VipsProgress *progress, int *last )
 
 	vips_get_tile_size( image, 
 		&tile_width, &tile_height, &nlines );
-	printf( _( "%s %s: %d threads, %d x %d tiles, groups of %d scanlines" ),
+	printf( _( "%s %s: %d x %d pixels, %d threads, %d x %d tiles, "
+		"%d lines in buffer" ),
 		g_get_prgname(), image->filename,
+		image->Xsize, image->Ysize,
 		vips_concurrency_get(),
 		tile_width, tile_height, nlines );
 	printf( "\n" );

libvips/resample/shrink.c

@@ -36,6 +36,8 @@
  * 	- some tuning .. tried an int coordinate path, not worthwhile
  * 16/11/12
  * 	- don't change xres/yres, see comment below
+ * 8/4/13
+ * 	- oops demand_hint was incorrect, thanks Jan
  */
 
 /*
@@ -331,12 +333,12 @@ vips_shrink_build( VipsObject *object )
 	if( vips_image_copy_fields( resample->out, resample->in ) )
 		return( -1 );
 
-	/* THINSTRIP will work, FATSTRIP will break seq mode. If you combine
-	 * shrink with conv you'll need to use a line cache to maintain
+	/* THINSTRIP will work, anything else will break seq mode. If you 
+	 * combine shrink with conv you'll need to use a line cache to maintain
 	 * sequentiality.
 	 */
 	vips_demand_hint( resample->out, 
-		VIPS_DEMAND_STYLE_ANY, resample->in, NULL );
+		VIPS_DEMAND_STYLE_THINSTRIP, resample->in, NULL );
 
 	/* Size output. Note: we round the output width down!
 	 *