remove limit on n image in composite

composite was limited to a max of 64 images ... remove the limit

see https://github.com/jcupitt/pyvips/issues/30

ChangeLog

@@ -3,6 +3,7 @@
 - fix a minor accidental ABI break in 8.6.0 -> 8.6.1 [remicollet]
 - fix read of plane-separate TIFFs with large strips [remicollet]
 - fix a C++ warning in composite.cpp [lovell]
+- remove number of images limit in composite
 
 10/12/17 started 8.6.1
 - fix mmap window new/free cycling 

libvips/conversion/composite.cpp

@@ -4,6 +4,8 @@
  * 	- from bandjoin.c
  * 30/11/17
  * 	- add composite2 class, to make a nice CLI interface
+ * 30/1/18
+ * 	- remove number of images limit
  */
 
 /*
@@ -53,10 +55,6 @@
 
 #include "pconversion.h"
 
-/* Maximum number of input images -- why not?
- */
-#define MAX_INPUT_IMAGES (64)
-
 /* Maximum number of image bands.
  */
 #define MAX_BANDS (64)
@@ -141,6 +139,88 @@ vips_composite_base_dispose( GObject *gobject )
 	G_OBJECT_CLASS( vips_composite_base_parent_class )->dispose( gobject );
 }
 
+/* Our sequence value.
+ */
+typedef struct {
+	VipsCompositeBase *composite;
+
+	/* Set of input regions.
+	 */
+	VipsRegion **ir;
+
+	/* For each input, an input pointer.
+	 */
+	VipsPel **p;
+
+} VipsCompositeSequence;
+
+static int
+vips_composite_stop( void *vseq, void *a, void *b )
+{
+	VipsCompositeSequence *seq = (VipsCompositeSequence *) vseq;
+
+        if( seq->ir ) {
+		int i;
+
+		for( i = 0; seq->ir[i]; i++ )
+			VIPS_UNREF( seq->ir[i] );
+		VIPS_FREE( seq->ir );
+	}
+
+	VIPS_FREE( seq->p );
+
+	VIPS_FREE( seq );
+
+	return( 0 );
+}
+
+static void *
+vips_composite_start( VipsImage *out, void *a, void *b )
+{
+	VipsImage **in = (VipsImage **) a;
+	VipsCompositeBase *composite = (VipsCompositeBase *) b;
+
+	VipsCompositeSequence *seq;
+	int i, n;
+
+	if( !(seq = VIPS_NEW( NULL, VipsCompositeSequence )) )
+		return( NULL );
+
+	seq->composite = composite;
+	seq->ir = NULL;
+	seq->p = NULL;
+
+	/* How many images?
+	 */
+	for( n = 0; in[n]; n++ )
+		;
+
+	/* Alocate space for region array.
+	 */
+	if( !(seq->ir = VIPS_ARRAY( NULL, n + 1, VipsRegion * )) ) {
+		vips_composite_stop( seq, NULL, NULL );
+		return( NULL );
+	}
+
+	/* Create a set of regions.
+	 */
+	for( i = 0; i < n; i++ )
+		if( !(seq->ir[i] = vips_region_new( in[i] )) ) {
+			vips_composite_stop( seq, NULL, NULL );
+			return( NULL );
+		}
+	seq->ir[n] = NULL;
+
+	/* Input pointers.
+	 */
+	if( !(seq->p = VIPS_ARRAY( NULL, n + 1, VipsPel * )) ) {
+		vips_composite_stop( seq, NULL, NULL );
+		return( NULL );
+	}
+
+	return( seq );
+}
+
 /* For each of the supported interpretations, the maximum value of each band.
  */
 static int
@@ -815,47 +895,46 @@ vips_combine_pixels3( VipsCompositeBase *composite, VipsPel *q, VipsPel **p )
 
 static int
 vips_composite_base_gen( VipsRegion *output_region,
-	void *seq, void *a, void *b, gboolean *stop )
+	void *vseq, void *a, void *b, gboolean *stop )
 {
-	VipsRegion **input_regions = (VipsRegion **) seq;
+	VipsCompositeSequence *seq = (VipsCompositeSequence *) vseq;
 	VipsCompositeBase *composite = (VipsCompositeBase *) b;
 	VipsRect *r = &output_region->valid;
 	int ps = VIPS_IMAGE_SIZEOF_PEL( output_region->im );
 
-	if( vips_reorder_prepare_many( output_region->im, input_regions, r ) )
+	if( vips_reorder_prepare_many( output_region->im, seq->ir, r ) )
 		return( -1 );
 
 	VIPS_GATE_START( "vips_composite_base_gen: work" );
 
 	for( int y = 0; y < r->height; y++ ) {
-		VipsPel *p[MAX_INPUT_IMAGES];
 		VipsPel *q;
 
 		for( int i = 0; i < composite->n; i++ )
-			p[i] = VIPS_REGION_ADDR( input_regions[i],
+			seq->p[i] = VIPS_REGION_ADDR( seq->ir[i],
 				r->left, r->top + y );
-		p[composite->n] = NULL;
+		seq->p[composite->n] = NULL;
 		q = VIPS_REGION_ADDR( output_region, r->left, r->top + y );
 
 		for( int x = 0; x < r->width; x++ ) {
-			switch( input_regions[0]->im->BandFmt ) {
+			switch( seq->ir[0]->im->BandFmt ) {
 			case VIPS_FORMAT_UCHAR: 	
 #ifdef HAVE_VECTOR_ARITH
 				if( composite->bands == 3 ) 
 					vips_combine_pixels3
 						<unsigned char, 0, UCHAR_MAX>
-						( composite, q, p );
+						( composite, q, seq->p );
 				else
 #endif 
 					vips_combine_pixels
 						<unsigned char, 0, UCHAR_MAX>
-						( composite, q, p );
+						( composite, q, seq->p );
 				break;
 
 			case VIPS_FORMAT_CHAR: 		
 				vips_combine_pixels
 					<signed char, SCHAR_MIN, SCHAR_MAX>
-					( composite, q, p );
+					( composite, q, seq->p );
 				break; 
 
 			case VIPS_FORMAT_USHORT: 	
@@ -863,30 +942,30 @@ vips_composite_base_gen( VipsRegion *output_region,
 				if( composite->bands == 3 ) 
 					vips_combine_pixels3
 						<unsigned short, 0, USHRT_MAX>
-						( composite, q, p );
+						( composite, q, seq->p );
 				else
 #endif 
 					vips_combine_pixels
 						<unsigned short, 0, USHRT_MAX>
-						( composite, q, p );
+						( composite, q, seq->p );
 				break; 
 
 			case VIPS_FORMAT_SHORT: 	
 				vips_combine_pixels
 					<signed short, SHRT_MIN, SHRT_MAX>
-					( composite, q, p );
+					( composite, q, seq->p );
 				break; 
 
 			case VIPS_FORMAT_UINT: 		
 				vips_combine_pixels
 					<unsigned int, 0, UINT_MAX>
-					( composite, q, p );
+					( composite, q, seq->p );
 				break; 
 
 			case VIPS_FORMAT_INT: 		
 				vips_combine_pixels
 					<signed int, INT_MIN, INT_MAX>
-					( composite, q, p );
+					( composite, q, seq->p );
 				break; 
 
 			case VIPS_FORMAT_FLOAT:
@@ -894,18 +973,18 @@ vips_composite_base_gen( VipsRegion *output_region,
 				if( composite->bands == 3 ) 
 					vips_combine_pixels3
 						<float, 0, USHRT_MAX>
-						( composite, q, p );
+						( composite, q, seq->p );
 				else
 #endif 
 					vips_combine_pixels
 						<float, 0, 0>
-						( composite, q, p );
+						( composite, q, seq->p );
 				break;
 
 			case VIPS_FORMAT_DOUBLE:
 				vips_combine_pixels
 					<double, 0, 0>
-					( composite, q, p );
+					( composite, q, seq->p );
 				break;
 
 			default:
@@ -914,7 +993,7 @@ vips_composite_base_gen( VipsRegion *output_region,
 			}
 
 			for( int i = 0; i < composite->n; i++ )
-				p[i] += ps;
+				seq->p[i] += ps;
 			q += ps;
 		}
 	}
@@ -991,12 +1070,6 @@ vips_composite_base_build( VipsObject *object )
 			break;
 		}
 
-	if( composite->n > MAX_INPUT_IMAGES ) {
-		vips_error( klass->nickname,
-			"%s", _( "too many input images" ) );
-		return( -1 );
-	}
-
 	/* Transform to compositing space. It defaults to sRGB or B_W, usually 
 	 * 8 bit, but 16 bit if any inputs are 16 bit.
 	 */
@@ -1086,7 +1159,9 @@ vips_composite_base_build( VipsObject *object )
 		return( -1 );
 
 	if( vips_image_generate( conversion->out,
-		vips_start_many, vips_composite_base_gen, vips_stop_many,
+		vips_composite_start, 
+		vips_composite_base_gen, 
+		vips_composite_stop,
 		in, composite ) )
 		return( -1 );