experiment with minimise in insert

try minimising sub after we've passed it

cplusplus/examples/test_overloads.cpp

@@ -34,7 +34,8 @@ equal_vector( std::vector<double> a, std::vector<double> b )
 				printf( "%g", a[i] );
 			}
 			printf( "], is [" );
-			for( unsigned int i = 0; i < a.size(); i++ ) { if( i > 0 )
+			for( unsigned int i = 0; i < a.size(); i++ ) { 
+				if( i > 0 )
 					printf( ", " ); 
 				printf( "%g", a[i] );
 			}

libvips/conversion/insert.c

@@ -28,6 +28,8 @@
  * 29/9/11
  * 	- rewrite as a class
  * 	- add expand, bg options
+ * 27/7/19
+ * 	- minimise sub when we're done with it
  */
 
 /*
@@ -103,6 +105,10 @@ typedef struct _VipsInsert {
 	VipsRect rout;		/* Output space */
 	VipsRect rmain;		/* Position of main in output */
 	VipsRect rsub;		/* Position of sub in output */
+
+	/* TRUE if we've minimise sub.
+	 */
+	gboolean sub_minimised;
 } VipsInsert;
 
 typedef VipsConversionClass VipsInsertClass;
@@ -187,9 +193,21 @@ vips_insert_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 	 */
 	vips_rect_intersectrect( &or->valid, &insert->rsub, &ovl );
 	if( vips_rect_includesrect( &insert->rmain, &or->valid ) &&
-		vips_rect_isempty( &ovl ) ) 
+		vips_rect_isempty( &ovl ) ) {
+		/* If we're now below the sub-image, and we're in sequential
+		 * mode, and we've not minimised it before, we can shut down
+		 * that input.
+		 */
+		if( vips_image_is_sequential( insert->sub ) &&  
+			r->top > VIPS_RECT_BOTTOM( &insert->rsub ) &&
+			!insert->sub_minimised ) { 
+			insert->sub_minimised = TRUE;
+			vips_image_minimise_all( insert->sub );
+		}
+
 		return( vips__insert_just_one( or, ir[0], 
 			insert->rmain.left, insert->rmain.top ) );
+	}
 
 	/* Output requires both (or neither) input. If it is not entirely 
 	 * inside both the main and the sub, then there is going to be some

libvips/include/vips/image.h

@@ -426,6 +426,8 @@ void vips_image_invalidate_all( VipsImage *image );
 
 void vips_image_minimise_all( VipsImage *image );
 
+gboolean vips_image_is_sequential( VipsImage *image );
+
 void vips_image_set_progress( VipsImage *image, gboolean progress );
 gboolean vips_image_iskilled( VipsImage *image );
 void vips_image_set_kill( VipsImage *image, gboolean kill );

libvips/iofuncs/image.c

@@ -1454,6 +1454,22 @@ vips_image_minimise_all( VipsImage *image )
 		(VipsSListMap2Fn) vips_image_minimise_all_cb, NULL, NULL );
 }
 
+/**
+ * vips_image_is_sequential: (method)
+ * @image: #VipsImage to minimise
+ *
+ * TRUE if any of the images upstream from @image were opened in sequential
+ * mode. Some operations change behaviour slightly in sequential mode to
+ * optimise memory behaviour.
+ *
+ * Returns: %TRUE if @image is in sequential mode.
+ */
+gboolean
+vips_image_is_sequential( VipsImage *image )
+{
+	return( vips_image_get_typeof( image, VIPS_META_SEQUENTIAL ) );
+}
+
 /* Attach a new time struct, if necessary, and reset it.
  */
 static int

libvips/resample/shrinkv.c

@@ -413,7 +413,7 @@ vips_shrinkv_build( VipsObject *object )
 	 * always have the previous XX lines of the shrunk image, and we won't
 	 * fetch out of order. 
 	 */
-	if( vips_image_get_typeof( in, VIPS_META_SEQUENTIAL ) ) { 
+	if( vips_image_is_sequential( in ) ) { 
 		g_info( "shrinkv sequential line cache" ); 
 
 		shrink->sequential = TRUE;